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

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{{#Wiki_filter:I UNITED STATES NUCLEAR REGULATORY
{{#Wiki_filter:I


COMMISSION
UNITED STATES


===OFFICE OF NUCLEAR REACTOR REGULATION===
NUCLEAR REGULATORY COMMISSION
WASHINGTON


D.C. 20555 September
OFFICE OF NUCLEAR REACTOR REGULATION


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


NOTICE 93-70: DEGRADATION
COUPONS
 
OF BORAFLEX NEUTRON ABSORBER COUPONS


==Addressees==
==Addressees==
All holders of operating
permits for nuclear power


licenses or construction
===All holders of operating licenses or construction===
reactors.


permits for nuclear power reactors.PurDose The U.S. Nuclear Regulatory
PurDose


Commission (NRC) is issuing this information
is issuing this information


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


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


significant
degradation of Boraflex neutron absorber      applicability to their facilities


problem pertaining
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.


to degradation
therefore, no specific action or written


of Boraflex neutron absorber coupons. It is expected that recipients
Background


will review the information
installed in the spent fuelpool


for applicability
Palisades has high-density fuel storage racksabsorbing material that was


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


and consider actions, as appropriate, to avoid similar problems.
manufactured by Brand Industrial Services,Boraflex is attached to the walls of


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


contained
each canister and is held in place by a stainless


in this information
welded to the walls.


notice are not NRC requirements;
Boraflex coupons to indicate the
therefore, no specific action or written response is required.Background


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


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


fuel storage racks installed
which may be due to exposure to high level        about the integrity of the


in the spent fuelpool that use Boraflex, a proprietary
interaction with pool water, raised questionsSignificant loss of Boraflex in the


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


material that was manufactured
high-density fuel racks could result in loss                    '
  the spent fuel pool.


by Brand Industrial
was required to test and inspect


Services, Incorporated (BISCO). The storage racks are supplied by Westinghouse.
Through a commitment to the NRC, Palisades The tests include opening the


The Boraflex is attached to the walls of each canister and is held in place by a stainless
the Boraflex coupons after 5 years of use.              determination, and a


steel wrapper, which is spot welded to the walls.The licensee has a surveillance
coupons for visual observation, neutron attenuation


program using Boraflex coupons to indicate the status of the Boraflex contained
Boraflex hardness test.


in the high density storage racks in the spent fuel pool. Recently observed degradation
DescriDtion of Circumstances


of several of these coupons, which may be due to exposure to high level gamma radiation
1993, 5 of the existing 10 Boraflex


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


with interaction
coupons were removed from the spent fuel pool,
  9309070206 tE


with pool water, raised questions
Phi        funt                  3- O7G    O1~


about the integrity
IN 93-70
                                                                        September 10, 1993 and 1 a short-set coupon (see Figure 1). During


of the Boraflex contained
removal of the full-length


in the storage racks. Significant
coupons a powdery substance and a grey debris cloud


loss of Boraflex in the high-density
were observed emanating


fuel racks could result in loss of the subcriticality
from the coupons. Further investigation of the full-length


margin in the spent fuel pool. 'Through a commitment
that one coupon had lost an estimated 90 percent                    coupons revealed


to the NRC, Palisades
of  its    Boraflex,   two others


was required to test and inspect the Boraflex coupons after 5 years of use. The tests include opening the coupons for visual observation, neutron attenuation
50 percent, and one 38 percent. Investigation of


determination, and a Boraflex hardness test.DescriDtion
that it had retained 100 percent of its Boraflex.   the  short-set      coupon  showed


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


During a period from August 17 through 19, 1993, 5 of the existing 10 Boraflex coupons were removed from the spent fuel pool, 4 being full-length
from different lots of material.                      the short-set coupon came


coupons 9309070206 Phi tE funt 3- O7G O1~
A principal difference between the short-set and
IN 93-70 September


10, 1993 and 1 a short-set
the full-length coupons is


coupon (see Figure 1). During removal of the full-length
their geometrical design. The short-set coupon consists


coupons a powdery substance
encapsulating the Boraflex with pool water accessing            of eight compartments


and a grey debris cloud were observed emanating from the coupons. Further investigation
coupons. However, in the full-length coupon Boraflex      only    the edges of the


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


coupons revealed that one coupon had lost an estimated
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


90 percent of its Boraflex, two others 50 percent, and one 38 percent. Investigation
In addition, the full-length coupon has a 12.7-mm    water    environment and flow.


