Information Notice 1997-14, Assessment of Spent Fuel Pool Cooling
-.
,
4;
.
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C. 20555-0001
March 28, 1997
ASSESSMENT OF SPENT FUEL POOL COOLING
Addressees
All holders of operating licenses or construction permits for nuclear power reactors.
Purpose
The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice to alert
addressees to results of an assessment performed by the Office for Analysis and Evaluation
of Operational Data (AEOD) on operating experience involving spent .jel pool (SFP) cooling
and inventory control. The AEOD assessment is detailed in NUREG-1275, Volume 12,
"Assessment of Spent Fuel Cooling," February 1997. It is expected that recipients will review
the information for applicability to their facilities and consider actions, as appropriate, to avoid
similar problems. However, suggestions contained in this information notice are not NRC
requirements; therefore, no specific action or written response is required.
Description of Circumstances
NRC's Executive Director for Operations directed AEOD to independently assess the
likelihood and consequences of an extended loss of SFP cooling or inventory. The
assessment focused on the collection and analysis of operating experience involving SFP
cooling and inventory control and comprised of six major tasks:
(1)
Develop generic configurations delineating SFP cooling and inventory control
equipment for a boiling-water reactor (BWR) and a pressurized-water reactor (PWR).
(2)
Review and assess more than 12 years of operating experience for domestic and
foreign reactors.
(3)
Visit six sites to gain an understanding of the physical configurations, practices, and
operating procedures for the licensees' SFPs.
(4)
Review applicable SFP regulations and the NRC Standard Review Plan
(NUREG-0800) for the acceptance criteria and the applicable regulatory guides.
(5)
Perform independent assessments of electrical systems, instrumentation, heat loads, and radiation levels associated with the SFP.
(6)
Estimate near-boiling frequencies utilizing probabilistic techniques.
9703 PDA
4FE morlCet70/4 9o38'
O I
97370253 j1 1yA;
O
-Ft-w+~1' so pWullEESa 1c
IN 97-14 March 28, 1997 The findings and conclusions of the AEOD assessment are summarized below.
The loss of SFP coolant inventory in excess of 1 foot has occurred 10 times over the
last 12 years at a rate of about once every 100 reactor-years. Loss of SFP cooling
with a temperature increase in excess of 11 OC [20 OF] has occurred 4 times in the
last 12 years at a rate of approximately 3 times every 1000 reactor-years. The
consequences of these actual events have not been severe; however, some events
resulted in loss of several feet of SFP coolant level and have continued for more than
24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. The primary cause of these events has been human error, most preva- lently, valve mispositionings. These errors are discussed in greater detail in
NUREG-1275, Volume 12.
The relative risk due to loss of spent fuel pool cooling is low in comparison with the
risk of events not involving SFPs. The review determined that the likelihood and
consequences of SFP loss-of-cooling events are highly dependent on human
performance (e.g., valve manipulations, crane manipulations, spent fuel handling
equipr,lent manipulations) and individual plant design features.
The efforts by utilities to reduce outage durations have resulted in full core off-loads
early in outages. This increased fuel pool heat load reduces the time available to
recover from a loss-of-SFP-cooling should such an event occur early in the outage.
On a plant specific basis the following observations are provided:
Failures of reactor cavity seals or gate seals or ineffective antisiphon devices could
potentially cause loss of SFP coolant inventory, which could potentially result in
uncovering the fuel or endangering makeup capability.
Ineffective configuration control was the most frequent cause of SFP loss-of-inventory
events and loss-of-cooling events.
At multi-unit sites with common pools, there is the potential for SFP boiling conditions
to affect safe-shutdown equipment for the operating unit, particularly during full core
off-loads.
Improved procedures and training which recognize the time frames over which SFP
events can proceed, the heat load and possibility of loss of inventory, could enhance
control room operator response to loss-of-inventory and loss-of-cooling SFP events.
