Information Notice 1999-03, Rev. 1: Exothermic Reactions Involving Dried Uranium Oxide Powder (Yellowcake): Difference between revisions

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{{#Wiki_filter:UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF FEDERAL AND STATE MATERIALS AND ENVIRONMENTAL MANAGEMENT PROGRAMS WASHINGTON, D.C. 20555 March 4, 2014 NRC INFORMATION NOTICE 1999-03, REV. 1: EXOTHERMIC REACTIONS INVOLVING         DRIED URANIUM OXIDE POWDER       (YELLOWCAKE)  
{{#Wiki_filter:UNITED STATES
 
NUCLEAR REGULATORY COMMISSION
 
OFFICE OF FEDERAL AND STATE MATERIALS
 
AND ENVIRONMENTAL MANAGEMENT PROGRAMS
 
WASHINGTON, D.C. 20555 March 4, 2014 NRC INFORMATION NOTICE 1999-03, REV. 1:                 EXOTHERMIC REACTIONS INVOLVING
 
DRIED URANIUM OXIDE POWDER
 
(YELLOWCAKE)


==ADDRESSEES==
==ADDRESSEES==
All operating uranium recovery facilities that produce uranium oxide powder (yellowcake). All Agreement States with the authority to regulate uranium mills (i.e., Utah, Colorado, Texas, Ohio, Illinois, and Washington).
All operating uranium recovery facilities that produce uranium oxide powder (yellowcake). All
 
Agreement States with the authority to regulate uranium mills (i.e., Utah, Colorado, Texas, Ohio, Illinois, and Washington).


==PURPOSE==
==PURPOSE==
The U.S. Nuclear Regulatory Commission (NRC) is is
The U.S. Nuclear Regulatory Commission (NRC) is issuing this Information Notice (IN) to alert


suing this Information Notice (IN) to alert licensees to recent events involving pressurized drums of dried uranium oxide powder (yellowcake).  This IN is a revision to IN 99-03 which previously discussed industry experience with pressurized 208-liter (55-gallon) metal drums (hereafter referred to as drums) and related exothermic reactions involving yellowcake material.  It is expected that recipients will review this
licensees to recent events involving pressurized drums of dried uranium oxide powder


information for applicability to their licensed activities and consider actions, as appropriate, to avoid similar problems. However, suggestions contained in this IN are not NRC requirements;  
(yellowcake). This IN is a revision to IN 99-03 which previously discussed industry experience
 
with pressurized 208-liter (55-gallon) metal drums (hereafter referred to as drums) and related
 
exothermic reactions involving yellowcake material. It is expected that recipients will review this
 
information for applicability to their licensed activities and consider actions, as appropriate, to
 
avoid similar problems. However, suggestions contained in this IN are not NRC requirements;
therefore, no specific action or written response is required.
therefore, no specific action or written response is required.


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The NRC is aware of at least nine different sites that have encountered problems with
The NRC is aware of at least nine different sites that have encountered problems with


pressurized drums. A brief description of two ev
pressurized drums. A brief description of two events is provided below. Both events resulted in


ents is provided below.  Both events resulted in uptakes of uranium by workers, and both have similar root causes.
uptakes of uranium by workers, and both have similar root causes.


In 2006 at a conventional mill, a worker attempted to open a drum filled with yellowcake that exhibited bulging. Unbeknownst to the worker, the sealed drum was pressurized. The pressure
In 2006 at a conventional mill, a worker attempted to open a drum filled with yellowcake that
 
exhibited bulging. Unbeknownst to the worker, the sealed drum was pressurized. The pressure


was apparently caused by the generation of oxygen gas within the drum from the decomposition
was apparently caused by the generation of oxygen gas within the drum from the decomposition


of hydrogen peroxide precipitated yellowcake product. When the drum sealing bolt was loosened, the pressure in the drum caused the lid to blow off the drum and strike the worker. The worker received an uptake of uranium, although the uptake was less than regulatory limits. Records indicate that the drum lid had remained unsealed for three hours after the drum had
of hydrogen peroxide precipitated yellowcake product. When the drum sealing bolt was
 
loosened, the pressure in the drum caused the lid to blow off the drum and strike the worker.
 
The worker received an uptake of uranium, although the uptake was less than regulatory limits.
 
Records indicate that the drum lid had remained unsealed for three hours after the drum had


been filled with yellowcake product, as required by site procedures.
been filled with yellowcake product, as required by site procedures.


ML14028A175 IN 1999-03, Rev. 1 Page 2 of
ML14028A175
 
IN 1999-03, Rev. 1 The facility operator conducted an investigation and identified the root cause as less than


5    The facility operator conducted an investigation and identified the root cause as less than adequate procedures. The facility operator concluded that the product did not completely cool, or off-gas, within the three-hour time interval. Corrective actions included revising the
adequate procedures. The facility operator concluded that the product did not completely cool, or off-gas, within the three-hour time interval. Corrective actions included revising the


applicable procedure to extend the drum sealing interval from three to four hours and providing additional training to site workers.
applicable procedure to extend the drum sealing interval from three to four hours and providing


The second incident occurred in 2012 at a uranium refinery in Canada while workers were opening a drum of yellowcake supplied by an in-situ uranium recovery facility. When a refinery
additional training to site workers.
 
The second incident occurred in 2012 at a uranium refinery in Canada while workers were
 
opening a drum of yellowcake supplied by an in-situ uranium recovery facility. When a refinery


worker loosened the ring clamp on the drum lid, the pressure in the drum (produced by an
worker loosened the ring clamp on the drum lid, the pressure in the drum (produced by an


unexpected build-up of oxygen gas) caused the lid to buckle. The escaping gas ejected
unexpected build-up of oxygen gas) caused the lid to buckle. The escaping gas ejected


approximately 20 kilograms (44 pounds) of dried, powder-like yellowcake material from the drum.  The incident resulted in three refinery workers receiving uptakes of uranium.  The refinery operator subsequently identified several other drums, supplied by the same uranium
approximately 20 kilograms (44 pounds) of dried, powder-like yellowcake material from the


recovery facility, which also showed signs of internal pressurization. The uranium recovery
drum. The incident resulted in three refinery workers receiving uptakes of uranium. The
 
refinery operator subsequently identified several other drums, supplied by the same uranium
 
recovery facility, which also showed signs of internal pressurization. The uranium recovery


facility operator conducted an investigation to determine the causes of the pressure buildup in
facility operator conducted an investigation to determine the causes of the pressure buildup in


the drums. The facility operator concluded that the drums became pressurized due to: (1) inadequate cooling and venting of the dried yellowcake product prior to sealing the drum lid; and (2) inadequate drying of the yellowcake product (i.e., inadequate dryer residence time).
the drums. The facility operator concluded that the drums became pressurized due to:
(1) inadequate cooling and venting of the dried yellowcake product prior to sealing the drum lid;
and (2) inadequate drying of the yellowcake product (i.e., inadequate dryer residence time).


The NRC later determined that inadequate procedures were contributing causes of the event.
The NRC later determined that inadequate procedures were contributing causes of the event.


==BACKGROUND==
==BACKGROUND==
The NRC issued IN 99-03 on January 29, 1999, to
The NRC issued IN 99-03 on January 29, 1999, to alert licensees to incidents involving


alert licensees to
exothermic reactions that occurred after packaging hydrogen peroxide precipitated yellowcake


incidents involving exothermic reactions that occurred after packaging hydrogen peroxide precipitated yellowcake powder into drums. The original IN discussed two types of exothermic reactions-oxygen generation as a byproduct of the drying process and hydrocarbon contaminants reacting with
powder into drums. The original IN discussed two types of exothermic reactionsoxygen


the yellowcake product. At that time, industry took corrective actions which included leaving the drums unsealed for a minimum of three hours and preventing oil and grease from being introduced into the precipitation and drying circuits.
generation as a byproduct of the drying process and hydrocarbon contaminants reacting with
 
the yellowcake product. At that time, industry took corrective actions which included leaving the
 
drums unsealed for a minimum of three hours and preventing oil and grease from being
 
introduced into the precipitation and drying circuits.


Since 1999, the uranium recovery industry has experienced several more pressurized drum
Since 1999, the uranium recovery industry has experienced several more pressurized drum


events. Because these events continued to occur, the causes may not be well understood by
events. Because these events continued to occur, the causes may not be well understood by


the industry. Further, past actions taken by industry to prevent pressurized drums may not have
the industry. Further, past actions taken by industry to prevent pressurized drums may not have


been fully effective.
been fully effective.
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The IN 99-03 also advised facility operators about exothermic reactions of yellowcake with
The IN 99-03 also advised facility operators about exothermic reactions of yellowcake with


organic materials. These reactions can cause spontaneous combustion of flammable materials
organic materials. These reactions can cause spontaneous combustion of flammable materials
 
such as oil that may enter the process circuit. Refer to Enclosure 1 for an expanded discussion


such as oil that may enter the process circuit.  Refer to Enclosure 1 for an expanded discussion of this hazard.
of this hazard.


==DISCUSSION==
==DISCUSSION==
In both the 2006 and 2012 instances, the fundamental cause of the pressurized drums was attributed to the build-up of oxygen gas in sealed containers.  The oxygen gas apparently originated from the decomposition of residual uranyl peroxide hydrates or hydrogen peroxide in the dried yellowcake product.  Both incidents indicate that the drum lids may have been sealed
In both the 2006 and 2012 instances, the fundamental cause of the pressurized drums was


onto the drums prior to the completion of the uranyl peroxide hydrate decomposition process. Both sites used a minimum three-hour time delay as mentioned in IN 99-03; however, this time
attributed to the build-up of oxygen gas in sealed containers. The oxygen gas apparently
 
originated from the decomposition of residual uranyl peroxide hydrates or hydrogen peroxide in
 
the dried yellowcake product. Both incidents indicate that the drum lids may have been sealed
 
onto the drums prior to the completion of the uranyl peroxide hydrate decomposition process.
 
Both sites used a minimum three-hour time delay as mentioned in IN 99-03; however, this time


delay must have been insufficient based on site-specific operational parameters.
delay must have been insufficient based on site-specific operational parameters.


IN 1999-03, Rev. 1 Page 3 of
IN 1999-03, Rev. 1 In early 2013, the NRC established a working group to: (1) review the generic implications of the


5    In early 2013, the NRC established a working group to: (1) review the generic implications of the most recent pressurized drum incident including the reasons why drums continue to become
most recent pressurized drum incident including the reasons why drums continue to become


pressurized; (2) identify industry experience with pressurized drums; and (3) ascertain whether
pressurized; (2) identify industry experience with pressurized drums; and (3) ascertain whether


there were any related trends across the industry. The working group consisted of NRC staff, industry representatives, and subject-matter expe
there were any related trends across the industry. The working group consisted of NRC staff, industry representatives, and subject-matter experts. The NRC used the findings of the working
 
group, as well as information solicited from 14 current and former uranium recovery facilities, in


rts. The NRC used the findings of the working group, as well as information solicited from 14 current and former uranium recovery facilities, in
the development of this revision to IN 99-03. As part of the revision process, the NRC is also


the development of this revision to IN 99-03.  As part of the revision process, the NRC is also correcting some of the chemical nomenclature used to describe the thermal decomposition
correcting some of the chemical nomenclature used to describe the thermal decomposition


process provided in the original IN. More importantly, as a result of industry experience gained since the NRC issued IN 99-03, this revised IN recognizes a broader range of relevant factors
process provided in the original IN. More importantly, as a result of industry experience gained
 
since the NRC issued IN 99-03, this revised IN recognizes a broader range of relevant factors


that could result in pressurized drums.
that could result in pressurized drums.
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The working group developed a questionnaire that was submitted to various national and
The working group developed a questionnaire that was submitted to various national and


international companies having direct experience processing or handling yellowcake. The
international companies having direct experience processing or handling yellowcake. The


working group received 14 responses from various entities. The responses were subdivided
working group received 14 responses from various entities. The responses were subdivided


into two basic categories-sites using ammonia precipitation circuits and sites using hydrogen peroxide precipitation circuits.  The survey responses provided the working group with detailed information about dryer and packaging operations at each site as well as industry experience
into two basic categoriessites using ammonia precipitation circuits and sites using hydrogen


with pressurized drums. If the facilities had experienced pressurized drum problems, the survey asked the respondents to explain the possible causes for the pressurizations.  As discussed in
peroxide precipitation circuits. The survey responses provided the working group with detailed


Enclosure 1, sites using the ammonia precipitation process with high-temperature calciners have not experienced pressurized drums.  Only sites using the hydrogen peroxide precipitation circuits have experienced pressurized drums.  Enclosure 3 provides a matrix of the operating parameters for the 11 sites using hydrogen peroxide precipitation circuits and the suspect causes of past drum pressurizations.
information about dryer and packaging operations at each site as well as industry experience


The working group concluded that many drum pressurizations were apparently caused by changes in the chemical composition of the yellowcake product after it had been placed into a sealed container.  The level of pressurization appears to be related to the cooling and venting
with pressurized drums. If the facilities had experienced pressurized drum problems, the survey


time of the product prior to sealing of the drum. The working group determined that the
asked the respondents to explain the possible causes for the pressurizations. As discussed in
 
Enclosure 1, sites using the ammonia precipitation process with high-temperature calciners
 
have not experienced pressurized drums. Only sites using the hydrogen peroxide precipitation
 
circuits have experienced pressurized drums. Enclosure 3 provides a matrix of the operating
 
parameters for the 11 sites using hydrogen peroxide precipitation circuits and the suspect
 
causes of past drum pressurizations.
 
The working group concluded that many drum pressurizations were apparently caused by
 
changes in the chemical composition of the yellowcake product after it had been placed into a
 
sealed container. The level of pressurization appears to be related to the cooling and venting
 
time of the product prior to sealing of the drum. The working group determined that the


minimum required cooling and venting time for recently dried yellowcake in an unsealed drum
minimum required cooling and venting time for recently dried yellowcake in an unsealed drum
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depends on the type of dryer, drying temperature, residence time (time product remains in
depends on the type of dryer, drying temperature, residence time (time product remains in


dryer), hold-up time (time interval between completion of drying cycle and when product is placed into drum), dryer feed rate, and product moisture content. These various operational parameters may ultimately contribute to oxygen gas buildup in yellowcake drums.
dryer), hold-up time (time interval between completion of drying cycle and when product is
 
placed into drum), dryer feed rate, and product moisture content. These various operational
 
parameters may ultimately contribute to oxygen gas buildup in yellowcake drums.


As noted earlier, multiple operators reported that they had experienced pressurized drum
As noted earlier, multiple operators reported that they had experienced pressurized drum
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problems, but the specific chemical reactions causing the pressurizations were not always clear.
problems, but the specific chemical reactions causing the pressurizations were not always clear.