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


coupon showed that it had retained 100 percent of its Boraflex.
water flow around the Boraflex. The licensee has        contributes      to the pool


===The licensee has determined===
removal or testing of the remaining five coupons      no  immediate      plans  for
that the Boraflex in the 4 full-length


coupons and the short-set
does intend to conduct neutron "blackness" testing  in  the   spent    fuel  pool,  but


coupon came from different
in the spring of 1994.


lots of material.A principal
The licensee also had initiated measurements of


difference
the


between the short-set
spent fuel pool water. No increase in silica above silica content of the


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


coupons is their geometrical
increased. Because silica filler material is a              concentration was


design. The short-set
constituent


coupon consists of eight compartments
presence of silica in the water may be an indication                of Boraflex, the


encapsulating
Boraflex in the fuel pool.                                of  degradation      of the


the Boraflex with pool water accessing
Discussion


only the edges of the coupons. However, in the full-length
Potential degradation mechanisms for Boraflex include


coupon Boraflex is sandwiched
changes the material characteristics of the base            (1) gamma flux, which


axially over the entire length of coupon and bolted between two 0.51-mm [0.020-inch]
environment, namely the accessibility of water to  polymer,      and (2) chemical
stainless


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


that a much larger area of the full-length
degradation of Boraflex in the coupons, or (2)      cause    of  the  observed


coupon was exposed to the pool water environment
the


and flow.In addition, the full-length
of Boraflex in the coupons to that in the storage correlation of the behavior


coupon has a 12.7-mm [0.5-inch]
racks.
hole through the metal strip on the top portion of the coupon, which contributes


to the pool water flow around the Boraflex.
Degradation of the Boraflex in fuel storage racks


The licensee has no immediate
subcriticality margin in the spent fuel pool. The could reduce the


plans for removal or testing of the remaining
5 percent subcriticality margin on the basis of       design basis assumes a


five coupons in the spent fuel pool, but does intend to conduct neutron "blackness" testing in the spring of 1994.The licensee also had initiated
boron concentration in the pool water, and minimumlowest    pool temperature, no


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


of the silica content of the spent fuel pool water. No increase in silica above normal 1-4 ppm levels have been observed except in instances
pool water and a complete loss of Boraflex from              assumed    no boron in the


when the pool boron concentration
reduced the subcriticality margin from greater    the  fuel    storage    racks. This


was increased.
than 5 percent to about


Because silica filler material is a constituent
2 percent. However, the licensee used the burnup


of Boraflex, the presence of silica in the water may be an indication
fuel in the criticality calculation. This is higher  for the currently stored


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


of the Boraflex in the fuel pool.Discussion
calcul ation.                                            than assumed in the design


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


degradation
pool, (2) increasing the


mechanisms
IN 93-70
                                                              September 10, 1993 spent fuel pool chemistry sampling frequency to daily, and (3) keeping the


for Boraflex include (1) gamma flux, which changes the material characteristics
boron concentration in the spent fuel pool above 1800 ppm, which exceeds the


of the base polymer, and (2) chemical environment, namely the accessibility
technical specification requirement for boron concentration. With these


of water to the Boraflex.
precautions a subcriticality margin greater than 5 percent would be


The licensee has not drawn firm conclusions
maintained.


as to (1) the root cause of the observed degradation
Degradation of Boraflex has been previously addressed by NRC in Information


of Boraflex in the coupons, or (2) the correlation
Notice 87-43, "Gaps in Neutron-Absorbing Material in High-Density Spent Fuel


of the behavior of Boraflex in the coupons to that in the storage racks.Degradation
Storage Racks," September 8, 1987. The Electric Power Research Institute, which has been studying this phenomenon for several years, has recently


of the Boraflex in fuel storage racks could reduce the subcriticality
published an interim report, "Boraflex Test Results and Evaluation,"
TR-101986, February 1993.