Insufficient control room instrumentation and non-safety-related power supplies to SFP
instrumentation may hinder operator response to SFP events.
1-.)
March 28, 1997 Discussion
The AEOD assessment found large variations in the designs and capabilities of SFPs and
related systems at individual nuclear plants. The AEOD assessment identified that the
frequency of loss-of-inventory events was relatively high compared to loss-of-cooling events, and prompt off-loads will lead to reduced time to boil if cooling is lost. A loss of SFP
inventory in combination with higher heat loads reduces the time to respond to SFP events.
Thus, the emphasis of the findings were on instrumentation to quickly alert the operators and
effective procedures and training to facilitate prompt operator response. The operating
experience review determined that loss-of-SFP-cooling events are infrequent and the
consequences of actual events have been small. The risk assessment indicates that the SFP
events are not a dominant contributor to overall plant risk. However, human error initiators
and operator actions required to mitigate an error are subject to large uncertainties, and there
are large variations in design vulnerabilities among plants. In summary the following areas
need emphasis:
(1)
Procedures and training to detect and respond to SFP loss-of-inventory and loss-of- cooling events, including those caused by loss of offsite power are needed and should
address configuration controls that can prevent and/or mitigate such events. They
should be consistent with the time frames over which SFP events can proceed at the
specific plant, recognizing the plant-specific heat load and the possibility of loss of
inventory because of cavity seal or gate failures.
(2)
Reliable instrumentation is necessary to monitor SFP temperature and level and SFP
area radiation, including periods following a loss of offsite power, in order to detect
SFP loss-of-inventory events and loss-of-cooling events in a timely manner.
(3)
Testing, maintenance, and configuration control of plant features such as reactor
cavity seals, gate seals, or antisiphon devices need to be examined for those plants
where failures could potentially cause loss of SFP coolant inventory sufficient to
endanger makeup capability or result in fuel uncovery.
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 or the appropriate Office of Nuclear Reactor Regulation (NRR) project manager.
Thomas T. Martin, Director
Division of Reactor Program Management
Office of Nuclear Reactor Regulation
Technical contacts:
Jose G. Ibarra, AEOD
Stephen Koenick, NRR
(301) 415-6345
(301) 415-2841 E-mail: jgi@nrc.gov
E-mail: ssk2@nrc.gov
Attachment: List of Recently Issued NRC Information Notices
Attachment
March 28, 1997 LIST OF RECENTLY ISSUED
NRC INFORMATION NOTICES
Information
Date of
Notice No.
Subject
Issuance
Issued to
97-13
Deficient Conditions
Associated with Pro- tective Coatings at
Nuclear Power Plants
03/24/97
All holders of OLs
or CPs for nuclear
power reactors
97-12
Potential Armature
Binding in General
Electric Type HGA
Relays
03/24/97
All holders of OLs
or CPs for nuclear
power reactors
92-27, Supp. 1
97-11
97-10
97-09
Thermally Induced
Accelerated Aging
and Failure of ITE/
Gould A.C. Relays
Used in Safety-Related
Applications
Cement Erosion from
Containment Subfounda- tions at Nuclear Power
Plants
Liner Plate Corrosion
in Concrete Containments
Inadequate Main Steam
Safety Valve (MSSV)
Setpoints and Perform- ance Issues Associated
with Long MSSV Inlet
Piping
03/21/97
03/21/97
03/13/97
03/12/97
All holders of OLs
or CPs for nuclear
power reactors
All holders of OLs
or CPs for nuclear
power reactors
All holders of OLs
or CPs for power
reactors
All holders of OLs
or CPs for nuclear
power reactors
OL = Operating License
CP = Construction Permit
March 28, 1997 Discussion
The AEOD assessment found large variations in the designs and capabilities of SFPs and
related systems at individual nuclear plants. The AEOD assessment identified that the
frequency of loss-of-inventory events was relatively high compared to loss-of-cooling events, and prompt off-loads will lead to reduced time to boil if cooling is lost. A loss of SFP
inventory in combination with higher heat loads reduces the time to respond to SFP events.
