ML20126K262
| ML20126K262 | |
| Person / Time | |
|---|---|
| Site: | Waterford  |
| Issue date: | 12/31/1992 |
| From: | Burski R ENTERGY OPERATIONS, INC. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| W3F192-0396, W3F192-396, NUDOCS 9301070080 | |
| Download: ML20126K262 (6) | |
Text
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33 W3F192-0396 A4.05 QA December 31, 1992 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555
Subject:
Waterford 3 SES Docket No. 50-382 License No. NPF-38 Boraflex Surveillance Program Gentlemen:
Waterford 3 committed in December 1987 to propose to the NRC by January 1, 1993 an appropriate surveillance program for surveillance of Boraflex in the s)ent fuel storage racks. The purpose of this letter is to provide to the NRC t1e information which satisfies this commitment including a discussion of the detailed commitments and the description of the proposed surveillance program.
This information is provided in the attachment to this letter.
Please contact me or Robert J. Murillo should there be any questions regarding this letter.
Very truly yours, 3
sk ir t'or, luclear Safety Rfj3/RJM/dc Attachment cc:
J.L. Milhoan, NRC Region IV D.L. Wigginton, NRC-NRR R.B. McGehee N.S. Reynolds NRC Resident Inspectors Office i
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1 Attachment to letter W3F192-0396 A.
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The pertinent information regarding the Boraflex surveillance program was documented in the following documents:
Louisiana Power and Light (LP&L) letter W3P87-2055 dated 9/16/87, LP&L Letter W3P87-2527 dated 12/15/87, and flRC Safety Evaluation Report (SER) dated 12/21/87. These documents established NRC and Waterford 3 agreement for the following commitments:
1.
The current Boraflex coupon surveillance commitment will not be j
performed.
2.
Waterford 3 will develop a log to track the gamma dose buildup in the spent fuel storage racks (SFSR).
3.
Waterford 3 will provide the NRC by January 1,1993 with-actual data, from nondestructive techniques, on several Boraflex panels to verify that the poison material has not been unacceptably degraded by the formation of gaps.
4.
Waterford 3 will provide the NRC by January 1, 1993 with a surveillance program to verify the effectiveness of the Boraflex
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poison material in the Waterford 3 spent fuel storage racks. This surveillance program will be based on the latest industry developments on Boraflex surveillance methods and technicues as well as studies on Boraflex degradation mechanisms from raciation exposure.
B.
Commitment Resolution The resolution for each of the foregoing commitments is the following:
1.
The Boraflex coupon surveillance program was terminated and is not active.
2.
Waterford 3 maintains a database of the calculated Boraflex panel gamma exposures in the Waterford 3 SFSR.
3.
Testing of Boraflex panels was performed in November,1992.
A review of the test results indicates that the Boraflex continues to perform its intended neutron attenuation function. Additional information is provided in section C of this attachment.
4.
The proposed surveillance program has been developed, and it is described in section D of this attachment.
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lett.ing of Boraflex Panels Testing of a representative sample of Boraflex panels was performed in November, 1992.
A review of the test results indicates that the Boraflex continues to perform its intended neutron attenuation function, lesting was conducted to test the highest exposed panels for gaps. The test results are therefore bounding on expected gap foroation in the Boraflex.
The following is a summary of the test results:
tiumber of Panels Tested 697 185 Total fiumber of Gaps Number of Panels With No Gap 53B 8.03E409 rads Average Exposure 1.66E410 rads Maximum Exposure 136 Number of Panels With 1 Gap 8.93E409 rads Average Exposure 1.66E+10 rads Maximum Exposure 2.17 inches Average Gap Size (A&D)
Maximum Gap Size (ALB) 3.57 inches Number of Panels With 2 Gaps 20 9.00E409 rads Average Exposure 1.62E+10 rads Maximum Exposure 2.04 inches Average Gap Size (A&B) 2.74 inches Maximum Gap Size (A&B)
Number of Panels With 3 Gaps 3
1.01E+10 rads Average Exposure 1.31E+10 rads Maximum Exposure 1.05 inches Average Gap Size (A&B) 1.24 inches Maximum Gap Size (A&B) lhe distribution of gaps size indicates that the Boraficx is performing as expected based on EPRl/ industry data. EPRI data indicates that after approximately 7x10E409 rads, shrinkage, and gap formation, of the panels reaches a maximum value.
We expect that the locations with fuel currently stored will have a mach lower number of gaps, due to being in lower exposed areas.
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L Attachment To letter W3fl92-0396 D.
Ducrfotion of Boraflex Survemance Proaram OldtG.t1Y.R The objectives of the Boraflex surveillance program are:
1.
To verify the effectiveness of the Boraflex poison material in the SFSR.
2.
To ensure the requirements of Techn.:al Specification 5.6.1 are met. These requirements are with; pent fuel storage racks are designed and shall be eaintained The s a.
A k.,, equivalent to less than or equal to 0.95 when flooded with unborated water, which includes a conservative allowance for uncertainties.
b.
A nominal 10.38 center-to-center distance between fuel assemblies placed in the spent fuel storage racks.
O.
To ascertain the rate of change (gap formation) in the Boraflex and determine the interval between surveillances, fielhadoloav J
The Boraflex surveillance program at' Waterford.3 will consist of the following:
1.
Tracking of tha gamma exposure of the Boraflex penels.
2.
Periodic nondestructive testing (" blackness" testing) of selected Boraflex panels to determine the extent of gap formation.
The prnposed schedule for the blackness testing is four (4) year intervals but no later than 12/31/94 for the next testing with the exact schedule being determined by the rata of gap formation.
The results of the nondestructive testing will be compared to industry data and EPRI sponsored research. The Waterford 3 SFSR criticality analysis will be. reviewed by April 15, 1993 based on-EPRI data for maximum expected gap formation. The review will be performed by modeling the current status of the Boraflex panels and projecting the expected gap formation -due to calculated exposure through 12/31/94. ' Data collected.tn November,1992 will provide a baseline for the trending _of gap formation.
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l Attachment To letter W3F192-0396 Waterford 3 will have lead exposure cells in the SFSR to ensure that degradation due to gamma exposure will be identified early.
These 16 cells will have freshly discharged fuel loaded into them following refueling outages, and these cells will be tested during each nondestructive test. The configuration of these cells in the SFSR is shown in Figure One (1).
FIGURE OE l
D Peripheral boundary no Boraflex
- tiormal Boraflex panol
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29 JO 31 32 Since these locations contain some of the leading exposure panels, fuel will not be placed into these cells until the review of the criticality analysis is complete. These lead exposure cells will provide data for the performance of Boraflex under gamma exposure and early indication of unacceptable trends.
These cells are expected to lead the SFSR in gap formation.
3.
Periodic destructive testing of selected panels if engineering assessment determines a need for destructive testing.
The need for destructive testing will be determined by a review of nondestructive test results, trend data, and industry experience.
4.
Monitoring of industry developments to determine the latest methods for testing Boraflex and to determine Boraflex performance at other sites.
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&1lachment To letter W3fl92-0396 l
Summary The Boraflex surveillance program will provide sufficient data to verify the effectiveness of the Boraflex poison material and to review the SFSR criticality analysis. Additionally, it will provide trending data for changes in the Boraflex with gamma exposure and thus provide a technical basis for taking early corrective action if problems ariso.
Th:
surveillance program satisfies the program ob;ectives and. provides assurance that the margin of safety in the SFSR will be maintained.
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