Information Notice 1995-38, Degradation of Boraflex Neutron Absorber in Spent Fuel Storage Racks
-
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C. 20555-0001 September 8, 1995 NRC INFORMATION NOTICE 95-38: DEGRADATION OF BORAFLEX NEUTRON ABSORBER IN
SPENT FUEL STORAGE RACKS
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 a potentially significant problem pertaining to
degradation of the Boraflex neutron absorber material in spent fuel storage
racks. 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.
Background
Degradation of Boraflex has been previously addressed by the NRC in
Information Notice (IN)87-43, "Gaps in Neutron-Absorbing Material in High- Density Spent Fuel Storage Racks," September 8, 1987, and IN 93-70,
"Degradation of Boraflex Neutron Absorber Coupons," September 10, 1993. The
Electric Power Research Institute (EPRI) has been studying the phenomenon of
Boraflex degradation for several years and recently issued EPRI report
TR-103300, "Guidelines for Boraflex Use in Spent-Fuel Storage Racks,"
December 1993, identifying two issues with respect to using Boraflex in spent
fuel storage racks. The first related to gamma radiation-induced shrinkage of
Boraflex and the potential to develop tears or gaps in the material. The
second concerned gradual long-term Boraflex degradation over the intended
service life of the racks as a result of gamma irradiation and exposure to the
spent fuel pool environment. This second issue has previously been observed
in degradation of Boraflex surveillance coupons at the Palisades plant
(IN 93-70), but further testing of the actual Palisades storage racks
indicated no similar degradation. Because of the relatively watertight
Boraflex panel enclosures in most spent fuel storage rack designs, this type
of degradation was typically not previously considered.
The potential exists for a gradual release of silica and boron carbide from
Boraflex following gamma irradiation and long-term exposure to the spent fuel
pool environment. When Boraflex is subjected to gamma radiation in the
aqueous environment of the pool, the silicon polymer matrix becomes degraded
and silica filler and boron carbide are released. Because Boraflex is
9509050009 2.d I o q
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- °?
iv> IN 95-38 September 8, 1995 polydimethyl siloxane
composed of approximately 25 percent silica, 25 percent of silica in the pool
polymer, and 50 percent boron carbide, the presence from Boraflex. The loss
provides an indication of depletion of boron carbide by slow dissolution
of boron carbide (washout) from Boraflex is characterized
a gradual thinning of the
of the silica from the surface of the Boraflex and Boraflex represents a
material. In a typical spent fuel pool, the irradiated and is the most
significant source of silica (several thousand kilograms) carbide loss will
likely source of pool silica contamination. Thematrix of fuel and Boraflex in
result in an increase in the reactivity of the
the spent fuel pool.
that influence the rate
EPRI report TR-103300 has identified several factors water around the Boraflex
of silica release from Boraflex. The presence of
influencing the rate of silica
panels is perhaps the most significant factor rack designs, this rate
dissolution from Boraflex. Because of the different also increases with
will vary from plant to plant. The rate of dissolution
suggesting that Boraflex
higher pool temperature and gamma exposure, low and by not placing
degradation can be reduced by keeping pool temperatures cells at each refueling
freshly discharged fuel assemblies in the same storage
outage.
Description of Circumstances
racks installed in the spent
The South Texas Project, Unit 1, has fuel storage The pool contains two rack
fuel pool that use Boraflex as a neutron absorber. high reactivity fuel
types. The Region 1 racks are designed to receive panels in a removable
assemblies, including fresh fuel, and use Boraflex for low reactivity spent
stainless steel box. The Region 2 racks are designed between the cell
fuel assembly storage and contain fixed Boraflex panels that adequate negative
walls. The Boraflex panels were designed to ensure
pool were accidentally flooded with
reactivity would be maintained if the
unborated water.
during August 1994 on
Blackness (neutron absorption) testing was performed storage racks to determine
selected South Texas Project Unit I spent fuel pool size and location of any
the condition of the Boraflex and to determine the to gap development, which
gaps that may have developed. However, in additionthat the Boraflex had
is a known phenomenon, the results also indicated
boron content in several of
significantly degraded due to a decrease of thethat had been designated to
the storage cells tested. Of the eight cells cells exhibited large
receive an accelerated gamma dose in Region 1, fivefeet] in length) postulated
areas of degradation (0.9 to 1.4 meters [3 to 4.5 caused by pool water
to result from accelerated dissolution of the Boraflex
high accumulated gamma dose.