Thus, the emphasis of the findings were on instrumentation to quickly alert the operators and
effective procedures and training to facilitate prompt operator response. The operating
experience review determined that loss-of-SFP-cooling events are infrequent and the
consequences of actual events have been small. The risk assessment indicates that the SFP
events are not a dominant contributor to overall plant risk. However, human error initiators
and operator actions required to mitigate an error are subject to large uncertainties, and there
are large variations in design vulnerabilities among plants. In summary the following areas
need emphasis:
(1)
Procedures and training to detect and respond to SFP loss-of-inventory and loss-of- cooling events, including those caused by loss of offsite power are needed and should
address configuration controls that can prevent and/or mitigate such events. They
should be consistent with the time frames over which SFP events can proceed at the
specific plant, recognizing the plant-specific heat load and the possibility of loss of
inventory because of cavity seal or gate failures.
(2)
Reliable instrumentation is necessary to monitor SFP temperature and level and SFP
area radiation, including periods following a loss of offsite power, In order to detect
SFP loss-of-inventory events and loss-of-cooling events in a timely manner.
(3)
Testing, maintenance, and configuration control of plant features such as reactor
cavity seals, gate seals, or antisiphon devices need to be examined for those plants
where failures could potentially cause loss of SFP coolant inventory sufficient to
endanger makeup capability or result in fuel uncovery.
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 or the appropriate Office of Nuclear Reactor Regulation (NRR) project manager.
original signed by
Thomas T. Martin, Director
Division of Reactor Program Management
Office of Nuclear Reactor Regulation
Technical contacts:
Jose G. Ibarra, AEOD
Stephen Koenick, NRR
(301) 415-6345
(301) 415-2841 E-mail: jgienrc.gov
E-mail: ssk2@nrc.gov
Attachment: List of Recently Issued NRC Information Notices
- SEE PREVIOUS CONCURRENCE
Tech Editor has reviewed & concurred on 01/09197
[OFFICIAL RECORD COPY) DOCUMENT NAME: G:XSSK2\\INSFP.D3 To receive a copy of this document, hIdicate hI the box:
C -
Copy w/o
attachment/enclosure 'E' -
Copy w/attachment/enclosure 'N'
- No copy
OFFICE
TECH CONTS*
I
C:PECB/DRPM*
D:D
NAME
JIBarra/SW i k AChaffee
T __rtin
DATE
101/13/97
03/10/97
031.I/97
IN 97-XX
March XX, 1997 Discussion
The AEOD assessment found large variations in the designs and capabilities of SFPs and
related systems at individual nuclear plants. The AEOD assessment identified that the
frequency of loss-of-inventory events was relatively high compared to loss-of-cooling events, and prompt off-loads will lead to reduced time to boil if cooling is lost. Both of these
conditions reduce the time to respond to SFP events. Thus, the emphasis of the findings
were on instrumentation to quickly alert the operators and effective procedures and training to
facilitate prompt operator response. The operating experience review determined that loss- of-SFP-cooling events are Infrequent and the consequences of actual events have been
small. The risk assessment indicates that the SFP events are not a dominant contributor to
overall plant risk. However, human error initiators and operator actions required to mitigate
an error are subject to large uncertainties, and there are large variations in design
vulnerabilities among plants. In summary the following areas need emphasis:
(1)
Procedures and training to detect and respond to SFP loss-of-inventory and loss-of- cooling events, including those caused by loss of offsite power are needed and should
address configuration controls that can prevent and/or mitigate such events. They
should be consistent with the time frames over which SFP events can proceed at the
specific plant, recognizing the plant-specific heat load and the possibility of loss of
inventory because of cavity seal or gate failures.
(2)
Reliable instrumentation is necessary to monitor SFP temperature and level and SFP
area radiation, including periods following a loss of offsite power, in order to detect
SFP loss-of-inventory events and loss-of-cooling events in a timely manner.
