ML19309H897
| ML19309H897 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 05/14/1980 |
| From: | Groce R Maine Yankee |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19309H898 | List: |
| References | |
| WMY-80-75, NUDOCS 8005200635 | |
| Download: ML19309H897 (2) | |
Text
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, MAIRE HARHEE 7:U.T ' '
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ENGINEERING OFFICE WESTGORD, MASSACHUSETTS 01581
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.,: y B.3.2.1 hNY 80-75 May 14, 1980 United States Nuclear Regulatory Commission Washington, DC 20555 Attention: Office of Nuclear Reactor Regulation
References:
( a '. License No. DPR-36 (Docket No. 50-309)
(b) MYAPC Letter to USNRC dated March 4, 1980
Enclosure:
(A) " Evaluation of Asymmetric LOCA-Related Loadings on the Reactor Coolant System at Maine Yankee"
Subject:
Maine Yankee Asymmetric LOCA Loading Evaluation
Dear Sir:
Maine Yankee has completed its evaluation of asymmetric LOCA loadings on the reactor pressure vessel, reactor internals and primary support system.
Enclosure (A) centains the evaluation results as well as a detailed description of the pipe rupture restraints installed during the recent winter refueling outage.
Results of our evaluation demonstrate that:
(a) upper bound asymmetric LOCA loads applied to the reactor pressure vessel supports are less than those used in original design calculations,
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(b) primary support system stresses due to normal operating, maximum hypothetical seismic and upper bound asymmetric LOCA conditions, computed using the methodology and conservatisms employed in original design analyses, are within origiral allowable stress limits stipulated in the Maine Yankee FSAR, and (c) maximum reactor internal loadings due to asymmetric LOCA are less than those originally considered for Maine Yankee.
The reduction in stress levels is attributed to the load diminution effect of the pipe rupture restraints as well as the high degree of conservatism used in developing original design LOCA loadings.
Unitcd Stctes Nuclect R gulstory Commission M y 14, 1980 Office of Nuclear Reactor Regulation Page 2 As discussed in Reference (b), relative to original LOCA loadings, there is no increase in reactor pressure vessel response to asymmetric LOCA loads.
Correspondingly, transient displacement loading due to reactor vessel response on ECCS and branch piping attached to intact loops and control element assemblies is not increased. Results of analyses of ECCS piping systems subjected to transient displacements transmitted to the intact loops, althoughnot finalized, reveal no compromise of structural integrity. Control element assembly functionability requirements and evaluation of their satisfaction of criteria are likewise being finalized. Evaluation methodology is described in Enclosure (A) and final results will be forthcoming.
Should you have any questions or wish to discuss the contents of this letter, please feel free to call.
Very truly yours, MAINE YANKEE ATOMIC POWER COMPANY Robert H. Groce Senior Engineer - Licensing AVR/ncj 1