Information Notice 1987-43, Gaps in Neutron-Absorbing Material in High-Density Spent Fuel Storage Racks: Difference between revisions

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SSINS No.:   6835 IN 87-43 UNITED STATES
SSINS No.:  
6835 IN 87-43


===UNITED STATES===
NUCLEAR REGULATORY COMMISSION
NUCLEAR REGULATORY COMMISSION


OFFICE OF NUCLEAR REACTOR REGULATION
===OFFICE OF NUCLEAR REACTOR REGULATION===
WASHINGTON D.C. 20555


WASHINGTON D.C. 20555 September 8, 1987 NRC INFORMATION NOTICENO. 87-43:   GAPS IN NEUTRON-ABSORBING MATERIAL
===September 8, 1987===
NRC INFORMATION NOTICENO. 87-43:  
GAPS IN NEUTRON-ABSORBING MATERIAL


,INHIGH-DENSITY SPENT FUEL STORAGE
,IN
 
HIGH-DENSITY SPENT FUEL STORAGE


RACKS
RACKS
Line 34: Line 41:
==Addressees==
==Addressees==
:
:
      All nuclear power reactor facilities holding an operating license or a con- struction permit.
All nuclear power reactor facilities holding an operating license or a con- struction permit.


==Purpose==
==Purpose==
:
:
      This notice is to alert recipients to a potentially significant problem per- taining to gaps identified in the neutron absorber component of the high- density spent fuel storage racks at Quad Cities Unit 1. The safety concern is
This notice is to alert recipients to a potentially significant problem per- taining to gaps identified in the neutron absorber component of the high- density spent fuel storage racks at Quad Cities Unit 1. The safety concern is


that certain gaps might excessively reduce the margin of nuclear subcriticality
that certain gaps might excessively reduce the margin of nuclear subcriticality


in the fuel pool. The NRC expects that recipients will review this notice for
in the fuel pool.
 
The NRC expects that recipients will review this notice for


applicability to their facilities and consider actions, if appropriate, to
applicability to their facilities and consider actions, if appropriate, to
Line 54: Line 63:
==Description of Circumstances==
==Description of Circumstances==
:
:
      On May 1, 1987, Commonwealth Edison Company (CECO), the licensee at Quad Cities
On May 1, 1987, Commonwealth Edison Company (CECO), the licensee at Quad Cities


1 and 2, presented data to the NRC regarding gaps measured in Boraflex,.a
1 and 2, presented data to the NRC regarding gaps measured in Boraflex,.a


neutron-absorbing material used in the high-density fuel storage racks manufac- tured by the Joseph Oat Corporation (OAT). Boraflex is a trade name for a
neutron-absorbing material used in the high-density fuel storage racks manufac- tured by the Joseph Oat Corporation (OAT).


===Boraflex is a trade name for a===
boron carbide dispersion in an elastomeric silicone matrix manufactured by
boron carbide dispersion in an elastomeric silicone matrix manufactured by


Bisco Products, Inc. (BISCO). Data pertaining to the gap size and distribution
Bisco Products, Inc. (BISCO).


===Data pertaining to the gap size and distribution===
had been obtained by National Nuclear Corporation.(NNC) under.contract to CECO.
had been obtained by National Nuclear Corporation.(NNC) under.contract to CECO.


The licensee had retained Northeast Technology Corporation (NETCO) to interpret
The licensee had retained Northeast Technology Corporation (NETCO) to interpret


the data. NETCO prefaced their assessment as preliminary, noting that avail- able data was limited, but concluded that the gap formation mechanism may be
the data.
 
NETCO prefaced their assessment as preliminary, noting that avail- able data was limited, but concluded that the gap formation mechanism may be


related to large local stresses in the Boraflex from fabrication-induced re- straint within the rack and to tearing and shrinkage of the material..
related to large local stresses in the Boraflex from fabrication-induced re- straint within the rack and to tearing and shrinkage of the material..


The average gap size is 1-1/2 inches, with the largest 4 inches..   The gaps
The average gap size is 1-1/2 inches, with the largest 4 inches.. The gaps
 
occur in the.upper two-thirds of the cell length.


occur in the.upper two-thirds of the cell length.        -
-
                    709010085
709010085


IN 87-43 September 8, 1987 These gaps are inferred from anomalies in "blackness" testing results by NNC.
IN 87-43 September 8, 1987 These gaps are inferred from anomalies in "blackness" testing results by NNC.
Line 85: Line 100:
CECO also discussed the effects these gaps might have on the approved safety
CECO also discussed the effects these gaps might have on the approved safety


analysis for the spent fuel storage racks. CECO used conservative assumptions
analysis for the spent fuel storage racks.


for gap size, gap location, and fuel burnup. Considerable margin in k-eff
===CECO used conservative assumptions===
for gap size, gap location, and fuel burnup.
 
