Information Notice 1993-70, Degradation of Boraflex Neutron Absorber Coupons: Difference between revisions

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| issue date = 09/10/1993
| issue date = 09/10/1993
| title = Degradation of Boraflex Neutron Absorber Coupons
| title = Degradation of Boraflex Neutron Absorber Coupons
| author name = Grimes B K
| author name = Grimes B
| author affiliation = NRC/NRR
| author affiliation = NRC/NRR
| addressee name =  
| addressee name =  
Line 14: Line 14:
| document type = NRC Information Notice
| document type = NRC Information Notice
| page count = 9
| page count = 9
| revision = 0
}}
}}
{{#Wiki_filter:IUNITED STATESNUCLEAR REGULATORY COMMISSIONOFFICE OF NUCLEAR REACTOR REGULATIONWASHINGTON D.C. 20555September 10, 1993NRC INFORMATION NOTICE 93-70: DEGRADATION OF BORAFLEX NEUTRON ABSORBERCOUPONS
{{#Wiki_filter:I
 
UNITED STATES
 
NUCLEAR REGULATORY COMMISSION
 
OFFICE OF NUCLEAR REACTOR REGULATION
 
WASHINGTON D.C. 20555 September 10, 1993 NRC INFORMATION NOTICE 93-70:     DEGRADATION OF BORAFLEX NEUTRON ABSORBER
 
COUPONS


==Addressees==
==Addressees==
All holders of operating licenses or construction permits for nuclear powerreactors.PurDoseThe U.S. Nuclear Regulatory Commission (NRC) is issuing this informationnotice to alert recipients to a potentially significant problem pertaining todegradation of Boraflex neutron absorber coupons. It is expected thatrecipients will review the information for applicability to their facilitiesand 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.BackgroundPalisades has high-density fuel storage racks installed in the spent fuelpoolthat use Boraflex, a proprietary neutron absorbing material that wasmanufactured by Brand Industrial Services, Incorporated (BISCO). The storageracks are supplied by Westinghouse. The Boraflex is attached to the walls ofeach canister and is held in place by a stainless steel wrapper, which is spotwelded to the walls.The licensee has a surveillance program using Boraflex coupons to indicate thestatus of the Boraflex contained in the high density storage racks in thespent fuel pool. Recently observed degradation of several of these coupons,which may be due to exposure to high level gamma radiation in conjunction withinteraction with pool water, raised questions about the integrity of theBoraflex contained in the storage racks. Significant loss of Boraflex in thehigh-density fuel racks could result in loss of the subcriticality margin inthe spent fuel pool. 'Through a commitment to the NRC, Palisades was required to test and inspectthe Boraflex coupons after 5 years of use. The tests include opening thecoupons for visual observation, neutron attenuation determination, and aBoraflex hardness test.DescriDtion of CircumstancesDuring a period from August 17 through 19, 1993, 5 of the existing 10 Boraflexcoupons were removed from the spent fuel pool, 4 being full-length coupons9309070206Phi tE funt 3- O7G O1~
permits for nuclear power
IN 93-70September 10, 1993 and 1 a short-set coupon (see Figure 1). During removal of the full-lengthcoupons a powdery substance and a grey debris cloud were observed emanatingfrom the coupons. Further investigation of the full-length coupons revealedthat one coupon had lost an estimated 90 percent of its Boraflex, two others50 percent, and one 38 percent. Investigation of the short-set coupon showedthat it had retained 100 percent of its Boraflex. The licensee has determinedthat the Boraflex in the 4 full-length coupons and the short-set coupon camefrom different lots of material.A principal difference between the short-set and the full-length coupons istheir geometrical design. The short-set coupon consists of eight compartmentsencapsulating the Boraflex with pool water accessing only the edges of thecoupons. However, in the full-length coupon Boraflex is sandwiched axiallyover the entire length of coupon and bolted between two 0.51-mm [0.020-inch]stainless steel metal strips. The licensee postulated that a much larger areaof the full-length coupon was exposed to the pool water environment and flow.In addition, the full-length coupon has a 12.7-mm [0.5-inch] hole through themetal strip on the top portion of the coupon, which contributes to the poolwater flow around the Boraflex. The licensee has no immediate plans forremoval or testing of the remaining five coupons in the spent fuel pool, butdoes intend to conduct neutron "blackness" testing in the spring of 1994.The licensee also had initiated measurements of the silica content of thespent fuel pool water. No increase in silica above normal 1-4 ppm levels havebeen observed except in instances when the pool boron concentration wasincreased. Because silica filler material is a constituent of Boraflex, thepresence of silica in the water may be an indication of degradation of theBoraflex in the fuel pool.DiscussionPotential degradation mechanisms for Boraflex include (1) gamma flux, whichchanges the material characteristics of the base polymer, and (2) chemicalenvironment, namely the accessibility of water to the Boraflex. The licenseehas not drawn firm conclusions as to (1) the root cause of the observeddegradation of Boraflex in the coupons, or (2) the correlation of the behaviorof Boraflex in the coupons to that in the storage racks.Degradation of the Boraflex in fuel storage racks could reduce thesubcriticality margin in the spent fuel pool. The design basis assumes a5 percent subcriticality margin on the basis of lowest pool temperature, noboron concentration in the pool water, and minimum spacing between fuelassemblies. In its preliminary analysis, the licensee assumed no boron in thepool water and a complete loss of Boraflex from the fuel storage racks. Thisreduced the subcriticality margin from greater than 5 percent to about2 percent. However, the licensee used the burnup for the currently storedfuel in the criticality calculation. This is higher than the design burnupvalue, implying less reactive fuel in the fuel pool than assumed in the designcalcul ation.The licensee took several compensatory measures, including (1) making theoperating staff aware not to dilute the spent fuel pool, (2) increasing the IN 93-70September 10, 1993 spent fuel pool chemistry sampling frequency to daily, and (3) keeping theboron concentration in the spent fuel pool above 1800 ppm, which exceeds thetechnical specification requirement for boron concentration. With theseprecautions a subcriticality margin greater than 5 percent would bemaintained.Degradation of Boraflex has been previously addressed by NRC in InformationNotice 87-43, "Gaps in Neutron-Absorbing Material in High-Density Spent FuelStorage Racks," September 8, 1987. The Electric Power Research Institute,which has been studying this phenomenon for several years, has recentlypublished an interim report, "Boraflex Test Results and Evaluation,"TR-101986, February 1993.This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contactone of the technical contacts listed below or the appropriate Office ofNuclear Reactor Regulation (NRR) project manager.(~/'Bran Grimes, DirectorDivision of Operating Reactor SupportOffice of Nuclear Regulatory RegulationTechnical contacts: Kombiz Salehi, RIII(708) 790-5782K. I Parczewski, NRR(301) 504-2705Larry Kopp, NRR(301) 504-2879Vern Hodge, NRR(301) 504-1861
 
