ML19271E701
| ML19271E701 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 05/31/1984 |
| From: | Kay J YANKEE ATOMIC ELECTRIC CO. |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19269A201 | List: |
| References | |
| FYR-84-63, NUDOCS 8406050110 | |
| Download: ML19271E701 (5) | |
Text
8 Telephone (617) 872-8100 l
TWX 7103837619 YANKEE ATOMIC ELECTRIC COMPANY rrR 84-s3 f.,.
2.C.2.1 1671 Worcester Road. Framingham, Massachusetts 01701
, YANKEE May 31, 1984 United Stater Nuclear Regulatory Commission Washington, D. C. 20555 Attention:
Office of Nuclear Reactor Regulation Reference (a) License No. DPR-3 (Docket No. 50-29)
(b) YAEC Letter to USNRC, dated March 9, 1984
Subject:
Exemption from the 10CFR Part 50, Appendix K Decay Heat Requirement; Uncertainty Study Information
Dear Sir:
This is to follow up the YAEC submittal to the NRC in Reference (b) which requested an exemption from Appendix K requirements on decay heat calculations.
The following points summarize our March 9, 1984 submittal:
1.
For DBA analyses at the Yankee Nuclear Power Station (YNPS), we proposed using the 1979 ANS Standard on Decay Heat in place of the Appendix K required model, which requires the use of the 1971 ANS proposed standard for infinite reactor operation with a 20% add-on for model uncertainty.
2.
The details of our proposed application of the 1979 Standard for YNPS were presented in the report YAEC-1399P, attached to the March 9, 1984 submittal. The report demonstrated that the 1979 Standard c.ould be conservatively applied by proper choice of input parameters and the adt.ition of 20 uncertainty.
3.
The impact of using the 1979 Standard (conservatively) in licensing LOCA analyses was assessed by using the current YAEC licensing evaluation model. The results showed that at the currently licensed PLHGR of 11.4 kW/ft, the peak clad temperature (PCT) would decrease from 21760F to 17080F due to the use of the 1979 Standard. Further, at a PLHGR of 12.75 kW/ft, the PCT was calculated to be 1892 F.
The PLHCR of 12.75 kW/ft represents the value at which YAEC would like to have the plant licensed.
4 The RELAP5YA system thermal-hydraulic code was used to carry out a more realistic LOCA calculation. At the currently licensed PLHGR of 11.4 kW/ft, the RELAr5YA analysis yielded a PCT of 12490F. This indicated a margin of 4590F (17080F to 12490F) between the realistic saalysis and the proposed licensing analysis, at a PLHGR of 11.4 kW/ft.
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s United States Nuclear Regulatory Commission May 31, 1984 Attention: Office of Nuclear Reactor Regulation Page 2 5.
We concluded that our request for an exemption from the Appendix K Decay Heat requirement was justified because, a) the 1979 Standard provides an accurate estimate of decay heat and its uncertainty, b) we have ensured that the 1979 Standard will be applied conservatively for licensing analysis, and c) e significant safety margin in PCT is retained in our proposed licensing model for YNPS.
Most of the above information was presented to the NRC staff at a meeting held on November 10, 1983. Additionaly, the staff requested additional sensitivity studies using RELAP5YA to demonstrate that uncertainty in PCT calculated by RELAP5YA would not exceed the margin between realistic and proposed licensing calculations.
This submittal documents the information requested by the staff at the November 10, 1983 meeting and addresses the uncertainty in the calculation of PCT by RELAP5YA. The attached report, YAEC-1431P, contains the details of our analyses. The major points are summarized below:
1.
Those parameters that would have significant impact on PCT have been identified and their nominal values and expected range of variation determined.
2.
The nominal value for the PLHGR was determined to be 10.93 kW/ft. The RELAP5YA calculation with nominal input variables and models yielded a PCT of 12000F. Thus there is a margin of about 7000F in uur proposed licensing calculation (PCT of 18920F at 12.75 kW/ft).