(3)
Testing, maintenance, and configuration control of plant features such as reactor
cavity seals, gate seals, or antisiphon devices need to be examined for those plants
where failures could potentially cause loss of SFP coolant inventory sufficient to
uncover the fuel or endanger makeup capability.
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 or the appropriate Office of Nuclear Reactor Regulation (NRR) project manager.
Thomas T. Martin, Director
Division of Reactor Program Management
Office of Nuclear Reactor Regulation
Technical contacts:
Jose G. Ibarra, AEOD
Stephen Koenick, NRR
(301) 415-6345
(301) 415-2841 E-mail: jgienrc.gov
E-mail: ssk2@nrc.gov
Attachment: List of Recently Issued NRC Information Notices
- SEE PREVIOUS CONCURRENCE
OFC
Tech Cont*
C:TechBranch*
C:PECBIDRPM
l C:SPSBIDSS
NAME
JlBarra/SKoenick
LMarsh
AChaffee*
MRubl
DATE
01/13197
02/20/97
3/10/97
3/1197 OFC
C:
CblCI B
D:DRPM
I
NAME j
as
_
_ari
DATE
3//t97 j 3/2Q97
3/X17 I____
OFFICA
RCORDC
OCUMENT NAME- G SSK2%INSFP.D3
IN 97-XX
March XX, 1997 conditions reduce the time to respond to SFP events. Thus, the emphasis of the findings
were on instrumentation to quickly alert the operators and effective procedures and training to
facilitate prompt operator response. The operating experience review determined that loss- of-SFP-cooling events are infrequent and the consequences of actual events have been
small. The risk assessment indicates that the SFP events are not a dominant contributor to
overall plant risk. However, human error initiators and operator actions required to mitigate
an error are subject to large uncertainties, and there are large variations in design
vulnerabilities among plants. In summary the following areas need emphasis:
(1)
Procedures and training to detect and respond to SFP loss-of-inventory and loss-of- cooling events, including those caused by loss of offsite power are needed and should
address configuration controls that can prevent andlor mitigate such events. They
should be consistent with the time frames over which SFP events can proceed at the
specific plant, recognizing the plant-specific heat load and the possibility of loss of
inventory because of cavity seal or gate failures.
(2)
Reliable instrumentation is necessary to monitor SFP temperature and level and SFP
area radiation, including periods following loss of offsite power, in order to detect SFP
loss-of-coolant inventory and loss of cooling events in a timely manner.
(3)
Testing, maintenance, and configuration control of plant features such as reactor
cavity seals, gate seals, or antisiphon devices need to be examined for those plants
where failures could potentially cause loss of SFP coolant Inventory sufficient to
uncover the fuel or endanger makeup capability.
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 or the appropriate Office of Nuclear Reactor Regulation (NRR) project manager.
Thomas T. Martin, Director
Division of Reactor Program Management
Office of Nuclear Reactor Regulation
Technical contacts:
Jose G. Ibarra, AEOD
Stephen Koenick, NRR
(301) 415-6345
(301) 415-2841 E-mail: jgienrc.gov
E-mail: ssk2@nrc.gov
Attachment: List of Recently Issued NRC Information Notices
- SEE PREVIOUS CONCURRENCE
OFC
Tech Cont*
C:TechBranch*
C:PECBIDRPM
D:DRPM
NAME
JlBarra/SKoenick
LMarsh
AChaffee
TMartin
DATE
01/13/97
02/20/97
1 /97 of
1~Ao4 I /97
-
-.-
-
-
t
r-Lrs
LesIA&Ar!K^^
1
.