===All holders of operating licenses or construction===
reactors.
 
PurDose
 
is issuing this information
 
The U.S. Nuclear Regulatory Commission (NRC) significant problem pertaining to
 
notice to alert recipients to a potentially coupons. It is expected that
 
degradation of Boraflex neutron absorber      applicability to their facilities
 
recipients will review the information foravoid similar problems. However, and consider actions, as appropriate, to notice are not NRC requirements;
suggestions contained in this information response is required.
 
therefore, no specific action or written
 
Background
 
installed in the spent fuelpool
 
Palisades has high-density fuel storage racksabsorbing material that was
 
that use Boraflex, a proprietary neutron       Incorporated (BISCO). The storage
 
manufactured by Brand Industrial Services,Boraflex is attached to the walls of
 
racks are supplied by Westinghouse. The               steel wrapper, which is spot
 
each canister and is held in place by a stainless
 
welded to the walls.
 
Boraflex coupons to indicate the
 
The licensee has a surveillance program using   density storage racks in the
 
status of the Boraflex contained in the high         of several of these coupons, spent fuel pool. Recently observed degradation gamma radiation in conjunction with
 
which may be due to exposure to high level         about the integrity of the
 
interaction with pool water, raised questionsSignificant loss of Boraflex in the
 
Boraflex contained in the storage racks.         of the subcriticality margin in
 
high-density fuel racks could result in loss                     '
  the spent fuel pool.
 
was required to test and inspect
 
Through a commitment to the NRC, Palisades The tests include opening the
 
the Boraflex coupons after 5 years of use.               determination, and a
 
coupons for visual observation, neutron attenuation
 
Boraflex hardness test.
 
DescriDtion of Circumstances
 
1993, 5 of the existing 10 Boraflex
 
During a period from August 17 through 19,         4 being full-length coupons
 
coupons were removed from the spent fuel pool,
  9309070206 tE
 
Phi        funt                 3- O7G     O1~
 
IN 93-70
                                                                        September 10, 1993 and 1 a short-set coupon (see Figure 1). During
 
removal of the full-length
 
coupons a powdery substance and a grey debris cloud
 
were observed emanating
 
from the coupons. Further investigation of the full-length
 
that one coupon had lost an estimated 90 percent                   coupons revealed
 
of   its   Boraflex,   two others
 
50 percent, and one 38 percent. Investigation of
 
that it had retained 100 percent of its Boraflex.   the  short-set      coupon  showed
 
that the Boraflex in the 4 full-length coupons and     The    licensee    has  determined
 
from different lots of material.                      the short-set coupon came
 
A principal difference between the short-set and
 
the full-length coupons is
 
their geometrical design. The short-set coupon consists
 
encapsulating the Boraflex with pool water accessing             of eight compartments
 
coupons. However, in the full-length coupon Boraflex     only    the edges of the
 
over the entire length of coupon and bolted between         is  sandwiched    axially
 
stainless steel metal strips. The licensee postulated  two   0.51-mm     [0.020-inch]
  of the full-length coupon was exposed to the pool           that a much larger area
 
In addition, the full-length coupon has a 12.7-mm   water    environment and flow.
 
metal strip on the top portion of the coupon, which   [0.5-inch]      hole through the
 
water flow around the Boraflex. The licensee has         contributes      to the pool
 
removal or testing of the remaining five coupons     no  immediate      plans  for
 
does intend to conduct neutron "blackness" testing in  the  spent    fuel  pool,  but
 
in the spring of 1994.
 
The licensee also had initiated measurements of
 
the
 
spent fuel pool water. No increase in silica above silica content of the
 
been observed except in instances when the pool boronnormal 1-4 ppm levels have
 
increased. Because silica filler material is a             concentration was
 
constituent
 
presence of silica in the water may be an indication                 of Boraflex, the
 
Boraflex in the fuel pool.                               of  degradation      of the
 
Discussion
 
Potential degradation mechanisms for Boraflex include
 
changes the material characteristics of the base             (1) gamma flux, which
 
environment, namely the accessibility of water to   polymer,      and (2) chemical
 
has not drawn firm conclusions as to (1) the root     the   Boraflex.        The licensee
 
degradation of Boraflex in the coupons, or (2)       cause    of  the  observed
 
the
 
of Boraflex in the coupons to that in the storage correlation of the behavior
 
racks.
 