Considerable margin in k-eff


appears to be available before the licensing limit of 0.95 would be approached.
appears to be available before the licensing limit of 0.95 would be approached.


In July 1986, Wisconsin Electric Company, the licensee at Point Beach 1 and 2, reported to the NRC that test coupons of Boraflex material had shown consider- able degradation under high radiation. However, the licensee asserted that
In July 1986, Wisconsin Electric Company, the licensee at Point Beach 1 and 2, reported to the NRC that test coupons of Boraflex material had shown consider- able degradation under high radiation.


===However, the licensee asserted that===
this result did not represent the actual condition of Boraflex used in its
this result did not represent the actual condition of Boraflex used in its


spent fuel storage racks because of differences in methods of encapsulation, sample geometry, and handling frequency. Additionally, the coupons had been
spent fuel storage racks because of differences in methods of encapsulation, sample geometry, and handling frequency.


===Additionally, the coupons had been===
subjected to about 5 times more radiation than is associated with the average
subjected to about 5 times more radiation than is associated with the average


fuel rack position. Subsequent examination of full-length panels disclosed
fuel rack position.


two results: in one panel examined for effects of the water environment but
Subsequent examination of full-length panels disclosed
 
two results:  
in one panel examined for effects of the water environment but


exposed to negligible gamma radiation, there was no degradation of the Boraflex.
exposed to negligible gamma radiation, there was no degradation of the Boraflex.
Line 128: Line 151:
Efforts to understand the gap formation have revealed several topics on which
Efforts to understand the gap formation have revealed several topics on which


information is needed. Accordingly, the material supplier (BISCO) and the
information is needed.
 
Accordingly, the material supplier (BISCO) and the


Electric Power Research Institute (EPRI) have undertaken research programs
Electric Power Research Institute (EPRI) have undertaken research programs


to collect this information. Some of their objectives are described below.
to collect this information.


The BISCO program  aims to establish with increased accuracy the relationship
Some of their objectives are described below.


between radiation  dose and size changes. The program also evaluates the
The BISCO program aims to establish with increased accuracy the relationship


potential effects  of handling and restraint, during and subsequent to the fuel
between radiation dose and size changes.


rack fabrication, on gap formation.
===The program also evaluates the===
potential effects of handling and restraint, during and subsequent to the fuel
 
rack fabrication, on gap formation.


The EPRI program will correlate data from utilities' neutron absorber coupon
The EPRI program will correlate data from utilities' neutron absorber coupon


surveillance programs. EPRI will further examine data obtained from CECO, as
surveillance programs.
 
EPRI will further examine data obtained from CECO, as


well as from BISCO and other sources, to improve the understanding of possible
well as from BISCO and other sources, to improve the understanding of possible
Line 160: Line 190:
The effect of rack design and manufacturing methods on the consequences of
The effect of rack design and manufacturing methods on the consequences of


stress, temperature, and chemical environment to irradiated Boraflex is uncer- tain. Recent blackness test results at Turkey Point, who uses a Westinghouse
stress, temperature, and chemical environment to irradiated Boraflex is uncer- tain.
 
Recent blackness test results at Turkey Point, who uses a Westinghouse


spent fuel storage rack, did not indicate the presence of gaps in the Boraflex.
spent fuel storage rack, did not indicate the presence of gaps in the Boraflex.
Line 166: Line 198:
The research programs are designed to evaluate each consequence and, In partic- ular, to improve the understanding of stress caused by method of attachment of
The research programs are designed to evaluate each consequence and, In partic- ular, to improve the understanding of stress caused by method of attachment of


the Boraflex panel to the stainless steel wall of the cell. -
the Boraflex panel to the stainless steel wall of the cell.
 
-
Together, these programs are designed to improve the industry understanding of
Together, these programs are designed to improve the industry understanding of


Line 181: Line 215:
hares E. Rossi, Director
hares E. Rossi, Director


_     _   -     -                         Division of Operational Events Assessment
_  
_  
-
-


===Division of Operational Events Assessment===
Office of Nuclear Reactor Regulation
Office of Nuclear Reactor Regulation


Technical Contacts:       Vern Hodge
Technical Contacts:
Vern Hodge


(301) 492-8196 Albert D. Morrongiello
(301) 492-8196


===Albert D. Morrongiello===
(309) 654-2227 Attachments:
(309) 654-2227 Attachments:
                                                                              Attachment 1
1. List of Plants Using Boraflex
1. List of Plants Using Boraflex                                               IN 87-43 Structures in the Spent Fuel Pool                                       September 8, 1987
 
2. List of Recently Issued NRC Information Notices LIST OF PLANTS WITH BORAFLEX
===Structures in the Spent Fuel Pool===
2. List of Recently Issued NRC Information Notices
 
