ML19257B051
| ML19257B051 | |
| Person / Time | |
|---|---|
| Issue date: | 03/05/1979 |
| From: | Rosa F Office of Nuclear Reactor Regulation |
| To: | Edison G NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| References | |
| REF-GTECI-A-30, REF-GTECI-EL, TASK-A-30, TASK-OR NUDOCS 8001150159 | |
| Download: ML19257B051 (2) | |
Text
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MAR 5 1979 4
MEMORANDUM FOR: Gordon Edison FROM:
Faust Rosa, Chief, Power $ystems Branch, DSS
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SUBJECT:
COMPLETED TASKS A ',
Reference:
Memo G. Edison to F. Rosa 2/21/79, on above subject In response to your referenced memorandum we have the following comments, keyed to the numbered parts of the memorandum.
Part 1 - Minimum Acceptable DC Power System As you state in this section, the analysis that concluded Haddam Neck was a good system to model for a detailed analysis is not documented. The following provides this documentation and the basis for a recharacterization of your statement that "no commercial LWR's exist in the United States with a less accep-table D.C. power system for licensing purposes."
Power Systems Branch received a verbal request from J. Pittman to provide the name of a plant that fit the minimum D.C. power system description. The basis for this request was that the
" typical" system documented in the Liss to Fitzpatrick memoran-dum of August 25, 1978 did not provide the level of detail required for a thorough fault tree analysis.
In response to this request, R. Fitzpatrick reviewed the matrix of questions and answers by operating plant enclosed as pr.rt of the D0R plant survey on DC power systems dated August 18, 1977.
A systematic review of all of the plants listed in that matrix revealed that Haddam Neck appeared to have no redundancies be-yond what is required tc meet the single failure criterion.
That is to say that there were nc spare battery chargers, no dedicated batteries for such things as switchyard control or diesel generator control, and so on. All other plants on that survey matrix had one or more of these extra items that made them in excess of the minimum required to meet the single failure criterion. This is the one and only basis for select-ing Haddam Neck as a reference plant.
Contact:
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1750 076 s o on s o /Sy 4
Gordon Edison MAR 5 1979 Based upon our analysis, as now documented above, we cannot support your characterization of Haddam Neck by the above cited quote from the first paragraph of the reference memorandum. We attribute this to the fact that both the original request and the response were provided over the telephone and two important items were lost along First, the analysis had no way of considering physical the.way.
implementation of the various documented designs and second, and exceedingly germane to this entire issue, Haddam Neck stated in this survey response that loss of a DC bus would not scram the reactor.
Many plants with more sophisticated arrangemer,ts were unable to make the same claim.
Part 2 - Basis for completion of Tasks in TAP A-30, Rev. 1, May 1976 We recommend the description for Task 1 be reworded as follows:
Task 1 - Detailed scoping of issue. This task is essentially com-plete based on the discussion in NUREG-0305 and the original scoping of the TAP itself.
Progress through the early tasks of the plan has provided further insight as to what is required toThe successfully complete and satisfactorily resolve this issue.
detailed scoping will be fully accomplished with the completion of the impending revision to the plan.
'g (-J A y,
up Faust Rosa, Chief Power Systems Branch Division of Systems Safety cc:
J. Pittman P. Baranowsky S. Hanauer R. Mattson G. Lainas 1750 077