Degradation of the Boraflex in fuel storage racks
 
subcriticality margin in the spent fuel pool. The could reduce the
 
5 percent subcriticality margin on the basis of       design basis assumes a
 
boron concentration in the pool water, and minimumlowest    pool temperature, no
 
assemblies. In its preliminary analysis, the licensee spacing      between fuel
 
pool water and a complete loss of Boraflex from               assumed    no boron in the
 
reduced the subcriticality margin from greater     the  fuel    storage    racks. This
 
than 5 percent to about
 
2 percent. However, the licensee used the burnup
 
fuel in the criticality calculation. This is higher   for the currently stored
 
value, implying less reactive fuel in the fuel pool than the design burnup
 
calcul ation.                                            than assumed in the design
 
The licensee took several compensatory measures, operating staff aware not to dilute the spent fuelincluding (1) making the
 
pool, (2) increasing the
 
IN 93-70
                                                              September 10, 1993 spent fuel pool chemistry sampling frequency to daily, and (3) keeping the
 
boron concentration in the spent fuel pool above 1800 ppm, which exceeds the
 
technical specification requirement for boron concentration. With these
 
precautions a subcriticality margin greater than 5 percent would be
 
maintained.
 
Degradation of Boraflex has been previously addressed by NRC in Information
 
Notice 87-43, "Gaps in Neutron-Absorbing Material in High-Density Spent Fuel
 
Storage Racks," September 8, 1987. The Electric Power Research Institute, which has been studying this phenomenon for several years, has recently
 
published an interim report, "Boraflex Test Results and Evaluation,"
TR-101986, February 1993.
 
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.
 
(~/'
                                      Bran     Grimes, Director
 
Division of Operating Reactor Support
 
Office of Nuclear Regulatory Regulation
 
Technical contacts: Kombiz Salehi, RIII
 
(708) 790-5782 K. I Parczewski, NRR
 
(301) 504-2705 Larry Kopp, NRR
 
(301) 504-2879 Vern Hodge, NRR
 
(301) 504-1861 Attachments:
  1. Figure 1, Palisades Boraflex Coupon Types
 
2. List of Recently Issued NRC Information Notices
 
IN 93-70
                          .-            tSeptember                                    10, 1993 spent fuel pool chemistry sampling frequency to daily, and (3) keeping the
 
boron concentration in the spent fuel pool above 1800 ppm, which exceeds the
 
technical specification requirement for boron concentration. With these
 
precautions a subcriticality margin greater than 5 percent would be
 
maintained.
 
Degradation of Boraflex has been previously addressed by NRC in Information
 
Notice 87-43, "Gaps in Neutron-Absorbing Material in High-Density Spent Fuel
 
Storage Racks," September 8, 1987. The Electric Power Research Institute, which has been studying this phenomenon for several years, has recently
 
published an interim report, "Boraflex Test Results and Evaluation,"
    TR-101986, February 1993.
 
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 Uy
 
Maian K.Grime$
                                              Brian K. Grimes, Director
 
Division of Operating Reactor Support
 
Office of Nuclear Regulatory Regulation
 
Technical contacts:    Kombiz Salehi, RIII


===Attachments:===
(708) 790-5782 K. I Parczewski, NRR
1. Figure 1, Palisades Boraflex Coupon Types2. List of Recently Issued NRC Information Notices IN 93-70.- tSeptember 10, 1993 spent fuel pool chemistry sampling frequency to daily, and (3) keeping theboron concentration in the spent fuel pool above 1800 ppm, which exceeds thetechnical specification requirement for boron concentration. With theseprecautions a subcriticality margin greater than 5 percent would bemaintained.Degradation of Boraflex has been previously addressed by NRC in InformationNotice 87-43, "Gaps in Neutron-Absorbing Material in High-Density Spent FuelStorage Racks," September 8, 1987. The Electric Power Research Institute,which has been studying this phenomenon for several years, has recentlypublished an interim report, "Boraflex Test Results and Evaluation,"TR-101986, February 1993.This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contactone of the technical contacts listed below or the appropriate Office ofNuclear Reactor Regulation (NRR) project manager.Original signed UyMaian K. Grime$Brian K. Grimes, DirectorDivision of Operating Reactor SupportOffice of Nuclear Regulatory RegulationTechnical contacts: Kombiz Salehi, RIII(708) 790-5782K. I Parczewski, NRR(301) 504-2705Larry Kopp, NRR(301) 504-2879Vern Hodge, NRR(301) 504-1861


===Attachments:===
(301) 504-2705 Larry Kopp, NRR
1. Figure 1, Palisades Boraflex Coupon Types2. List of Recently Issued NRC Information Notices*SEE PREVIOUS CONCURRENCEOFFICE OGCB:DORS:NRR DRS:RIII DD:DRS:RIII SRXB:DSSA:NRR C:SRXB:DSSA:NRRNAME *CVHodge *KSalehi *WLForney *LIKopp *RCJonesDATE 09/02/93 09/02/93 09/02/93 09/03/93 09/03/93Tech Ed D:DSSA EMCB:DE:NRR EMCB:DE:NRR C:EMCB:DE:NRR C:OEAB:DORS*DGable *ACThadani *JStrosnider *KlParczewski *RAHermann *AEChaffee09/01/93 09/04/93 01J0 M22 09/03/93 09/03/93 09/03/9311 _ _ _ _ ,_C:OGCB:DORS:NRR*GHMarcus j I09/03/93 09/7 /93DOCUMENI NAME: 93-/U.IN K>IN 93-xx ISeptember xx, 993This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contactone of the technical contacts listed below or the appropriate Office of !Nuclear Reactor Regulation (NRR) project manager. IBrian K. Grimes, DirectorDivision of Operating Reactor SupiOffice of Nuclear Regulatory Regul0ortat on
 