===Attachment 1===
IN 87-43


===September 8, 1987 LIST OF PLANTS WITH BORAFLEX===
STRUCTURES IN THE SPENT FUEL POOL
STRUCTURES IN THE SPENT FUEL POOL


1. Arkansas 1,2                         16.  Peach Bottom 2.3
1. Arkansas 1,2
                      2. Beaver Valley 1                     17. Pilgrim
2. Beaver Valley 1
3. Diablo Canyon 1,2
4. Calvert Cliffs 2
5. Farley 1,2
6. Fermi 2*
7. Ft. Calhoun


3. Diablo Canyon 1,2                    18.  Pt. Beach 1,2
8.
                      4. Calvert Cliffs 2                    19.  Pr. Island 1,2
                      5. Farley 1,2                          20.  Quad Cities 1,2*
                      6. Fermi 2*                            21.  Rancho Seco*
                      7. Ft. Calhoun                          22.  River Bend


8. Ginna                               23.  Robinson 2
Ginna
                      9. Grand Gulf 1,2*                      24.  Summer*
                      10. McGuire 1,2                          25.  Trojan


11. Millstone 1,2,3                     26.  Turkey Pt. 3,4
9. Grand Gulf 1,2*
                      12. Nine Ni. Pt. 1,2                     27.  Waterford 3
10.
                      13. North Anna 1,2                       28. Seabrook 1,2
 
                      14. Oconee 1,2,3                         29. Watts Bar 1,2
McGuire 1,2
                      15. Oyster Creek*                        30. Comanche Peak 1,2
11. Millstone 1,2,3
                                                              31.   Harris
12.
 
===Nine Ni. Pt. 1,2===
13. North Anna 1,2
14. Oconee 1,2,3
15. Oyster Creek*
16. Peach Bottom 2.3
17. Pilgrim
 
18. Pt. Beach 1,2
19. Pr. Island 1,2
20. Quad Cities 1,2*
21. Rancho Seco*
22. River Bend
 
23. Robinson 2
24. Summer*
25. Trojan
 
26. Turkey Pt. 3,4
27. Waterford 3
28. Seabrook 1,2
29. Watts Bar 1,2
30. Comanche Peak 1,2
31. Harris


*Plants having spent fuel storage racks fabricated by Joseph Oat Corporation.
*Plants having spent fuel storage racks fabricated by Joseph Oat Corporation.


/                                                       \_J     Attachment 2 IN 87-43 September 8, 1987 LIST OF RECENTLY ISSUED
/  
\\_J
 
===Attachment 2===
IN 87-43
 
===September 8, 1987===
LIST OF RECENTLY ISSUED
 
===INFORMATION NOTICES 1987===
Tnfnrwmtinn
 
n.._
--
Noti c
 
No.
 
87-42
87-41
87-40
87-39
87-38
87-37
87-36
87-35 Subfect
 
===Diesel Generator Fuse===
Contacts
 
===Failures of Certain Brown===
Boveri Electric Circuit
 
Breakers
 
===Backseating Valves Routinely===
to Prevent Packing Leakage
 
===Control of Hot Particle===
Contamination at Nuclear
 
===Power Plants===
Inadequate or Inadvertent
 
===Blocking of Valve Movement===
Compliance with the General
 
===License Provisions of===
10 CFR Part 31
 
===Significant Unexpected===
Erosion of Feedwater Lines


INFORMATION NOTICES 1987 Tnfnrwmtinn                                    n.._ --
Reactor Trip Breaker.
                                                                                    uasu    or


Noti c  No.    Subfect                          Issuance        Issued to
u1etinghouse Modal OSm4I6_


87-42          Diesel Generator Fuse            9/4/87          All nuclear power
===Failed to Open on Manual===
Initiation from the Control


Contacts                                          reactor facilities
Room
 
uasu or
 
Issuance
 
Issued to
 
9/4/87
 
===All nuclear power===
reactor facilities


holding an OL or CP.
holding an OL or CP.


87-41          Failures of Certain Brown        8/31/87         All nuclear power
8/31/87  


Boveri Electric Circuit                          reactor facilities
===All nuclear power===
reactor facilities


Breakers                                          holding an OL or CP.
holding an OL or CP.


87-40          Backseating Valves Routinely      8/31/87         All nuclear power
8/31/87  


to Prevent Packing Leakage                        reactor facilities
===All nuclear power===
reactor facilities


holding an OL or CP.
holding an OL or CP.


87-39          Control of Hot Particle          8/21/87         All nuclear power
8/21/87  


Contamination at Nuclear                          reactor facilities
===All nuclear power===
reactor facilities


Power Plants                                      and spent.fuel
and spent.fuel


storage facilities
storage facilities
Line 255: Line 388:
license or CP.
license or CP.