3.
Sensitivity studies with RELAP5YA were carried out by perturbing the important variables and models at a 20 uucertainty level or higher.
4 The resulting combined uncertainty in PCT, using a sum-of-squares approach, was determined to be 2150F.
5.
This uncertainty is much lower than 7000F and still leaves a safety margin of about 5000F in our proposed licensing model.
The above information was presented to the NRC staff at a meeting held on April 26, 1984 At this meeting, the staff identified several additional concerns on RELAP5YA's ability to predict a PWR large break LOCA analysis, quantification of a code blas, scaling factors to account for model scaling, need for a res'ponte matrix for statistical analysis, and the validity of the combined uncertainty approach used in our analysis.
YAEC-1431P addresses the staff questions.
Furthermore, the safety margin of about 5000F in PCT still available af ter accounting for the calculated uncertainties is more than sufficient to account for any postulated additional uncertainties.
8 United States Nuclear Regulatory Commission May 31, 1984 Attention: Office of Nuclear Reactor Regulation Page 3 Therefore, we conclude that, together with the March 9,1984 submittal, we have provided sufficient justification for an exemption from the 1971 ANS Standard on Decay Heat requirement of 20CFR50.46 Appendix K use in for licensing analyses at the Yankee Nuclear Power Station.
The documentation provided in YAEC-1431F contains,information considered proprietary to Yankee Atomic Electric Company. This documentation is submitted in confidence and is to be used solely for the purpose for which it is furnished. As such, this documentation is not to be reproduced, transmitted, disclosed, or used otherwise in whole or part without prior authorization of Yankee Atomic Electric Company, Nuclear Services Division.
In accordance with 10CFR2.790(b)(1), an affidavit attesting to the proprietary nature of YAEC-1431P is attached.
If you have any question, please contact us.
Very truly yours, YANKEE ATOMIC ELECTRIC COMPANY J. A. Kay Senior Engineer - Licensing AH/tja Attachments e
AFFIDAVIT PURSUANT TO 10CFR2.790 YANKEE ATOMIC ELECTRIC COMPANY)
NUCLEAR SERVICES DIVISION
)
COMMONVEALTH OF MASSACHUSETTS )
MIDDLESEX COUNTY
)
as I, L. H. Heider, depose and say that I am the Vice President of Yankee Atomic Electric Company, duly authorized to make this affidavit, and have reviewed or caused to have reviewed the information which is identified as proprietary. I am submitting this affidavit in conformance with the provisions of 10CFR2.790 of the Commission's regulations for withholding this information.
The information for which proprietary treatment is sought is contained in the report, YAEC-1431P.
Fursuant to the provisions of Paragraph (b)(4) of Section 2.790 of the Commission's regulations, the following is furnished for consideration by the Commission in determining whether the information sougnt to be withheld from public disclosure, included in the above referenced document, should be withheld.
1.
The material contained in this transmittal was obtained at considerable expense to Yankee Atomic Electric Company and the release of which would seriously affect our competitive position.
2.
The material contained in this transmittal is of *he type customarily held in confidence and not customtrf, disclosed to the public.
3.
This information is being transmitted to the Commission in confidence. Under the provisions of 10CFR2.790 with the understanding that it is to be received in confidence by the Commission.
AFFIDAVIT PURSUANT TO 10CFR2.790 (Continued) 4 This information is for Commission internal use only and should not be released to persons or organizations outside the Directorate of Regulation and the ACRS without prior approval of Yankee Atomic Electric Company.
Should it become necessary to release this information to such persons as part of the review procedure, please contact Yankee Atomic Electric Company and we will make the necessary arrangements required to protect our proprietary interests.
Further deponent sayeth not.
Y&
/
M H. He'ider Vice President Sworn to before me this 31 day of May 1984
..?.'.O' d obert H. Groce Notary Public
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D' Hy Commission Erpires September 14, 1984
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