ML19329C223
| ML19329C223 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 04/30/1976 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19329C220 | List: |
| References | |
| NUDOCS 8002120943 | |
| Download: ML19329C223 (4) | |
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- O REVISIONS TO THE DRAFT SAFETY EVALUATION REPORT DAVIS-BESSE NUCLEAR POWER STATION, UNIT 1 DOCKET NO.:
50-346 1.
Delete the last five paragraphs of Section 6.2.1 and replace them with the following:
"The CRAFT computer program has been accepted by the NRC for calculating mass and energy releases to the containment during the blowdown phase of the postulated accident. An additional measure of conservatism has been added by not allowing any credit to be taken for the possible quenching action of ECCS fluid on the exiting steam.
"We have performed a confirmatory containment analysis for a postulated double-ended, hot-leg break based on the mass and energy release rates calculated by the applicant for the blowdown period. Using the CONTEMPT computer code (Reference 1 and 2), we calculated a peak containment pressure of 38.0 psig. The Davis-Besse Unit 1 containment vessel is designed for a maximum pressure of 40 psig. The results of our analysis confirm the acceptability of the peak pressure calculated by the appli-cant. We therefore conclude that the containment design pres::ure is acceptable.
"The applicant has also analyzed the containment response to a postulated main steam line failure. The applicant calculated a peak containment vessel pressure of about 22 psig for this accident.
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. "The applicant has analyzed the pressure response within various containment interior compartments.
We have calculated pressures greater than the applicant and the design conditions in our con-firmatory analysis. We will need justification of the subcompartment modeling and information concerning pressure loads across the reactor vessel supports. We will require the applicant.to provide this infor-mation 'and will report on the acceptability of the subcompartment analysis in a supplement to the Safety Evaluation Report.
"We have evaluated the containaent system functional design in accordance with the General Design Criteria stated in 10 CFR Part 50 of the Comission's Regulations and, in particular, Criteria 16 and 50. We will need to resolve the differences in the calculated subcompartment pressures before we can conclude that the design pressures are adequate."
4 2.
Delete the third paragraph of Section 6.2.3 and replace it with the following:
"The applicant has analyzed the pressure response of the shield building following a postulated loss-of-coolant accident.
The applicant calcu-lates that about 65 seconds is required to establish a negative pressure after the emergency ventilation system becomes operational which is about 90 seconds after the accident. As part of the pre-operational and periodic in-service inspection and test programs, the applicant will confinn the operability of the system components and
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. equipment, and the functional capability of the system to maintain a negative pressure within prescribed limits. We will also require the applicant to verify the time required to depressurize the shield building and establish a negative pressure."
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DAVIS-BESSEL NUCLEAR POWER STATION, UNIT 1 CONTAINMENT SYSTEMS BRANCH REQUEST FOR ADDITIONAL INFORMATION 1.
With regard to the reactor cavity analysis, for each flow path provide an L/A (ft'I) ratio, where "L" is the average distance the fluid flows in that flow path and "A" is the effective cross-sectional' area.
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