ML20248A855
| ML20248A855 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 05/31/1989 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20248A853 | List: |
| References | |
| NUDOCS 8906080213 | |
| Download: ML20248A855 (4) | |
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~ 4 50,0 9'o UNITED STATES 8
NUCLEAR REGULATORY COMMISSION o
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i WASHWGTON, D. C. 20555
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.124 TO PROVISIONAL' OPERATING LICENSE NO. ~ DPR-20 CONSUMERS POWER COMPANY PALISADES PLANT DOCKET NO. 50-255 1
1.0 INTRODUCTION
J By letter dated February 25, 1987, Consumers Power Company (the licensee) requested amendment to the Technical Specifications (TSs) appended to Provisional Operating License No. DPR-20 for the Palisades Plant.
The proposed amendment.would provide for modifications that were made to the recirculation actuation system (RAS) logic.
The modifications changed the system logic from two-out-of-four logic to one-out-of-two-taken-twice logic.
In addition, an editorial change in the Basis relating to an earlier amendment also was proposed.
- 2. 0 EVALUATION As a result of a design deficiency described in Consumers Power Company letter dated September 18,1986, (LER 86-034), Consumers Power Company, under the provisions of 10 CFR 50.59, modified the RAS to a one-out-of-two-taken-twice logic from the existing two-out-of-four logic.
This change removed the potential for damage to the safety injection pumps in the event a single failure of the DC bus was followed by a safety injection signal.
l The original logic arrangement would have aligned certain valves such that the safety injection pumps would take suction from a dry containment sump.
1 If a safety injection signal were then received with this valve line-up, significant high pressure-safety-injection pump and containment-spray pump damage could occur.
This, coupled with other consequences of the initial failure, could result in an event that would be outside the design basis for the facility.
l To account for the modification to the RAS logic, certain TSs changes are l
proposed by Consumers Power Company.
The proposed changes and our l
evaluation are as follows:
i 2.1 Proposed Change Section 1.2.
A sentence is proposed to be added to the definition of Degree of Redundancy to indicate that the definition does not apply to the one-out-of-two-taken-twice RAS
- logic, Evaluation We agree with Consumers Power Company's assertion that for the modified RAS logic, the definition of Degree of Redundancy does not apply. We, therefore, find this proposed change acceptable.
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.. t 2.2 Proposed Change Section 1.2.
A sentence is proposed to be added to the definition of Engineered Safety Features System Logic that would state that the RAS is initiated by a one-out-of-two-taken-twice I
logic.
Evaluation This change would clarify the definition of Engineered Safety Features System Logic by indicating that the RAS uses a different logic than other engineered safety features. We find this change
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acceptable.
2.3 Proposed Change Section 3.17, Basis.
Consumers Power Company proposes to. delete ~
the reference to the turbine runback signal.
Evaluation On November 15, 1988, the Commission issued Amendment 118 in response to an application submitted March 25, 1988.
That.
application proposed this change, and it.was incorporated into the TSs by Amendment 118.
No further action, the'refore, is required for this item.
2.4 Proposed Change Section 3.17, Basis.
A paragraph is proposed to be added that describes the change to the RAS logic.
Included in the paragraph would be an explanation for bypassing an inoperable channel and the purpose for the restriction on the duratjon of a bypassed channel.
Evalur. tion The proposed paragraph is consistent with the change made to the RAS logic and provides an explanation for the need to bypass an inoperable channel.
The time restriction also is explained.
As the proposed addition provides additional information and clarification, we find the proposed paragraph acceptable.
2.5 Proposed Change Table 3.17.4, Item 1.
This item would be changed to be consistent with the modified RAS logic.
The minimum number of operable channels would be increased to 4 from 2 and the minimum degree of redundancy would no longer apply.
Further, bypassing one inoperable channel would now be permitted.
Additionally, footnote b would be changed to indicate that if a channel is inoperable, it shall be bypassed.
Previously, an inoperable channel'would have had to nave been in a tripped condition.
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.# Evaluation.
As a result of the modifications to'the RAS logic, the minimum number of channels required to be operable is increased to four; however, with this logic, when a channel becomes inoperable it would be allowed to be placed in bypass vice trip.
Placing the' channel;in bypass provides protection against premature RAS actuation from a DC bus failure (the concern which prompted the logic modification).
This action _(bypassing) would introduce the possibility of not receiving an actuation signal when required.
However, we have evaluated this conditicn and have
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determined that the potential for not receiving the signal when required is not as significant as a premature RAS signal. This is because in the event of failure to receive a required signal for recirculation, there is sufficient time available for the operators to recognize the failure and take manual action to effect the transfer.
To minimize the risk of this occurrence, a i
seven day limit is imposed for the duration of the bypassed condition.
<We find the proposed change to the TSs is acceptable in that the i
increase in the required minimum number of channels'to be i
operable is consistent with the changes made to the RAS logic, and that the bypassing of an inoperable channel for up to seven days provides a reasonable amount of time to complete any necessary repairs to a malfunctioning SIRWT level channel.
This period is consistent with other TS action statements for similar emergency equipment; i.e., emergency diesel generators.
3.0 ENVIRONMENTAL CONSIDERATION
This amendment involves a change in the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and a change in a surveillance requirement.
We have determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure.
The Commission has previously issued a proposed finding 1
l that this amendment involves no significant hazards consideration and there J
l has been no public comment on such finding.
Accordingly, this amendment I
meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the issuance j
of this amendment.
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4.0 CONCLUSION
We have concluded, based on the considerations discussed above, that (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (2) such activities will
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... be conducted in compliance with the Commission's regulations, and the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.
Date: May 31, 1989 Principal Contributor:
Albert W. De Agazio 9
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