ML20058E237
| ML20058E237 | |
| Person / Time | |
|---|---|
| Site: | Clinton  |
| Issue date: | 11/01/1990 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20058E236 | List: |
| References | |
| NUDOCS 9011070089 | |
| Download: ML20058E237 (3) | |
Text
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UNITED STATES l'
Ig NUCLE AR REGULATOPY COMMISSION o
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 52 TO FACILITY OPERATING LICENSE NO. NPF-62 ILLIN0IS POWER COMPANY, ET AL, CLINTON POWER STATION, UNIT NO. 1 DOCKET NO. 50-461 1.0 lhiRODUCT10N By Stter dated November 20, 1989, Illinois Power (IP) proposed changes to Clinton Power Station Technical Specifications.
The change is to increase Allowed Outage Time (A0T) and Surveillance Test Interval (STI) of the Self Test System (STS) provided in the Clinton design to automatically test Nuclear System Protection System (NSPS) logic.
The change also proposed to use STS in the manual mode when the automatic mode of STS is found inoperable.
The STS is designed to perform automatic surveillance testing of NS95 circuitry which includes logics associated with the Reactor Protection System (RPS), Emergency Core Cooling System (ECCS), and Containment and Reactor Vessel isolation Control System.
The STS injects short-duration test signal pulses in the NSPS Logic to verify proper response of the logic to various input combirations. When in automatic mode, the STS injects test pulses in the logic at one-hour ST!.
The STS normally operate. to automatically test all four NSPS divisions in a continuous, cyclit, manner.
The STS ceases to operate in automatic mode if failure is detected in any one of the four divisional logics.
The STS test sequence can be manually restored to automatic operation for the remaining three divisions.
Once 4
the failure is corrected, the STS can then be restored to fully automatic operation fr all four oivisions.
The primary purpose of the STS is to improve the availability of the Safety Systems Instrumentation by minimizing tht time to detect and determine the failure location.
The current Technica' Specification limiting condition for operation (LCO) requires the STS ontrability in fully automatic mode in plant operating modes 1 thru 5.
If an inoperable STS is not restored to fully automatic operation wi'.hin 30 days, the plant is required to shut down within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. The testing capability of the STS in matiual mode is not util','ed in the current Tech.ical Specifications.
The proposed change calls for a 90 days A0T for the restoration of an inoperable STS to fuliy automatic operation during plant operating modes 4 and 5.
If the inoperable STS cannot be restored to fully automatic or,eration within the A0T (30 days for plant operating modes 1, 2, and 3 and 90 days for modes 4 and 5), the STS will be switched to manual mode.
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'The. manual STS testing will. be performed at least once per 7 days during i
plant operating modes 1, 2, 3 and at least once per 90 days during modes 4 L
and.5.
If_the inoperable STS is not restored to fully automatic operation a
L within the A0T or the manual testing cannot be performed as required in i
modes.1, 2, 3, the operation mode will be changed in accordence with the s4 current'LCO.' However, for similar conditions in modes 4 and 5, the proposed change requires suspending core alteration and all operations with
'a potential for draining the= reactor vessel, verifying all insertable control rods to be fully inserted, and' locking the reactor mode switch in 6
,tne-shutdown position within one hour.
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'2.0- EVALUATION t
=The current'LCO for STS does not address two concerns:
(1)whataction
'should be taken when the LC0 cannot be met during shutdown / refueling
'l modes,'and (2) why the STS should not be used in manual mode when its y
automatic mode:is not restored within the specified A0T. The Clinton STS km is designad with the capability to perform testing in manual mode comparable
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in degree with;its automatic mode of operation.
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LThe' current LCO action only addresses the condition in which the STS is not Loperatin' in the fully' automatic mode during power operation.
Also the j
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current A0T for STS re'storation to fully automatic operation during i
shutdown / refueling modes is no different than that for the plant operating 1
modes.
Based on the number of demands on the safety systems during. modes 1,L2, and 3 versus modes 4 and 5, a longer. A0T for restoring STS to fully w
N automatic l operation should be permitted for modes-4 and 5 relative to that
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established for modes-l, 2,.and 3.
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t (Regarding1the-second concern, the current LCO, requires plant shutdown if the STS is3 not restored to fully automatic operation.within. the specified 3
- A0T.. A(provision for manually controlling the STS should be included in 1
tthe LC0'to; avoid unnecessary plant: shutdown'. Also'the safety-system y
, Jinstrumentation logic circuits testing by STS.in; manual mode-is comparable.
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.in accuracy to the manual testing of;the relay! logic circuits at the d
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(plantswhichdo:nothaveSTS..
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s The priposed A0T extension for an-inoperative automatic STS in modes'4 and '
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LJ (5 and theLproposed STI extension for the STS in manual. mode, are based on-1 L
the analysis in BWR Owners; group; response (1985; GE document NEDC-30844-1
'and: Technical! Specification improvement analysis in the 1985 GE document'
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NEDC;20851)Lto:the NRC GenerictLetter 83-28. The: 11censee's comparison of j
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- W hthe. analysis results'. indicates no significant effect on the
- overall average l
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- Reactor 1 Protection'Systemi(RPS) failure' frequency-(unavailability) within
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the/7-daycSTIL;forithe manual operation of' the STS in operating modes 1, 2
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.and 3...-Similarly, the RPS unavailability was' evaluated for.an; inoperative-3 i
a f ' f ability for 3-months., A0T and 3-months STI of the STS to be comparable with operating modesL4 and 5.
The~ licensee found the calculated RPS unavail-0
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,j the RPS unavailability of relay
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Based on comparison of the analysis results with those of tie relay plant values, the licensee concluded that the proposed action to use STS>in manual mode instead of initiating-plant shutdown and the proposed A0T and STis are acceptable.
The licensee has proposed an additional action for an unlikely condition in modes 4 and 5 when the STS cannot be restored to fully automatic mode and also cannot be switched to the manual mode. Theiaction involves suspending core alteration-and operat'.ans with al potential for draining the reactor vessel, verifying all insertable control' rods to fully inserted, and lockinglthe mode switch in the eutdown oosition.. This proposed action q.
4 will place the plant in a condition whic1 minimites possible challenges to the safety systems, especially the RPS. All three proposed actions are conservative and enhance plant safety.
-Based on the above evaluation, the staff concludes that the proposed changes to the-Technical Specification do not involve an unreviewed safety N question. The proposed changes only affect operation of the STS, involve no change to the plant safety system design, do not directly affect in operation-of the associated safety systems, and are acceptable.
3.0 ENVIRONMENTAL CONSIDERATION
<This. amendment involves a change to a requirement with respect to the instal-lation or use.of a-facility-component located within the restricted area as defined in 10'CFR part 20 or a change to a surveillance requirement. The staff has determined that the amendment' involves no significant increase in
.may?(amounts, and.no significant change in the types, of any effluents thatbe released the dual.or__ cumulative occupational vadiation exposure; The Commission has pre-~
"viously issued.a proposed finding that this amendment involves no signifi-cant hazards-consideration and there has1been no public comment'on such finding.
- Accordingly.-this amendment meets the eligibility criteria.for categorical e'xclusion set forth in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR 51.22(b), no environmente' impact statement nor environmental assessment need be prepared in conned sn with the issuance of this amendment 4.0DCONCUoS10N lThe staff has concluded, based on the considerations; discussed above, that:
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y (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 l'
. activities will be conducted in compliance with the Commission's regulations
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'andtthe, issuance'of this amendment will not be inimical to the common defenseL
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and security or to the health and safety of the public.
Principal = Contributor:
- 1. Ahmed NRR Dated:-
November 1, 1990 c
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