(301) 504-2879 Vern Hodge, NRR
 
(301) 504-1861 Attachments:
    1. Figure 1, Palisades Boraflex Coupon Types
 
2. List of Recently Issued NRC Information Notices
 
*SEE PREVIOUS CONCURRENCE
 
OFFICE    OGCB:DORS:NRR       DRS:RIII       DD:DRS:RIII       SRXB:DSSA:NRR   C:SRXB:DSSA:NRR
 
NAME      *CVHodge           *KSalehi       *WLForney         *LIKopp         *RCJones
 
DATE      09/02/93           09/02/93       09/02/93           09/03/93         09/03/93 Tech Ed     D:DSSA           EMCB:DE:NRR       EMCB:DE:NRR         C:EMCB:DE:NRR   C:OEAB:DORS
 
*DGable     *ACThadani       *JStrosnider     *KlParczewski       *RAHermann       *AEChaffee
 
09/01/93   09/04/93         01J0M22          09/03/93             09/03/93       09/03/93
                        11 _ _   _   _ ,_
C:OGCB:DORS:NRR
 
*GHMarcus         j                     I
 
09/03/93           09/7 /93 DOCUMENI NAME:   93-/U.IN
 
K>
                                                                                  IN 93-xx       I
 
September xx, 1993 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.                                     I
 
Brian K. Grimes, Director
 
Division of Operating Reactor Supi 0ort
 
Office of Nuclear Regulatory Regul at on


===Technical Contact:===
===Technical Contact:===
Kombiz Salehi,(708) 790-5782RIIIK. I Parczewski, NRR(301) 504-2705Larry Kopp, NRR(301) 504-2879Vern Hodge, NRR(301) 504-1861


===Attachments:===
===Kombiz Salehi, RIII===
1. Figure 1, Palisades Boraflex Coupon Types2. List of Recently Issued NRC Information Notices*SEE PREVIOUS CONCURRENCE... ..... -..' at .-law. 1OFFICEOGCB:DORS:NRRDRS: RI I¢ .RPDD DR4:RIIIrSRXB:DSSA:NRR: L/C:SRXB:DSSA:NRRLNAME CVHodge KSalehi WLForney LIKop RC ones,DATE O /l2/93 CO/72/93 £ /O2I93 7/3 /93 /3 /93*Tech Ed D:DSS r EMCB:DE:NRR _MCB:DE:NRS C: 7 U D NRR IOEAB:DORSACThada i Strosnider XParczewski RAHermann j 0aef ffee/9 / /9 /3 /93 '1 /,3/93 § /3 /93 ___________.. _.93C:OGCB:DORS:NR4D:DORS:NRRGHMarcus OI M BKGrimesq/13 /93 / /93DOCUMENT NAME: PALN0902.CVH4Adr of ads? >.4 A 42XsK 4-ct-M etO 4 vJIN 93-xxSeptember xx, 993The licensee took several compensatory measures, including (1) making theoperating staff aware to not dilute the spent fuel pool, (2) increasing thespent fuel pool chemistry sampling frequency to daily, and (3) keeping theboron concentration in the spent fuel pool above 1800 ppm, which exceeds thetechnical specification requirement for boron concentration.Degradation of Boraflex has been previously addressed by NRC in InformationNotice 87-43, "Gaps in Neutron-Absorbing Material in High-Density Spent FuelStorage Racks," September 8, 1987. The Electric Power Research Institute, whohas been studying this phenomenon for several years, has recently published aninterim report, "Boraflex Test Results and Evaluation," TR-101986, February1993.This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contactthe technical contact listed below or the appropriate Office of NuclearReactor Regulation (NRR) project manager.Brian K. Grimes, DirectorDivision of Operating Reactor SupportOffice of Nuclear Regulatory Regulation
                                  (708) 790-5782 K. I Parczewski, NRR
 
(301) 504-2705 Larry Kopp, NRR
 
(301) 504-2879 Vern Hodge, NRR
 
(301) 504-1861 Attachments:      1. Figure 1, Palisades Boraflex Coupon Types
 
2. List of Recently Issued NRC Information Notices
 
*SEE PREVIOUS CONCURRENCE. .. .....   -     .   .   ' - .
 
at 1                                  law.
 
:          L/
  OFFICE    OGCB:DORS:NRR          DRS: RI I¢ .RP DD DR4:RIIIr      SRXB:DSSA:NRR   C:SRXB:DSSA:NRRL
 
NAME      CVHodge                 KSalehi         WLForney         LIKop           RC ones, DATE     O /l2/93                 CO/72/93       £ /O2I93         7/3 /93           /3 /93
  *Tech Ed
 
/9 D:DSS
 
ACThada i
 
/ .._.93
                      /9 r     EMCB:DE:NRR
 
Strosnider
 
/3/93
                                                      _MCB:DE:NRS C:7 XParczewski
 
'1 /,3/93         §
                                                                                UNRR
 
/3/93 D
 
RAHermann      j
 
IOEAB:DORS
 
0aefffee
 
___________
  C:OGCB:DORS:NR4            D:DORS:NRR
 
GHMarcus OI M             BKGrimes
 
q/13 /93                   / /93 DOCUMENT NAME:       PALN0902.CVH
 
4Adr of   ads?             >
    .4 A 42XsK       4-ct-M         etO   4
 
vJ
 
IN 93-xx
 
September xx, 1993 The licensee took several compensatory measures, including (1) making the
 
operating staff aware to not dilute the spent fuel pool, (2) increasing the
 
spent fuel pool chemistry sampling frequency to daily, and (3) keeping the
 
boron concentration in the spent fuel pool above 1800 ppm, which exceeds the
 
technical specification requirement for boron concentration.
 