flow through the panel enclosures as well as the
Fort Calhoun Station. As
Similar Boraflex degradation was discovered at thestorage racks containing
part of their rerack project, the old spent fuel 1994 to determine the
Boraflex were removed and disassembled in December Boraflex racks which
condition of the Boraflex. Two cells from the removedwere inspected. Only
had experienced the highest gamma flux since 1983 panels from these cells
40 percent of the Boraflex remained in one of the loss of Boraflex. An
while another panel in the same cell exhibited no
s>< IN 95-38 September 8, 1995 subsequent
adjacent cell had a panel which had some Boraflex loss butboron-10 areal
attenuation and density tests confirmed that the average
The new Fort
density still exceeded the material minimum certifications.
Calhoun Station storage racks do not contain Boraflex.
Discussion
fuel storage racks
Because Boraflex is used in the South Texas Project spentBoraflex could result
for absorption of neutrons, a reduction in the amount of configuration, which
in an increase in the reactivity of the spent fuel pool criterion of k~ff no
may approach, or even exceed, the current NRC acceptance
greater than 0.95.
& Power
In response to the identified Boraflex problem, Houston Lighting restrictions to
Company, the licensee for the South Texas Project, developed1 for discharged
not use the substantially degraded storage cells in Region neutron
spent fuel. In addition, the licensee is developing a long-term
absorption panel management plan, as well as a dose-to-degradation
for use of the spent
correlation, which will aid in establishing restrictions criticality
fuel racks in both Units 1 and 2. The licensee also cited by at least
analyses that showed that the fuel will remain subcriticalboron concentration
5 percent, even with no Boraflex, as long as the soluble
is at least 2,500 ppm.
is normally borated
Although pressurized-water reactor spent fuel pool water requirements do not
to approximately 2,000 ppm of boron, current regulatory conditions. Many
allow credit for the soluble boron except under accident Because BWR
boiling-water reactor (BWR) storage racks also contain Boraflex. Boraflex
spent fuel pool water does not contain boron, any significant
margin.
degradation in a BWR pool may challenge the 5 percent subcritical
response. If
This information notice requires no specific action or writtenplease contact
you have any questions about the information in this notice, Office of
one of the technical contacts listed below or the appropriate
Nuclear Reactor Regulation (NRR) project manager.
n'Mis .Crut tor
Division of Reactor Program Management
Office of Nuclear Reactor Regulation
Technical contacts: Laurence I. Kopp, NRR
(301) 415-2879 K. I. Parczewski, NRR
(301) 415-2705 Attachment:
List of Recently Issued NRC Information Notices
A~I.' fref
A,.Achment
IN 95-38 September 8, 1995 LIST OF RECENTLY ISSUED
NRC INFORMATION NOTICES
Information Date of
Notice No. Subject Issuance Issued to
95-37 Inadequate Offsite Power 09/07/95 All holders of OLs or CPs
System Voltages during for nuclear power reactors.
Design-Basis Events
95-36 Potential Problems with 08/29/95 All holders of OLs or CPs
Post-Fire Emergency for nuclear power reactors.
Lighting
95-35 Degraded Ability of 08/28/95 All holders of OLs or CPs
Steam Generators to for pressurized water
Remove Decay Heat by reactors (PWRs).
Natural Circulation
95-34 Air Actuator and Supply 08/25/95 All holders of OLs or CPs
Air Regulator Problems in for nuclear power reactors.
Copes-Vulcan Pressurizer
Power-Operated Relief Valves
93-83, Potential Loss of Spent 08/24/95 All holders of OLs or CPs
Supp. 1 Fuel Pool Cooling After a for nuclear power reactors.
Loss-of-Coolant Accident
or a Loss of Offsite Power
95-33 Switchgear Fire and 08/23/95 All holders of OLs or CPs
Partial Loss of Offsite for nuclear power reactors.
Power at Waterford
Generating Station, Unit 3
95-10, Potential for Loss of 08/11/95 All holders of OLs or CPs
Supp. 2 Automatic Engineered for nuclear power reactors.
Safety Features Actuation
95-32 Thermo-Lag 330-1 Flame 08/10/95 All holders of OLs or CPs
Spread Test Results for nuclear power reactors.