In their survey responses, facility operators provided two general corrective actions to address the pressurized drum issue-increasing the cooling/venting time before the lid is sealed onto the drum and conducting visual inspections of the drums for signs of pressurization prior to shipment. These operators found that increasing the cooling and venting time before sealing
In their survey responses, facility operators provided two general corrective actions to address
 
the pressurized drum issueincreasing the cooling/venting time before the lid is sealed onto the
 
drum and conducting visual inspections of the drums for signs of pressurization prior to
 
shipment. These operators found that increasing the cooling and venting time before sealing
 
the drums and inspecting the drums before shipment appear to have resolved the problem. A


the drums and inspecting the drums before ship
range of cooling and venting times was reported, from 4 to 24 hours (see Enclosure 3). In


ment appear to have resolved the problem.  A range of cooling and venting times was reported, from 4 to 24 hours (see Enclosure 3).  In several instances, facility operators chose to extend the cooling and venting times in response
several instances, facility operators chose to extend the cooling and venting times in response


to past experiences with pressurized drums. Each facility operator should evaluate their
to past experiences with pressurized drums. Each facility operator should evaluate their


operations and decide how to implement site-specific corrective actions as necessary to prevent
operations and decide how to implement site-specific corrective actions as necessary to prevent
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pressurized drums.
pressurized drums.


IN 1999-03, Rev. 1 Page 4 of
IN 1999-03, Rev. 1 The working group found that many operators did not measure their product temperature
 
directly, and that discrepancies existed between the maximum dryer temperature and the


5    The working group found that many operators did not measure their product temperature directly, and that discrepancies existed between the maximum dryer temperature and the
chemical composition of their final product. It is product temperature, not dryer temperature, which ultimately drives the thermal decomposition process. The working group concluded that, for typical U.S. facilities utilizing hydrogen peroxide precipitation and drying temperatures below


chemical composition of their final product.  It is product temperature, not dryer temperature, which ultimately drives the thermal decomposition process.  The working group concluded that, for typical U.S. facilities utilizing hydrogen peroxide precipitation and drying temperatures below 800 degrees Celsius (°C) [1472 degrees Fahrenheit (°F)], a cooling and venting period of 12 to 24 hours appears sufficient to prevent oxygen gas buildup in yellowcake drums. Above dryer
800 degrees Celsius (°C) [1472 degrees Fahrenheit (°F)], a cooling and venting period of 12 to
 
24 hours appears sufficient to prevent oxygen gas buildup in yellowcake drums. Above dryer


temperatures of approximately 800 °C (1472 °F), it is expected that the uranyl peroxide product
temperatures of approximately 800 °C (1472 °F), it is expected that the uranyl peroxide product


will be converted to UO
will be converted to UO3 (uranium trioxide) product. Oxygen production is not expected to occur
 
after the uranyl peroxide product has been completely converted to UO3 product. For dryers


3 (uranium trioxide) product.  Oxygen production is not expected to occur after the uranyl peroxide product has been completely converted to UO
operating below 800 °C (1472 °F), shorter periods of yellowcake cooling and venting prior to


3 product.  For dryers operating below 800 °C (1472 °F), shorter periods of yellowcake cooling and venting prior to securing the drum lid may be ineffective to prevent oxygen buildup in sealed drums.
securing the drum lid may be ineffective to prevent oxygen buildup in sealed drums.


CONCLUSION
CONCLUSION


Based on its working group findings and questi
Based on its working group findings and questionnaire responses, NRC concludes that:
    The most likely cause for the drum pressurization events was attributed to continued
 
decomposition of dried uranium product and the production of oxygen after the drums have
 
been filled and sealed.
 
For facilities utilizing hydrogen peroxide precipitation and drying temperatures below 800°C
 
(1472°F), a cooling and venting period of at least 12 hours appears to be necessary to
 
prevent oxygen gas build-up in yellowcake drums. Shorter periods may be ineffective.
 
Many operators have elected to implement a cooling and venting time of 24 hours.


onnaire responses, NRC concludes that:
To prevent drum pressurizations, facility operators have implemented two basic corrective
  The most likely cause for the drum pressurization events was attributed to continued decomposition of dried uranium product and the production of oxygen after the drums have been filled and sealed.  For facilities utilizing hydrogen peroxide precipitation and drying temperatures below 800
°C (1472°F), a cooling and venting period of


at least 12 hours appears to be necessary to prevent oxygen gas build-up in yellowcake drums.  Shorter periods may be ineffective.  Many operators have elected to implement a cooling and venting time of 24 hours.  To prevent drum pressurizations, facility operators have implemented two basic corrective actions-increasing the cooling/venting time before the lid is sealed and conducting visual inspections of the drums for signs of pressurization prior to shipment.    Facility operators should evaluate the potential for organic-based exothermic reactions, as discussed in Enclosure 1.  Facility operators should develop protocols to minimize the potential for organics, including oils and greases, to enter into yellowcake process circuits.  In addition to being industrial and radiological hazards to workers, shipments of uranium yellowcake in packages with internal pressures that reduce the effectiveness of the
actionsincreasing the cooling/venting time before the lid is sealed and conducting visual


packages are prohibited by U.S. Department of Transportation regulations.  Enclosure 1 provides additional information about these regulations.
inspections of the drums for signs of pressurization prior to shipment.


IN 1999-03, Rev. 1 Page 5 of
Facility operators should evaluate the potential for organic-based exothermic reactions, as


5 
discussed in Enclosure 1. Facility operators should develop protocols to minimize the
 
potential for organics, including oils and greases, to enter into yellowcake process circuits.
 
In addition to being industrial and radiological hazards to workers, shipments of uranium
 
yellowcake in packages with internal pressures that reduce the effectiveness of the
 
packages are prohibited by U.S. Department of Transportation regulations. Enclosure 1 provides additional information about these regulations.
 
IN 1999-03, Rev. 1


==CONTACT==
==CONTACT==
This information notice requires no specific action or written response. If you have any
This information notice requires no specific action or written response. If you have any


questions about the information in this notice, please contact one of the technical contacts listed
questions about the information in this notice, please contact one of the technical contacts listed
Line 185: Line 304:
below.
below.


/RA Aby Mohseni for/  
/RA Aby Mohseni for/
Larry W. Camper, Director
                                      Larry W. Camper, Director
 
Division of Waste Management


Division of Waste Management    and Environmental Protection
and Environmental Protection


Office of Federal and State Materials
Office of Federal and State Materials
Line 194: Line 315:
and Environmental Management Programs
and Environmental Management Programs


Contacts: Robert Evans, Region IV   (817) 200-1234 Robert.Evans@nrc.gov
Contacts:     Robert Evans, Region IV
 
(817) 200-1234 Robert.Evans@nrc.gov


Ronald Burrows, FSME
Ronald Burrows, FSME


(301) 415-6443   Ronald.Burrows@nrc.gov
(301) 415-6443 Ronald.Burrows@nrc.gov


Thomas McLaughlin, FSME
Thomas McLaughlin, FSME
Line 204: Line 327:
(301) 415-5869 Thomas.Mclaughlin@nrc.gov
(301) 415-5869 Thomas.Mclaughlin@nrc.gov


Enclosures:  
Enclosures:
1. Detailed Technical Discussion
1. Detailed Technical Discussion


Line 216: Line 339:


==CONTACT==
==CONTACT==
This information notice requires no specific action or written response. If you have any
This information notice requires no specific action or written response. If you have any


questions about the information in this notice, please contact one of the technical contacts listed
questions about the information in this notice, please contact one of the technical contacts listed


below.     /RA Aby Mohseni for/
below.


Larry W. Camper, Director
/RA Aby Mohseni for/
                                        Larry W. Camper, Director


Division of Waste Management
Division of Waste Management
Line 232: Line 356:
and Environmental Management Programs
and Environmental Management Programs


Contacts: Robert Evans, Region IV
Contacts:         Robert Evans, Region IV


(817) 200-1234 Robert.Evans@nrc.gov
(817) 200-1234 Robert.Evans@nrc.gov
Line 240: Line 364:
(301) 415-6443 Ronald.Burrows@nrc.gov
(301) 415-6443 Ronald.Burrows@nrc.gov


Thomas McLaughlin, FSME   (301) 415-5869  Thomas.Mclaughlin@nrc.gov
Thomas McLaughlin, FSME


Enclosures:  
(301) 415-5869 Thomas.Mclaughlin@nrc.gov
1. Detailed Technical Discussion 2. Bibliography 3. Survey Results for Facilities Using Hydrogen Peroxide Precipitation
 
Enclosures:
1. Detailed Technical Discussion
 
2. Bibliography
 
3. Survey Results for Facilities Using Hydrogen Peroxide Precipitation


4. FSME Recently Issued Generic Communications
4. FSME Recently Issued Generic Communications


ML14028A175 RIV:DNMS/RSFS
ML14028A175 RIV:DNMS/RSFS             C:DNMS/RSFS                DD:DNMS                D:DNMS


C:DNMS/RSFS DD:DNMS D:DNMS RJEvans DBSpitzberg VHCampbell AVegal /RA/ Via email Via email Via email 10/24/13 11/06/13 01/02/14 12/31/13 FSME:DMSSA FSME:DWMEP DWMEP/DURLD C:DWMEP/DURLD ARMcIntosh RABurrows TGMcLaughlin BvonTill Via email Via email Via email Via email 10/24/13 10/28/13 10/28/13 10/29/13 NSIR FSME:DMSSA
RJEvans               DBSpitzberg               VHCampbell               AVegal


FSME:DILR
/RA/                  Via email                Via email              Via email


OGC/GCLR/RMR CGrigsby DWhite JCai TLStokes Via email Via email Via email Via email 10/28/13 10/24/13 11/05/13 12/17/13 OE/EB NMSS DD:DWMEP/DURLD D:  MSSA TMarenchin HJGonzalez DPersinko
10/24/13               11/06/13                 01/02/14              12/31/13 FSME:DMSSA              FSME:DWMEP              DWMEP/DURLD            C:DWMEP/DURLD


JMoses for  LDudes Via email Via email /RA/ /RA/ 11/14/13 11/08/13 01/24/14 02/28/14 D:DWMEP    AMohseni for  LWCamper    /RA/    03/04/14    OFFICIAL RECORD COPY
ARMcIntosh              RABurrows              TGMcLaughlin                BvonTill


IN 1999-03, Rev. 1 Enclosure 1 Page 1 of
Via email                Via email                Via email              Via email


7  Detailed Technical Discussion
10/24/13                10/28/13                  10/28/13              10/29/13 NSIR                FSME:DMSSA                FSME:DILR            OGC/GCLR/RMR


At least nine uranium recovery facilities have experienced pressurized drum events.  The reasons for these pressurization events varied from facility to facility (see Enclosure 3 for a
CGrigsby                DWhite                    JCai                TLStokes


complete list of suspected causes for the drum pressurizations).  The actual causes of previous
Via email                Via email                Via email              Via email


drum pressurization events are still in question.  The causes may include the decomposition of
10/28/13                10/24/13                  11/05/13              12/17/13 OE/EB                  NMSS              DD:DWMEP/DURLD              D: MSSA


free hydrogen peroxide (H
TMarenchin              HJGonzalez                                      JMoses for


2 O 2) carried over with the dried yellowcake, decomposition of uranyl peroxide product, production of steam from residual water, reaction of uranium compounds with
DPersinko


inorganics, or perhaps a combination of these causes. In addition, a reliable and accurate
LDudes
 
Via email                Via email                  /RA/                  /RA/
          11/14/13                11/08/13                  01/24/14              02/28/14 D:DWMEP
 
AMohseni for
 
LWCamper
 
/RA/
          03/04/14 OFFICIAL RECORD COPY
 
IN 1999-03, Rev. 1 Enclosure 1 Detailed Technical Discussion
 
At least nine uranium recovery facilities have experienced pressurized drum events. The
 
reasons for these pressurization events varied from facility to facility (see Enclosure 3 for a
 
complete list of suspected causes for the drum pressurizations). The actual causes of previous
 
drum pressurization events are still in question. The causes may include the decomposition of
 
free hydrogen peroxide (H2O2) carried over with the dried yellowcake, decomposition of uranyl
 
peroxide product, production of steam from residual water, reaction of uranium compounds with
 
inorganics, or perhaps a combination of these causes. In addition, a reliable and accurate


chemical test for free hydrogen peroxide in yellowcake has not been validated which would
chemical test for free hydrogen peroxide in yellowcake has not been validated which would
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allow facilities to precisely determine the actual causes for these types of incidents.
allow facilities to precisely determine the actual causes for these types of incidents.


The NRC's working group identified several topics that are discussed in detail below. The
The NRCs working group identified several topics that are discussed in detail below. The
 
working groups findings are based on the information that was identified or made available to


working group's findings are based on the information that was identified or made available to
the group, in part, through uranium recovery facility responses to surveys. Two of the 14 surveys were conducted for sites that are no longer in service, meaning that some of the


the group, in part, through uranium recovery facility responses to surveys.  Two of the 14 surveys were conducted for sites that are no longer in service, meaning that some of the information presented in the survey may be based on individual recollections versus formal
information presented in the survey may be based on individual recollections versus formal


documentation.
documentation.
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Precipitation with Ammonia and Use of a Calciner to Dry Yellowcake
Precipitation with Ammonia and Use of a Calciner to Dry Yellowcake


Three facility operators out of 14 reported using ammonia precipitation instead of hydrogen peroxide precipitation.  These operators also dried their precipitated product at high temperatures in a calciner.  There was no evidence that the ammonia precipitation process, in
Three facility operators out of 14 reported using ammonia precipitation instead of hydrogen


combination with a calciner, had ever resulted in pressurized drums. Therefore, these types of facilities are excluded from the current discussion about H
peroxide precipitation. These operators also dried their precipitated product at high


2 O 2 precipitated product.
temperatures in a calciner. There was no evidence that the ammonia precipitation process, in
 
combination with a calciner, had ever resulted in pressurized drums. Therefore, these types of
 
facilities are excluded from the current discussion about H2O2 precipitated product.


The Chemistry of Hydrogen Peroxide Precipitated Yellowcake
The Chemistry of Hydrogen Peroxide Precipitated Yellowcake


Facilities using the hydrogen peroxide precipitation process may create pressurized drums if their operational processes are not appropriately controlled.  The chemical product of precipitation depends on the temperature of the solution undergoing precipitation.  Based on the
Facilities using the hydrogen peroxide precipitation process may create pressurized drums if


survey results, hydrogen peroxide precipitation typically occurs under ambient conditions. At temperatures below 50°C (122°F), the precipitate is generally of the form UO
their operational processes are not appropriately controlled. The chemical product of


4
precipitation depends on the temperature of the solution undergoing precipitation. Based on the
* 4H 2 O (uranyl peroxide tetrahydrate). The final desired product is UO


4
survey results, hydrogen peroxide precipitation typically occurs under ambient conditions. At
* 2H 2O (uranyl peroxide dihydrate).


