ML20137S459
| ML20137S459 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 11/22/1985 |
| From: | Opeka J, Sears C NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES |
| To: | Novak T Office of Nuclear Reactor Regulation |
| References | |
| A05322, A5322, NUDOCS 8512060245 | |
| Download: ML20137S459 (3) | |
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(203) 66s-5000 November 22,1985 Docket No. 50-423 A05322 Director of Nuclear Reactor Regulttion Mr. T. M. Novak, Assistant Director Division of Licensing U. S. Nuclear Regulatory Commission Washington, D. C. 20555
Reference:
(1)
T. M. Novak letter to 3. F. Opeka, Probabilistic Safety Study for Millstone Nuclear Power S tation, Unit 3,
dated October 17, 1985.
Dear Mr. Novak:
Millstone Nuclear Power Station, Unit No. 3 Risk Evaluation Report Northeast Nuclear Energy Company (NNECO) was requested to respond to several comments offered by the Staff in a letter dated October 17,1985 which provided an overall assessment of the Millstone Unit 3 Probabilistic Safety Study (PSS). The majority of the Staff comments centered on the treatment of seismic events which exceed the design basis for Millstone Unit No. 3.
In the Risk Evaluation Report, transmitted by Reference (1), the Staff has made observations regarding plant improvements which are worthy of further consideration. We recognize the Staff's interest in this matter and we share the objectives of evaluating potential improvements in nuclear plant safety.
Although the results of the Millstone Unit 3 PSS show that the plant meets our corporate objectives regarding nuclear safety in terms of both public risks and severe core damage frequency, we are giving further consideration to the four specific recommended improvements identified by the Staff (in Reference (1)) as follows:
1.
" Engineering analysis for upgrading the diesel generator lube oil cooler anchorage system."
The anchor bolts for the coolers currently have a safety factor 5.35 times greater than currently required. We will reevaluate the seismic integrity of the oil cooler anchorage system and implement any appropriate design changes by the end of June,1986.
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.,,.. 2.
" Feasibility of manually operated, AC-independent containment spray system."
The PSS will be updated to reflect as-built design and current survellance procedures. The PSS will then be used to assess the risk reduction for the AC-independent containment spray system. Appropriate changes to plant design and procedures will be identified and implemented by startup from the first refueling outage.
3..
" Operator training and procedures to recover from earthquake induced relay chatter."
The emergency procedures will be upgraded as necessary to cope with such an event by June 1986. Full training and implementation of the upgraded procedures will be completed by August 1986.
4.-
" Emergency procedures to recover cooling to selected rooms by alternate methods.
We will analyze corrective actions required for a loss of HVAC, identify appropriate design and procedural improvements and implement them by startup from the first refueling outage.
These commitments and their dates are consistent with minimizing procedural confusion for the operator during initial startup and testing. The dates will permit thorough examination of the issues as well as thoughtful preparation and implementation of procedures and changes; further it will allow focus of NU resources to achievement of high safety levels at all of our plants.
Because of the demonstrated high safety level for Millstone 3, our corporate risk assesnnent priorities are focusing on our operating nuclear units where large benefits from the application of PRA techniques are being identified.
As part of our overall risk assessment effort, we have completed a Millstone Unit No. I Level 1 PSS as part of our ISAP commitments. We are also at this time completing a Level 1 PSS of the Haddam Neck Facility. This effort is also in support of ISAP and is currently consuming the majority of our PRA resources.
We ar9 n the midst of scheduling the next phase of our corporate plan for living i
PRA'stl) which involves the completing of a Level 1 PSS for Millstone Unit No.2.
(1)
The plan was discussed in some detail with representatives from both Region I and the NRR Staff at the request of Dr. Murley during a meeting in our Berlin offices on June 3,1985.
r
. We trust this letter provides the necessary clarification of our commitments for factoring the improvements identified by the Staff in Reference (1) into the Millstone Unit 3 PSS reevaluation. If further clarification is necessary, contact me directly.
Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY S 3.DM
- 3. F. Opeka '
Senior Vice President By: C. F. Sears Vice President l
'