ML20210L538
| ML20210L538 | |
| Person / Time | |
|---|---|
| Issue date: | 09/25/1986 |
| From: | Novak T Office of Nuclear Reactor Regulation |
| To: | Bernero R Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20209E138 | List: |
| References | |
| FOIA-87-10 NUDOCS 8610020083 | |
| Download: ML20210L538 (2) | |
Text
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9 go UNITED STATES
[
g g NUCLEAR REGULATORY COMMISSION
.* 5 j WASHINGTON, D. C. 20555
\...../ .
gge 25 Y MEMORANDUM FOR: Robert M. Bernero, Director Division of BWR Licensing FROM: Thomas M. Novak, Acting Director Division of PWR Licensing - A
SUBJECT:
REVIEW 0F GENERIC REOUIREMENTS FOR BWR CONTAINMENT RESPONSE TO SEVERE ACCIDENTS As requested in your memorandum of September 3, 1986 we have reviewed the Draft Generic Letter for Proposed BWR Containment Requirements. We have
-restricted our comments to the technical issues related to the proposed requirements and have not commented on policy issues such as whether the imposition of new requirements at this time is consistent with the Severe Accident Policy Statement or the IDCOR review process.
With regard to the specific technical improvements proposed in the draft generic letter, we have the following comments:
- 1. The requirement for wetwell venting, as described in the regulatory analysis, indicates a preference for venting "at or near design pressures."
i For Mark III plants, with a design pressure of 15 psig, venting at such a low setpoint is unnecessary since the ultimate capacity of the contain-l ment, with margin, is about 60 psig. Furthermore, the requirement for Venting capability is not accompanied by a description of a specific l
i objective, such as the prevention of gross containment failure by I
overpressurization due to energy addition up to a given rate. The notion that all available venting paths should be considered and used symptomatically by matching venting requirements with venting capabilities seems a hopelessly complex task for plant personnel in the face of a severe accident. Is the operator expected to anticipate or
_ diagnose core melt / vessel failure phenomena, and thereby properly select the requisite vent paths?
The discussion of venting requirements does not address station blackout sequences, yet other improvements make explicit reference to such scenarios. If DBL considers venting capability during a blackout unnecessary, then clarification would be helpful.
I
- 2. The requirement related to drywell and wetwell sprays should also be accompanied by a more heat removal capacity) precise . Requiring statement adequateofheat thedissipation objective (e.g., a given and fission product attenuation at flow rates capable of being delivered by fire pumps is too vague.
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., Robert M. Bernero - - _. _. _
Requirements for both sprays and venting appear redundant if the requirement for the sprays is intended to facilitate heat removal and concomitant depressurization.
- 3. _,The requirement related to hydrogen control addresses only Mark I and II containments and requires protection for blackout sequences. Omission of Mark III containments which rely on AC powered hydrogen igniters from this requirement is conspicuous and should be addressed.
b 4 A% j Thomas . Novak, Acting Director Division of PWR Licensing - A cc: R. Housto G. Lainas H. Thompson M. Srinivasan J. Zwolinski D. Muller E. Adensam '
W. Butler B. Liaw M. Hodges L. Hulman D. Vassallo
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