Converting the tetrahydrate form (UO
temperatures below 50°C (122°F), the precipitate is generally of the form UO4
* 4H2O (uranyl


4
peroxide tetrahydrate). The final desired product is UO4
* 4H 2O) of uranyl peroxide to the desired dihydrate form (UO 4
* 2H2O (uranyl peroxide dihydrate).
* 2H 2O) occurs quickly under typical drying conditions. For example, laboratory samples


of UO 4
Converting the tetrahydrate form (UO4
* 4H 2O will dehydrate to UO
* 4H2O) of uranyl peroxide to the desired dihydrate form


4
(UO4
* 2H 2O in about one hour when dried at 100°C (212°F) (product temperature, not dryer temperature).  Typical maximum dryer temperatures at facilities using hydrogen peroxide precipitation range from 130°C (266°F) to 649°C (1200°F), with most facilities operating well below 300°C (572°F). Of course, laboratory studies do not take into
* 2H2O) occurs quickly under typical drying conditions. For example, laboratory samples


account industrial scale production issues such as difficulty in ensuring uniform drying temperature of the product and desired moisture content. The composition of the final product will depend on a variety of drying conditions including dryer temperature, heating time, heating
of UO4
* 4H2O will dehydrate to UO4
* 2H2O in about one hour when dried at 100°C (212°F)
(product temperature, not dryer temperature). Typical maximum dryer temperatures at facilities
 
using hydrogen peroxide precipitation range from 130°C (266°F) to 649°C (1200°F), with most
 
facilities operating well below 300°C (572°F). Of course, laboratory studies do not take into
 
account industrial scale production issues such as difficulty in ensuring uniform drying
 
temperature of the product and desired moisture content. The composition of the final product
 
will depend on a variety of drying conditions including dryer temperature, heating time, heating


rate, feed rate, product temperature, water content, hydrogen peroxide content, pressure, etc.
rate, feed rate, product temperature, water content, hydrogen peroxide content, pressure, etc.
Line 323: Line 496:
As a result of all of these variables affecting the final product, it is likely that other chemical
As a result of all of these variables affecting the final product, it is likely that other chemical


species are forming. The compound UO
species are forming. The compound UO4
* 2H2O does not undergo dehydration like UO4 *
 
IN 1999-03, Rev. 1 Enclosure 1 4H2O, but rather loses oxygen and water simultaneously (i.e., it decomposes to another
 
compound). Uranium trioxide (UO3) will form at around 500°C (932°F) (product temperature),
so for most facilities this reaction is not expected to occur. However, a range of uranium
 
compounds between UO4
* 2H2O and UO3, are likely to form under current typical drying
 
temperatures and drying times. As a group, these intermediate compounds are referred to as
 
amorphous UOX, where (3x3.5). While UO4
* 2H2O is considered the most stable form of
 
uranyl peroxide, amorphous UOX is considered unstable with respect to the decomposition to
 
UO3 even at room temperature. Table 1 demonstrates one example of dryer temperature
 
versus product formation.
 
Table 1 Drying Temperature and product composition: Phases identified in hydrogen peroxide


4
precipitated yellowcake dryer product by X-ray diffractometry1 Dryer
* 2H 2O does not undergo dehydration like UO


4 * 
Sample          Discharge                    Amorphous
IN 1999-03, Rev. 1 Enclosure 1 Page 2 of


7  4H 2O, but rather loses oxygen and water simultaneously (i.e., it decomposes to another
UO4*2H2O                  UO3      U3O8 ID        Temperature                        UOx


compound).  Uranium trioxide (UO
(°C)
                001              as-is              X


3) will form at around 500°C (932°F) (product temperature), so for most facilities this reaction is not expected to occur.  However, a range of uranium
015              125              X


compounds between UO
002              131              X


4
022              145              X
* 2H 2O and UO 3 , are likely to form under current typical drying temperatures and drying times.  As a group, these intermediate compounds are referred to as


amorphous UO
016              150              X


X , where (3x3.5).  While UO
003              175              X


4
017              175              X
* 2H 2O is considered the most stable form of


uranyl peroxide, amorphous UO
004              225            Trace          X


X is considered unstable with respect to the decomposition to
005              275                            X


UO 3 even at room temperature.  Table 1 demonstrates one example of dryer temperature
006              325                            X


versus product formation.
018              375                            X
 
019              400                            X
 
008              425                            X
 
020              425                            X
 
021              450                            X
 
023              475                            X
 
010              525                            X        4.30%
                011              575                                      X
 
012              625                                      X


Table 1 Drying Temperature and product composition: Phases identified in hydrogen peroxide precipitated yellowcake dryer product by X-ray diffractometry
014              769                                                X


1 Sample ID Dryer Discharge
1 empty cells indicate not detected


Temperature (°C) UO 4*2H 2 OAmorphous UO x UO 3 U 3 O 8 001 as-is X    015 125 X    002 131 X    022 145 X    016 150 X    003 175 X    017 175 X    004 225 Trace X  005 275  X  006 325  X  018 375  X  019 400  X  008 425  X  020 425  X  021 450  X  023 475  X  010 525  X 4.30%  011 575  X  012 625  X  014 769    X 1empty cells indicate not detected
In addition, amorphous UOX has been reported to react with free water to liberate oxygen gas.


===In addition, amorphous UO===
It is not clear whether this is a reaction resulting in UO3, or some other type of reaction.
X has been reported to react with free water to liberate oxygen gas.  It is not clear whether this is a reaction resulting in UO


3, or some other type of reaction.  Experiments to date have demonstrated this effect by mixing relatively large amounts of water with amorphous UO
Experiments to date have demonstrated this effect by mixing relatively large amounts of water


X. Figure 1 demonstrates this phenomenon. It is unknown what effect residual moisture at levels typical of uranium recovery facilities has on amorphous UO
with amorphous UOX. Figure 1 demonstrates this phenomenon. It is unknown what effect


===X. It has also been found that neither UO===
residual moisture at levels typical of uranium recovery facilities has on amorphous UOX. It has
4
* 2H 2 O nor UO 3 react with water in this manner.


IN 1999-03, Rev. 1 Enclosure 1 Page 3 of
also been found that neither UO4
* 2H2O nor UO3 react with water in this manner.


7  Figure 1 Product chemistry: Dried hydrogen peroxide precipitated yellowcake reactivity with water
IN 1999-03, Rev. 1 Enclosure 1 Figure 1 Product chemistry: Dried hydrogen peroxide precipitated yellowcake reactivity with water


Addition of Excess Hydrogen Peroxide During Precipitation Process
Addition of Excess Hydrogen Peroxide During Precipitation Process


A stoichiometric excess of hydrogen peroxide is required to optimize precipitation of uranyl peroxide yellow cake. The degree of excess is determined by the composition of the uranium bearing solution (feed stock for precipitation). Molybdenum, vanadium, and other reactive metals contained in the feed stock react with hydrogen peroxide to form soluble complexes. In addition, some fraction of hydrogen peroxide may decompose during the precipitation process. Facility operators should be aware that some of this excess hydrogen peroxide may be carried
A stoichiometric excess of hydrogen peroxide is required to optimize precipitation of uranyl
 
peroxide yellow cake. The degree of excess is determined by the composition of the uranium
 
bearing solution (feed stock for precipitation). Molybdenum, vanadium, and other reactive
 
metals contained in the feed stock react with hydrogen peroxide to form soluble complexes. In
 
addition, some fraction of hydrogen peroxide may decompose during the precipitation process.
 
Facility operators should be aware that some of this excess hydrogen peroxide may be carried


over into the drying process. The working group understands that an effective drying cycle should eliminate this excess hydrogen peroxide.
over into the drying process. The working group understands that an effective drying cycle
 
should eliminate this excess hydrogen peroxide.


Stability of Hydrogen Peroxide in the Presence of Uranyl Peroxide Solids
Stability of Hydrogen Peroxide in the Presence of Uranyl Peroxide Solids


Precipitation of dissolved uranium by the addition of hydrogen peroxide is a well-known and common process within the uranium recovery industry.  It has been demonstrated that this precipitation process is a reversible chemical reaction.  One consequence is that an excess of
Precipitation of dissolved uranium by the addition of hydrogen peroxide is a well-known and


dissolved hydrogen peroxide must be maintained in solution to drive the precipitation reaction to completion and, hence, to minimize dissolved uranium losses in resulting waste streams.
common process within the uranium recovery industry. It has been demonstrated that this


The use of excess hydrogen peroxide is a common practice in the uranium industry where the maintenance of low uranium tails in the precipitation process is desired. The filtrate fluids
precipitation process is a reversible chemical reaction. One consequence is that an excess of


associated with the resulting uranyl peroxide slurry must also contain a modest but finite concentration of dissolved hydrogen peroxide to avoid dissolution of uranyl peroxide solids.  As a result, moist uranyl peroxide slurries entering any drying equipment may contain a small but finite concentration of dissolved hydrogen peroxide.
dissolved hydrogen peroxide must be maintained in solution to drive the precipitation reaction to


IN 1999-03, Rev. 1 Enclosure 1 Page 4 of
completion and, hence, to minimize dissolved uranium losses in resulting waste streams. The


7  Industrial hydrogen peroxide solutions are relatively stable as long as they are properly stored at moderate temperatures, maintained at a pH below 5, and do not come into contact with
use of excess hydrogen peroxide is a common practice in the uranium industry where the


impurities, especially metals.  Uranyl peroxide solids are typically precipitated at low pH (2-4) under ambient conditions in the presence of small amounts of excess hydrogen peroxide. The resulting slurries are usually pressed and washed at ambient conditions in a filter press
maintenance of low uranium tails in the precipitation process is desired. The filtrate fluids


operation to remove soluble filtrate impurities from the filter cake.  The acidity of the wet cake will likely remain low keeping any residual free hydrogen peroxide relatively stable.  This free hydrogen peroxide will, however, begin to decompose over time to oxygen gas and water as it remains in contact with the uranyl peroxide solids.  The rate of this decomposition is unknown
associated with the resulting uranyl peroxide slurry must also contain a modest but finite


and, if a test were to be performed to measure residual free hydrogen peroxide, it would have to be performed on fresh uranyl peroxide solids to minimize the subsequent decomposition of hydrogen peroxide. This may explain why it has been difficult to measure free hydrogen peroxide in filter cake samples as the time to perform the tests might be too long for the
concentration of dissolved hydrogen peroxide to avoid dissolution of uranyl peroxide solids. As
 
a result, moist uranyl peroxide slurries entering any drying equipment may contain a small but
 
finite concentration of dissolved hydrogen peroxide.
 
IN 1999-03, Rev. 1 Enclosure 1 Industrial hydrogen peroxide solutions are relatively stable as long as they are properly stored at
 
moderate temperatures, maintained at a pH below 5, and do not come into contact with
 
impurities, especially metals. Uranyl peroxide solids are typically precipitated at low pH (2-4)
under ambient conditions in the presence of small amounts of excess hydrogen peroxide. The
 
resulting slurries are usually pressed and washed at ambient conditions in a filter press
 
operation to remove soluble filtrate impurities from the filter cake. The acidity of the wet cake
 
will likely remain low keeping any residual free hydrogen peroxide relatively stable. This free
 
hydrogen peroxide will, however, begin to decompose over time to oxygen gas and water as it
 
remains in contact with the uranyl peroxide solids. The rate of this decomposition is unknown
 
and, if a test were to be performed to measure residual free hydrogen peroxide, it would have to
 
be performed on fresh uranyl peroxide solids to minimize the subsequent decomposition of
 
hydrogen peroxide. This may explain why it has been difficult to measure free hydrogen
 
peroxide in filter cake samples as the time to perform the tests might be too long for the


hydrogen peroxide to remain stable and not decompose.
hydrogen peroxide to remain stable and not decompose.


The other condition under which hydrogen peroxide can decompose is elevated temperature. Hydrogen peroxide will slowly decompose at room temperature.  The rate of decomposition will increase as temperature increases.  If any free hydrogen peroxide enters the dryer it will likely
The other condition under which hydrogen peroxide can decompose is elevated temperature.


decompose as the temperature of the uranyl solids increases.  However, if the free hydrogen peroxide fails to instantly decompose upon entry into the drying chamber, the residual hydrogen peroxide may be captured in the uranyl peroxide crystalline structure during the drying process.
Hydrogen peroxide will slowly decompose at room temperature. The rate of decomposition will


Facility operators should try to minimize the amount of residual free hydrogen peroxide in the product prior to the drying process.
increase as temperature increases. If any free hydrogen peroxide enters the dryer it will likely
 
decompose as the temperature of the uranyl solids increases. However, if the free hydrogen
 
peroxide fails to instantly decompose upon entry into the drying chamber, the residual hydrogen
 
peroxide may be captured in the uranyl peroxide crystalline structure during the drying process.
 
Facility operators should try to minimize the amount of residual free hydrogen peroxide in the
 
product prior to the drying process.


Drying Temperature of Uranyl Peroxide in Rotary Vacuum Dryers
Drying Temperature of Uranyl Peroxide in Rotary Vacuum Dryers


While different dryer types and precipitation processes are utilized in the industry, the majority of facility operators uses hydrogen peroxide precipitation and employs some type of rotary vacuum dryer that operates at a relatively low temperature. These systems are typically batch
While different dryer types and precipitation processes are utilized in the industry, the majority of
 
facility operators uses hydrogen peroxide precipitation and employs some type of rotary vacuum
 
dryer that operates at a relatively low temperature. These systems are typically batch


operations with ambient temperature yellowcake slurry introduced into a pre-heated chamber at
operations with ambient temperature yellowcake slurry introduced into a pre-heated chamber at


atmospheric pressure. The chamber is then sealed and depressurized. The sub-atmospheric
atmospheric pressure. The chamber is then sealed and depressurized. The sub-atmospheric


pressure within the chamber (i.e., the vacuum) does not remain constant during the drying
pressure within the chamber (i.e., the vacuum) does not remain constant during the drying


cycle. Rather, the pressure continuously decreases as water vapor is liberated and evacuated from the chamber via the vacuum pump circuit. The vapor capacity of the vacuum pump limits the operational vacuum (pressure) within the chamber. During the period in which boiling of
cycle. Rather, the pressure continuously decreases as water vapor is liberated and evacuated
 
from the chamber via the vacuum pump circuit. The vapor capacity of the vacuum pump limits
 
the operational vacuum (pressure) within the chamber. During the period in which boiling of


free moisture is the principle process within the drying chamber, the temperature of the
free moisture is the principle process within the drying chamber, the temperature of the


yellowcake solids is tied to the boiling point of water at that pressure. Near the end of the drying
yellowcake solids is tied to the boiling point of water at that pressure. Near the end of the drying


cycle, sufficient free moisture has been removed and the pressure within the chamber decreases and approaches a steady state.  As this condition is reached, the yellowcake temperature rapidly rises toward the temperature of the heating surfaces within the drying
cycle, sufficient free moisture has been removed and the pressure within the chamber


chamber. Essentially, there are two phases to the batch vacuum drying cycle.  The first is
decreases and approaches a steady state. As this condition is reached, the yellowcake


controlled by the temperature-pressure relationship of boiling water and the capacity of the
temperature rapidly rises toward the temperature of the heating surfaces within the drying


vacuum pump to remove water vapor. In the second phase, the vacuum pump vapor capacity is no longer limiting and the temperature of the solids is controlled by heat transfer between the vessel surfaces and the yellowcake solids.
chamber. Essentially, there are two phases to the batch vacuum drying cycle. The first is


Regardless of the temperature of the dryer, there is still a minimum time necessary where
controlled by the temperature-pressure relationship of boiling water and the capacity of the


moisture is driven off before the yellowcake is heated to above 100°C (212°F), the point where
vacuum pump to remove water vapor. In the second phase, the vacuum pump vapor capacity


UO 4
is no longer limiting and the temperature of the solids is controlled by heat transfer between the
* 2H 2O starts to be created.  Continued heating of the product can therefore lead to


IN 1999-03, Rev. 1 Enclosure 1 Page 5 of
vessel surfaces and the yellowcake solids.


