ML19309B572
| ML19309B572 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 04/02/1980 |
| From: | Dewitt R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19309B573 | List: |
| References | |
| NUDOCS 8004040309 | |
| Download: ML19309B572 (3) | |
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'G, General offices; 1945 Parnell Road, Jackson, Mehigen 49201 * ($17) 788-1217 April 2, 1980 Mr Harold R Denton, Director Office of Nuclear Reactor Regulation US Nuclear Regulatory Commission Washington, DC 20555 DOCKET 50-155 - LICENSE DPR BIG ROCK POINT PLANT - PROPOSED OVERALL RISK ASSESSMENT During our meeting of March 20, 1980, certain issues relating to the proposed Big Rock Point risk assessment were discussed which were not addressed in my February 22, 1980 letter. These issues are summarized below and additional information is provided for your consideration in responding to my previous letter.
One issue we discussed was changes to the list of items for which deferral was requested in my February 22, 1980 letter. These changes are summarized in to this letter. provides a brief description of the methodology to be used in developing the risk model of Big Rock Point. The detailed methodology to be used for the special studies mentioned in Attachment 2 will be developed as part of our overall program. This development will thus occur under the guidance of the Review Group discussed during our meeting. As we discussed, you are invited to designate a member of your probabilistic analysis staff to sit on our Review Group and be actively involved in the development of our program.
I look forward to receiving the name of your representative.
During the meeting, you questioned what additional " compensatory measures" we could take at Big Rock Point to reduce current public risk below the level assured by NRC requirements. This subject has been thoroughly reviewed by my staff.
Our review reiterated that all actions to improve safety which can practically be accomplished in a short period are currently being implemented. Accordingly, we consider that any " compensatory measures" offered at this time could only be j
superficial and with minimal technical basis. Our review did, however, identify several actions which are already being taken which have not previously been reported to the NRC. These actions are:
1.
A fifth operating shift has been established to provide more training of operating personriel than was previously possible. This additional training time is currently being devoted to providing operations personnel a thorough understanding of all plant systems.
2.
The on-duty superintendents (on-call Management representatives) are scheduled to receive three days of extensive simulator training near the end of April.
Approximately 27 off-normal conditions will be covered during this training.
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3.
All shift technical advisors recently completed training at the General Electric simulator.
4.
A detailed plant review is under way to ensure that all plant system valves are correctly shown on piping and instrument drawings (P& ids). This review will include a walkdown of all systems followed by final drawing revision.
Walkdowns of accessible systems should be completed in May; systems inaccessible during operation will be addressed at the first plant outage of sufficient length.
5.
A modification to emergency condenser initiation logic is under consideration to improve availability of this emergency heat sink. The modification will provide an automatic opening signal to the condenser loop inlet valves. This will address the unusual situation in which an inlet valve is closed even though the tube bundle is intact (eg, when leakage through the normally closed outlet valve is detected and the inlet is closed to prevent water or steam cutting of the outlet valves). This modification will be accomplished if an evaluation of potential technical concerns (water hammer, thermal shock, etc) concludes it is acceptable Consumers Power Company considers that the best " compensatory measure" for Big Rock Point would be prompt completion of a thorough risk assessment. The proposed risk assessment will use the best technical methods available to quantify the contribution of each of Big Rock Point's unique design features to overall risk.
This will provide a defensible technical basis for determining whether modifications should be made to reduce public risk.
If modifications are necessary, the analysis will help determine which ones are most effective.
Such a logical, technically based evaluation would be a significant improvement over the current method of generalizing requirements tailored for a modern plant to Big Rock Point.
The proposed study will be complete within a year.
In closing, I must state that I am concerned about the comments you made at our l
meeting indicating that NRC may be unable to approve deferral of any required plant modifications. Let me reiterate that our basic purpose in performing this study is to identify plant modifications which might be necessary to reduce overall risk; the projected costs of these modifications will then be evaluated to determine whether continued operation is economically justified.
Several of the modifications for which we have rquested deferral could seriously affect this economic evaluation. At this point in time, I consider approval to defer those items of large cost and uncertain benefit a necessary step which must be taken prior to the conduct of the risk assessment.
Russell B DeWitt (Signed)
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Russell B DeWitt Vice President Nuclear Operations Attachments
BIG ROCK POINT MODIFICATIONS TO BE EFERRED PENDING COMPLETION OF THE RISK ASSESSMENT The list of items to be deferred transmitted with our February 22, 1980 letter should be modified as follows:
1.
Delete Item 1 "High steam drum level feedwater trip" - This project was initiated in response to BWR Owners Group consideration of the advisabil-ity of installing such trips in lieu of some relief valve testing. The BWR Owners a'oup has since concluded that addition of such trips should not be recommended. Accordingly, Consumers Power Company has terminated effort on this project.
It will only be reinstated if a need is identified in the future which is not apparent at this time.
2.
Add " Meteorological Tower" - While installation of a meteorological tower meeting Regulatory Guide requirements has not yet been made a requirement, NRC emergency planning personnel have indicsted it is under serious con-sideration.
It is estimated that such a meteorological tower would cost approximately $300,000. Procedures currently exist to estimate atmospheric stability and plume direction without a tower. Verification is available by contacting the US Coast Guard in Charlevoix or Federal Aviation Administration in Pc11ston.
Installation of a tower would probably save no more than five minutes in this determination.
Big Rock Point's small core size limits the amount of radioactivity avail-able for release. A cor bination of poor meteorology (Pasquill F) and a one meter por second or lower windspeed would be required for any event to result in concentrations necessitating evacuation of the closest moderate population density area (Charlevoix, five miles). At this low windspeed, at least two hours would be available prior to plume arrival at Charlevoix.
In light of these facts, the marginal improvement a tower I
would produce appears unwarranted. The risk assessment should provide information which can be used to evaluate the necessity of s ch an installation.
3.
Add " Relocation of Off-Site Emergency Operations Center" - This center is currently about 15 miles from the plant. NUREG-0654, although not yet a requirement, specifies that it be within one mile. Consumers Power i
Company considers that this is unwise since it would require evacuation of the center for a large scale accident, thereby, rendering unavailable the support this center is intended to provide in precisely such an event.
In any case, Consumers Power Company considers it inadvisable to disestablish l
and move the existing, functional center before information germane to this decision which will be developed by the risk asessment is available.
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