ML20238F280
| ML20238F280 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 09/10/1987 |
| From: | Matt Young NRC OFFICE OF THE GENERAL COUNSEL (OGC) |
| To: | Cole R, Lazo R, Luebke E Atomic Safety and Licensing Board Panel |
| References | |
| CON-#387-4365 IEIN-87-043, IEIN-87-43, OLA-2, NUDOCS 8709160056 | |
| Download: ML20238F280 (6) | |
Text
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- 'o, UNITED STATES 8'3 E,g NUCLEAR REGULATORY COMMISSION O'Q' ' If y
>E WASHINGTON, D. C 20555
'87 SEP 14 P 130
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September 10, 1987
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Dr. Robert M. Lazo, Chairman Dr. P,lchard F. Cole Administrative Judge Administrative Judge Atomic Safety and Licensing Board Atomic Safety and Licensing Board U.S. Nuclear Regulatory Commission U.S. Nuclear Regulatory Commission Washington, DC 20555 Washington, DC 20555 Dr. Emmeth A. Luebke Administrative Judge Atomic Safety and Licensing Board U.S. Nuclear Regulatory Commission Washington, DC 20555 In the Matter of FLORIDA POWER AND LIGHT COViPANY (Turkey Point Plant, Unit Nos. 3 and 4)
Docket Nos. 50-250, 50-251 OLA-2 (SFP Expansion)
Dear Administrative Judges:
Enclosed for your informatin is a copy of NRC Information Notice No. 87-43:
" Caps in Neutron-Absorbing Material in High-Density Spent Fuel Stor-age Racks," which was sent to all nuclear power plant licensees.
Copies of the information notice are being transmitted to the parties by means of this letter.
Sincere!
Mitzi
. Young Counsel for NRC Staff i
Enclosure:
As stated cc w/ encl.:
Service List 8709160056 070910 PDR ADOCK 05000250 ON
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55 INS No.: ~6835 gn IN 87-43
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UNITED'5TATES-NUCLEAR REGULATORY COMMISSION 0FFICE-0F. NUCLEAR REACTOR REGULATION WASHINGTON D.C. 20555 September 8,.1987 NRC INFORMATION NOTICE NO. 87-43:GAPS IN NEUTRON-ABSORBING MATERIAL IN HIGH-DENSITY SPENT FUEL STORAGE RACKS Addressees:
'l All nuclear power reactor facilities holding ~ an operating license or a con-struction permit.
Purposef l
taining to gaps identified in the neutron absorber comp density' spent fuel storage racks at Quad Cities Unit 1.
The safety concern is that certain gaps might excessively reduce.the margin of nuclear subcriticall
- l 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.
action or written response is required.in this notice do not constitute
.However suggestions Description of Circumstances:
On May 1, 1987, Commonwealth Edison Company (CECO), the licensee at Quad 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 Bisco Products, Inc. (BISCO). boron carbide dispersion in an elastomeric had been obtained by National Nuclear Corporation (NNC) under con The licensee had retained Northeast Technology Corporation (NETC0) to inte the data.
NETCO prefaced their assessment as preliminary, noting that avail-1 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 occur in the upper.two-thirds of the cell length, The gaps 8709010085 i
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a IN 87-43 M
September 8, 1987 Page 2 of 3 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 tne scent 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.e'pproached.
In. July 3986, 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 f
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 date 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 l
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IN 87-43 September 8, 1987 Page'3 of 3
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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 ef f ect of rack design and manuf acturing methods on the consequences of I
stress, temperature, and chemical environroent 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 consegrence and, in partic-ular, to improve the understanding of stress caused by m;thod 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 l
Administrator of the appropriate regional office or this office.
7
_ &*m 5 (b.&&
harles E. Rossi, Director Division of Operational Events Assessment l
Office of Nuclear Reactor Regulation Technical Contacts:
Vern Hodge (301) 492-8196 Albert D. Morrongiello (309) 654-2227 Attachments:
1 1.
List of Plants Using Boraflex Structures in the Spent fuel Pool 2.
List of Recently Issued NRC Information Notices 1
1
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-a IN 87-43 September 8, 1987 Page 1 of 1 LIST OF PLANTS WITH BORAFLEX STRUCTURES IN THE SPENT FUEL POOL i
1.
Arkansas 1.2 16.
Peach Bottom 2,3 2.
Beaver Valley 1 17.
Pilgrim 3.
Diablo Canyon 1,2 18.
Pt. Beach 1,2 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 9.
Grand Gulf 1,2*
24 Summer
- 10.
McGuire 1,2 25.
Trojan IL Millstone 1,2,3 26.
Turkey Pt. 3,4 12.
Nine Mi. Pt. 1,2 27.
Waterford 3
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13.
North Anna 1,2 28.
Seabrook 1,2 14.
Oconee 1,2,3 29.
Watts Bar 1,2 15.
Oyster Creek
- 30.
Comanche Peak 1,2 31.
Harris i
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- Plants having spent fuel storage racks fabricated by Joseph O t Corporation.
a i
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4 IN 87-43.
September 8, 1987
' LIST OF RECENTLY ISSUED INFORMATION.N0TICES 1987 Information Date of Notice No.
Subject Issuance Issued t'o
'87-42 Diesel Generator Fuse 9/4/87 All nuclear. power.
Contacts reactor facilities holding an OL or CP.
87 Failures of Certain Brown 8/31/87 All nuclear power P
Boveri Electric Circuit reactor facilities Breakers holding an OL or CP.,
.L
'87-40 Backseating Valves Routinely 8/31/87 All nuclear power to Prevent Packing Leakage reactor facilities holding.an OL or CP.-
'87 Control of Hot Particle 8/21/87 All nuclear power Contamination at Nuclear reactor facilities Power Plants and spent fuel storage facilities holding an NRC
-license or CP.
87-38 Inadequate or Inadvertent 8/17/87 All nuclear power Blocking of. Valve Movement reactor facilities holding an OL or CP.
- l 87 Compliance with the General 8/10/87 All persons specifi-License Provisions of cally licensed to 10 CFR Part 31 manufacture or to I
initially transfer devices containing radioactive material to general licensees, as defined in 10 CFR Part 31.
87-36 Significant Unexpected 8/4/87 All nuclear power Erosion of Feedwater Lines reactor facilities-holding an OL or CP.
- i 87-35 Reactor Trip Breaker,.
7/30/87 All nuclear power
)
Westinghouse Model DS-416, reactor facilities Failed to Open on Manual holding an OL or Initiation from the Control CP employing W D5-416 1
Room reactor trip breakers.
l' OL = Operating License l
CP = Construction Permit i
1 t