7  conversion to hydrated UO
Regardless of the temperature of the dryer, there is still a minimum time necessary where


4 (uranyl peroxide); however, there is
moisture is driven off before the yellowcake is heated to above 100°C (212°F), the point where


likely limited time for conversion
UO4
* 2H2O starts to be created. Continued heating of the product can therefore lead to


of UO 4 to UO 3 (uranium trioxide).  As such, any remaining UO
IN 1999-03, Rev. 1 Enclosure 1 conversion to hydrated UO4 (uranyl peroxide); however, there is likely limited time for conversion


4 that does not convert to the
of UO4 to UO3 (uranium trioxide). As such, any remaining UO4 that does not convert to the


more stable UO
more stable UO3 could lead to drum pressurization. Therefore, it is important for facility


3 could lead to drum pressurization.  Therefore, it is important for facility operators to control the drying process parameters, including temperature, to control product
operators to control the drying process parameters, including temperature, to control product


chemistry.
chemistry.
Line 463: Line 727:
Potential Reactions for Uranyl Peroxide Yellowcake in the Presence of Organic Matter
Potential Reactions for Uranyl Peroxide Yellowcake in the Presence of Organic Matter


Five of 11 respondents that used hydrogen peroxide (H
Five of 11 respondents that used hydrogen peroxide (H2O2) precipitation process reported that


2 O 2) precipitation process reported that they have experienced exothermic reactions in yellowcake due to organic contamination, and five of 11 reported that they pay special attention to hydrocarbon contamination.
they have experienced exothermic reactions in yellowcake due to organic contamination, and


The reaction of H
five of 11 reported that they pay special attention to hydrocarbon contamination.


2 O 2 with organics is a well-known but complex reaction. When H
The reaction of H2O2 with organics is a well-known but complex reaction. When H2O2 is in the


2 O 2 is in the presence of most organic matter, the hydrogen peroxide can react with the organic to form
presence of most organic matter, the hydrogen peroxide can react with the organic to form


organic peroxide compounds which are usually unstable or can cause the organic to be
organic peroxide compounds which are usually unstable or can cause the organic to be


oxidized, i.e., "chemically burned."  When organic peroxide compounds are formed they have been known to detonate, i.e., cause spontaneous combustion or cause oxidation reactions to occur.  These latter reactions result in the evolution of heat (from the "burning" of the organics)
oxidized, i.e., chemically burned. When organic peroxide compounds are formed they have


and the evolution of CO
been known to detonate, i.e., cause spontaneous combustion or cause oxidation reactions to


2 (carbon dioxide), CO (carbon monoxide), and H
occur. These latter reactions result in the evolution of heat (from the burning of the organics)
and the evolution of CO2 (carbon dioxide), CO (carbon monoxide), and H2O (water) depending


2O (water) depending upon the completion of the reaction. When hydrogen peroxide reacts in this way with organics
upon the completion of the reaction. When hydrogen peroxide reacts in this way with organics


there is always a signature gas evolution which will be indicative of the reaction taking place.
there is always a signature gas evolution which will be indicative of the reaction taking place.


Under certain conditions of temperature, metal catalysts, and reactant concentrations, organics can react with the hydrogen peroxide.  This interaction results in a complex, multi-step reaction
Under certain conditions of temperature, metal catalysts, and reactant concentrations, organics


which typically forms many intermediate hydroxyl radicals as the oxidation reaction is on-going. This process can be simplified as follows:
can react with the hydrogen peroxide. This interaction results in a complex, multi-step reaction


H 2 O 2 + Organics (CxHy) A B C-. CO 2 + CO + H 2 O + Heat
which typically forms many intermediate hydroxyl radicals as the oxidation reaction is on-going.
 
This process can be simplified as follows:
        H2O2 + Organics (CxHy) A B C. CO2 + CO + H2O + Heat


Where A, B, C, etc. are the intermediate compounds that form prior to full oxidation (compounds
Where A, B, C, etc. are the intermediate compounds that form prior to full oxidation (compounds


that contain OOH- or OH- radicals). The end result of this chain of reactions is that the organic is "chemically burned" and the signature off-gases of this reaction are CO
that contain OOH- or OH- radicals). The end result of this chain of reactions is that the organic is
 
chemically burned and the signature off-gases of this reaction are CO2 + CO + H2O plus heat.


2 + CO + H 2O plus heat.
When these intermediate compounds form, they combine unstably bound oxygen together with


When these intermediate compounds form, they combine unstably bound oxygen together with hydrogen and carbon in the same molecule, and these organic peroxides can ignite easily and
hydrogen and carbon in the same molecule, and these organic peroxides can ignite easily and


burn rapidly and intensely. When organic peroxide begins to decompose, the heat produced by
burn rapidly and intensely. When organic peroxide begins to decompose, the heat produced by


its decomposition may not dissipate as quickly as it is generated which can result in increasing
its decomposition may not dissipate as quickly as it is generated which can result in increasing


temperatures which further intensifies the rate of exothermic decomposition. This can create a dangerous situation known as a self-accelerating decomposition.
temperatures which further intensifies the rate of exothermic decomposition. This can create a
 
dangerous situation known as a self-accelerating decomposition.


When wet yellowcake is introduced into a dryer system it is important that the product not
When wet yellowcake is introduced into a dryer system it is important that the product not


contain organic matter as the reactions of any residual H
contain organic matter as the reactions of any residual H2O2 or decomposed uranyl peroxide
 
hydrate can occur. For trace amounts of organics, this will likely not be an issue as the dryer
 
can dissipate any heat that is formed by these reactions, or the organic will be driven off by the


2 O 2 or decomposed uranyl peroxide hydrate can occur.  For trace amounts of organics, this will likely not be an issue as the dryer can dissipate any heat that is formed by these reactions, or the organic will be driven off by the heat of the drying operation. If, however, larger amounts of organics were to be introduced into
heat of the drying operation. If, however, larger amounts of organics were to be introduced into


the dryer, a self-accelerating reaction can occur where the heat cannot be dissipated, high
the dryer, a self-accelerating reaction can occur where the heat cannot be dissipated, high


temperatures are generated, and a violent reaction is possible. This has occurred in some dryer
temperatures are generated, and a violent reaction is possible. This has occurred in some dryer


facilities when there was a mechanical failure in the dryer which caused large quantities of
facilities when there was a mechanical failure in the dryer which caused large quantities of
Line 519: Line 795:
organics such as oil to be introduced into the dried yellowcake at elevated temperatures.
organics such as oil to be introduced into the dried yellowcake at elevated temperatures.


IN 1999-03, Rev. 1 Enclosure 1 Page 6 of
IN 1999-03, Rev. 1 Enclosure 1 If the yellowcake is dried at high temperatures as in a calciner, the problem of organic reactions
 
is less likely since the higher temperatures encountered in the dryer will drive off the volatile


7    If the yellowcake is dried at high temperatures as in a calciner, the problem of organic reactions
organics and decompose any organic peroxides that might have been formed. In a low


is less likely since the higher temperatures encountered in the dryer will drive off the volatile
temperature dryer, some organics can remain with the dried uranyl peroxide hydrates and


organics and decompose any organic peroxides
become unstable in the dryer or when removed from the dryer. This could have consequences


that might have been formed.  In a low temperature dryer, some organics can remain with the dried uranyl peroxide hydrates and
for drummed material as the decomposition of any organic peroxide can generate heat plus


become unstable in the dryer or when removed from the dryer. This could have consequences for drummed material as the decomposition of any organic peroxide can generate heat plus
CO2, CO, and H2O. The consequence of this could be the slow generation of combustion gases


===CO 2, CO, and H===
(for small amounts of organics) or a more violent reaction if large amounts of organic peroxides
2O.  The consequence of this could be the slow generation of combustion gases (for small amounts of organics) or a more violent reaction if large amounts of organic peroxides


begin to decompose and generate heat which can cause a self-accelerating reaction to occur.
begin to decompose and generate heat which can cause a self-accelerating reaction to occur.


In summary, facility operators should be aware that organic reactions are possible with yellowcake product, and operators should try to locate and eliminate potential sources of
In summary, facility operators should be aware that organic reactions are possible with
 
yellowcake product, and operators should try to locate and eliminate potential sources of


organic matter from entering into the precipitation and drying circuits.
organic matter from entering into the precipitation and drying circuits.
Line 542: Line 821:
Packaging (Drumming) of Yellowcake
Packaging (Drumming) of Yellowcake


Dried yellowcake is almost exclusively stored and shipped in 208-liter (55 gallon) steel drums. In the U.S., the drums must meet U.S. Department of Transportation specifications if the facility
Dried yellowcake is almost exclusively stored and shipped in 208-liter (55 gallon) steel drums.


operator plans to ship yellowcake material in the drums. Facilities use new drums, reconditioned (used) drums, or a combination of both, depending on drum availability and/or
In the U.S., the drums must meet U.S. Department of Transportation specifications if the facility


cost. It is critical that operators ensure that drums used to ship yellowcake do not have any organic material (such as oil or grease) in them. Employees must be trained and informed about the serious complications of organic material in drums to ensure that drums used for
operator plans to ship yellowcake material in the drums. Facilities use new drums, reconditioned (used) drums, or a combination of both, depending on drum availability and/or
 
cost. It is critical that operators ensure that drums used to ship yellowcake do not have any
 
organic material (such as oil or grease) in them. Employees must be trained and informed
 
about the serious complications of organic material in drums to ensure that drums used for


shipment are received from the suppliers in acceptable condition and the facility does not
shipment are received from the suppliers in acceptable condition and the facility does not
Line 558: Line 843:
drum pressurization incidents due to the tighter seal of such drums compared to reconditioned
drum pressurization incidents due to the tighter seal of such drums compared to reconditioned


drums and lids. The tighter seal could prevent the off gassing from escaping the drum, thereby
drums and lids. The tighter seal could prevent the off gassing from escaping the drum, thereby


leading to pressurization. Although this condition is still possible with new drums or reconditioned drums that happen to have better seals, the working group believes that appropriate controls, such as adequate cooling and venting times, will prevent any significant potential for gas build up and drum pressurization.
leading to pressurization. Although this condition is still possible with new drums or
 
reconditioned drums that happen to have better seals, the working group believes that
 
appropriate controls, such as adequate cooling and venting times, will prevent any significant
 
potential for gas build up and drum pressurization.


To limit the potential of shipping a drum of yellowcake that has been pressurized due to an
To limit the potential of shipping a drum of yellowcake that has been pressurized due to an


unexpected cause, including a human factor, it is strongly suggested that operators include as part of their final pre-shipment inspection a procedure to check each drum for pressurization. This can be accomplished by a visual inspection of drum lids and a physical check by pushing on the lid and checking for deflection and/or tapping the lid with a rubber mallet to assess
unexpected cause, including a human factor, it is strongly suggested that operators include as
 
part of their final pre-shipment inspection a procedure to check each drum for pressurization.
 
This can be accomplished by a visual inspection of drum lids and a physical check by pushing
 
on the lid and checking for deflection and/or tapping the lid with a rubber mallet to assess
 
deflection and the tone resulting from the tapping. Any drums suspected of pressurization
 
should be returned to the drumming area and carefully depressurized and opened to confirm


deflection and the tone resulting from the tapping.  Any drums suspected of pressurization
conditions and causes, if appropriate. Operators should also develop controls to manage the


should be returned to the drumming area and carefully depressurized and opened to confirm conditions and causes, if appropriate.  Operators should also develop controls to manage the risk of the addition of excess free moisture/water to open drums of product. The working group
risk of the addition of excess free moisture/water to open drums of product. The working group


is aware that one study indicated that pressure is generated from the addition of water into
is aware that one study indicated that pressure is generated from the addition of water into


amorphous product. For example, operators should avoid spraying unsealed drums with water to avoid the possibility of adding free water to the dried product.
amorphous product. For example, operators should avoid spraying unsealed drums with water


IN 1999-03, Rev. 1 Enclosure 1 Page 7 of
to avoid the possibility of adding free water to the dried product.


7  Shipment of Pressurized Drums
IN 1999-03, Rev. 1 Enclosure 1 Shipment of Pressurized Drums


A facility operator who ships pressurized drums may be in violation of U.S. Department of
A facility operator who ships pressurized drums may be in violation of U.S. Department of


Transportation regulations. In particular, the shipment of pressurized drums may violate
Transportation regulations. In particular, the shipment of pressurized drums may violate
 
regulations 49 CFR 173.24(b)(3) and 49 CFR 173.475(a). Regulation 173.24(b)(3) states that


regulations 49 CFR 173.24(b)(3) and 49 CFR 173.475(a).  Regulation 173.24(b)(3) states that
there will be no mixture of gases or vapors in the package which could, through any credible


there will be no mixture of gases or vapors in the package which could, through any credible spontaneous increase of heat or pressure, significantly reduce the effectiveness of the packaging.  Regulation 173.475(a) states that, before each shipment of any Class 7 (radioactive) materials package, the offeror (the facility operator who offers the drum for
spontaneous increase of heat or pressure, significantly reduce the effectiveness of the


shipment) must ensure, by examination or appropriate tests, that the packaging is proper for the contents to be shipped. Based on these two regulations, a standard metal drum may not be the proper package for pressurized uranium product because the pressurization reduces the effectiveness of the packaging. Further, the packaging process may be inadequate if it allows
packaging. Regulation 173.475(a) states that, before each shipment of any Class 7 (radioactive) materials package, the offeror (the facility operator who offers the drum for
 
shipment) must ensure, by examination or appropriate tests, that the packaging is proper for the
 
contents to be shipped. Based on these two regulations, a standard metal drum may not be the
 
proper package for pressurized uranium product because the pressurization reduces the
 
effectiveness of the packaging. Further, the packaging process may be inadequate if it allows


gases and vapors to increase the internal pressure of the package (the drum), resulting in rapid
gases and vapors to increase the internal pressure of the package (the drum), resulting in rapid
Line 592: Line 903:
and uncontrolled depressurization when the package is opened.
and uncontrolled depressurization when the package is opened.