87-38          Inadequate or Inadvertent        8/17/87       All nuclear power
8/17/87  


Blocking of Valve Movement                        reactor facilities
===All nuclear power===
reactor facilities


holding an OL or CP.
holding an OL or CP.


87-37          Compliance with the General      8/10/87       All persons specifi- License Provisions of                            cally licensed to
8/10/87 All persons specifi- cally licensed to


10 CFR Part 31                                  manufacture or to
manufacture or to
 
Initially transfer


===Initially transfer===
devices containing
devices containing


Line 275: Line 408:
Part 31.
Part 31.


87-36          Significant Unexpected          8/4/87         All nuclear power
8/4/87  


Erosion of Feedwater Lines                      reactor facilities
===All nuclear power===
reactor facilities


holding an OL or CP.
holding an OL or CP.


87-35          Reactor Trip Breaker.            7/30/87         All nuclear power
7/30/87  
 
===All nuclear power===
-
-mactui
 
fEacz11 ties -
holdthg an OL or


u1etinghouse Modal OSm4I6_                  - -mactui fEacz11 ties -
CP eploying W DS-416 reactor trip Breakers.
                                                  Failed to Open on Manual                        holdthg an OL or


Initiation from the Control                      CPeploying WDS-416 Room                                            reactor trip Breakers.
===OL a Operating License===
UNITED STATES


OL a Operating License
===CP a Construction Permit===
NUCLEAR REGULATORY COMMISSION


UNITED STATES            CPa Construction  Permit
===WASHINGTON, D.C. 20555===
OFFICIAL BUSINESS


FIRST CLSS MAIL
PENALTY FOR PRIVATE USE. $300


NUCLEAR REGULATORY COMMISSION                                                                                      POSTAGE
===FIRST CLSS MAIL===
POSTAGE


* FEES PAID
* FEES PAID


WASHINGTON, D.C. 20555                                                                                              USNIIC
USNIIC


PERMIT No. 0-67 OFFICIAL BUSINESS
PERMIT No. 0-67
 
PENALTY FOR PRIVATE USE. $300


IN 87-43 September 8, 1987 to model the specific Quad Cities experience considering absorbed gamma dose as a
IN 87-43 September 8, 1987 to model the specific Quad Cities experience considering absorbed gamma dose as a
Line 312: Line 454:
The effect of rack design and manufacturing methods on the consequences of
The effect of rack design and manufacturing methods on the consequences of


stress, temperature, and chemical environment to irradiated Boraflex is uncer- tain. Recent blackness test results at Turkey Point, who uses a Westinghouse
stress, temperature, and chemical environment to irradiated Boraflex is uncer- tain.
 
Recent blackness test results at Turkey Point, who uses a Westinghouse


spent fuel storage rack, did not indicate the presence of gaps in the Boraflex.
spent fuel storage rack, did not indicate the presence of gaps in the Boraflex.
Line 332: Line 476:
Administrator of the appropriate regional office or this office.
Administrator of the appropriate regional office or this office.


Charles E. Rossi, Director
===Charles E. Rossi, Director===
 
Division of Operational Events Assessment
Division of Operational Events Assessment


Office of Nuclear Reactor Regulation
===Office of Nuclear Reactor Regulation===
Technical Contacts:
Vern Hodge


Technical Contacts:  Vern Hodge
(301) 492-8196
 
(301) 492-8196 Albert D. Morrongiello


===Albert D. Morrongiello===
(309) 654-2227 Attachments:
(309) 654-2227 Attachments:
1. List of Plants Using Boraflex
1. List of Plants Using Boraflex


Structures in the Spent Fuel Pool
===Structures in the Spent Fuel Pool===
 
2. List of Recently Issued NRC Information Notices
2. List of Recently Issued NRC Information Notices


Line 352: Line 495:


0// /87
0// /87
*OGCB:DOEA:NRR *AC/ECEB:DEST:NRR   *RI:QUAD       *PPMB:ARM *t/dGCB:DOEA:NRR
*OGCB:DOEA:NRR *AC/ECEB:DEST:NRR
 
*RI:QUAD
 
*PPMB:ARM *t/dGCB:DOEA:NRR
 
CVHodge
 
CMcCracken
 
AMorrongiello TechEd


CVHodge        CMcCracken          AMorrongiello  TechEd    CHBerlinger
CHBerlinger


08/20/87       08/26/87             08/25/87       07/17/87 08/24/87
08/20/87  
08/26/87  
08/25/87  
07/17/87 08/24/87


IN 87-XX
IN 87-XX
Line 392: Line 548:
Administrator of the appropriate regional office or this office.
Administrator of the appropriate regional office or this office.


