ML20043B534
| ML20043B534 | |
| Person / Time | |
|---|---|
| Site: | Clinton  |
| Issue date: | 05/24/1990 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20043B531 | List: |
| References | |
| NUDOCS 9005300159 | |
| Download: ML20043B534 (2) | |
Text
.
p owy _
T'V(
UNITED $TATES E
m NUCLEAR REGULATORY COMMISSION fh WASHING TON, D, C. 20665 '
^ -
s p
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION l
SUPPORTING AMENDMENT NO.
36 TO FACILITY OPERATING LICENSE NO. NPF-62 CLINTON POWER STATION, UNIT NO. 1 ILLINOIS POWER COMPANY DOCKET NO. 50-461
1.0 INTRODUCTION
By letter dated October 30, 1987, the Illinois Power Company (IP), et al.
(thelicensees)requestedanamendmenttoFacilityOperatingLicenseNo.NPF-62 for the Clinton Power Station, Unit 1.
The proposed amendment would add an ACTION to. Technical Specification 3.5.1 for an inoperable Automatic Depressurization System (ADS) low pressure alarm system instrumentation channel (s).
2.0 EVALUATION At Clinton, the automatic depressurization system (ADS) uses selected safety / relief valves (SRVs) for depressurization of the reactor. The purpose of the air accumulators for the ADS is to provide the SRVs that are in the ADS with sufficient air supply to cycle the valves open should the normal ADS air supply fail. The ADS accumulators are designed to provide two SRV actuations at 70% of drywell design pressure, which is equivalent to five actuations at atmospheric pressure. The air accumulators and associated equipment and instrumentation are designed to perform-their safety function in an accident environment for 100 days following an accident.. Air leakage from the accumulators must be accounted for in order to assure that the inventory of compressed air in the accumu'iators is available for their safety funttion.
Section 3/4.5 of the Clinton Technical Specifications contains Surveillance Requirements for the ADS accumulators low pressure alarm system. However, thereuis no ACTION included in the Limiting Conditions for, Operation Section of the specification that addresses the alarms. The ACTIONS currently specified only address inoperability of the ADS valves themselves.
Inoperdbility of an ADS accumulator low pressure alarm system does not necessarily constitute inoperability of the associated ADS valves.
The as-built design at Clinton includes redundant instrumentation to determine the status of ADS accumulator pressure even with the Technical Specification required alarm inoperable. ADS accumulator header pressure (the process veriable monitored by the primary instrument) can be periodically verified using the direct pressure instrument provided in the main control room. This instrument is also powered from a divisional safety-related power supply and was installed to the requirements of Regulatory Guide 1.97.
In l$bbb P
~
,3 2
addition, a non-safety low pressure alarm from the individual accumulator pressure switches is also provided in the main control room.
The-proposed action statement for inoperable ADS accumulator low pressure alarm system instrumentation would require verifying adequate pressure every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and restoring the alarm to operable within 30 days or to submit a Special Report to the NRC.
In addition, the provisions of Specification 3.0.4 would not be applicable. The periodic verification in the proposed action would be on a frequent enough basis that a satisfactory assessment of ADS operability would be provided. Clinton Supplemental Safety Evaluation Report No. 5 reviewed a calculation that demonstrated the capability of the ADS accumulators to meet the ADS needs for a 7-day period without replenishment. The alternate verification is also consistent with action requirements that have been approved for similar facilities. The proposed compensatory action is therefore acceptable to the staff. The extended restoration period and the 3.0.4 exemption are also acceptable since the loss of the alarm does not affect ADS operability and there is satisfactory availability of backup instrumentation for determining ADS accumulator i
pressure status.
3.0 ENVIRONMENTAL CONSIDERATION
Pursuant to 10 CFR 51.21, 51.32, and 51.35, an environmental assessment and finding of no significant impact has been prepared and published (55 FR 21277) in the Federal _ Register on May 23, 1990.
Accordingly, based upon the environ-mental assessment, the Commission had determined that the issuance of this amendment will not have a significant effect on the quality of the human environ-
. ment and that no environmental impact statement need be prepared.
4.0 CONCLUSION
The staff has concluded, based on the considerations discussed above, that:
(1) there is reasonable assurance that the health and safety of the j
public will not be endangered by operation in the proposed manner, and l
(2) such activities will be conducted in compliance with the Comission's l
regulations and the issuance of this amendment will not be inimical to the common defense and the security nor to the health and safety of the public.
Principal Contributor John B. Hickman, NRR/PD111-2 Dated: May 24, 1990 1
a l-L L
l
.