Facility operators should also be aware of regulation 49 CFR 173.22(a)(4). This regulation requires persons who offer hazardous material for transportation to comply with the
Facility operators should also be aware of regulation 49 CFR 173.22(a)(4). This regulation


manufacturers' instructions for packaging.  This regulation applies to drums that have been
requires persons who offer hazardous material for transportation to comply with the


certified by the Department of Transportation and marked or stenciled accordingly.  Many drum manufacturers provide specific instructions for proper closure of the drum, including a
manufacturers instructions for packaging. This regulation applies to drums that have been


requirement to torque the drum seals. Facility operators should be aware of any specific closure instructions provided by the manufacturer or distributer of their certified drums, if these
certified by the Department of Transportation and marked or stenciled accordingly. Many drum
 
manufacturers provide specific instructions for proper closure of the drum, including a
 
requirement to torque the drum seals. Facility operators should be aware of any specific
 
closure instructions provided by the manufacturer or distributer of their certified drums, if these


drums are used to transport yellowcake material.
drums are used to transport yellowcake material.


===Suggestions for the Uranium Recovery Industry===
===Suggestions for the Uranium Recovery Industry===
  The working group suggests that the information presented in this IN be supplemented by the uranium recovery industry. The working group suggests that the industry consider expanding
The working group suggests that the information presented in this IN be supplemented by the
 
uranium recovery industry. The working group suggests that the industry consider expanding


the information by determining the chemical species of their product, product temperature versus holding time prior to sealing, impact of excess hydrogen peroxide on the decomposition
the information by determining the chemical species of their product, product temperature


process, rate of moisture reduction in the dryer, optimum drying parameters (feed rate, temperature, and residence time), and development of procedures and training program to alert workers of the potential risks.  For example, facility workers should be made aware that drying is a dynamic process and the change of any process parameter, such as feed rate or dryer
versus holding time prior to sealing, impact of excess hydrogen peroxide on the decomposition


temperature, may result in a product that is incompletely dried.  Facility operators should use this information to establish site-specific parameters to assure that drum pressurizations do not occur.    Facility operators should consider establishing procedures or other protocols to identify and
process, rate of moisture reduction in the dryer, optimum drying parameters (feed rate, temperature, and residence time), and development of procedures and training program to alert


manage pressurized drums. These procedures should include inspections of the drums for both
workers of the potential risks. For example, facility workers should be made aware that drying is


pressurization and integrity prior to transport.  This inspection should be complete even if the
a dynamic process and the change of any process parameter, such as feed rate or dryer


drum is stored for an extended period of time prior to actual shipment. Finally, the receiver of shipped drums should also inspect drums for pressurization upon receipt and before opening a
temperature, may result in a product that is incompletely dried. Facility operators should use
 
this information to establish site-specific parameters to assure that drum pressurizations do not
 
occur.
 
Facility operators should consider establishing procedures or other protocols to identify and
 
manage pressurized drums. These procedures should include inspections of the drums for both
 
pressurization and integrity prior to transport. This inspection should be complete even if the
 
drum is stored for an extended period of time prior to actual shipment. Finally, the receiver of
 
shipped drums should also inspect drums for pressurization upon receipt and before opening a


sealed drum.
sealed drum.


IN 1999-03, Rev. 1 Enclosure 2 Page 1 of
IN 1999-03, Rev. 1 Enclosure 2 Bibliography


2  Bibliography
Boggs, J. E., & El-Chehabi, M. (1957). The thermal decomposition of uranium peroxide, UO4 *
        2H2O. Journal of the American Chemical Society, 79(16), 4258-4260.


Boggs, J. E., & El-Chehabi, M. (1957). The thermal decomposition of uranium peroxide, UO
Brady, L. J., Susano, C. D., & Lawson, C. E. (1948). Chemical and physical properties of


4
uranium peroxide. Report AECD-2366. Oak Ridge, TN: U.S. Atomic Energy
* 2H 2 O. Journal of the American Chemical Society, 79(16), 4258-4260.


Brady, L. J., Susano, C. D., & Lawson, C. E. (1948). Chemical and physical properties of uranium peroxide. Report AECD-2366. Oak Ridge, TN: U.S. Atomic Energy Commission, Technical Information Branch.
Commission, Technical Information Branch.


Cordfunke, E. H. P. (1961). -UO 3: Its preparation and thermal stability. Journal of Inorganic and Nuclear Chemistry 23
Cordfunke, E. H. P. (1961). -UO3: Its preparation and thermal stability. Journal of Inorganic
(3-4), 23, 285-286.


Cordfunke, E. H. P., & Aling, P. (1963). Thermal decomposition of hydrated uranium peroxides. Journal of the Royal Netherlands Chemical Society, 82, 257-263.
and Nuclear Chemistry 23(3-4), 23, 285-286.
 
Cordfunke, E. H. P., & Aling, P. (1963). Thermal decomposition of hydrated uranium peroxides.
 
Journal of the Royal Netherlands Chemical Society, 82, 257-263.


Cordfunke, E. H. P., & Van Der Giessen, A. A. (1963). Pseudomorphic decomposition of
Cordfunke, E. H. P., & Van Der Giessen, A. A. (1963). Pseudomorphic decomposition of


uranium peroxide into UO
uranium peroxide into UO3. Journal of Inorganic and Nuclear Chemistry 25(5), 553-554.


3. Journal of Inorganic and Nuclear Chemistry 25
El-Chehabi, M. (1957). Decomposition of uranium peroxide. (Masters Thesis). The University
(5), 553-554.


El-Chehabi, M. (1957). Decomposition of uranium peroxide. (Master's Thesis). The University
of Texas.


of Texas.
Gayer, K. H., & Thompson, L. C. (1958). The solubility of uranium peroxide in acidic and basic
 
media at 25 °C. Canadian Journal of Chemistry 36(12), 1649-1652.


Gayer, K. H., & Thompson, L. C. (1958). The solubility of uranium peroxide in acidic and basic
Gupta, C. K., & Singh, H. (2003). Uranium resource processing: Secondary resources. Berlin:
        Springer-Verlag.


media at 25
Harrington, C. D., & Ruehle, A. E. (Eds.). (1959). Uranium production technology. Princeton, N.J.:Van Nostrand.
°C. Canadian Journal of Chemistry 36
(12), 1649-1652.


Gupta, C. K., & Singh, H. (2003). Uranium resource processing:  Secondary resources.  Berlin:  
Hausen, D. M. (1998). Characterizing and classifying uranium yellow cakes: A background.
Springer-Verlag.


Harrington, C. D., & Ruehle, A. E. (Eds.). (1959).  Uranium production technology.  Princeton, N.J.:Van Nostrand.
JOM 50(12), 45-47.


Hausen, D. M. (1998). Characterizing and classifying uranium yellow cakes: A background. JOM 50(12), 45-47.
Katz, J. J., & Rabinowitch, E. (1951). The chemistry of uranium: The element, its binary and


Katz, J. J., & Rabinowitch, E. (1951). The chemistry of uranium: The element, its binary and
related compounds (Part I). New York, NY: McGraw-Hill Book Company, Inc.


related compounds (Part I). New York, NY:  McGraw-Hill Book Company, Inc.
Leininger, R. F., Hunt, J. P., & Koshland, D. E. (1958). Composition and thermal decomposition


Leininger, R. F., Hunt, J. P., & Koshland, D. E. (1958). Composition and thermal decomposition
of uranyl peroxide (Paper 69). Chemistry of uranium: Collected papers, TID-5290,
        Book 2 (704-721). Oak Ridge, TN: U.S. Atomic Energy Commission Technical


of uranyl peroxide (Paper 69).  Chemistry of uranium: Collected papers, TID-5290, Book 2 (704-721). Oak Ridge, TN:  U.S. Atomic Energy Commission Technical Information Service Extension
Information Service Extension


Merritt, R.C. (1971). The extractive metallurgy of uranium. Golden, CO: Colorado School of Mines Research Institute.
Merritt, R.C. (1971). The extractive metallurgy of uranium. Golden, CO: Colorado School of


Metzger, R., et al. (1997).  Solubility characterization of airborne uranium from an in-situ uranium processing plant.
Mines Research Institute.


Health Physics 72(3), 418-422.
Metzger, R., et al. (1997). Solubility characterization of airborne uranium from an in-situ


Moore, R. L., & Watts Jr., R. A. (1952).
uranium processing plant. Health Physics 72(3), 418-422.


===Production of UO===
Moore, R. L., & Watts Jr., R. A. (1952). Production of UO3 by calcination of uranyl peroxide, Document No. HW-26531. Richland, WA: Hanford Works.
3 by calcination of uranyl peroxide , Document No. HW-26531. Richland, WA: Hanford Works.


IN 1999-03, Rev. 1 Enclosure 2 Page 2 of
IN 1999-03, Rev. 1 Enclosure 2 Patton, F. S. (1963). Enriched uranium processing. New York, NY: Macmillan Co.


2    Patton, F. S. (1963). Enriched uranium processing. New York, NY: Macmillan Co.
Rich, R. L. (2007). Inorganic reactions in water. Berlin: Springer-Verlag.


Rich, R. L. (2007). Inorganic reactions in water.  Berlin: Springer-Verlag.
Rodgers, C., & Dyck, B. (2012). Uranium peroxide precipitate drying temperature relationships.


Rodgers, C., & Dyck, B. (2012).  Uranium peroxide precipitate drying temperature relationships.
CIM Journal 3(3), 149-156.


===CIM Journal 3===
Sato, T. (1961). Uranium peroxide hydrates. Die Naturwissenschaften 48(21), 668.
(3), 149-156.


Sato, T. (1961). Uranium peroxide hydrates. Die Naturwissenschaften 48
Sato, T. (1963). Preparation of uranium peroxide hydrates. Journal of Applied Chemistry 13(8),
(21), 668.
      361-365.


Sato, T. (1963). Preparation of uranium peroxide hydrates. Journal of Applied Chemistry 13(8), 361-365.
Sato, T. (1976). Thermal decomposition of uranium peroxide hydrates. Journal of Applied


Sato, T. (1976).  Thermal decomposition of uranium peroxide hydrates.  Journal of Applied Chemistry and Biotechnology 26(4), 207-213.
Chemistry and Biotechnology 26(4), 207-213.


Silverman, L. & Sallach, R. A. (1961). Two uranyl peroxides. Journal of Physical Chemistry
Silverman, L. & Sallach, R. A. (1961). Two uranyl peroxides. Journal of Physical Chemistry


65(2), 370-371.
65(2), 370-371.


Thein, S. M., & Bereolos, P. J. (2000). Thermal stabilization of
Thein, S. M., & Bereolos, P. J. (2000). Thermal stabilization of 233UO2, 233UO3, and 233U3O8, Report ORNL/TM-2000/82. Oak Ridge, TN: Oak Ridge National Laboratory.
 
Walenta, K. (1974). On studtite and its composition. American Mineralogist 59, 166-171.


233 UO 2 , 233 UO 3 , and 233 U 3 O 8 , Report ORNL/TM-2000/82. Oak Ridge, TN:  Oak Ridge National Laboratory.
The data for Table 1 comes from Laboratory Characterization of Dryer Test Products, Cameco


Walenta, K. (1974).  On studtite and its composition.  American Mineralogist 59, 166-171.
Corporation, Gerhard Heinrich, John Krause, Mike Murchie, November 2009.


The data for Table 1 comes from "Laboratory Characterization of Dryer Test Products," Cameco
The data for Figure 1 comes from Laboratory Characterization of Dryer Test Products, Cameco Corporation, Gerhard Heinrich, John Krause, Mike Murchie, November, 2009 but was


Corporation, Gerhard Heinrich, John Krause, Mike Murchie, November 2009.
adapted and updated for a presentation to the CNSC: Rabbit Lake UOC Drying Process, Cameco Corporation, Kirk Lamont, November 2012.
 
IN 1999-03, Rev. 1 Enclosure 3 Survey Results for Facilities Using Hydrogen Peroxide Precipitation


The data for Figure 1 comes from "Laboratory Characterization of Dryer Test Products," Cameco Corporation, Gerhard Heinrich, John Krause, Mike Murchie, November, 2009 but was
Time in Dryer      Dryer      Yellowcake Temp        Cooling and        Percent (%)          Have You Experienced        Suspected Causes of


adapted and updated for a presentation to the CNSC: "Rabbit Lake UOC Drying Process,"
(hours)      Temp (oC)        (oC) When            Venting      Moisture in Dried              Any Drum            Drum Pressurizations
Cameco Corporation, Kirk Lamont, November 2012.


IN 1999-03, Rev. 1 Enclosure 3 Page 1 of
Barreled        Time (hours)*      Yellowcake              Pressurizations?


1   Survey Results for Facilities Using Hydrogen Peroxide Precipitation Time in Dryer (hours)  Dryer Temp (o C) Yellowcake Temp
12-16          232        Not measured              >12              0 - 1.5                      No


(oC) When Barreled Cooling and
Limit of 2
    18-20          164              130                24-72                <1                        Yes              Decay of residual H2O2
    36-48          160              160                  24                  <1                        Yes                  Not determined


Venting Time (hours)* Percent (%)
21-22          163              138                  24                1-8,                      Yes                Moisture vaporizing
Moisture in Dried Yellowcake Have You Experienced Any Drum Pressurizations? Suspected Causes of Drum Pressurizations


12-16  232 Not measured >12 0 - 1.5 Limit of 2 No 18-20 164 130 24-72 <1 Yes Decay of residual H
Typically                                                (steam)
                                                                              3-5
      6            130              <80            Described as              <2                       No


2 O 2 36-48  160 160 24 <1 Yes Not determined
minimal


21-22  163 138 24 1-8, Typically
16-20          235        Not measured              >12              0.5-1.5                      Yes                Decay of H2O2 and


3-5 Yes Moisture vaporizing (steam) 6  130 <80 Described as
Limit of 2                                      sealing drums too soon


"minimal" <2 No  16-20  235 Not measured >12 0.5-1.5
4.5-6          649              66            Previously 3,            1-4                        Yes              Cooling time and drying


===Limit of 2 Yes Decay of H===
changed to 24                                                              time too short
2 O 2 and sealing drums too soon


4.5-6 649 66 Previously 3, changed to 241-4 Yes Cooling time and drying
6             371            < 371                  4           no moisture                    Yes                  Decay of H2O2 Unknown        Not given        Unknown          a number of      Not measured                      Yes               Excess H2O2 added


time too short
hours                                                              during precipitation


6  371 < 371 4 "no moisture" Yes Decay of H
20-30          150              <90                  12              1-4 w/w                      Yes               Hot yellowcake added


2 O 2 Unknown Not given Unknown "a number of
to moist drum


hours" Not measured Yes Excess H
1.5            245              80                >3                0.5-2.0                      Yes                     Unknown


2 O 2 added during precipitation 20-30 150 <90 12 1-4 w/w Yes Hot yellowcake added
* Cooling and venting times are current times, or the most recent times for facilities that are no longer in operation. Several sites increased their


to moist drum 1.5 245 80 >3 0.5-2.0 Yes Unknown
cooling and venting times in response to previous pressurized drum events or in response to IN 1999-03.