margin in the spent fuel pool. The design basis assumes a 5 percent subcriticality
This information notice requires no specific action or written response. If


margin on the basis of lowest pool temperature, no boron concentration
you have any questions about the information in this notice, please contact


in the pool water, and minimum spacing between fuel assemblies.
one of the technical contacts listed below or the appropriate Office of


In its preliminary
Nuclear Reactor Regulation (NRR) project manager.


analysis, the licensee assumed no boron in the pool water and a complete loss of Boraflex from the fuel storage racks. This reduced the subcriticality
(~/'
                                      Bran    Grimes, Director


margin from greater than 5 percent to about 2 percent. However, the licensee used the burnup for the currently
Division of Operating Reactor Support


stored fuel in the criticality
Office of Nuclear Regulatory Regulation


calculation.
Technical contacts:  Kombiz Salehi, RIII


This is higher than the design burnup value, implying less reactive fuel in the fuel pool than assumed in the design calcul ation.The licensee took several compensatory
(708) 790-5782 K. I Parczewski, NRR


measures, including
(301) 504-2705 Larry Kopp, NRR


(1) making the operating
(301) 504-2879 Vern Hodge, NRR


staff aware not to dilute the spent fuel pool, (2) increasing
(301) 504-1861 Attachments:
  1. Figure 1, Palisades Boraflex Coupon Types


the
2. List of Recently Issued NRC Information Notices


IN 93-70 September
IN 93-70
                          .-            tSeptember                                    10, 1993 spent fuel pool chemistry sampling frequency to daily, and (3) keeping the


10, 1993 spent fuel pool chemistry
boron concentration in the spent fuel pool above 1800 ppm, which exceeds the


sampling frequency
technical specification requirement for boron concentration. With these


to daily, and (3) keeping the boron concentration
precautions a subcriticality margin greater than 5 percent would be


in the spent fuel pool above 1800 ppm, which exceeds the technical
maintained.


specification
Degradation of Boraflex has been previously addressed by NRC in Information


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


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


With these precautions
published an interim report, "Boraflex Test Results and Evaluation,"
    TR-101986, February 1993.


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


margin greater than 5 percent would be maintained.
you have any questions about the information in this notice, please contact


Degradation
one of the technical contacts listed below or the appropriate Office of


of Boraflex has been previously
Nuclear Reactor Regulation (NRR) project manager.


addressed
Original signed Uy


by NRC in Information
Maian K.Grime$
                                              Brian K. Grimes, Director


Notice 87-43, "Gaps in Neutron-Absorbing
Division of Operating Reactor Support


Material in High-Density
Office of Nuclear Regulatory Regulation


Spent Fuel Storage Racks," September
Technical contacts:    Kombiz Salehi, RIII


8, 1987. The Electric Power Research Institute, which has been studying this phenomenon
(708) 790-5782 K. I Parczewski, NRR


for several years, has recently published
(301) 504-2705 Larry Kopp, NRR


an interim report, "Boraflex
(301) 504-2879 Vern Hodge, NRR


Test Results and Evaluation," TR-101986, February 1993.This information
(301) 504-1861 Attachments:
    1. Figure 1, Palisades Boraflex Coupon Types


notice requires no specific action or written response.
2. List of Recently Issued NRC Information Notices


If you have any questions
*SEE PREVIOUS CONCURRENCE


about the information
OFFICE    OGCB:DORS:NRR      DRS:RIII      DD:DRS:RIII        SRXB:DSSA:NRR    C:SRXB:DSSA:NRR


in this notice, please contact one of the technical
NAME      *CVHodge            *KSalehi      *WLForney          *LIKopp          *RCJones


contacts listed below or the appropriate
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


Office of Nuclear Reactor Regulation (NRR) project manager.(~/'Bran Grimes, Director Division of Operating
*DGable    *ACThadani        *JStrosnider      *KlParczewski      *RAHermann      *AEChaffee


Reactor Support Office of Nuclear Regulatory
09/01/93    09/04/93          01J0M22          09/03/93            09/03/93        09/03/93
                        11 _ _  _  _ ,_
C:OGCB:DORS:NRR