I
N
OVI-IMAL K~LUIL)J LUUITJ ULLUMMI'4 I PUVI.7 I%-'XZj'
.J
f3/007
IN 97-XX
March XX, 1997 conditions reduce the time to respond to SFP events. Thus, the emphasis of the findings
were on instrumentation to quickly alert the operators and effective procedures and training to
facilitate prompt operator response. The operating experience review determined that loss- of-SFP-cooling events are infrequent and the consequences of actual events have been
small. The risk assessment indicates that the SFP events are not a dominant contributor to
overall plant risk. However, because human error initiators and operator action required to
detect and correct an error are subject to large uncertainties and the large variation in design
vulnerabilities, the NRC would like to highlight to the industry:
(1)
The importance of procedures and training to detect and respond to SFP loss-of- inventory and loss-of-cooling events, including those caused by loss of offsite power.
The procedures and training needed to address configuration controls that can
prevent and/or mitigate such events. The procedures and training should be
consistent with the time frames over which SFP events can proceed at the specific
plant, recognizing the plant-specific heat load and the possibility of loss of inventory
due to cavity seal or gate failures.
(2)
The importance of having reliable instrumentation to monitor SFP temperature and
level and SFP area radiation, including during periods when offsite power has been
lost, in order to detect SFP loss-of-coolant inventory and loss of cooling events in a
timely manner.
(3)
The importance of testing, maintenance, and configuration control of plant features
such as reactor cavity seals or gate seals, or antisiphon devices for those plants
where failures could potentially cause loss of SFP coolant inventory sufficient to
uncover the fuel or endanger makeup capability.
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 or the appropriate Office of Nuclear Reactor Regulation (NRR) project manager.
Thomas T. Martin, Director
Division of Reactor Program Management
Office of Nuclear Reactor Regulation
Technical contacts:
Jose G. Ibarra, AEOD
Stephen Koenick, NRR
(301) 415-6345
(301) 415-2841 E-mail: jgienrc.gov
E-mail: ssk2@nrc.gov
- SEE PREVIOUS CONCURRENCE
Attachment: List of Recently Issued NRC Information Notices
OFC
Tech Cont*
C:TechBranch*
C:PECBIDRPM
D:DRPM
NAME
JlBarra/SKoenick
LMarsh
AChaffee
TMartin
DATE J 01/13/97
02/20/97
/ /97
1I /97
___._ .
.*
Ace 5 T
h
- . IveeL
&IsCE
rI
-
mUF+/-I(.AL Kt-LAJI(U tLUIYj UU~U~mr- I NiVhric
%J--5KUr4rrA.LF
-
.-.
>
IN 97-XX
March XX, 1997 conditions reduce the time to respond to SFP events. Thus, the emphasis of the findings
were on instrumentation to quickly alert the operators and effective procedures and training to
facilitate prompt operator response. The operating experience review determined that loss- of-SFP-cooling events are infrequent and the consequences of actual events have been
small. The risk assessment indicates that the SFP events are not a dominant contributor to
overall plant risk. However, because human error initiators and operator action required to
detect and correct an error are subject to large uncertainties and the large variation in design
vulnerabilities, the NRC would like to highlight to the industry:
(1)
The importance of procedures and training to detect and respond to SFP loss-of- inventory and loss-of-cooling events, including those caused by loss of offsite power.
The procedures and training needed to address configuration controls that can
prevent and/or mitigate such events. The procedures and training should be
consistent with the time frames over which SFP events can proceed at the specific
plant, recognizing the plant-specific heat load and the possibility of loss of inventory
due to cavity seal or gate failures.
(2)
The importance of having reliable instrumentation to monitor SFP temperature and
level and SFP area radiation, including during periods when offsite power has been
lost, in order to detect SFP loss-of-coolant inventory and loss of cooling events in a
timely manner.
(3)
The importance of testing, maintenance, and configuration control of plant features
such as reactor cavity seals or gate seals, or antisiphon devices for those plants
where failures could potentially cause loss of SFP coolant inventory sufficient to
uncover the fuel or endanger makeup capability.
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 or the appropriate Office of Nuclear Reactor Regulation (NRR) project manager.