* Cooling and venting times are current times, or the most recent times for facilities that are no longer in operation.  Several sites increased their cooling and venting times in response to previous pressurized drum events or in response to IN 1999-03.
IN 1999-03, Rev. 1 Enclosure 4 List of Recently Issued Office of Federal and State Materials


IN 1999-03, Rev. 1  Enclosure 4 List of Recently Issued Office of Federal and State Materials  and Environmental Management Programs Generic Communications
and Environmental Management Programs Generic Communications


Date GC No. Subject
Date       GC No.                 Subject


==Addressees==
==Addressees==
11/15/2013 IN-2013-22 Recent Licensing
11/15/2013   IN-2013-22   Recent Licensing             All materials licensees, certificate


Submittals Containing
Submittals Containing       holders, applicants, and other


Personally Identifiable
Personally Identifiable     entities subject to regulation by the


Information All materials licensees, certificate holders, applicants, and other entities subject to regulation by the
Information                 U.S. Nuclear Regulatory


U.S. Nuclear Regulatory
Commission for the use of source, byproduct, and special nuclear


Commission for the use of source, byproduct, and special nuclear
material. All Radiation Control


material. All Radiation Control Program Directors and State
Program Directors and State


Liaison Officers.
Liaison Officers.


10/17/2013 RIS-2013-17 Resuming Normal Interactions Between the
10/17/2013 RIS-2013-17 Resuming Normal               All U.S. Nuclear Regulatory


NRC and NRC
Interactions Between the    Commission (NRC) licensees, NRC and NRC                 certificate holders, permit holders, Stakeholders Following an    and applicants; all Agreement and


Stakeholders Following an Agency Shutdown
Agency Shutdown             Non-Agreement States, and State


All U.S. Nuclear Regulatory
Liaison Officers; and other
 
Commission (NRC) licensees, certificate holders, permit holders, and applicants; all Agreement and Non-Agreement States, and State Liaison Officers; and other


interested stakeholders.
interested stakeholders.


10/09/2013 RIS-2013-16, Supp. 1 Interactions Between the
10/09/2013 RIS-2013-16, Interactions Between the     All U.S. Nuclear Regulatory
 
NRC and NRC Stakeholders During a Lapse of Agency
 
Appropriations


All U.S. Nuclear Regulatory
Supp. 1    NRC and NRC                  Commission (NRC) licensees, Stakeholders During a        certificate holders, permit holders, Lapse of Agency              and applicants; all Agreement and


Commission (NRC) licensees, certificate holders, permit holders, and applicants; all Agreement and
Appropriations              Non-Agreement States, and State
 
Non-Agreement States, and State


Liaison Officers; and other
Liaison Officers; and other
Line 802: Line 1,133:
interested stakeholders.
interested stakeholders.


10/01/2013 RIS-2013-16 Interactions Between the
10/01/2013 RIS-2013-16 Interactions Between the       All U.S. Nuclear Regulatory


NRC and NRC Stakeholders During a
NRC and NRC                 Commission (NRC) licensees, Stakeholders During a       certificate holders, permit holders, Lapse of Agency              and applicants; all Agreement and


Lapse of Agency
Appropriations              Non-Agreement States, and State


Appropriations
Liaison Officers; and other


All U.S. Nuclear Regulatory
interested stakeholders.


Commission (NRC) licensees, certificate holders, permit holders, and applicants; all Agreement and
09/16/2013    IA-03-02    Criteria for Reporting      All Radiation Control Program


Non-Agreement States, and State
Cybersecurity Incidents      Directors and State Liaison


Liaison Officers; and other interested stakeholders.
Officers. All Increased Controls


09/16/2013 IA-03-02 Criteria for Reporting
(IC) materials licensees. All


Cybersecurity Incidents All Radiation Control Program Directors and State Liaison
licensees possessing Category 2 and higher materials.


Officers. All Increased Controls
IN 1999-03, Rev. 1 Enclosure 4 List of Recently Issued Office of Federal and State Materials


(IC) materials licensees.  All licensees possessing Category 2 and higher materials.
and Environmental Management Programs Generic Communications


IN 1999-03, Rev. 1  Enclosure 4 List of Recently Issued Office of Federal and State Materials  and Environmental Management Programs Generic Communications
Date        GC No.                 Subject


Date GC No. Subject
==Addressees==
09/11/2013 RIS-2013-14 Reporting Transactions              All industrial radiography and well


==Addressees==
Involving Temporary            logging licensees, and all Radiation
09/11/2013 RIS-2013-14 Reporting Transactions


Involving Temporary Jobsites to the National
Jobsites to the National       Control Program Directors and


Source Tracking System All industrial radiography and well logging licensees, and all Radiation
Source Tracking System         State Liaison Officers


Control Program Directors and
Note: This list contains the six most recently issued generic communications, issued by the


State Liaison Officers Note:  This list contains the six most recently issued generic communications, issued by the
Office of Federal and State Materials and Environmental Management Programs. A full listing


Office of Federal and State Materials and Environmental Management Programs.  A full listing of  all generic communications may be viewed at the NRC public Web site at the following
of all generic communications may be viewed at the NRC public Web site at the following


address: http://www.nrc.gov/reading-rm/doc-collections/gen-comm/index.html}}
address: http://www.nrc.gov/reading-rm/doc-collections/gen-comm/index.html}}


{{Information notice-Nav}}
{{Information notice-Nav}}

Revision as of 09:06, 4 November 2019

Rev. 1: Exothermic Reactions Involving Dried Uranium Oxide Powder (Yellowcake)
ML14028A175
Person / Time
Site: Beaver Valley, Millstone, Hatch, Monticello, Calvert Cliffs, Dresden, Davis Besse, Peach Bottom, Browns Ferry, Salem, Oconee, Mcguire, Nine Mile Point, Palisades, Palo Verde, Perry, Indian Point, Fermi, Kewaunee, Catawba, Harris, Wolf Creek, Saint Lucie, Point Beach, Oyster Creek, Watts Bar, Hope Creek, Grand Gulf, Cooper, Sequoyah, Byron, Pilgrim, Arkansas Nuclear, Braidwood, Susquehanna, Summer, Prairie Island, Columbia, Seabrook, Brunswick, Surry, Limerick, North Anna, Turkey Point, River Bend, Vermont Yankee, Crystal River, Haddam Neck, Ginna, Diablo Canyon, Callaway, Vogtle, Waterford, Duane Arnold, Farley, Robinson, Clinton, South Texas, San Onofre, Cook, Comanche Peak, Yankee Rowe, Maine Yankee, Quad Cities, Humboldt Bay, La Crosse, Big Rock Point, Rancho Seco, Zion, Midland, Bellefonte, Fort Calhoun, FitzPatrick, McGuire, LaSalle, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant, Crane
Issue date: 03/04/2014
From: Camper L
NRC/FSME/DWMEP
To:
Evans R
References
IN-99-003, Rev 1
Download: ML14028A175 (18)
v • d • e


UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF FEDERAL AND STATE MATERIALS

AND ENVIRONMENTAL MANAGEMENT PROGRAMS

WASHINGTON, D.C. 20555 March 4, 2014 NRC INFORMATION NOTICE 1999-03, REV. 1: EXOTHERMIC REACTIONS INVOLVING

DRIED URANIUM OXIDE POWDER

(YELLOWCAKE)

ADDRESSEES

All operating uranium recovery facilities that produce uranium oxide powder (yellowcake). All

Agreement States with the authority to regulate uranium mills (i.e., Utah, Colorado, Texas, Ohio, Illinois, and Washington).

PURPOSE

The U.S. Nuclear Regulatory Commission (NRC) is issuing this Information Notice (IN) to alert

licensees to recent events involving pressurized drums of dried uranium oxide powder

(yellowcake). This IN is a revision to IN 99-03 which previously discussed industry experience

with pressurized 208-liter (55-gallon) metal drums (hereafter referred to as drums) and related

exothermic reactions involving yellowcake material. It is expected that recipients will review this

information for applicability to their licensed activities and consider actions, as appropriate, to

avoid similar problems. However, suggestions contained in this IN are not NRC requirements;

therefore, no specific action or written response is required.

DESCRIPTION OF CIRCUMSTANCES

The NRC is aware of at least nine different sites that have encountered problems with

pressurized drums. A brief description of two events is provided below. Both events resulted in

uptakes of uranium by workers, and both have similar root causes.

In 2006 at a conventional mill, a worker attempted to open a drum filled with yellowcake that

exhibited bulging. Unbeknownst to the worker, the sealed drum was pressurized. The pressure

was apparently caused by the generation of oxygen gas within the drum from the decomposition

of hydrogen peroxide precipitated yellowcake product. When the drum sealing bolt was

loosened, the pressure in the drum caused the lid to blow off the drum and strike the worker.

The worker received an uptake of uranium, although the uptake was less than regulatory limits.

Records indicate that the drum lid had remained unsealed for three hours after the drum had

been filled with yellowcake product, as required by site procedures.

ML14028A175

IN 1999-03, Rev. 1 The facility operator conducted an investigation and identified the root cause as less than

adequate procedures. The facility operator concluded that the product did not completely cool, or off-gas, within the three-hour time interval. Corrective actions included revising the

applicable procedure to extend the drum sealing interval from three to four hours and providing

additional training to site workers.

The second incident occurred in 2012 at a uranium refinery in Canada while workers were

opening a drum of yellowcake supplied by an in-situ uranium recovery facility. When a refinery

worker loosened the ring clamp on the drum lid, the pressure in the drum (produced by an

unexpected build-up of oxygen gas) caused the lid to buckle. The escaping gas ejected

approximately 20 kilograms (44 pounds) of dried, powder-like yellowcake material from the

drum. The incident resulted in three refinery workers receiving uptakes of uranium. The

refinery operator subsequently identified several other drums, supplied by the same uranium

recovery facility, which also showed signs of internal pressurization. The uranium recovery

facility operator conducted an investigation to determine the causes of the pressure buildup in

the drums. The facility operator concluded that the drums became pressurized due to:

(1) inadequate cooling and venting of the dried yellowcake product prior to sealing the drum lid;

and (2) inadequate drying of the yellowcake product (i.e., inadequate dryer residence time).

The NRC later determined that inadequate procedures were contributing causes of the event.

BACKGROUND

The NRC issued IN 99-03 on January 29, 1999, to alert licensees to incidents involving

exothermic reactions that occurred after packaging hydrogen peroxide precipitated yellowcake

powder into drums. The original IN discussed two types of exothermic reactionsoxygen

generation as a byproduct of the drying process and hydrocarbon contaminants reacting with

the yellowcake product. At that time, industry took corrective actions which included leaving the

drums unsealed for a minimum of three hours and preventing oil and grease from being

introduced into the precipitation and drying circuits.

Since 1999, the uranium recovery industry has experienced several more pressurized drum

events. Because these events continued to occur, the causes may not be well understood by

the industry. Further, past actions taken by industry to prevent pressurized drums may not have

been fully effective.

The IN 99-03 also advised facility operators about exothermic reactions of yellowcake with

organic materials. These reactions can cause spontaneous combustion of flammable materials

such as oil that may enter the process circuit. Refer to Enclosure 1 for an expanded discussion

of this hazard.

DISCUSSION

In both the 2006 and 2012 instances, the fundamental cause of the pressurized drums was

attributed to the build-up of oxygen gas in sealed containers. The oxygen gas apparently

originated from the decomposition of residual uranyl peroxide hydrates or hydrogen peroxide in

the dried yellowcake product. Both incidents indicate that the drum lids may have been sealed

onto the drums prior to the completion of the uranyl peroxide hydrate decomposition process.

Both sites used a minimum three-hour time delay as mentioned in IN 99-03; however, this time

delay must have been insufficient based on site-specific operational parameters.

IN 1999-03, Rev. 1 In early 2013, the NRC established a working group to: (1) review the generic implications of the

most recent pressurized drum incident including the reasons why drums continue to become

pressurized; (2) identify industry experience with pressurized drums; and (3) ascertain whether

there were any related trends across the industry. The working group consisted of NRC staff, industry representatives, and subject-matter experts. The NRC used the findings of the working

group, as well as information solicited from 14 current and former uranium recovery facilities, in

the development of this revision to IN 99-03. As part of the revision process, the NRC is also

correcting some of the chemical nomenclature used to describe the thermal decomposition

process provided in the original IN. More importantly, as a result of industry experience gained

since the NRC issued IN 99-03, this revised IN recognizes a broader range of relevant factors

that could result in pressurized drums.

The working group developed a questionnaire that was submitted to various national and

international companies having direct experience processing or handling yellowcake. The

working group received 14 responses from various entities. The responses were subdivided

into two basic categoriessites using ammonia precipitation circuits and sites using hydrogen

peroxide precipitation circuits. The survey responses provided the working group with detailed

information about dryer and packaging operations at each site as well as industry experience

with pressurized drums. If the facilities had experienced pressurized drum problems, the survey

asked the respondents to explain the possible causes for the pressurizations. As discussed in

Enclosure 1, sites using the ammonia precipitation process with high-temperature calciners

have not experienced pressurized drums. Only sites using the hydrogen peroxide precipitation

circuits have experienced pressurized drums. Enclosure 3 provides a matrix of the operating

parameters for the 11 sites using hydrogen peroxide precipitation circuits and the suspect

causes of past drum pressurizations.

The working group concluded that many drum pressurizations were apparently caused by

changes in the chemical composition of the yellowcake product after it had been placed into a

sealed container. The level of pressurization appears to be related to the cooling and venting

time of the product prior to sealing of the drum. The working group determined that the

minimum required cooling and venting time for recently dried yellowcake in an unsealed drum

depends on the type of dryer, drying temperature, residence time (time product remains in

dryer), hold-up time (time interval between completion of drying cycle and when product is

placed into drum), dryer feed rate, and product moisture content. These various operational

parameters may ultimately contribute to oxygen gas buildup in yellowcake drums.

As noted earlier, multiple operators reported that they had experienced pressurized drum

problems, but the specific chemical reactions causing the pressurizations were not always clear.

In their survey responses, facility operators provided two general corrective actions to address

the pressurized drum issueincreasing the cooling/venting time before the lid is sealed onto the

drum and conducting visual inspections of the drums for signs of pressurization prior to

shipment. These operators found that increasing the cooling and venting time before sealing

the drums and inspecting the drums before shipment appear to have resolved the problem. A

range of cooling and venting times was reported, from 4 to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> (see Enclosure 3). In

several instances, facility operators chose to extend the cooling and venting times in response

to past experiences with pressurized drums. Each facility operator should evaluate their

operations and decide how to implement site-specific corrective actions as necessary to prevent

pressurized drums.

IN 1999-03, Rev. 1 The working group found that many operators did not measure their product temperature

directly, and that discrepancies existed between the maximum dryer temperature and the

chemical composition of their final product. It is product temperature, not dryer temperature, which ultimately drives the thermal decomposition process. The working group concluded that, for typical U.S. facilities utilizing hydrogen peroxide precipitation and drying temperatures below

800 degrees Celsius (°C) [1472 degrees Fahrenheit (°F)], a cooling and venting period of 12 to

24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> appears sufficient to prevent oxygen gas buildup in yellowcake drums. Above dryer

temperatures of approximately 800 °C (1472 °F), it is expected that the uranyl peroxide product

will be converted to UO3 (uranium trioxide) product. Oxygen production is not expected to occur

after the uranyl peroxide product has been completely converted to UO3 product. For dryers

operating below 800 °C (1472 °F), shorter periods of yellowcake cooling and venting prior to

securing the drum lid may be ineffective to prevent oxygen buildup in sealed drums.