Charles E. Rossi, Director
===Charles E. Rossi, Director===
 
Division of Operational Events Assessment
Division of Operational Events Assessment


Office of Nuclear Reactor Regulation
===Office of Nuclear Reactor Regulation===
Technical Contacts: Vern Hodge


Technical Contacts:    Vern Hodge
(301) 492-8196
 
(301) 492-8196 Albert D. Morrongiello


===Albert D. Morrongiello===
(309) 654-2227 Attachments:
(309) 654-2227 Attachments:
          1. List of Plants Using Boraflex
1. List of Plants Using Boraflex
 
Structures in the Spent Fuel Pool


===Structures in the Spent Fuel Pool===
2. List of Recently Issued Information Notices
2. List of Recently Issued Information Notices


Line 415: Line 569:
_r~d~t-_(_CERossi
_r~d~t-_(_CERossi


6           b0                                           On08//87 OGCB:DOEA:NRR   AC/ CEB:DEST:NRR     Rr:QUAD       *PPMB:ARM C/OGCB:DOEA:NRR4 CVHodge         CMcCracken           AMorrongiello   TechEd   CHBerlinger CP6
6 b0  
          084;0/87         o8/aIb/87           08/;S787       07/17/87 08Lpt/87
On08/  
/87 OGCB:DOEA:NRR AC/ CEB:DEST:NRR
 
Rr:QUAD
 
*PPMB:ARM C/OGCB:DOEA:NRR4 CVHodge
 
CMcCracken
 
AMorrongiello TechEd
 
===CHBerlinger CP6===
084;0/87 o8/aIb/87  
08/;S787  
07/17/87  
08Lpt/87


IN 87-XX
IN 87-XX
Line 460: Line 629:
Administrator of the appropriate regional office or this office.
Administrator of the appropriate regional office or this office.


Charles E. Rossi, Director
===Charles E. Rossi, Director===
 
Division of Operational Events Assessment
Division of Operational Events Assessment


Office of Nuclear Reactor Regulation
===Office of Nuclear Reactor Regulation===
Technical Contacts:
Vern Hodge


Technical Contacts:  Vern Hodge
(301) 492-8196
 
(301) 492-8196 Albert D. Morrongiello


===Albert D. Morrongiello===
(309) 654-2227 Attachments:
(309) 654-2227 Attachments:
1. List of Potentially Affected Plants
1. List of Potentially Affected Plants
Line 475: Line 644:
2. List of Recently Issued Information Notices
2. List of Recently Issued Information Notices


OGCB:DOEA:NRR       RI:QUAD         PPMB:ARM C/OGCB:DOEA:NRR     D/DOEA:NRR
OGCB:DOEA:NRR
 
RI:QUAD
 
PPMB:ARM C/OGCB:DOEA:NRR
 
D/DOEA:NRR
 
CYHodge
 
AMorrongiello TechEd
 
CHBerlinger


CYHodge              AMorrongiello  TechEd    CHBerlinger        CERossi
CERossi


07/ /87             07/ /87         07/11/87 07/ /87               07/ /87}}
07/ /87  
07/ /87  
07/11/87 07/ /87  
07/ /87}}


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

Latest revision as of 10:35, 16 January 2025

Gaps in Neutron-Absorbing Material in High-Density Spent Fuel Storage Racks
ML031130349
Person / Time
Site: Beaver Valley, Millstone, Hatch, Monticello, Calvert Cliffs, Dresden, Davis Besse, Peach Bottom, Browns Ferry, Salem, Oconee, Mcguire, Nine Mile Point, Palisades, Palo Verde, Perry, Indian Point, Fermi, Kewaunee, Catawba, Harris, Wolf Creek, Saint Lucie, Point Beach, Oyster Creek, Watts Bar, Hope Creek, Grand Gulf, Cooper, Sequoyah, Byron, Pilgrim, Arkansas Nuclear, Braidwood, Susquehanna, Summer, Prairie Island, Columbia, Seabrook, Brunswick, Surry, Limerick, North Anna, Turkey Point, River Bend, Vermont Yankee, Crystal River, Haddam Neck, Ginna, Diablo Canyon, Callaway, Vogtle, Waterford, Duane Arnold, Farley, Robinson, Clinton, South Texas, San Onofre, Cook, Comanche Peak, Yankee Rowe, Maine Yankee, Quad Cities, Humboldt Bay, La Crosse, Big Rock Point, Rancho Seco, Zion, Midland, Bellefonte, Fort Calhoun, FitzPatrick, McGuire, LaSalle, 05000000, Zimmer, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant, Skagit, Marble Hill, Crane
Issue date: 09/08/1987
From: Rossi C
Office of Nuclear Reactor Regulation
To:
References
-nr IN-87-043, NUDOCS 8709010085
Download: ML031130349 (7)
v • d • e


Q

- >

I

SSINS No.:

6835 IN 87-43

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON D.C. 20555

September 8, 1987

NRC INFORMATION NOTICENO. 87-43:

GAPS IN NEUTRON-ABSORBING MATERIAL

,IN

HIGH-DENSITY SPENT FUEL STORAGE

RACKS

Addressees

All nuclear power reactor facilities holding an operating license or a con- struction permit.

