Information Notice 1999-03, Exothermic Reactors Involving Dried Uranium Oxide Powder (Yellowcake)

Exothermic Reactors Involving Dried Uranium Oxide Powder (Yellowcake)
	ML031210421
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:	01/29/1999
From:	Greeves J; NRC/NMSS/DWM
To:	;
References
	IN-99-003, NUDOCS 9901250252
	Download: ML031210421 (10)
	v • d • e

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR MATERIAL SAFETY AND SAFEGUARDS

WASHINGTON, D.C. 20555

January 29, 1999 NRC INFORMATION NOTICE 99-03:

EXOTHERMIC REACTIONS INVOLVING DRIED

URANIUM OXIDE POWDER (YELLOWCAKE)

Addressees

All operating uranium recovery facilities that produce uranium oxide powder (U308)(yellowcake).

Purpose

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

licensees to recent incidents involving strong exothermic reactions that occurred during the

packaging of low-temperature or vacuum-dried U30, hydrogen peroxide precipitated

(yellowcake) powder. 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 nor written response is required.

Description of Circumstances

On four separate occasions involving different licensees, dry U308 hydrogen peroxide

precipitated (yellowcake) powder, packaged in 208.2 liter (55 gallon) drums, was observed to

have undergone strong exothermic reactions after the drying and packaging process. These

scenarios can be placed into two categories: 1) generation of oxygen as a byproduct of the

production process; and 2) hydrocarbon contaminants reacting with U308 hydrogen peroxide

precipitated (yellowcake) product. The incidents date as far back as 1984 and as recently as

July 1998.

Category 1: On two separate occasions, licensees experienced expansion of the sealed drums

from generation of oxygen from the decay of hydrogen peroxide. In the production process, hydrogen peroxide is used to precipitate uranium in the form of uranium oxide (UxOx). This

precipitate is then pressed through a filter, dried in an oven and packaged in drums for

shipment. Even though the dryer temperatures reached 537.70 C (10000F), converting the

precipitate to uranate peroxide (U04-2H 20), sufficient hydrogen peroxide either remained in the

product or was generated to develop oxygen pressure by the following reactions:

U0 4 + 4H20-UO3+ H202 I +3H 201

2H202 - 2H20 + 02 t

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IN 99-03 January29, 1999 The production of gases was sufficient to bulge the lids and sides of the drums, as well as

cause a pressure excursion, when a lid was removed, sufficient to eject about one-fourth of the

drummed U308 (yellowcake) 90.7 kilograms (-200 pounds) onto workers and through isolation

doors.

Cateaory 2: On two separate occasions, licensees experienced a violent exothermic reaction

when hydrocarbon contaminants were mixed with U308 hydrogen peroxide precipitated

(yellowcake) product. At one facility, a leaky flange in a bag filter allowed lubricating oil to leak

into the production process, and a deformed tank paddle allowed oil seepage into the mixing

tank. At another facility, oils from various process stages were introduced into the sump

system and eventually reintroduced into the production line. Both cases yielded an energetic

exothermic reaction. With one barrel, the lid had been melted onto the rim in one spot, and

another reached a temperature of 648.90C (12000F) within the drum. Subsequent examination

of the contents revealed several discolored layers, indicating extreme oxidation of product

powder in various stages.

Discussion

Category 1: Analyses of the incidents estimated 103.4 kilopascal (15-pounds-per-square-inch)

pressure on the lids. Drum pressure began to rise most rapidly in the first hour, but peaked at

3-4 hours. Pressure began to subside at 5 hours5.787037e-5 days 0.00139 hours 8.267196e-6 weeks 1.9025e-6 months . Other drums showed bulges and

deformities, but excess gases had bled off. Analysis of the trapped gases yielded 62 percent

oxygen, further indicating an oxygen generation from the decay of hydrogen peroxide.

Although no workers were injured, several received uptakes of uranium even though respiratory

protection was used.

The oxygen generation incidents were isolated incidents that originated with the use of newer

drums or other modifications of equipment which allowed excessive pressures. For one

licensee, the incident was a result of using newer drums with airtight seals. Older drums had

less efficient seals that allowed pressure to escape as it was generated. Both licensees

instituted corrective actions consisting mainly of leaving the lids off the drums for a minimum

of 3 hours3.472222e-5 days 8.333333e-4 hours 4.960317e-6 weeks 1.1415e-6 months after filling. Corrective actions appear to have been sufficient to prevent

future incidents.

Category 2: Since uranium is a pyrophoric metal, especially in fines or powder form, any

contaminant in contact with yellowcake powder can be hazardous. Hydrocarbons such as

lubricating oils and grease are very likely to cause an unstable condition in the packed

yellowcake powder.

In one incident, a leaky flange on a bag filter allowed lubricating oil to leak into and mix with the

yellowcake powder in a dryer tank. Once the exothermic reaction began, temperatures rose

sufficiently to turn residual water to steam, covering the room with yellowcake powder. The

leak was found and repaired, but the room had to be decontaminated. As the next batch of

yellowcake was processed, a severely bent paddle inside the mixing tank allowed further oil to

again mix into the yellowcake. After the product was packaged, temperatures again rose inside

the drum to produce sufficient steam pressure to blow the lid off. The licensee then found and

corrected the bent paddle. Corrective actions included installation of oil pressure relief valves

and a hot oil boiler cutoff with a temperature controller.