Degradation of Boraflex has been previously addressed by NRC in Information
 
Notice 87-43, "Gaps in Neutron-Absorbing Material in High-Density Spent Fuel
 
Storage Racks," September 8, 1987. The Electric Power Research Institute, who
 
has been studying this phenomenon for several years, has recently published an
 
interim report, "Boraflex Test Results and Evaluation," TR-101986, February
 
1993.
 
This information notice requires no specific action or written response. If
 
you have any questions about the information in this notice, please contact
 
the technical contact listed below or the appropriate Office of Nuclear
 
Reactor Regulation (NRR) project manager.
 
Brian K. Grimes, Director
 
Division of Operating Reactor Support
 
Office of Nuclear Regulatory Regulation


===Technical Contact:===
===Technical Contact:===
Kombiz Salehi, RIII(708)790-5782K. I Parczewski, NRR Larry Kopp, NRR Vern Hodge, NRR(301) 504-2705 (301) 504-2879 (301) 504-1861


===Attachments:===
===Kombiz Salehi, RIII===
1. Figure 1, Palisades Boraflex Coupon Types2. List of Recently Issued NRC Information NoticesrnmriIDDrrr*CFF DDVITNIC.3c LL. VUL J UVIRUURAJWOFFICE lOGCB:DORS:NRR DRS:RIII D:DRS:RIII SRXB:DSSA:NRR C:SRXB:DSSA:NRRNAME CVHodge Ug KSalehi TOMartin LIKopp RCJonesDATE Oq/ol0/93 / /93 / /93 /93 /93Tech Ed D:DSSA EMCB:DE:NRR EMCB:DE:ND C:EMCB:DE:NRR C:OEAB:DORSq j ACTHADANI JStrosnider KIParczews'ki RAHermann AEChaffee____ /93 /_/93 /_/93 9 /l/93 /L/93 / /93C:OGCB:DORS:NRRD:DORS:NRRGHMarcus [BKGrimes/ /93 J / /93DOCUMENT NAME: PALNOFIG.CVH K-IAttachment 1IN 93-70September 10, 1993 Figure 1_Palisades Boraflex aCoupon TypesaBodfes mate wboned bloom twoI3Shoet M Paf kn*QIi..I I3i i3_..I:I --I39r Iale i ! 2III4 i..4I.IIE Li Axtachment 2IN 93-70September 10, 1993Page 1 of ILIST OF RECENTLY ISSUEDNRC INFORMATION NOTICESInformation Date ofNotice No. Subject Issuance Issued to93-6993-6892-16,Supp. 293-6793-6693-6593-6493-63Radiography Events atOperating Power ReactorsFailure of Pump ShaftCoupling Caused byTemper Embrittlementduring ManufactureLoss of Flow from theResidual Heat RemovalPump during RefuelingCavity DraindownBursting of HighPressure CoolantInjection Steam LineRupture Discs InjuresPlant PersonnelSwitchover to Hot-LegInjection FollowingA Loss-of-CoolantAccident in Pres-surized Water ReactorsReactor Trips Causedby Breaker Testingwith Fault ProtectionBypassedPeriodic Testing andPreventive Maintenanceof Molded Case CircuitBreakersImproper Use of SolubleWeld Purge Dam Material09/02/9309/01/9308/23/9308/16/9308/16/9308/13/93All holders of OLs or CPsfor nuclear power reactorsand all radiographylicensees.All holders of OLs or CPsfor nuclear power reactors.All holders of OLs or CPsfor nuclear power reactors.All holders of OLs or CPsfor nuclear power reactors.All holders of OLs or CPsfor pressurized waterreactors.Al 1forholders of OLs or CPsnuclear power reactors.08/12/9308/11/93All holders of OLs or CPsfor nuclear power reactors.All holders of OLs or CPsfor nuclear power reactors.* OL = Operating LicenseCP = Construction Permit}}
                                  (708)790-5782 K. I Parczewski, NRR            Larry Kopp, NRR  Vern Hodge, NRR
 
(301) 504-2705                  (301) 504-2879    (301) 504-1861 Attachments:        1. Figure 1, Palisades Boraflex Coupon Types
 
2. List of Recently Issued NRC Information Notices
 
*CFF
 
.3c
 
LL.
 
DDVITNIC
 
UVIRUURAJW
 
VUL J
 
rnmriIDDrrr
 
OFFICE lOGCB:DORS:NRR             DRS:RIII     D:DRS:RIII   SRXB:DSSA:NRR     C:SRXB:DSSA:NRR
 
NAME          CVHodge Ug         KSalehi     TOMartin       LIKopp           RCJones
 
DATE        Oq/ol0/93             / /93         / /93             /93             /93 Tech Ed         D:DSSA           EMCB:DE:NRR     EMCB:DE:ND       C:EMCB:DE:NRR     C:OEAB:DORS
 
q    j           ACTHADANI       JStrosnider     KIParczews'ki     RAHermann       AEChaffee
 
____      /93           /_/93         /_/93       9 /l/93               /L/93           / /93 C:OGCB:DORS:NRR            D:DORS:NRR
 
GHMarcus                  [BKGrimes
 
/ /93               J / /93 DOCUMENT NAME:           PALNOFIG.CVH
 
K-I
 
Attachment 1 IN 93-70
                                      September 10, 1993 Figure 1_              Q
 
Palisades Boraflex   a.             .
 
