ML19346A202
| ML19346A202 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 05/12/1981 |
| From: | Mark J Advisory Committee on Reactor Safeguards |
| To: | Hendrie J NRC COMMISSION (OCM) |
| Shared Package | |
| ML19346A201 | List: |
| References | |
| NUDOCS 8106050385 | |
| Download: ML19346A202 (2) | |
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~g UNITED STATES o
,I NUCLEAR REGULATORY COMMISSION ADVISORY COMMITTEE ON REACTOR SAFEGUARDS Q
WASMNGTON, D. C. 20655 O
May 12, 1981 Honorable Joseph M. Hendrie Chaiman U. S. Nuclear Regulatory Commission Washington, D. C.
20555
SUBJECT:
PRESSURE INJECTION AND RESIDU
Dear Dr. Hendrie:
Commissioner Gilinsky, in a separate statement dated August 20 the full power authorization for the North Anna Nuclear Pla t U i
, 1980 on that it appeared that the low pressure injection (LPI) and r n
n t 2, no'.ed removal (RHR) systems could be improved substantially in terms of th esidual heat ability to deal with accidents.
The specific changes suggested were the er environmental qualification of the RHR system and the addition of a exchanger to the LPI system.
en Reactor Safeguards (ACRS) and the NRC Staff. des sory Comaittee At a meeting of an Ad Hoc ACRS Subcommittee on Decay Heat Remo held on May 5,1981 and again at a meeting of the ACRS on May 7 ystems NRC Staff and the North Anna licensee discussed the Nor
, 1981, the removal systems and the modifications proposed by Commissioner G cay heat The Staff has concluded that the existing North Anna design confo review criteria, the proposed modifications would rms with significantly.
The licensee described the design bases for the LPI and RHR systems and the ability of the plant to cope with a spectru ms Further, results were presented of a study conduct m of abnormal Brookhaven National Laboratory which indicated there would be littl a
y The study pointed out that the North Anna LPI system e or no d: sign a significant improvement over that of the Surry system anal s in its the Reactor Safety Study, WASH-1400.
yzed in probability calculated f8r Surry.One accident sequence (S,,C) wh o the core melt of preliminary Task Action Plan A-45, on the Unreso p on decay heat removal requirements, which had been presented to the ACRS April 10,1981. -
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Honorable Joseph M. Mendrie May 12,1981 We concur with Commissioner Gilinsky's desire to improve the reliability of decay heat removal systems. Probabilistic and deterministic assessments have concluded that potential failures in decay heat removal systems are major contributors to risk in operation of light water reactors. We con-clude that aggressive development of Task A-45 and rapid implementation of any new decay heat removal requirements deriving from the Task Action Plan will best serve to improve the reliability of such systems for all LWRs, including North Anna. We have listed below several suggestions which we believe will improve the Task Action Plan, and we urge the Commission to take these into account while assigning a high priority to Task A-45.
The plan should give careful consideration to alternative decay heat removal systems, such as those used in some foreign LWRs and reviewed in the current Sandia study being conducted for RES.
Probabilistic studies such as RSSMAP, RSS, and IREP should furnish valuable insights in assessing system improvements, but engineering evaluation should not rely solely on these studies.
The estimated completion date,1984, is not likely to be realized for the ambitious program outlined unless the Commission assigas high priority to the work and allo-cates Staff resources to assure its timely completion.
We understand that a draft Task Action Plan for Task A-45 will be available
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in the very near future. We request the opportunity to comment on the plan in more detail.
l Sincerely, AH J. Carson Mark Chairman O
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