IN 99-03 January29, 1999 In a recent incident, a licensee had routinely washed equipment contaminants into a dryer room

sump. This contained not only uranium contamination, but exposed oils and grease from

equipment maintenance and dryer heating oils from spills and leaks. The sump contents were

transferred to a holding tank, where the yellowcake and contaminants settled to the bottom.

When the system was cleaned, the heel from this tank was put into a thickening tank to recover

any trapped product. The process, however, did not remove the contaminants. Yellowcake

tended to agglutinate onto the hydrocarbons, preventing them from being surface-skimmed, and final dryer temperatures were not sufficient to drive off the hydrocarbons. When the

contaminated yellowcake was packaged into drums, the residual heat from dryer operations

initiated an exothermic oxidation reaction. Since yellowcake is relatively dense, it acted as an

insulator, retaining reaction energy that further increased the rate of reaction. Seven drums of

product reacted with increased temperatures and oxidation of material. Corrective actions

included installation of oil drip pans for collecting all possible oil/grease leaks, and sending the

oil-yellowcake contaminants as waste rather than attempting to recover product through

the system.

This IN requires no specific action nor written response. If you have any questions about the

information in this notice, please contact the technical contacts listed below, or the appropriate

NRC office.

John T. Greeves, Director

Division of Waste Management

Office of Nuclear Material Safety

and Safeguards

Technical Contacts:

Douglas S. Simpkins, RIV

(817) 860-8220

E-mail: dss@nrc.gov

D. Blair Spitzberg, Ph.D., RIV

(817) 860-8191 E-mail: dbs@nrc.gov

John H. Lusher, NMSS

(301) 415-7694 E-Mail: jhl@nrc.gov

Attachments:

1.

List of Recently Issued NMSS Information Notices

J 1

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2.

List of Recently Issued NRC Information Notices

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wlu4q t~ l

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'Attachment

1 IN 99-03

January 29, 1999 LIST OF RECENTLY ISSUED

NMSS INFORMATION NOTICES

Information

Notice No.

99-02 Subject

Date of

Issuance

Issued to

.

Guidance to Users on the

Implementation of a New

Single-Source Dose-

Calculation Formalism and Revised

Air-Kerma Strength Standard

for Iodine-125 Sealed Sources

1/21/99

All medical licensees authorized to

conduct brachytherapy

treatments.

99-01

98-33

98-30

97-91 Supp. 1

98-20

98-18

98-17 Deterioration of High-Efficiency

Particulate Air Filters in a

Pressurized Water Reactor

Containment Fan Cooler Unit

NRC Regulations Prohibit

Agreements that Restrict or

Discourage an Employee from

Participating in Protected Activities

Effect of the Year 2000

Computer Problem on NRC

Licensees and Certificate Holders

Recent Failure of Control

Cables Used on Amersham

Model 660 Posilock Radiography

Systems

Problems With Emergency

Preparedness Respiratory

Protection Programs

Recent Contamination Incidences

Resulting from Failure to Perform

Adequate Surveys

Federal Bureau of Investigations

(FBI) Awareness of National

Security Issues and Responses

(ANSIR) Program

1/20/99

8/28/98

8/12/98

8/10/98

6/3/98

5/13/98

5/7/98

All holders of licences for nuclear

power, research and test reactors;

and fuel cycle facilities.

All holders of a Nuclear

Regulatory Commissission license

All material and fuel cycle

licensees and certificate holders

All industrial radiography

licensees.

All holders of operating licenses

for nuclear power reactors; non- power reactors; all fuel cycle and

material licensees required to

have an NRC-approved

emergency plan.

Part 35 Medical Licensees

All U.S. Nuclear Regulatory

Commission fuel cycle and power

and non-power reactor licensees

Attachment 2

IN 99-03

January 29, 1999 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information

Date of

Notice No.

Subject

Issuance

Issued to

99-02 Guidance to Users on the

1/21/99

All medical licensees authorized

Implementation of a New

Single-Source Dose-

Calculation Formalism and Revised

Air-Kerma Strength Standard

for Iodine-125 Sealed Sources

to conduct brachytherapy

treatments.

99-01

98-45

98-44

98-43 Deterioration of High-Efficiency

Particulate Air Filters in a

Pressurized Water Reactor

Containment Fan Cooler Unit

01/20/99 Cavitation Erosion of Letdown Line 12/15/98

Orifices Resulstin in Fatigue Cracking

of Pipe Welds

Ten-year Inservice Inspection

12/10/98 (ISI) Program Update for Licensees

that Intend to Implement Risk-Informed

ISI of Piping

All holders of licenses for nuclear

power, research and test reactors;

and fuel cycle facilities.

All holders of operating licenses

for nuclear power reactors, except

those that have permanently

ceased operations and have

certified that fuel has been

permanently removed from the

reactor.

All holder of operating licenses

for nuclear power reactors, except

those that have permanently

ceased operations and have

certified that fuel has been

permanently removed from the

reactor

All holder of operating licenses

for nuclear power reactors, except

those licensees that have

permanently ceased operations

and have certified that fuel has

been permanently removed from

the reactor vessel

Leaks in the Emergency Diesel

Generator Lubricating Oil and

Jacket Cooling Water Piping

12/04/98 OL = Operating License

CP = Construction Permit

*

IN 99-03 January 29, 1999 In a recent incident, a licensee had routinely washed equipment contaminants into a dryer room