CONCLUSION

Based on its working group findings and questionnaire responses, NRC concludes that:

The most likely cause for the drum pressurization events was attributed to continued

decomposition of dried uranium product and the production of oxygen after the drums have

been filled and sealed.

For facilities utilizing hydrogen peroxide precipitation and drying temperatures below 800°C

(1472°F), a cooling and venting period of at least 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> appears to be necessary to

prevent oxygen gas build-up in yellowcake drums. Shorter periods may be ineffective.

Many operators have elected to implement a cooling and venting time of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

To prevent drum pressurizations, facility operators have implemented two basic corrective

actionsincreasing the cooling/venting time before the lid is sealed and conducting visual

inspections of the drums for signs of pressurization prior to shipment.

Facility operators should evaluate the potential for organic-based exothermic reactions, as

discussed in Enclosure 1. Facility operators should develop protocols to minimize the

potential for organics, including oils and greases, to enter into yellowcake process circuits.

In addition to being industrial and radiological hazards to workers, shipments of uranium

yellowcake in packages with internal pressures that reduce the effectiveness of the

packages are prohibited by U.S. Department of Transportation regulations. Enclosure 1 provides additional information about these regulations.

IN 1999-03, Rev. 1

CONTACT

This information notice requires no specific action or written response. If you have any

questions about the information in this notice, please contact one of the technical contacts listed

below.

/RA Aby Mohseni for/

Larry W. Camper, Director

Division of Waste Management

and Environmental Protection

Office of Federal and State Materials

and Environmental Management Programs

Contacts: Robert Evans, Region IV

(817) 200-1234 Robert.Evans@nrc.gov

Ronald Burrows, FSME

(301) 415-6443 Ronald.Burrows@nrc.gov

Thomas McLaughlin, FSME

(301) 415-5869 Thomas.Mclaughlin@nrc.gov

Enclosures:

1. Detailed Technical Discussion

2. Bibliography

3. Survey Results for Facilities Using Hydrogen Peroxide Precipitation

4. FSME Recently Issued Generic Communications

IN 1999-03, Rev. 1

CONTACT

This information notice requires no specific action or written response. If you have any

questions about the information in this notice, please contact one of the technical contacts listed

below.

/RA Aby Mohseni for/

Larry W. Camper, Director

Division of Waste Management

and Environmental Protection

Office of Federal and State Materials

and Environmental Management Programs

Contacts: Robert Evans, Region IV

(817) 200-1234 Robert.Evans@nrc.gov

Ronald Burrows, FSME

(301) 415-6443 Ronald.Burrows@nrc.gov

Thomas McLaughlin, FSME

(301) 415-5869 Thomas.Mclaughlin@nrc.gov

Enclosures:

1. Detailed Technical Discussion

2. Bibliography

3. Survey Results for Facilities Using Hydrogen Peroxide Precipitation

4. FSME Recently Issued Generic Communications

ML14028A175 RIV:DNMS/RSFS C:DNMS/RSFS DD:DNMS D:DNMS

RJEvans DBSpitzberg VHCampbell AVegal

/RA/ Via email Via email Via email

10/24/13 11/06/13 01/02/14 12/31/13 FSME:DMSSA FSME:DWMEP DWMEP/DURLD C:DWMEP/DURLD

ARMcIntosh RABurrows TGMcLaughlin BvonTill

Via email Via email Via email Via email

10/24/13 10/28/13 10/28/13 10/29/13 NSIR FSME:DMSSA FSME:DILR OGC/GCLR/RMR

CGrigsby DWhite JCai TLStokes

Via email Via email Via email Via email

10/28/13 10/24/13 11/05/13 12/17/13 OE/EB NMSS DD:DWMEP/DURLD D: MSSA

TMarenchin HJGonzalez JMoses for

DPersinko

LDudes

Via email Via email /RA/ /RA/

11/14/13 11/08/13 01/24/14 02/28/14 D:DWMEP

AMohseni for

LWCamper

/RA/

03/04/14 OFFICIAL RECORD COPY

IN 1999-03, Rev. 1 Enclosure 1 Detailed Technical Discussion

At least nine uranium recovery facilities have experienced pressurized drum events. The

reasons for these pressurization events varied from facility to facility (see Enclosure 3 for a

complete list of suspected causes for the drum pressurizations). The actual causes of previous

drum pressurization events are still in question. The causes may include the decomposition of

free hydrogen peroxide (H2O2) carried over with the dried yellowcake, decomposition of uranyl

peroxide product, production of steam from residual water, reaction of uranium compounds with

inorganics, or perhaps a combination of these causes. In addition, a reliable and accurate

chemical test for free hydrogen peroxide in yellowcake has not been validated which would

allow facilities to precisely determine the actual causes for these types of incidents.

The NRCs working group identified several topics that are discussed in detail below. The

working groups findings are based on the information that was identified or made available to

the group, in part, through uranium recovery facility responses to surveys. Two of the 14 surveys were conducted for sites that are no longer in service, meaning that some of the

information presented in the survey may be based on individual recollections versus formal

documentation.

Precipitation with Ammonia and Use of a Calciner to Dry Yellowcake

Three facility operators out of 14 reported using ammonia precipitation instead of hydrogen

peroxide precipitation. These operators also dried their precipitated product at high

temperatures in a calciner. There was no evidence that the ammonia precipitation process, in

combination with a calciner, had ever resulted in pressurized drums. Therefore, these types of

facilities are excluded from the current discussion about H2O2 precipitated product.

The Chemistry of Hydrogen Peroxide Precipitated Yellowcake

Facilities using the hydrogen peroxide precipitation process may create pressurized drums if

their operational processes are not appropriately controlled. The chemical product of

precipitation depends on the temperature of the solution undergoing precipitation. Based on the

survey results, hydrogen peroxide precipitation typically occurs under ambient conditions. At

temperatures below 50°C (122°F), the precipitate is generally of the form UO4

  • 4H2O (uranyl

peroxide tetrahydrate). The final desired product is UO4

  • 2H2O (uranyl peroxide dihydrate).

Converting the tetrahydrate form (UO4

  • 4H2O) of uranyl peroxide to the desired dihydrate form

(UO4

  • 2H2O) occurs quickly under typical drying conditions. For example, laboratory samples

of UO4

  • 4H2O will dehydrate to UO4
  • 2H2O in about one hour when dried at 100°C (212°F)

(product temperature, not dryer temperature). Typical maximum dryer temperatures at facilities

using hydrogen peroxide precipitation range from 130°C (266°F) to 649°C (1200°F), with most

facilities operating well below 300°C (572°F). Of course, laboratory studies do not take into

account industrial scale production issues such as difficulty in ensuring uniform drying

temperature of the product and desired moisture content. The composition of the final product

will depend on a variety of drying conditions including dryer temperature, heating time, heating

rate, feed rate, product temperature, water content, hydrogen peroxide content, pressure, etc.

As a result of all of these variables affecting the final product, it is likely that other chemical

species are forming. The compound UO4

  • 2H2O does not undergo dehydration like UO4 *

IN 1999-03, Rev. 1 Enclosure 1 4H2O, but rather loses oxygen and water simultaneously (i.e., it decomposes to another

compound). Uranium trioxide (UO3) will form at around 500°C (932°F) (product temperature),

so for most facilities this reaction is not expected to occur. However, a range of uranium

compounds between UO4

  • 2H2O and UO3, are likely to form under current typical drying

temperatures and drying times. As a group, these intermediate compounds are referred to as

amorphous UOX, where (3x3.5). While UO4

  • 2H2O is considered the most stable form of

uranyl peroxide, amorphous UOX is considered unstable with respect to the decomposition to

UO3 even at room temperature. Table 1 demonstrates one example of dryer temperature

versus product formation.

Table 1 Drying Temperature and product composition: Phases identified in hydrogen peroxide

precipitated yellowcake dryer product by X-ray diffractometry1 Dryer

Sample Discharge Amorphous

UO4*2H2O UO3 U3O8 ID Temperature UOx

(°C)

001 as-is X

015 125 X

002 131 X

022 145 X

016 150 X

003 175 X

017 175 X

004 225 Trace X

005 275 X

006 325 X

018 375 X

019 400 X

008 425 X

020 425 X

021 450 X

023 475 X

010 525 X 4.30%

011 575 X

012 625 X

014 769 X

1 empty cells indicate not detected

In addition, amorphous UOX has been reported to react with free water to liberate oxygen gas.

It is not clear whether this is a reaction resulting in UO3, or some other type of reaction.

Experiments to date have demonstrated this effect by mixing relatively large amounts of water

with amorphous UOX. Figure 1 demonstrates this phenomenon. It is unknown what effect

residual moisture at levels typical of uranium recovery facilities has on amorphous UOX. It has

also been found that neither UO4

  • 2H2O nor UO3 react with water in this manner.

IN 1999-03, Rev. 1 Enclosure 1 Figure 1 Product chemistry: Dried hydrogen peroxide precipitated yellowcake reactivity with water

Addition of Excess Hydrogen Peroxide During Precipitation Process

A stoichiometric excess of hydrogen peroxide is required to optimize precipitation of uranyl

peroxide yellow cake. The degree of excess is determined by the composition of the uranium

bearing solution (feed stock for precipitation). Molybdenum, vanadium, and other reactive

metals contained in the feed stock react with hydrogen peroxide to form soluble complexes. In

addition, some fraction of hydrogen peroxide may decompose during the precipitation process.

Facility operators should be aware that some of this excess hydrogen peroxide may be carried

over into the drying process. The working group understands that an effective drying cycle

should eliminate this excess hydrogen peroxide.

Stability of Hydrogen Peroxide in the Presence of Uranyl Peroxide Solids

Precipitation of dissolved uranium by the addition of hydrogen peroxide is a well-known and

common process within the uranium recovery industry. It has been demonstrated that this

precipitation process is a reversible chemical reaction. One consequence is that an excess of

dissolved hydrogen peroxide must be maintained in solution to drive the precipitation reaction to

completion and, hence, to minimize dissolved uranium losses in resulting waste streams. The

use of excess hydrogen peroxide is a common practice in the uranium industry where the

maintenance of low uranium tails in the precipitation process is desired. The filtrate fluids

associated with the resulting uranyl peroxide slurry must also contain a modest but finite

concentration of dissolved hydrogen peroxide to avoid dissolution of uranyl peroxide solids. As

a result, moist uranyl peroxide slurries entering any drying equipment may contain a small but

finite concentration of dissolved hydrogen peroxide.

IN 1999-03, Rev. 1 Enclosure 1 Industrial hydrogen peroxide solutions are relatively stable as long as they are properly stored at

moderate temperatures, maintained at a pH below 5, and do not come into contact with

impurities, especially metals. Uranyl peroxide solids are typically precipitated at low pH (2-4)

under ambient conditions in the presence of small amounts of excess hydrogen peroxide. The

resulting slurries are usually pressed and washed at ambient conditions in a filter press

operation to remove soluble filtrate impurities from the filter cake. The acidity of the wet cake

will likely remain low keeping any residual free hydrogen peroxide relatively stable. This free

hydrogen peroxide will, however, begin to decompose over time to oxygen gas and water as it

remains in contact with the uranyl peroxide solids. The rate of this decomposition is unknown

and, if a test were to be performed to measure residual free hydrogen peroxide, it would have to

be performed on fresh uranyl peroxide solids to minimize the subsequent decomposition of

hydrogen peroxide. This may explain why it has been difficult to measure free hydrogen

peroxide in filter cake samples as the time to perform the tests might be too long for the

hydrogen peroxide to remain stable and not decompose.

The other condition under which hydrogen peroxide can decompose is elevated temperature.

Hydrogen peroxide will slowly decompose at room temperature. The rate of decomposition will

increase as temperature increases. If any free hydrogen peroxide enters the dryer it will likely

decompose as the temperature of the uranyl solids increases. However, if the free hydrogen

peroxide fails to instantly decompose upon entry into the drying chamber, the residual hydrogen

peroxide may be captured in the uranyl peroxide crystalline structure during the drying process.

Facility operators should try to minimize the amount of residual free hydrogen peroxide in the

product prior to the drying process.

Drying Temperature of Uranyl Peroxide in Rotary Vacuum Dryers

While different dryer types and precipitation processes are utilized in the industry, the majority of

facility operators uses hydrogen peroxide precipitation and employs some type of rotary vacuum

dryer that operates at a relatively low temperature. These systems are typically batch

operations with ambient temperature yellowcake slurry introduced into a pre-heated chamber at

atmospheric pressure. The chamber is then sealed and depressurized. The sub-atmospheric

pressure within the chamber (i.e., the vacuum) does not remain constant during the drying

cycle. Rather, the pressure continuously decreases as water vapor is liberated and evacuated

from the chamber via the vacuum pump circuit. The vapor capacity of the vacuum pump limits

the operational vacuum (pressure) within the chamber. During the period in which boiling of

free moisture is the principle process within the drying chamber, the temperature of the

yellowcake solids is tied to the boiling point of water at that pressure. Near the end of the drying

cycle, sufficient free moisture has been removed and the pressure within the chamber

decreases and approaches a steady state. As this condition is reached, the yellowcake

temperature rapidly rises toward the temperature of the heating surfaces within the drying

chamber. Essentially, there are two phases to the batch vacuum drying cycle. The first is

controlled by the temperature-pressure relationship of boiling water and the capacity of the

vacuum pump to remove water vapor. In the second phase, the vacuum pump vapor capacity

is no longer limiting and the temperature of the solids is controlled by heat transfer between the

vessel surfaces and the yellowcake solids.

Regardless of the temperature of the dryer, there is still a minimum time necessary where

moisture is driven off before the yellowcake is heated to above 100°C (212°F), the point where

UO4

  • 2H2O starts to be created. Continued heating of the product can therefore lead to

IN 1999-03, Rev. 1 Enclosure 1 conversion to hydrated UO4 (uranyl peroxide); however, there is likely limited time for conversion

of UO4 to UO3 (uranium trioxide). As such, any remaining UO4 that does not convert to the

more stable UO3 could lead to drum pressurization. Therefore, it is important for facility

operators to control the drying process parameters, including temperature, to control product

chemistry.

Potential Reactions for Uranyl Peroxide Yellowcake in the Presence of Organic Matter

Five of 11 respondents that used hydrogen peroxide (H2O2) precipitation process reported that

they have experienced exothermic reactions in yellowcake due to organic contamination, and

five of 11 reported that they pay special attention to hydrocarbon contamination.

The reaction of H2O2 with organics is a well-known but complex reaction. When H2O2 is in the

presence of most organic matter, the hydrogen peroxide can react with the organic to form

organic peroxide compounds which are usually unstable or can cause the organic to be

oxidized, i.e., chemically burned. When organic peroxide compounds are formed they have

been known to detonate, i.e., cause spontaneous combustion or cause oxidation reactions to

occur. These latter reactions result in the evolution of heat (from the burning of the organics)

and the evolution of CO2 (carbon dioxide), CO (carbon monoxide), and H2O (water) depending

upon the completion of the reaction. When hydrogen peroxide reacts in this way with organics

there is always a signature gas evolution which will be indicative of the reaction taking place.