95-31 Motor-Operated Valve 08/09/95 All holders of OLs or CPs
Failure Caused by Stem for nuclear power reactors.
Protector Pipe Inter- ference
OL = Operating License
CP - Construction Permit
'V September 8, 1995 adjacent cell had a panel which had some Boraflex loss but subsequent
attenuation and density tests confirmed that the average boron-10'areal
density still exceeded the material minimum certifications. The new Fort
Calhoun Station storage racks do not contain Boraflex.
Discussion
Because Boraflex is used in the South Texas Project spent fuel storage racks
for absorption of neutrons, a reduction in the amount of Boraflex could result
in an increase in the reactivity of the spent fuel pool configuration, which
may approach, or even exceed, the current NRC acceptance criterion of kff no
greater than 0.95.
In response to the identified Boraflex problem, Houston Lighting & Power
Company, the licensee for the South Texas Project, developed restrictions to
not use the substantially degraded storage cells in Region 1 for discharged
spent fuel. In addition, the licensee is developing a long-term neutron
absorption panel management plan, as well as a dose-to-degradation
correlation, which will aid in establishing restrictions for use of the spent
fuel racks in both Units 1 and 2. The licensee also cited criticality
analyses that showed that the fuel will remain subcritical by at least
5 percent, even with no Boraflex, as long as the soluble boron concentration
is at least 2,500 ppm.
Although pressurized-water reactor spent fuel pool water is normally borated
to approximately 2,000 ppm of boron, current regulatory requirements do not
allow credit for the soluble boron except under accident conditions. Many
boiling-water reactor (BWR) storage racks also contain Boraflex. Because BWR
spent fuel pool water does not contain boron, any significant Boraflex
degradation in a BWR pool may challenge the 5 percent subcritical margin.
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.
orig /s/'d by DMCrutchfield
Dennis M. Crutchfield, Director
Division of Reactor Program Management
Office of Nuclear Reactor Regulation
Technical contacts: Laurence I. Kopp, NRR
(301) 415-2879 K. I. Parczewski, NRR
(301) 415-2705 Attachment: List of Recently Issued NRC Information Notices
DOCUMENT NAME: 95-38.IN *See previous concurrence
To receive a copy of this docurnent, Indicate Inthe box: wCw a Copy without attachmentlenclosure 'E' = Copy with attachment/enclosure 'N' = No copy - ---- -
RXB:DSSA E EMCB:DE E OECB:DOPS E ADM:PUB N SC/EMCB:DE m
OFFICE
NAME
DATE
LIKopp*
06/27/95 JKIParczewski*
06/28/95 PCWen*
06/27/95 Tech Editor*
06/27/95 RAHermann*
06/29/95 OFFICE C/EMCB:DE IE S/SRXB:DSSA IE E CDSSA E SC/PECB:DRPM N
NAME JRStrosnider* EWWEiss* RCJones* GMHolahan* EFGoodwin*
DATE 107/03/955/95 07/07/95 08/02/95 08/03/9 OFFICE PECB:DRPM lE C/PECB:DRPM N D/DRP i 111 NAME RJKiessel* AEChaffee* DCrut efibld _
DATE 08/21/95 08/25/95 09/ Ir/95 OFFICIAL RECORD COPY
- ~ IN 95-XX
August xx, 1995 attenuation and density tests confirmed that the average boron-10 areal
density still exceeded the material minimum certifications. The new Fort
Calhoun Station storage racks do not contain Boraflex.
Discussion
Because Boraflex is used in the South Texas Project spent fuel storage racks
for absorption of neutrons, a reduction in the amount of Boraflex could result
In an increase in the reactivity of the spent fuel pool configuration, which
may approach, or even exceed, the current NRC acceptance criterion of keff no
greater than 0.95.
In response to the identified Boraflex problem, Houston Lighting & Power
Company, the licensee for the South Texas Project, developed restrictions to
not use the substantially degraded storage cells in Region 1 for discharged
spent fuel. In addition, the licensee is developing a long-term neutron
absorption panel management plan, as well as a dose-to-degradation
correlation, which will aid in establishing restrictions for use of the spent
fuel racks in both Units 1 and 2. The licensee also cited criticality
analyses that showed that the fuel will remain subcritical by at least 5 percent, even with no Boraflex, as long as the soluble boron concentration is
at least 2,500 ppm.