Purpose

This notice is to alert recipients to a potentially significant problem per- taining to gaps identified in the neutron absorber component of the high- density spent fuel storage racks at Quad Cities Unit 1. The safety concern is

that certain gaps might excessively reduce the margin of nuclear subcriticality

in the fuel pool.

The NRC expects that recipients will review this notice for

applicability to their facilities and consider actions, if appropriate, to

preclude a similar problem occurring at their facilities. However, suggestions

in-this notice do not constitute NRC requirements; therefore, no specific

action or written response is required..

Description of Circumstances

On May 1, 1987, Commonwealth Edison Company (CECO), the licensee at Quad Cities

1 and 2, presented data to the NRC regarding gaps measured in Boraflex,.a

neutron-absorbing material used in the high-density fuel storage racks manufac- tured by the Joseph Oat Corporation (OAT).

Boraflex is a trade name for a

boron carbide dispersion in an elastomeric silicone matrix manufactured by

Bisco Products, Inc. (BISCO).

Data pertaining to the gap size and distribution

had been obtained by National Nuclear Corporation.(NNC) under.contract to CECO.

The licensee had retained Northeast Technology Corporation (NETCO) to interpret

the data.

NETCO prefaced their assessment as preliminary, noting that avail- able data was limited, but concluded that the gap formation mechanism may be

related to large local stresses in the Boraflex from fabrication-induced re- straint within the rack and to tearing and shrinkage of the material..

The average gap size is 1-1/2 inches, with the largest 4 inches.. The gaps

occur in the.upper two-thirds of the cell length.

-

709010085

IN 87-43 September 8, 1987 These gaps are inferred from anomalies in "blackness" testing results by NNC.

The existence of a gap in the Quad Cities neutron absorber panel has been

confirmed by underwater neutron radiography conducted by Nusurtec, Inc.

CECO also discussed the effects these gaps might have on the approved safety

analysis for the spent fuel storage racks.

CECO used conservative assumptions

for gap size, gap location, and fuel burnup.

Considerable margin in k-eff

appears to be available before the licensing limit of 0.95 would be approached.

In July 1986, Wisconsin Electric Company, the licensee at Point Beach 1 and 2, reported to the NRC that test coupons of Boraflex material had shown consider- able degradation under high radiation.

However, the licensee asserted that

this result did not represent the actual condition of Boraflex used in its

spent fuel storage racks because of differences in methods of encapsulation, sample geometry, and handling frequency.

Additionally, the coupons had been

subjected to about 5 times more radiation than is associated with the average

fuel rack position.

Subsequent examination of full-length panels disclosed

two results:

in one panel examined for effects of the water environment but

exposed to negligible gamma radiation, there was no degradation of the Boraflex.

In another panel exposed to significant gamma radiation, 1-2 percent of the

surface showed a gray discoloration at the edges, similar to the degradation

of the coupons.

Discussion:

The concern is that separation of the neutron-absorbing material used in high

density fuel storage racks might compromise safety. Although Quad Cities

reports that its racks, even with gaps in the Boraflex as large as 4 inches, can meet the criticality criterion of k-eff less than or equal to 0.95, this

may not be the case for larger gaps or for other plants. A list of the 31 sites

using Boraflex is given in Attachment 1. Related information is given in

"Behavior of High-Density Spent-Fuel Storage Racks," EPRI NP-4724, Electric

Power Research Institute, August 1986.

Efforts to understand the gap formation have revealed several topics on which

information is needed.

Accordingly, the material supplier (BISCO) and the

Electric Power Research Institute (EPRI) have undertaken research programs

to collect this information.

Some of their objectives are described below.

The BISCO program aims to establish with increased accuracy the relationship

between radiation dose and size changes.

The program also evaluates the

potential effects of handling and restraint, during and subsequent to the fuel

rack fabrication, on gap formation.

The EPRI program will correlate data from utilities' neutron absorber coupon

surveillance programs.

EPRI will further examine data obtained from CECO, as

well as from BISCO and other sources, to improve the understanding of possible

or actual gap formation models, including the effects of rack fabrication

methods and irradiation damage mechanisms. The EPRI Program will also attempt

IN 87-43 September 8, 1987 to model the specific Quad Cities experience considering absorbed gamma dose as a

function of axial elevation, neutron absorbing sheet restraint, and fractional

change in length.