Regulation
*GHMarcus          j                    I


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


contacts:
K>
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:
                                                                                  IN 93-xx        I
1. Figure 1, Palisades


Boraflex Coupon Types 2. List of Recently Issued NRC Information
September xx, 1993 This information notice requires no specific action or written response. If


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


IN 93-70.- tSeptember
one of the technical contacts listed below or the appropriate Office of !
    Nuclear Reactor Regulation (NRR) project manager.                                     I


10, 1993 spent fuel pool chemistry
Brian K. Grimes, Director


sampling frequency
Division of Operating Reactor Supi 0ort


to daily, and (3) keeping the boron concentration
Office of Nuclear Regulatory Regul at on


in the spent fuel pool above 1800 ppm, which exceeds the technical
===Technical Contact:===


specification
===Kombiz Salehi, RIII===
                                  (708) 790-5782 K. I Parczewski, NRR


requirement
(301) 504-2705 Larry Kopp, NRR


for boron concentration.
(301) 504-2879 Vern Hodge, NRR


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


a subcriticality
2. List of Recently Issued NRC Information Notices


margin greater than 5 percent would be maintained.
*SEE PREVIOUS CONCURRENCE. .. .....    -      .    .    ' - .


Degradation
at 1                                  law.


of Boraflex has been previously
:          L/
  OFFICE    OGCB:DORS:NRR          DRS: RI I¢ .RP DD DR4:RIIIr      SRXB:DSSA:NRR    C:SRXB:DSSA:NRRL


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


by NRC in Information
/9 D:DSS


Notice 87-43, "Gaps in Neutron-Absorbing
ACThada i


Material in High-Density
/ .._.93
                      /9 r    EMCB:DE:NRR


Spent Fuel Storage Racks," September
Strosnider


8, 1987. The Electric Power Research Institute, which has been studying this phenomenon
/3/93
                                                      _MCB:DE:NRS C:7 XParczewski


for several years, has recently published
'1 /,3/93        §
                                                                                UNRR


an interim report, "Boraflex
/3/93 D


Test Results and Evaluation," TR-101986, February 1993.This information
RAHermann      j


notice requires no specific action or written response.
IOEAB:DORS


If you have any questions
0aefffee


about the information
___________
  C:OGCB:DORS:NR4            D:DORS:NRR


in this notice, please contact one of the technical
GHMarcus OI M              BKGrimes


contacts listed below or the appropriate
q/13 /93                  / /93 DOCUMENT NAME:      PALN0902.CVH


Office of Nuclear Reactor Regulation (NRR) project manager.Original signed Uy Maian K. Grime$Brian K. Grimes, Director Division of Operating
4Adr of   ads?              >
    .4  A 42XsK        4-ct-M        etO    4


Reactor Support Office of Nuclear Regulatory
vJ


Regulation
IN 93-xx


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


contacts:
operating staff aware to not dilute the spent fuel pool, (2) increasing the
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
spent fuel pool chemistry sampling frequency to daily, and (3) keeping the


Notices*SEE PREVIOUS CONCURRENCE
boron concentration in the spent fuel pool above 1800 ppm, which exceeds the


OFFICE OGCB:DORS:NRR
technical specification requirement for boron concentration.


DRS:RIII DD:DRS:RIII
Degradation of Boraflex has been previously addressed by NRC in Information


SRXB:DSSA:NRR
Notice 87-43, "Gaps in Neutron-Absorbing Material in High-Density Spent Fuel


C:SRXB:DSSA:NRR
Storage Racks," September 8, 1987. The Electric Power Research Institute, who


NAME *CVHodge *KSalehi *WLForney
has been studying this phenomenon for several years, has recently published an


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


EMCB:DE:NRR
1993.


C:EMCB:DE:NRR
This information notice requires no specific action or written response. If


C:OEAB:DORS
you have any questions about the information in this notice, please contact


*DGable *ACThadani
the technical contact listed below or the appropriate Office of Nuclear


*JStrosnider
Reactor Regulation (NRR) project manager.