Coupon Types                  Ii
 
a
 
I    I
 
Bodfes mate w              i
 
boned bloom two      3i
 
3_..
 
I:
                                  I
 
3
  39rIa                            I - -I
 
le i 2! Shoet M          Pafkn*  I
 
I
 
i
 
I4
                                      .   . 4
                                              .I  I
 
I
 
E    Li
 
Axtachment 2 IN 93-70
                                                            September 10, 1993 Page 1 of I
 
LIST OF RECENTLY ISSUED
 
NRC INFORMATION NOTICES
 
Information                                    Date of
 
Notice No.             Subject               Issuance   Issued to
 
93-69          Radiography Events at          09/02/93  All holders of OLs or CPs
 
Operating Power Reactors                  for nuclear power reactors
 
and all radiography
 
licensees.
 
93-68          Failure of Pump Shaft          09/01/93  All holders of OLs or CPs
 
Coupling Caused by                        for nuclear power reactors.
 
Temper Embrittlement
 
during Manufacture
 
92-16,          Loss of Flow from the          08/23/93  All holders of OLs or CPs
 
Supp. 2        Residual Heat Removal                    for nuclear power reactors.
 
Pump during Refueling
 
Cavity Draindown
 
93-67          Bursting of High              08/16/93  All holders of OLs or CPs
 
Pressure Coolant                          for nuclear power reactors.
 
Injection Steam Line
 
Rupture Discs Injures
 
Plant Personnel
 
93-66          Switchover to Hot-Leg          08/16/93  All holders of OLs or CPs
 
Injection Following                      for pressurized water
 
A Loss-of-Coolant                          reactors.
 
Accident in Pres- surized Water Reactors
 
93-65          Reactor Trips Caused          08/13/93  Al 1 holders of OLs or CPs
 
by Breaker Testing                        for nuclear power reactors.
 
with Fault Protection
 
Bypassed
 
93-64          Periodic Testing and          08/12/93  All holders of OLs or CPs
 
Preventive Maintenance                    for nuclear power reactors.
 
of Molded Case Circuit
 
Breakers
 
93-63          Improper Use of Soluble        08/11/93  All holders of OLs or CPs
 
Weld Purge Dam Material                  for nuclear power reactors.
 
* OL = Operating License
 
CP = Construction Permit}}


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

Latest revision as of 04:24, 24 November 2019

Degradation of Boraflex Neutron Absorber Coupons
ML031070107
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, Three Mile Island, 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  Entergy icon.png
Issue date: 09/10/1993
From: Grimes B
Office of Nuclear Reactor Regulation
To:
References
-nr IN-93-070, NUDOCS 9309070206
Download: ML031070107 (9)
v • d • e


I

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON D.C. 20555 September 10, 1993 NRC INFORMATION NOTICE 93-70: DEGRADATION OF BORAFLEX NEUTRON ABSORBER

COUPONS

Addressees

permits for nuclear power

All holders of operating licenses or construction

reactors.

PurDose

is issuing this information

The U.S. Nuclear Regulatory Commission (NRC) significant problem pertaining to

notice to alert recipients to a potentially coupons. It is expected that

degradation of Boraflex neutron absorber applicability to their facilities

recipients will review the information foravoid similar problems. However, and consider actions, as appropriate, to notice are not NRC requirements;

suggestions contained in this information response is required.

therefore, no specific action or written

Background

installed in the spent fuelpool

Palisades has high-density fuel storage racksabsorbing material that was

that use Boraflex, a proprietary neutron Incorporated (BISCO). The storage

manufactured by Brand Industrial Services,Boraflex is attached to the walls of

racks are supplied by Westinghouse. The steel wrapper, which is spot

each canister and is held in place by a stainless

welded to the walls.

Boraflex coupons to indicate the

The licensee has a surveillance program using density storage racks in the

status of the Boraflex contained in the high of several of these coupons, spent fuel pool. Recently observed degradation gamma radiation in conjunction with

which may be due to exposure to high level about the integrity of the

interaction with pool water, raised questionsSignificant loss of Boraflex in the

Boraflex contained in the storage racks. of the subcriticality margin in

high-density fuel racks could result in loss '

the spent fuel pool.

was required to test and inspect

Through a commitment to the NRC, Palisades The tests include opening the

the Boraflex coupons after 5 years of use. determination, and a

coupons for visual observation, neutron attenuation

Boraflex hardness test.

DescriDtion of Circumstances

1993, 5 of the existing 10 Boraflex

During a period from August 17 through 19, 4 being full-length coupons

coupons were removed from the spent fuel pool,

9309070206 tE

Phi funt 3- O7G O1~

IN 93-70

September 10, 1993 and 1 a short-set coupon (see Figure 1). During

removal of the full-length

coupons a powdery substance and a grey debris cloud

were observed emanating

from the coupons. Further investigation of the full-length

that one coupon had lost an estimated 90 percent coupons revealed

of its Boraflex, two others

50 percent, and one 38 percent. Investigation of

that it had retained 100 percent of its Boraflex. the short-set coupon showed

that the Boraflex in the 4 full-length coupons and The licensee has determined

from different lots of material. the short-set coupon came

A principal difference between the short-set and

the full-length coupons is

their geometrical design. The short-set coupon consists

encapsulating the Boraflex with pool water accessing of eight compartments

coupons. However, in the full-length coupon Boraflex only the edges of the

over the entire length of coupon and bolted between is sandwiched axially

stainless steel metal strips. The licensee postulated two 0.51-mm [0.020-inch]

of the full-length coupon was exposed to the pool that a much larger area

In addition, the full-length coupon has a 12.7-mm water environment and flow.

metal strip on the top portion of the coupon, which [0.5-inch] hole through the

water flow around the Boraflex. The licensee has contributes to the pool

removal or testing of the remaining five coupons no immediate plans for

does intend to conduct neutron "blackness" testing in the spent fuel pool, but

in the spring of 1994.