Although pressurized-water reactor spent fuel pool water is normally borated
to approximately 2,000 ppm of boron, current regulatory requirements do not
allow credit for the soluble boron except under accident conditions. Many
boiling-water reactor (BWR) storage racks also contain Boraflex. Because BWR
spent fuel pool water does not contain boron, any significant Boraflex
degradation in a BWR pool may challenge the 5-percent subcritical margin.
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.
Dennis M. Crutchfield, Director
Division of Reactor Program Management
Office of Nuclear Reactor Regulation
Technical contacts: Laurence I. Kopp, NRR
(301) 415-2879 K. I. Parczewski, NRR
(301) 415-2705 Attachment: List of Recently Issued NRC Information Notices
DOCUMENT NAME: G:\PETER\BORAFLEX.IN *See previous concurrence No copy
To receive a copy of this document, indicate In the box: wCw - Copy without attachment/enclosure E = Copy with attachment/enclosure "NF -
OFFICE SRXB:DSSA E EMCB:DE E OECB:DOPS E ADM:PUB N SC/EMCB:DE LE
NAME LIKopp* KIParczewski* PCWen* Tech Editor* RAHermann*
DATE 06/27/95 106/28/95 06/27/95 06/27/95 06/29/95 OFFICDE IC, E IE E/SRXB:DSSA I /DSSA l IE SC/PECB:DRPM N
NAME IJRStrosnider* EWWEiss* RCJones* GMHolahan* EFGoodwin*
E07/05/95 07/07/95 08/02/95 08/03/95 OFFICE PECB:DRPM E C/PECB:DRPM N D/DRPM L
NAME RJKessel* AEChaffee*i DCrutchfield
DATE 08/21/95 08/25/95 / /95 OFFICIAL RECORD COPY
+\ a\5b
IN 95-XX
August xx, 1995 the material minimum certifications. No other storage cells exhibited as
significant a loss of Boraflex. The new Fort Calhoun Station storage racks do
not contain Boraflex.
Discussion
Because Boraflex is used in the South Texas Project spent fuel storage racks
for nonproductive absorption of neutrons, a reduction in the amount of
Boraflex could result in an increase in the reactivity of the spent fuel pool
configuration, which may approach, or even exceed, the current NRC acceptance
criterion of ke no greater than 0.95. The NRC has established this
5-percent subcrgticality margin to comply with General Design Criterion 62,
"Prevention of Criticality in Fuel Storage and Handling."
In response to the identified Boraflex problem, Houston Lighting & Power
Company, the licensee for the South Texas Project, developed restrictions to
not use the substantially degraded storage cells in Region 1 for discharged
spent fuel. In addition, the licensee is developing a long-term neutron
absorption panel management plan, as well as a dose-to-degradation
correlation, which will aid in establishing restrictions for use of the spent
fuel racks in both Units 1 and 2. The licensee also cited criticality
analyses that showed that the fuel will remain subcritical by at least 5 percent, even with no Boraflex, as long as the soluble boron concentration is
at least 2,500 ppm.
Although pressurized-water reactor spent fuel pool water is normally borated
to approximately 2,000 ppm of boron, current regulatory requirements do not
allow credit for the soluble boron except under accident conditions. Many
boiling-water reactor (BWR) storage racks also contain Boraflex. Because BWR
spent fuel pool water does not contain boron, any significant Boraflex
degradation in a BWR pool may provide a more significant challenge to the
5-percent subcritical margin.
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.
Dennis M. Crutchfield, Director
Division of Reactor Program Management
Office of Nuclear Reactor Regulation
Technical contacts: Laurence I. Kopp, NRR
(301) 415-2879 K. I. Parczewski, NRR
(301) 415-2705 Attachment: List of Recently Issued NRC Information Notices
DOCUMENT NAME: G:\PETER\BORAFLEX.IN *See previous concurrence
'Ed - Copy with attachmentlenciosure 'N' - No copy
To receive a copy of this document, Indicate Inthe box: AC.