*KlParczewski
Brian K. Grimes, Director


*RAHermann
Division of Operating Reactor Support


*AEChaffee
Office of Nuclear Regulatory Regulation


09/01/93 09/04/93 01J0 M22 09/03/93 09/03/93 09/03/93 11 _ _ _ _ ,_C:OGCB:DORS:NRR
===Technical Contact:===


*GHMarcus
===Kombiz Salehi, RIII===
                                  (708)790-5782 K. I Parczewski, NRR            Larry Kopp, NRR  Vern Hodge, NRR


j I 09/03/93 09/7 /93 DOCUMENI NAME: 93-/U.IN
(301) 504-2705                  (301) 504-2879    (301) 504-1861 Attachments:         1. Figure 1, Palisades Boraflex Coupon Types


K>IN 93-xx I September
2. List of Recently Issued NRC Information Notices


xx, 1993 This information
*CFF


notice requires no specific action or written response.
.3c


If you have any questions
LL.


about the information
DDVITNIC


in this notice, please contact one of the technical
UVIRUURAJW


contacts listed below or the appropriate
VUL J


Office of !Nuclear Reactor Regulation (NRR) project manager. I Brian K. Grimes, Director Division of Operating
rnmriIDDrrr


Reactor Supi Office of Nuclear Regulatory
OFFICE lOGCB:DORS:NRR            DRS:RIII      D:DRS:RIII    SRXB:DSSA:NRR    C:SRXB:DSSA:NRR


Regul 0ort at on Technical
NAME          CVHodge Ug          KSalehi      TOMartin      LIKopp            RCJones


Contact: Kombiz Salehi, (708) 790-5782 RIII K. I Parczewski, NRR (301) 504-2705 Larry Kopp, NRR (301) 504-2879 Vern Hodge, NRR (301) 504-1861 Attachments:
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
1. Figure 1, Palisades


Boraflex Coupon Types 2. List of Recently Issued NRC Information
q    j          ACTHADANI        JStrosnider    KIParczews'ki    RAHermann        AEChaffee


Notices*SEE PREVIOUS CONCURRENCE
____      /93          /_/93          /_/93      9 /l/93              /L/93          / /93 C:OGCB:DORS:NRR            D:DORS:NRR


... ..... -..' at .-law. 1 OFFICE OGCB:DORS:NRR
GHMarcus                  [BKGrimes


DRS: RI I¢ .RP DD DR4:RIIIr SRXB:DSSA:NRR
/ /93                J / /93 DOCUMENT NAME:           PALNOFIG.CVH


: L/C:SRXB:DSSA:NRRL
K-I


NAME 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
Attachment 1 IN 93-70
                                      September 10, 1993 Figure 1_              Q


_MCB:DE:NRS
Palisades Boraflex    a.            .


C: 7 U D NRR IOEAB:DORS
Coupon Types                  Ii


ACThada i Strosnider
a


XParczewski
I    I


RAHermann
Bodfes mate w              i


j 0aef ffee/9 / /9 /3 /93 '1 /,3/93 § /3 /93 ___________
boned bloom two      3i
.. _.93 C:OGCB:DORS:NR4 D:DORS:NRR


GHMarcus OI M BKGrimes q/13 /93 / /93 DOCUMENT NAME: PALN0902.CVH
3_..


4Adr of ads? >.4 A 42XsK 4-ct-M etO 4 vJ IN 93-xx September
I:
                                  I


xx, 1993 The licensee took several compensatory
3
  39rIa                            I - -I


measures, including
le i  2! Shoet M          Pafkn*  I


(1) making the operating
I


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


the spent fuel pool chemistry
I4
                                      .  .  4
                                              .I  I


sampling frequency
I


to daily, and (3) keeping the boron concentration
E    Li


in the spent fuel pool above 1800 ppm, which exceeds the technical
Axtachment 2 IN 93-70
                                                            September 10, 1993 Page 1 of I


specification
LIST OF RECENTLY ISSUED


requirement
NRC INFORMATION NOTICES


for boron concentration.
Information                                    Date of


Degradation
Notice No.              Subject                Issuance  Issued to


of Boraflex has been previously
93-69          Radiography Events at          09/02/93  All holders of OLs or CPs


addressed
Operating Power Reactors                  for nuclear power reactors


by NRC in Information
and all radiography


Notice 87-43, "Gaps in Neutron-Absorbing
licensees.