The licensee also had initiated measurements of

the

spent fuel pool water. No increase in silica above silica content of the

been observed except in instances when the pool boronnormal 1-4 ppm levels have

increased. Because silica filler material is a concentration was

constituent

presence of silica in the water may be an indication of Boraflex, the

Boraflex in the fuel pool. of degradation of the

Discussion

Potential degradation mechanisms for Boraflex include

changes the material characteristics of the base (1) gamma flux, which

environment, namely the accessibility of water to polymer, and (2) chemical

has not drawn firm conclusions as to (1) the root the Boraflex. The licensee

degradation of Boraflex in the coupons, or (2) cause of the observed

the

of Boraflex in the coupons to that in the storage correlation of the behavior

racks.

Degradation of the Boraflex in fuel storage racks

subcriticality margin in the spent fuel pool. The could reduce the

5 percent subcriticality margin on the basis of design basis assumes a

boron concentration in the pool water, and minimumlowest pool temperature, no

assemblies. In its preliminary analysis, the licensee spacing between fuel

pool water and a complete loss of Boraflex from assumed no boron in the

reduced the subcriticality margin from greater the fuel storage racks. This

than 5 percent to about

2 percent. However, the licensee used the burnup

fuel in the criticality calculation. This is higher for the currently stored

value, implying less reactive fuel in the fuel pool than the design burnup

calcul ation. than assumed in the design

The licensee took several compensatory measures, operating staff aware not to dilute the spent fuelincluding (1) making the

pool, (2) increasing the

IN 93-70

September 10, 1993 spent fuel pool chemistry sampling frequency to daily, and (3) keeping the

boron concentration in the spent fuel pool above 1800 ppm, which exceeds the

technical specification requirement for boron concentration. With these

precautions a subcriticality margin greater than 5 percent would be

maintained.

Degradation of Boraflex has been previously addressed by NRC in Information

Notice 87-43, "Gaps in Neutron-Absorbing Material in High-Density Spent Fuel

Storage Racks," September 8, 1987. The Electric Power Research Institute, which has been studying this phenomenon for several years, has recently

published an interim report, "Boraflex Test Results and Evaluation,"

TR-101986, February 1993.

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.

(~/'

Bran Grimes, Director

Division of Operating Reactor Support

Office of Nuclear Regulatory Regulation

Technical contacts: Kombiz Salehi, RIII

(708) 790-5782 K. I Parczewski, NRR

(301) 504-2705 Larry Kopp, NRR

(301) 504-2879 Vern Hodge, NRR

(301) 504-1861 Attachments:

1. Figure 1, Palisades Boraflex Coupon Types

2. List of Recently Issued NRC Information Notices

IN 93-70

.- tSeptember 10, 1993 spent fuel pool chemistry sampling frequency to daily, and (3) keeping the

boron concentration in the spent fuel pool above 1800 ppm, which exceeds the

technical specification requirement for boron concentration. With these

precautions a subcriticality margin greater than 5 percent would be

maintained.

Degradation of Boraflex has been previously addressed by NRC in Information

Notice 87-43, "Gaps in Neutron-Absorbing Material in High-Density Spent Fuel

Storage Racks," September 8, 1987. The Electric Power Research Institute, which has been studying this phenomenon for several years, has recently

published an interim report, "Boraflex Test Results and Evaluation,"

TR-101986, February 1993.

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 Uy

Maian K.Grime$

Brian K. Grimes, Director

Division of Operating Reactor Support

Office of Nuclear Regulatory Regulation

Technical contacts: Kombiz Salehi, RIII

(708) 790-5782 K. I Parczewski, NRR

(301) 504-2705 Larry Kopp, NRR

(301) 504-2879 Vern Hodge, NRR

(301) 504-1861 Attachments:

1. Figure 1, Palisades Boraflex Coupon Types

2. List of Recently Issued NRC Information Notices

  • SEE PREVIOUS CONCURRENCE

OFFICE OGCB:DORS:NRR DRS:RIII DD:DRS:RIII SRXB:DSSA:NRR C:SRXB:DSSA:NRR

NAME *CVHodge *KSalehi *WLForney *LIKopp *RCJones

DATE 09/02/93 09/02/93 09/02/93 09/03/93 09/03/93 Tech Ed D:DSSA EMCB:DE:NRR EMCB:DE:NRR C:EMCB:DE:NRR C:OEAB:DORS

  • DGable *ACThadani *JStrosnider *KlParczewski *RAHermann *AEChaffee

09/01/93 09/04/93 01J0M22 09/03/93 09/03/93 09/03/93

11 _ _ _ _ ,_

C:OGCB:DORS:NRR

  • GHMarcus j I

09/03/93 09/7 /93 DOCUMENI NAME: 93-/U.IN

K>

IN 93-xx I

September xx, 1993 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. I

Brian K. Grimes, Director

Division of Operating Reactor Supi 0ort

Office of Nuclear Regulatory Regul at on

Technical Contact:

Kombiz Salehi, RIII

(708) 790-5782 K. I Parczewski, NRR

(301) 504-2705 Larry Kopp, NRR

(301) 504-2879 Vern Hodge, NRR

(301) 504-1861 Attachments: 1. Figure 1, Palisades Boraflex Coupon Types

2. List of Recently Issued NRC Information Notices

  • SEE PREVIOUS CONCURRENCE. .. ..... - . . ' - .

at 1 law.