- Copy without attachnent/enclosure
OFFICE SRXB:DSSA KE M j]E jj OECB:DOPS E ADM:PUB I N SC/EMCB:DE-l E
NAME LIKopp* KIParczewski* PCWen* Tech Editor* jRAHermann*
DATE 06/27/95 06/28/95 06/27/95 06/27/95 106/29/95 OFFICE C/EMCB:D E IE C/SRXB:DSSA [E D/DSSA I[ SC/PECB:DRPM N
NAME JRStrosnider* EWWEiss* RCJones* GEFGoodwi*
DATE 107/03/95 07/05/95 07_07_95 _ 08/02/95____
_ __ __
OFFICE PECB:DRPM E C/PEW. I D/DRPM
NAME RJKiessel* AECt -,e DCrutchfield l _l
DATE 08/21/95 I/ /95 / /95 _
IN 95-XX
August xx, 1995 In response to the identified Boraflex problem, Houston Lighting & Power
Company, the licensee for the South Texas Project, developed restrictions not
to use the substantially degraded storage cells in Region 1 for discharged
spent fuel. In addition, the licensee is developing a long-term neutron
absorption panel management plan, as well as a dose-to-degradation
correlation, which will aid in establishing restrictions for use of the spent
fuel racks in both Units 1 and 2. The licensee also cited criticality
analyses that showed that the racks will remain subcritical by at least 5 percent, even with no Boraflex, as long as the soluble boron concentration is
at least 2,500 ppm.
Although pressurized-water reactor spent fuel pool water is normally borated
to approximately 2,000 ppm of boron, current regulatory requirements do not
allow credit for the soluble boron except under accident conditions. Many
boiling-water reactor (BWR) storage racks also contain Boraflex. Because BWR
spent fuel pool water does not contain boron, any significant Boraflex
degradation in a BWR pool may more realistically challenge the 5-percent
subcritical margin.
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.
Dennis M. Crutchfield, Director
Division of Reactor Program Management
Office of Nuclear Reactor Regulation
Technical contacts: Laurence I. Kopp, NRR
(301) 415-2879 K. I. Parczewski, NRR
(301) 415-2705 Attachment:
List of Recently Issued NRC Information Notices
DOCUMENT NAME: G:\PETER\BORAFLEX.IN
To receive a copy of this document, Indicate Inthe box: 'C' - Copy without attachment/enclosure 'E Copy with attachment/enclosure 'N' - No copy
OFFICE SRXB:DSSA I E EMCB:DE E OECB:DOPS EADM:PUB SC/EMCB:DE E
NAME LIKopp* KIParczewskl* PCWen* Tech Editor* RAHermann*
DATE 6/27/95 6/28/95 6/27/95 6/27/95 6/29/95 OFFICE C/EMCB:DE I EJSC/SRXB:DSSA C/SRXB:DSSA E D/DSSA SC/PECB:DRPM
NAME JRStrosnider* IEWWEiss* RCJones* GMHolahan* EEGoodwin
DATE 7/3 /95 1 7/5,q 7/7/95 8/2/95 t:di/95 OFFICE PECB:DRPM " JWCB:DRPMi I D/DRPM I
NAME lRJKiesselAEChaffee ATg3 DMCrutchfield
DATE
/I
K1 I /95 OFFICIAL
/S/9F /95 RECORD COPY
- See previous concurrence
V-> IN 95-XX
July xx, 1995 In response to the identified Boraflex problem, Houston Lighting & Power not
Company, the licensee for the South Texas Project, developed restrictions
to use the substantially degraded storage cells in Region 1 for discharged
spent fuel. In addition, the licensee is developing a long-term neutron
absorption panel management plan, as well as a dose-to-degradation
correlation, which will aid in establishing restrictions for use of the spent
fuel racks in both Units 1 and 2. The licensee also cited criticality 5 analyses that showed that the racks will remain subcritical by at least
percent, even with no Boraflex, as long as the soluble boron concentration is
at least 2,500 ppm.
Although pressurized-water reactor spent fuel pool water is normally borated
to approximately 2,000 ppm of boron, current regulatory requirements do not
allow credit for the soluble boron except under accident conditions. Many BWR
boiling-water reactor (BWR) storage racks also contain Boraflex. Because
spent fuel pool water does not contain boron, any significant Boraflex
degradation in a BWR pool may more realistically challenge the 5-percent
subcritical margin.
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.
Brian K. Grimes, Director
Division of Project Support
Office of Nuclear Reactor Regulation
Technical contacts: Laurence I. Kopp, NRR
(301) 415-2879 K. I. Parczewski, NRR
(301) 415-2705 Attachment:
List of Recently Issued NRC Information Notices
DOCUMENT NAME: G:\PETER\BORAFLEX.IN
NC" = Copy without attachment/encLosure "E' = Copy with
To receive a copy of this document, indicate in the box:
attachment/enclosure 'M"= No copy _ __ . _ .