Material in High-Density
93-68          Failure of Pump Shaft          09/01/93  All holders of OLs or CPs


Spent Fuel Storage Racks," September
Coupling Caused by                        for nuclear power reactors.


8, 1987. The Electric Power Research Institute, who has been studying this phenomenon
Temper Embrittlement


for several years, has recently published
during Manufacture


an interim report, "Boraflex
92-16,         Loss of Flow from the          08/23/93  All holders of OLs or CPs


Test Results and Evaluation," TR-101986, February 1993.This information
Supp. 2        Residual Heat Removal                    for nuclear power reactors.


notice requires no specific action or written response.
Pump during Refueling


If you have any questions
Cavity Draindown


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


in this notice, please contact the technical
Pressure Coolant                          for nuclear power reactors.


contact listed below or the appropriate
Injection Steam Line


Office of Nuclear Reactor Regulation (NRR) project manager.Brian K. Grimes, Director Division of Operating
Rupture Discs Injures


Reactor Support Office of Nuclear Regulatory
Plant Personnel


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


Technical
Injection Following                      for pressurized water


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:
A Loss-of-Coolant                          reactors.
1. Figure 1, Palisades


Boraflex Coupon Types 2. List of Recently Issued NRC Information
Accident in Pres- surized Water Reactors


===Notices rnmriIDDrrr===
93-65          Reactor Trips Caused          08/13/93  Al 1 holders of OLs or CPs
*CFF DDVITNIC.3c LL. VUL J UVIRUURAJW


OFFICE lOGCB:DORS:NRR
by Breaker Testing                        for nuclear power reactors.


DRS:RIII D:DRS:RIII
with Fault Protection


SRXB:DSSA:NRR
Bypassed


C:SRXB:DSSA:NRR
93-64          Periodic Testing and          08/12/93  All holders of OLs or CPs


NAME CVHodge Ug KSalehi TOMartin LIKopp RCJones DATE Oq/ol0/93
Preventive Maintenance                    for nuclear power reactors.
/ /93 / /93 /93 /93 Tech Ed D:DSSA EMCB:DE:NRR


EMCB:DE:ND
of Molded Case Circuit


C:EMCB:DE:NRR
Breakers
 
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_Palisades
 
Boraflex a Coupon Types a Bodfes mate w boned bloom two I 3 Shoet M Paf kn*Q Ii..I I 3i i 3_..I: I --I 39r Ia le i ! 2 I I I4 i..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 93-68 92-16, Supp. 2 93-67 93-66 93-65 93-64 93-63 Radiography
 
Events at Operating
 
Power Reactors Failure of Pump Shaft Coupling Caused by Temper Embrittlement
 
during Manufacture
 
Loss of Flow from the Residual Heat Removal Pump during Refueling Cavity Draindown Bursting of High Pressure Coolant Injection
 
Steam Line Rupture Discs Injures Plant Personnel Switchover
 
to Hot-Leg Injection
 
Following A Loss-of-Coolant
 
Accident in Pres-surized Water Reactors Reactor Trips Caused by Breaker Testing with Fault Protection
 
Bypassed Periodic Testing and Preventive
 
Maintenance
 
of Molded Case Circuit Breakers Improper Use of Soluble Weld Purge Dam Material 09/02/93 09/01/93 08/23/93 08/16/93 08/16/93 08/13/93 All holders of OLs or CPs for nuclear power reactors and all radiography
 
licensees.


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 nuclear power reactors.All holders of OLs or CPs for pressurized
93-63          Improper Use of Soluble        08/11/93  All holders of OLs or CPs


water reactors.Al 1 for holders of OLs or CPs nuclear power reactors.08/12/93 08/11/93 All holders of OLs or CPs for nuclear power reactors.All holders of OLs or CPs for nuclear power reactors.* OL = Operating
Weld Purge Dam Material                  for nuclear power reactors.


License CP = Construction
* OL = Operating License


Permit}}
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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