Under certain conditions of temperature, metal catalysts, and reactant concentrations, organics

can react with the hydrogen peroxide. This interaction results in a complex, multi-step reaction

which typically forms many intermediate hydroxyl radicals as the oxidation reaction is on-going.

This process can be simplified as follows:

H2O2 + Organics (CxHy) A B C. CO2 + CO + H2O + Heat

Where A, B, C, etc. are the intermediate compounds that form prior to full oxidation (compounds

that contain OOH- or OH- radicals). The end result of this chain of reactions is that the organic is

chemically burned and the signature off-gases of this reaction are CO2 + CO + H2O plus heat.

When these intermediate compounds form, they combine unstably bound oxygen together with

hydrogen and carbon in the same molecule, and these organic peroxides can ignite easily and

burn rapidly and intensely. When organic peroxide begins to decompose, the heat produced by

its decomposition may not dissipate as quickly as it is generated which can result in increasing

temperatures which further intensifies the rate of exothermic decomposition. This can create a

dangerous situation known as a self-accelerating decomposition.

When wet yellowcake is introduced into a dryer system it is important that the product not

contain organic matter as the reactions of any residual H2O2 or decomposed uranyl peroxide

hydrate can occur. For trace amounts of organics, this will likely not be an issue as the dryer

can dissipate any heat that is formed by these reactions, or the organic will be driven off by the

heat of the drying operation. If, however, larger amounts of organics were to be introduced into

the dryer, a self-accelerating reaction can occur where the heat cannot be dissipated, high

temperatures are generated, and a violent reaction is possible. This has occurred in some dryer

facilities when there was a mechanical failure in the dryer which caused large quantities of

organics such as oil to be introduced into the dried yellowcake at elevated temperatures.

IN 1999-03, Rev. 1 Enclosure 1 If the yellowcake is dried at high temperatures as in a calciner, the problem of organic reactions

is less likely since the higher temperatures encountered in the dryer will drive off the volatile

organics and decompose any organic peroxides that might have been formed. In a low

temperature dryer, some organics can remain with the dried uranyl peroxide hydrates and

become unstable in the dryer or when removed from the dryer. This could have consequences

for drummed material as the decomposition of any organic peroxide can generate heat plus

CO2, CO, and H2O. The consequence of this could be the slow generation of combustion gases

(for small amounts of organics) or a more violent reaction if large amounts of organic peroxides

begin to decompose and generate heat which can cause a self-accelerating reaction to occur.

In summary, facility operators should be aware that organic reactions are possible with

yellowcake product, and operators should try to locate and eliminate potential sources of

organic matter from entering into the precipitation and drying circuits.

Packaging (Drumming) of Yellowcake

Dried yellowcake is almost exclusively stored and shipped in 208-liter (55 gallon) steel drums.

In the U.S., the drums must meet U.S. Department of Transportation specifications if the facility

operator plans to ship yellowcake material in the drums. Facilities use new drums, reconditioned (used) drums, or a combination of both, depending on drum availability and/or

cost. It is critical that operators ensure that drums used to ship yellowcake do not have any

organic material (such as oil or grease) in them. Employees must be trained and informed

about the serious complications of organic material in drums to ensure that drums used for

shipment are received from the suppliers in acceptable condition and the facility does not

inadvertently use such drums for another purpose that could result in organic material

contamination prior to filling with yellowcake.

Information Notice 99-03 cautioned that new drums and lids could be a potential causal factor in

drum pressurization incidents due to the tighter seal of such drums compared to reconditioned

drums and lids. The tighter seal could prevent the off gassing from escaping the drum, thereby

leading to pressurization. Although this condition is still possible with new drums or

reconditioned drums that happen to have better seals, the working group believes that

appropriate controls, such as adequate cooling and venting times, will prevent any significant

potential for gas build up and drum pressurization.

To limit the potential of shipping a drum of yellowcake that has been pressurized due to an

unexpected cause, including a human factor, it is strongly suggested that operators include as

part of their final pre-shipment inspection a procedure to check each drum for pressurization.

This can be accomplished by a visual inspection of drum lids and a physical check by pushing

on the lid and checking for deflection and/or tapping the lid with a rubber mallet to assess

deflection and the tone resulting from the tapping. Any drums suspected of pressurization

should be returned to the drumming area and carefully depressurized and opened to confirm

conditions and causes, if appropriate. Operators should also develop controls to manage the

risk of the addition of excess free moisture/water to open drums of product. The working group

is aware that one study indicated that pressure is generated from the addition of water into

amorphous product. For example, operators should avoid spraying unsealed drums with water

to avoid the possibility of adding free water to the dried product.

IN 1999-03, Rev. 1 Enclosure 1 Shipment of Pressurized Drums

A facility operator who ships pressurized drums may be in violation of U.S. Department of

Transportation regulations. In particular, the shipment of pressurized drums may violate

regulations 49 CFR 173.24(b)(3) and 49 CFR 173.475(a). Regulation 173.24(b)(3) states that

there will be no mixture of gases or vapors in the package which could, through any credible

spontaneous increase of heat or pressure, significantly reduce the effectiveness of the

packaging. Regulation 173.475(a) states that, before each shipment of any Class 7 (radioactive) materials package, the offeror (the facility operator who offers the drum for

shipment) must ensure, by examination or appropriate tests, that the packaging is proper for the

contents to be shipped. Based on these two regulations, a standard metal drum may not be the

proper package for pressurized uranium product because the pressurization reduces the

effectiveness of the packaging. Further, the packaging process may be inadequate if it allows

gases and vapors to increase the internal pressure of the package (the drum), resulting in rapid

and uncontrolled depressurization when the package is opened.

Facility operators should also be aware of regulation 49 CFR 173.22(a)(4). This regulation

requires persons who offer hazardous material for transportation to comply with the

manufacturers instructions for packaging. This regulation applies to drums that have been

certified by the Department of Transportation and marked or stenciled accordingly. Many drum

manufacturers provide specific instructions for proper closure of the drum, including a

requirement to torque the drum seals. Facility operators should be aware of any specific

closure instructions provided by the manufacturer or distributer of their certified drums, if these

drums are used to transport yellowcake material.

Suggestions for the Uranium Recovery Industry

The working group suggests that the information presented in this IN be supplemented by the

uranium recovery industry. The working group suggests that the industry consider expanding

the information by determining the chemical species of their product, product temperature

versus holding time prior to sealing, impact of excess hydrogen peroxide on the decomposition

process, rate of moisture reduction in the dryer, optimum drying parameters (feed rate, temperature, and residence time), and development of procedures and training program to alert

workers of the potential risks. For example, facility workers should be made aware that drying is

a dynamic process and the change of any process parameter, such as feed rate or dryer

temperature, may result in a product that is incompletely dried. Facility operators should use

this information to establish site-specific parameters to assure that drum pressurizations do not

occur.

Facility operators should consider establishing procedures or other protocols to identify and

manage pressurized drums. These procedures should include inspections of the drums for both

pressurization and integrity prior to transport. This inspection should be complete even if the

drum is stored for an extended period of time prior to actual shipment. Finally, the receiver of

shipped drums should also inspect drums for pressurization upon receipt and before opening a

sealed drum.

IN 1999-03, Rev. 1 Enclosure 2 Bibliography

Boggs, J. E., & El-Chehabi, M. (1957). The thermal decomposition of uranium peroxide, UO4 *

2H2O. Journal of the American Chemical Society, 79(16), 4258-4260.

Brady, L. J., Susano, C. D., & Lawson, C. E. (1948). Chemical and physical properties of

uranium peroxide. Report AECD-2366. Oak Ridge, TN: U.S. Atomic Energy

Commission, Technical Information Branch.

Cordfunke, E. H. P. (1961). -UO3: Its preparation and thermal stability. Journal of Inorganic

and Nuclear Chemistry 23(3-4), 23, 285-286.

Cordfunke, E. H. P., & Aling, P. (1963). Thermal decomposition of hydrated uranium peroxides.

Journal of the Royal Netherlands Chemical Society, 82, 257-263.

Cordfunke, E. H. P., & Van Der Giessen, A. A. (1963). Pseudomorphic decomposition of

uranium peroxide into UO3. Journal of Inorganic and Nuclear Chemistry 25(5), 553-554.

El-Chehabi, M. (1957). Decomposition of uranium peroxide. (Masters Thesis). The University

of Texas.

Gayer, K. H., & Thompson, L. C. (1958). The solubility of uranium peroxide in acidic and basic

media at 25 °C. Canadian Journal of Chemistry 36(12), 1649-1652.

Gupta, C. K., & Singh, H. (2003). Uranium resource processing: Secondary resources. Berlin:

Springer-Verlag.

Harrington, C. D., & Ruehle, A. E. (Eds.). (1959). Uranium production technology. Princeton, N.J.:Van Nostrand.

Hausen, D. M. (1998). Characterizing and classifying uranium yellow cakes: A background.

JOM 50(12), 45-47.

Katz, J. J., & Rabinowitch, E. (1951). The chemistry of uranium: The element, its binary and

related compounds (Part I). New York, NY: McGraw-Hill Book Company, Inc.

Leininger, R. F., Hunt, J. P., & Koshland, D. E. (1958). Composition and thermal decomposition

of uranyl peroxide (Paper 69). Chemistry of uranium: Collected papers, TID-5290,

Book 2 (704-721). Oak Ridge, TN: U.S. Atomic Energy Commission Technical

Information Service Extension

Merritt, R.C. (1971). The extractive metallurgy of uranium. Golden, CO: Colorado School of

Mines Research Institute.

Metzger, R., et al. (1997). Solubility characterization of airborne uranium from an in-situ

uranium processing plant. Health Physics 72(3), 418-422.

Moore, R. L., & Watts Jr., R. A. (1952). Production of UO3 by calcination of uranyl peroxide, Document No. HW-26531. Richland, WA: Hanford Works.

IN 1999-03, Rev. 1 Enclosure 2 Patton, F. S. (1963). Enriched uranium processing. New York, NY: Macmillan Co.

Rich, R. L. (2007). Inorganic reactions in water. Berlin: Springer-Verlag.

Rodgers, C., & Dyck, B. (2012). Uranium peroxide precipitate drying temperature relationships.

CIM Journal 3(3), 149-156.

Sato, T. (1961). Uranium peroxide hydrates. Die Naturwissenschaften 48(21), 668.

Sato, T. (1963). Preparation of uranium peroxide hydrates. Journal of Applied Chemistry 13(8),

361-365.

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65(2), 370-371.

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Walenta, K. (1974). On studtite and its composition. American Mineralogist 59, 166-171.

The data for Table 1 comes from Laboratory Characterization of Dryer Test Products, Cameco

Corporation, Gerhard Heinrich, John Krause, Mike Murchie, November 2009.

The data for Figure 1 comes from Laboratory Characterization of Dryer Test Products, Cameco Corporation, Gerhard Heinrich, John Krause, Mike Murchie, November, 2009 but was

adapted and updated for a presentation to the CNSC: Rabbit Lake UOC Drying Process, Cameco Corporation, Kirk Lamont, November 2012.

IN 1999-03, Rev. 1 Enclosure 3 Survey Results for Facilities Using Hydrogen Peroxide Precipitation

Time in Dryer Dryer Yellowcake Temp Cooling and Percent (%) Have You Experienced Suspected Causes of

(hours) Temp (oC) (oC) When Venting Moisture in Dried Any Drum Drum Pressurizations

Barreled Time (hours)* Yellowcake Pressurizations?

12-16 232 Not measured >12 0 - 1.5 No

Limit of 2

18-20 164 130 24-72 <1 Yes Decay of residual H2O2

36-48 160 160 24 <1 Yes Not determined

21-22 163 138 24 1-8, Yes Moisture vaporizing

Typically (steam)

3-5

6 130 <80 Described as <2 No

minimal

16-20 235 Not measured >12 0.5-1.5 Yes Decay of H2O2 and

Limit of 2 sealing drums too soon

4.5-6 649 66 Previously 3, 1-4 Yes Cooling time and drying

changed to 24 time too short

6 371 < 371 4 no moisture Yes Decay of H2O2 Unknown Not given Unknown a number of Not measured Yes Excess H2O2 added

hours during precipitation

20-30 150 <90 12 1-4 w/w Yes Hot yellowcake added

to moist drum

1.5 245 80 >3 0.5-2.0 Yes Unknown

  • Cooling and venting times are current times, or the most recent times for facilities that are no longer in operation. Several sites increased their

cooling and venting times in response to previous pressurized drum events or in response to IN 1999-03.

IN 1999-03, Rev. 1 Enclosure 4 List of Recently Issued Office of Federal and State Materials

and Environmental Management Programs Generic Communications

Date GC No. Subject

Addressees

11/15/2013 IN-2013-22 Recent Licensing All materials licensees, certificate

Submittals Containing holders, applicants, and other

Personally Identifiable entities subject to regulation by the

Information U.S. Nuclear Regulatory

Commission for the use of source, byproduct, and special nuclear

material. All Radiation Control

Program Directors and State

Liaison Officers.

10/17/2013 RIS-2013-17 Resuming Normal All U.S. Nuclear Regulatory

Interactions Between the Commission (NRC) licensees, NRC and NRC certificate holders, permit holders, Stakeholders Following an and applicants; all Agreement and

Agency Shutdown Non-Agreement States, and State

Liaison Officers; and other

interested stakeholders.

10/09/2013 RIS-2013-16, Interactions Between the All U.S. Nuclear Regulatory

Supp. 1 NRC and NRC Commission (NRC) licensees, Stakeholders During a certificate holders, permit holders, Lapse of Agency and applicants; all Agreement and

Appropriations Non-Agreement States, and State

Liaison Officers; and other

interested stakeholders.

10/01/2013 RIS-2013-16 Interactions Between the All U.S. Nuclear Regulatory

NRC and NRC Commission (NRC) licensees, Stakeholders During a certificate holders, permit holders, Lapse of Agency and applicants; all Agreement and

Appropriations Non-Agreement States, and State

Liaison Officers; and other

interested stakeholders.

09/16/2013 IA-03-02 Criteria for Reporting All Radiation Control Program

Cybersecurity Incidents Directors and State Liaison

Officers. All Increased Controls

(IC) materials licensees. All

licensees possessing Category 2 and higher materials.

IN 1999-03, Rev. 1 Enclosure 4 List of Recently Issued Office of Federal and State Materials

and Environmental Management Programs Generic Communications

Date GC No. Subject

Addressees

09/11/2013 RIS-2013-14 Reporting Transactions All industrial radiography and well

Involving Temporary logging licensees, and all Radiation

Jobsites to the National Control Program Directors and

Source Tracking System State Liaison Officers

Note: This list contains the six most recently issued generic communications, issued by the

Office of Federal and State Materials and Environmental Management Programs. A full listing

of all generic communications may be viewed at the NRC public Web site at the following

address: http://www.nrc.gov/reading-rm/doc-collections/gen-comm/index.html


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