The effect of rack design and manufacturing methods on the consequences of

stress, temperature, and chemical environment to irradiated Boraflex is uncer- tain.

Recent blackness test results at Turkey Point, who uses a Westinghouse

spent fuel storage rack, did not indicate the presence of gaps in the Boraflex.

The research programs are designed to evaluate each consequence and, In partic- ular, to improve the understanding of stress caused by method of attachment of

the Boraflex panel to the stainless steel wall of the cell.

-

Together, these programs are designed to improve the industry understanding of

the safety implications of the observed gaps in the Boraflex neutron absorber

component of the OAT high-density spent-fuel storage racks at Quad Cities.

No specific action or written response is required by this information notice.

If you have any questions about this matter, please contact the Regional

Administrator of the appropriate regional office or this office.

hares E. Rossi, Director

_

_

-

-

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contacts:

Vern Hodge

(301) 492-8196

Albert D. Morrongiello

(309) 654-2227 Attachments:

1. List of Plants Using Boraflex

Structures in the Spent Fuel Pool

2. List of Recently Issued NRC Information Notices

Attachment 1

IN 87-43

September 8, 1987 LIST OF PLANTS WITH BORAFLEX

STRUCTURES IN THE SPENT FUEL POOL

1. Arkansas 1,2

2. Beaver Valley 1

3. Diablo Canyon 1,2

4. Calvert Cliffs 2

5. Farley 1,2

6. Fermi 2*

7. Ft. Calhoun

8.

Ginna

9. Grand Gulf 1,2*

10.

McGuire 1,2

11. Millstone 1,2,3

12.

Nine Ni. Pt. 1,2

13. North Anna 1,2

14. Oconee 1,2,3

15. Oyster Creek*

16. Peach Bottom 2.3

17. Pilgrim

18. Pt. Beach 1,2

19. Pr. Island 1,2

20. Quad Cities 1,2*

21. Rancho Seco*

22. River Bend

23. Robinson 2

24. Summer*

25. Trojan

26. Turkey Pt. 3,4

27. Waterford 3

28. Seabrook 1,2

29. Watts Bar 1,2

30. Comanche Peak 1,2

31. Harris

  • Plants having spent fuel storage racks fabricated by Joseph Oat Corporation.

/

\\_J

Attachment 2

IN 87-43

September 8, 1987

LIST OF RECENTLY ISSUED

INFORMATION NOTICES 1987

Tnfnrwmtinn

n.._

--

Noti c

No.

87-42

87-41

87-40

87-39

87-38

87-37

87-36

87-35 Subfect

Diesel Generator Fuse

Contacts

Failures of Certain Brown

Boveri Electric Circuit

Breakers

Backseating Valves Routinely

to Prevent Packing Leakage

Control of Hot Particle

Contamination at Nuclear

Power Plants

Inadequate or Inadvertent

Blocking of Valve Movement

Compliance with the General

License Provisions of

10 CFR Part 31

Significant Unexpected

Erosion of Feedwater Lines

Reactor Trip Breaker.

u1etinghouse Modal OSm4I6_

Failed to Open on Manual

Initiation from the Control

Room

uasu or

Issuance

Issued to

9/4/87

All nuclear power

reactor facilities

holding an OL or CP.

8/31/87

All nuclear power

reactor facilities

holding an OL or CP.

8/31/87

All nuclear power

reactor facilities

holding an OL or CP.

8/21/87

All nuclear power

reactor facilities

and spent.fuel

storage facilities

holding an NRC

license or CP.

8/17/87

All nuclear power

reactor facilities

holding an OL or CP.

8/10/87 All persons specifi- cally licensed to

manufacture or to

Initially transfer

devices containing

radioactive material

to general licensees, as defined in 10 CFR

Part 31.

8/4/87

All nuclear power

reactor facilities

holding an OL or CP.

7/30/87

All nuclear power

-

-mactui

fEacz11 ties -

holdthg an OL or

CP eploying W DS-416 reactor trip Breakers.

OL a Operating License

UNITED STATES

CP a Construction Permit

NUCLEAR REGULATORY COMMISSION

WASHINGTON, D.C. 20555

OFFICIAL BUSINESS

PENALTY FOR PRIVATE USE. $300

FIRST CLSS MAIL

POSTAGE

  • FEES PAID

USNIIC

PERMIT No. 0-67

IN 87-43 September 8, 1987 to model the specific Quad Cities experience considering absorbed gamma dose as a

function of axial elevation, neutron absorbing sheet restraint, and fractional

change in length.

The effect of rack design and manufacturing methods on the consequences of

stress, temperature, and chemical environment to irradiated Boraflex is uncer- tain.

Recent blackness test results at Turkey Point, who uses a Westinghouse

spent fuel storage rack, did not indicate the presence of gaps in the Boraflex.