L/

OFFICE OGCB:DORS:NRR DRS: RI I¢ .RP DD DR4:RIIIr SRXB:DSSA:NRR C:SRXB:DSSA:NRRL

NAME CVHodge KSalehi WLForney LIKop RC ones, DATE O /l2/93 CO/72/93 £ /O2I93 7/3 /93 /3 /93

  • Tech Ed

/9 D:DSS

ACThada i

/ .._.93

/9 r EMCB:DE:NRR

Strosnider

/3/93

_MCB:DE:NRS C:7 XParczewski

'1 /,3/93 §

UNRR

/3/93 D

RAHermann j

IOEAB:DORS

0aefffee

___________

C:OGCB:DORS:NR4 D:DORS:NRR

GHMarcus OI M BKGrimes

q/13 /93 / /93 DOCUMENT NAME: PALN0902.CVH

4Adr of ads? >

.4 A 42XsK 4-ct-M etO 4

vJ

IN 93-xx

September xx, 1993 The licensee took several compensatory measures, including (1) making the

operating staff aware to not dilute the spent fuel pool, (2) increasing the

spent fuel pool chemistry sampling frequency to daily, and (3) keeping the

boron concentration in the spent fuel pool above 1800 ppm, which exceeds the

technical specification requirement for boron concentration.

Degradation of Boraflex has been previously addressed by NRC in Information

Notice 87-43, "Gaps in Neutron-Absorbing Material in High-Density Spent Fuel

Storage Racks," September 8, 1987. The Electric Power Research Institute, who

has been studying this phenomenon for several years, has recently published an

interim report, "Boraflex Test Results and Evaluation," TR-101986, February

1993.

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

you have any questions about the information in this notice, please contact

the technical contact listed below or the appropriate Office of Nuclear

Reactor Regulation (NRR) project manager.

Brian K. Grimes, Director

Division of Operating Reactor Support

Office of Nuclear Regulatory Regulation

Technical Contact:

Kombiz Salehi, RIII

(708)790-5782 K. I Parczewski, NRR Larry Kopp, NRR Vern Hodge, NRR

(301) 504-2705 (301) 504-2879 (301) 504-1861 Attachments: 1. Figure 1, Palisades Boraflex Coupon Types

2. List of Recently Issued NRC Information Notices

  • CFF

.3c

LL.

DDVITNIC

UVIRUURAJW

VUL J

rnmriIDDrrr

OFFICE lOGCB:DORS:NRR DRS:RIII D:DRS:RIII SRXB:DSSA:NRR C:SRXB:DSSA:NRR

NAME CVHodge Ug KSalehi TOMartin LIKopp RCJones

DATE Oq/ol0/93 / /93 / /93 /93 /93 Tech Ed D:DSSA EMCB:DE:NRR EMCB:DE:ND C:EMCB:DE:NRR C:OEAB:DORS

q j ACTHADANI JStrosnider KIParczews'ki RAHermann AEChaffee

____ /93 /_/93 /_/93 9 /l/93 /L/93 / /93 C:OGCB:DORS:NRR D:DORS:NRR

GHMarcus [BKGrimes

/ /93 J / /93 DOCUMENT NAME: PALNOFIG.CVH

K-I

Attachment 1 IN 93-70

September 10, 1993 Figure 1_ Q

Palisades Boraflex a. .

Coupon Types Ii

a

I I

Bodfes mate w i

boned bloom two 3i

3_..

I:

I

3

39rIa I - -I

le i 2! Shoet M Pafkn* I

I

i

I4

. . 4

.I I

I

E Li

Axtachment 2 IN 93-70

September 10, 1993 Page 1 of I

LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information Date of

Notice No. Subject Issuance Issued to

93-69 Radiography Events at 09/02/93 All holders of OLs or CPs

Operating Power Reactors for nuclear power reactors

and all radiography

licensees.

93-68 Failure of Pump Shaft 09/01/93 All holders of OLs or CPs

Coupling Caused by for nuclear power reactors.

Temper Embrittlement

during Manufacture

92-16, Loss of Flow from the 08/23/93 All holders of OLs or CPs

Supp. 2 Residual Heat Removal for nuclear power reactors.

Pump during Refueling

Cavity Draindown

93-67 Bursting of High 08/16/93 All holders of OLs or CPs

Pressure Coolant for nuclear power reactors.

Injection Steam Line

Rupture Discs Injures

Plant Personnel

93-66 Switchover to Hot-Leg 08/16/93 All holders of OLs or CPs

Injection Following for pressurized water

A Loss-of-Coolant reactors.

Accident in Pres- surized Water Reactors

93-65 Reactor Trips Caused 08/13/93 Al 1 holders of OLs or CPs

by Breaker Testing for nuclear power reactors.

with Fault Protection

Bypassed

93-64 Periodic Testing and 08/12/93 All holders of OLs or CPs

Preventive Maintenance for nuclear power reactors.

of Molded Case Circuit

Breakers

93-63 Improper Use of Soluble 08/11/93 All holders of OLs or CPs

Weld Purge Dam Material for nuclear power reactors.

  • OL = Operating License

CP = Construction Permit


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