SRXB:DSSA E l CB:DE j E CB:DJP jj A PSC/EMCB:DE I E
OFFICE
NAME LIKopp* KIParczewski* PCWen* Tech Editor* RAHermann*
DATE 6/27/95 6/28/95 6/27/95 6/27/.95 1# 6/29/95 OFFICE C/EMCB:DE E SC/SRXB:DSSA CSRXB:DSSAm ECB:DOPS
NAME JRStrosnider* EWWEiss* RCJones* X 1 ah'iVEFGoodwin
DATE 7/3 /95 7/5/95 7/7/95 / /95 95 OFFICE OECB:DOPS C/OECB:DOPS D/DOPS
NAME RJKiessel AEChaffee BKGrimes II
DATE I /95 I /95 I /95 OFFICIAL RECORD COPY
- See previous concurrence
DOCUMENT NAME: G:\PETER\BORAFLEX.IN
'E - Copy with attachment/onclosure N - No copy
document, Indicate In the box:
To receive a copy of this C, - Copy without attachmentlenclosure
SRXB:DSSA E EMCB:DE E OECB:DOPS E ADM:PUB([ SC/EMCB:DE E
OFFICE
NAME LIKopp* KIParczewski* PCWen* Tech Editor* RAHermann*
DATE 6/27/95 6/28/95 6/27/95 6/27/95 6/29/95 OFFICE C/EMCB:DE E /SRXB:DSSA C/SRXB;: A E D/DSSA SC/OECB:DOPS
NAME JRStrosnider* EWWEiss* RCJonef>RPve EFGoodwin
DATE 7/3 /95 7/5/95 7/ 7 /I /95 / /95 OFFICE OECB:DOPS C/OECB:DOPS l_ D/DOPS_
NAME RJKiessel AEChaffee BKGrimes I
DATE / /95 / /95 I /95 OFFICIAL RECORD COPY
- See previous concurrence
--2 IN 95-XX
July xx, 1995 In response to the identified Boraflex problem, Houston Lighting & Power
Company, the licensee for the South Texas Project, developed restrictions not
to use the substantially degraded storage cells in Region 1 for discharged
spent fuel. In addition, the licensee is developing a long-term neutron
absorption panel management plan, as well as a dose-to-degradation
correlation, which will aid in establishing restrictions for use of the spent
fuel racks in both Units I and 2. The licensee also cited criticality
analyses that showed that the racks will remain subcritical by at least 5 percent, even with no Boraflex, as long as the soluble boron concentration is
at least 2,500 ppm.
Although pressurized-water reactor spent fuel pool water is normally borated
to approximately 2,000 ppm of boron, current regulatory requirements do not
allow credit for the soluble boron except under accident conditions. Many
boiling-water reactor (BWR) storage racks also contain Boraflex. Because BWR
spent fuel pool water does not contain, boron, any significant Boraflex
degradation in a BWR pool may more realistically challenge the 5-percent
subcritical margin.
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.
Brian K. Grimes, Director
Division of Project Support
Office of Nuclear Reactor Regulation
Technical contacts: Laurence I. Kopp, NRR
(301) 415-2879 K. I. Parczewski, NRR
(301) 415-2705 Attachment:
List of Recently Issued NRC Information Notices
DOCUMENT NAME: G:\PETER\BORAFLEX.IN
To receive a copy of this document, indicate in the box: IC"I Copy without attachment/enclosure "E" = Copy with
attachment/enclosure I" I No copy
lOFFICE SRXB:DSSA EMECB:DOPS E l SC/EMCB:DE I]
INAME LIKopp KIParczewsk PCWen Tech Eitofr RAHermanI_
lDATE /97/95 n /8/95 6/,/j-/95 8/:)7/j951 OFFICE C/EMCB:DWM IC£ SC/SRXBWA C/SRXB:DSSA D/DSSA SC/OECB:DOPS ]
NAME JRStrosni EWWEist3 RCJones GMHolahan EFGoodwin
DATE /3/9,5 7/ / /95 / /95 / _/95 OFFICE OECB:DOPS C/OECB:DOPS D/DOPS 1 111 NAME RJKiessel AEChaffee BKGrimes
DATE / /95 / /95 / /95 OFFICIAL RECORD COPY