The research programs are designed to evaluate each consequence and, in partic- ular, to improve the understanding of stress caused by method of attachment of

the Boraflex panel to the stainless steel wall of the cell.

Together, these programs are designed to improve the industry understanding of

the safety implications of the observed gaps in the Boraflex neutron absorber

component of the OAT high-density spent-fuel storage racks at Quad Cities.

No specific action or written response is required by this information notice.

If you have any questions about this matter, please contact the Regional

Administrator of the appropriate regional office or this office.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contacts:

Vern Hodge

(301) 492-8196

Albert D. Morrongiello

(309) 654-2227 Attachments:

1. List of Plants Using Boraflex

Structures in the Spent Fuel Pool

2. List of Recently Issued NRC Information Notices

  • SEE PREVIOUS CONCURRENCES

0// /87

  • OGCB:DOEA:NRR *AC/ECEB:DEST:NRR
  • RI:QUAD
  • PPMB:ARM *t/dGCB:DOEA:NRR

CVHodge

CMcCracken

AMorrongiello TechEd

CHBerlinger

08/20/87

08/26/87

08/25/87

07/17/87 08/24/87

IN 87-XX

t 'August

xx, 1987 to model the specific Quad Cities experience utilizing absorbed gamma dose as a

function of axial elevation, fractional change in length and neutron absorbing

sheet restraint.

The effect of rack design and manufacturing methods on the consequences of

stress, temperature, and chemical environment to irradiated Boraflex is uncer- tain. Recent blackness test results at Turkey Point, who uses a Westinghouse

spent fuel storage rack, did not Indicate the presence of gaps in the Boraflex.

The research programs are designed to evaluate each consequence and, in partic- ular, to improve the understanding of stress caused by method of attachment or

entrapment of the Boraflex panel to the stainless steel wall of the cell.

Together, these programs are designed to improve the industry understanding of

the safety implications of the observed gaps in the Boraflex neutron absorber

component of the OAT high-density spent-fuel storage racks at Quad Cities. To

date, the NRC has not received information to prompt a more immediate address- ing of this issue.

No specific action or written response is required by this information notice.

If you have any questions about this matter, please contact the Regional

Administrator of the appropriate regional office or this office.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contacts: Vern Hodge

(301) 492-8196

Albert D. Morrongiello

(309) 654-2227 Attachments:

1. List of Plants Using Boraflex

Structures in the Spent Fuel Pool

2. List of Recently Issued Information Notices

  • SEE PREVIOUS CONCURRENCES

D/DOEA:NRR

_r~d~t-_(_CERossi

6 b0

On08/

/87 OGCB:DOEA:NRR AC/ CEB:DEST:NRR

Rr:QUAD

  • PPMB:ARM C/OGCB:DOEA:NRR4 CVHodge

CMcCracken

AMorrongiello TechEd

CHBerlinger CP6

084;0/87 o8/aIb/87

08/;S787

07/17/87

08Lpt/87

IN 87-XX

July xx, 1987 of maximum gap size, on which the determination of k-eff rests. MaJor uncer- tainties in this picture include isotropy of volume changes, damage mechanism, and influence of stress, temperature, and chemical environment.

Volume changes are assumed isotropic. If untrue, the presently estimated

maximum gap size would be significantly affected.

The radiation damage mechanism is uncertain. Crosslinking leads to shrinkage, whereas scissioning leads to increased friability of the material. In the

absence of low dose data, it is presently assumed that crosslinking damage is

proportional to dose; thus it is thought that crosslinking is about complete at

1-2 E 10 rads. The degraded Point Beach coupons were given a dose of this

magnitude, however the essentially nondegraded Point Beach panels and Quad

Cities panels and representative positions in spent fuel pool storage racks are

associated with doses from 3 to 6 times smaller than this range of values.

Stress, temperature, and chemical environment may influence the estimate of

maximum gap size and hence pool criticality. In particular, to improve the

understanding of stress, the EPRI program will determine the dependence of gap

formation on the method of attaching the Boraflex panel to the stainless steel

wall of the storage rack cell.

Together, these programs are designed to improve the industry's understanding

of the safety implications of the observed degradation of Boraflex.

No specific action or written response is required by this information notice.

If you have any questions about this matter, please contact the Regional

Administrator of the appropriate regional office or this office.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contacts:

Vern Hodge

(301) 492-8196

Albert D. Morrongiello

(309) 654-2227 Attachments:

1. List of Potentially Affected Plants

2. List of Recently Issued Information Notices

OGCB:DOEA:NRR

RI:QUAD

PPMB:ARM C/OGCB:DOEA:NRR

D/DOEA:NRR

CYHodge

AMorrongiello TechEd

CHBerlinger

CERossi

07/ /87

07/ /87

07/11/87 07/ /87

07/ /87


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