ML20150D904
| ML20150D904 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 11/30/1978 |
| From: | Rosztoczy Z Office of Nuclear Reactor Regulation |
| To: | Butler W Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 7812110022 | |
| Download: ML20150D904 (1) | |
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liEMORANDUM FOR: Walter Butler, Chief, Containment Systems Branch, DSS FRDri:
Zoltan R. Rosztoczy, Chief, Analysis Brcnch, DSS
SUBJECT:
PALO VERDE 3 AND 4 MAIN STEAM LINE BREAK In your letter of Nov. 3,1978 ycu requested that the Analysis Branch review the acceptability and the conservatism of the mass and energy release data used by the applicant to analyze the containment response to a postulated main steam lice break.
The applicant utilized the massaand energy release data in the CESSAR PSAR. This data was approved for analysis of CESSAR plants in the NRC Safety Evaluation Report dated December 1975.
The main steam system is not included in CESSAR and the blowdown from this system is not included in the CESSAR raass and energy release data.
The applicant for Palo Verde calculates 14.6 x 100 BTU's of steam to be contained in the steam system and adds this instantaneously to the contairunent at the time of peak pressure. This assumption is conservative since the rate of steam flow is maximized.
A more realistic assumption would be to release the steam over a one second time interval at 5 seconds into the accident when the main steam isolation valves close.
We understand that CE plans to include a flow restrictor in the steam generator outlet nozzles for CESSAR plants. The restriction would limit
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occurrance of the 7.3 ft. gut 25% of the full break area and would preclude the break flow area to ab t85% full area) break identified as the worst case.
In conclusion we believe that the mass and energy release data used to analyze the containment response to a main stesm line break is conservative.
Zoltan R. Rosztoczy, Chief Analysis Branch Division of Systems Safety cc:
R. Tedesco P. Norian R. Stright W. Jensen J. Shapaker J. Guttmann S. Brown C. Tinkler DSS;A1.
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