Thomas T. Martin, Director
Division of Reactor Program Management
Office of Nuclear Reactor Regulation
Technical contacts:
Jose G. Ibarra, AEOD
Stephen Koenick, NRR
(301) 415-6345
(301) 415-2841 E-Mail: jgi@nrc.gov
E-Mail: ssk2@nrc.gov
- SEE PREVIOUS CONCURRENCE
Attachment: List of Recently Issued NRC Information Notices
OFC
Tech Cont*
C:TechBranch*
[C:PECB/DRPM
D:DRPM
NAME
JiBarra/SKoenick
LMarsh
AChaffee
TMartin
DATE
01/13/97 j 02/20197
_ /197
/1 97 OFFICIALRECORD CiPY] DOCUMENT NAME: G:\\SSK2\\lNSFP.D3
1b3\\,\\
IN 97-XX
February XX, 1997 instrumentation to quickly alert the operators and effective procedures and
training to facilitate prompt operator response. The operating experience
review determined that loss-of-SFP-cooling events are infrequent and the
consequences of actual events have been small. The risk assessment indicates
that the SFP events are not a dominant contributor to overall plant risk.
However, because human error initiators and operator action required to detect
and correct an error are subject to large uncertainties and the large
variation in design vulnerabilities. the NRC would like to highlight to the
industry:
(1) The importance of procedures and training to detect and respond to SFP
loss-of-inventory and loss-of-cooling events, including those caused by
loss of offsite power. The procedures and training needed to address
configuration controls that can prevent and/or mitigate such events.
The procedures and training should be consistent with the time frames
over which SFP events can proceed at the specific plant. recognizing the
plant-specific heat load and the possibility of loss of inventory due to
cavity seal or gate failures.
(2) The importance of having reliable instrumentation to monitor SFP
temperature and level and SFP area radiation, including during periods
when offsite power has been lost, in order to detect SFP loss-of-coolant
inventory and loss of cooling events in a timely manner.
(3) The importance of testing, maintenance, and configuration control of
plant features such as reactor cavity seals or gate seals, or antisiphon
devices for those plants where failures could potentially cause loss of
SFP coolant inventory sufficient to uncover the fuel or endanger makeup
capability.
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 or the appropriate Office of
Nuclear Reactor Regulation (NRR) project manager.
Thomas T. Martin, Director
Division of Reactor Program Management
Office of Nuclear Reactor Regulation
Technical contacts:
Jose G. Ibarra, AEOD
Stephen Koenick, NRR
(301) 415-6345
(301) 415-2841 E-Mail: jgi@nrc.gov
E-Mail: ssk2@nrc.gov
Attachment:
List of Recently Issued NRC Information Notices
I
Tech Cont
C:TechBranch
C:PECB/DRPM
D:DRPM
NAME
_
AChaffee
TMartin
DATE
I /97 j 'v./097
/ /97
/ /97 OFFICIAL RECORD COPY] DOCUMENT NAME: G:\\SSK2\\INSFP.D2
-
-
.
I
IN 97-XX
February XX, 1997 .
=
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 or the appropriate Office of
Nuclear Reactor Regulation (NRR) project manager.
Thomas T. Martin, Director
Division of Reactor Program Management
Office of Nuclear Reactor Regulation
Technical contacts:
Jose G. Ibarra, AEOD
(301) 415-6345 E-Mail: jgi@nrc.gov
Stephen Koenick, NRR
(301) 415-2841 E-Mail: ssk2@nrc.gov
Attachment:
List of Recently Issued NRC Information Notices
co -,vr
_
__
.
_
_
_
OFC
Tech Cont
C:TechBr ch
'C:PECB/DRPM
D:DRPM
lNAME &A1
. 5$0
wk-s .Rn4-+61 AChaffee
TMartinl
I DATE
I //q/97
/ /21/97
/ /97
/ /97 l
LOFFICIAL RECORD COPY] DOCUMENT NAME:
G:\\SSK2\\INSFP.D2