ML20210M811
| ML20210M811 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 09/09/1986 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20210M809 | List: |
| References | |
| TAC-54732, NUDOCS 8610060021 | |
| Download: ML20210M811 (5) | |
Text
l pen o,,
UNITED STATES
[
g NUCLEAR REGULATORY COMMISSION g
p WASHINGTON, D. C. 20555
\\...../
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 55 TO NPF-10 AND AMENDMENT NO. 44 TO NPF-15 SOUTHERN CALIFORNIA EDISON COMPANY, ET AL.
SAN ON0FRE NUCLEAR GENERATING STATION, UNITS 2 & 3 DOCKETNOS.50-361AND50-3h2 INTRODUCTION Southern California Edison Company (SCE), on behalf of itself and the other licensees, San Diego Gas and Electric Company, The City of Riverside, California, and The City of Anaheim, California, has submitted a number of applications for license amendments for San Onofre Nuclear Generating Station (SONGS), Units 2 and 3.
The NRC staff's evaluation of two of these applications is described below.
PROPOSED CHANGE PCN-140 The Emergency Core Cooling System (ECCS) and its subsystems provide core cooling in the event of a loss-of-coolant accident. TechnicalSpecification(TS) 4.5.2.a requires verification at least once per twelve hours of proper valve position for the specified ECCS valves. Manual valves14-081 and 14-082, which are required by Technical Specification 4.5.2.a to be locked open, serve as isolation valves for valve HV-0396. The flow path in which these three valves are located serves as a bypass to the normal ECCS flowpath, isolation of which has no effect on ECCS operability. Valves14-081 and 14-082 do not have remote position indication and, therefore, require local position verifica-tion. This necessitates frequent (e.g., at least once per twelve hours) entry into a radiation area and unnecessary personnel exposure. The proposed change which is applicable only to Unit 3, would delete valves14-081 and 14-082 from surveillance requirement 4.5.2.a. so that it will no longer be necessary to verify their positions every twelve hours. This change makes the Unit 3 technical specifications conform to those of Unit 2.
Standard Review Plan Section 6.3, " Emergency Core Cooling System," states that the frequency and scope of periodic ECCS surveillance testing to verify operability must be adequate.
In addition, 10 CFR 20 states that personnel radiation exposure should be kept as low as reasonably achievable. The closure of valves14-081 and 14-082 (isolation valves for HV 0396 (nonnally closed)) has been previously analyzed for this configuration in the Final Safety Analysis Report l
l 8610060021 860709 PDR ADOCK 05000361 P
PDR l
i
(FSAR) failure modes and effect analysis of the Unit 3 safety injection system (FSAR Table 6.3-1 for Unit 3, Item 14).
It was concluded that inadvertent closure of these valves would have no effect on ECCS operation, since two other valves (i.e., HV 8160 (open) and HV 8161 (open)) allow valves14-081 and 14-082 to be bypassed and provide the nonnal ECCS flowpath.
The proposed change to Technical Specification 4.5.2.a will make this technical specification for Unit 3 consistent with the current technical specification at San Onofre Unit 2.
The proposed change is consistent with the Standard Review Plan, since adequate ECCS surveillance testing will still be maintained and personnel radiation exposure will be reduced. Theiefore, the staff concludes that the proposed change to Technical Specification 4.5.2.a is acceptable.
PROPOSED CHANGE PCN-189 The ECCS is designed to mitigate the consequences of a loss of coolant accident (LOCA). On detection of a LOCA, the ECCS is automatically actuated by a safety injection actuation signal (SIAS) and maintains core cooling by pumping water into the reactor coolant system, initially from the refueling water storage tank (RWST). Water spilling from the break in the RCS accumulates on the containment floor. On low level in the RWST, a recirculation actuation signal (RAS) is generated, realigning the ECCS pumps to take suction from the containment sump, establishing recirculation.
In small break LOCA's, RCS pressure may remain hi developed by the high pressure safety injection (gher than the maximum pressure 1
HPSI)pumpsfollowingECCS actuation. Damage to the HPSI pumps would result after a relatively short period in this condition if a minimum flow is not maintained through the pumps.
To prevent HPSI pump damage, minimum flow is guaranteed by the ECCS miniflow lines from the ECCS pump discharge to the RWST.
It is desirable to close the ECCS miniflow lines following initiation of recirculation of prevent radioactive water from being pumped from the containment sump to the RWST. The RWST is vented to the atmosphere creating a potential release path.
Originally, the ECCS miniflow valves were closed automatically on a RAS generated from low RWST level.
Following an event in December, 1982 involving simultaneous SIAS and RAS (i.e., ECCS pumps started and ECCS miniflow valves closed), RAS was removed from the miniflow valves to preclude damage to the ECCS pumps. Currently, closure of the ECCS miniflow valves is manually initiated by the operator. A design change (DCP 6234) is proposed at San Onofre to restore automatic ECCS miniflow valve closure. With the design change, both low RWST level and high containment sump level will be required for automatic closure of the ECCS miniflow valves. Conditioning ECCS miniflow valve closure on low RWST level and high sump level will preclude an event involving simultaneous SIAS and RAS from damaging the ECCS pumps.
a f
1
To reflect the above design change, the following changes to the technical specifications are proposed by the licensee:
1.
TS 3.3.2, Table 3.3-5 specifies response times for ESF equipment.
The proposed change would add the ECCS miniflow isolation valves to the equipment included in Table 3.3-5 as actuated by a recirculation both Units 2 and 3) which includes an allowance for,is specified (for actuation signal. A response time of 50.7 seconds, diesel generator starting and load sequencing. A note is added to indicate that the closure of the ECCS miniflow valves on a RAS is conditioned by high containment sump level.
2.
TS 3/4.5.2 specifies operability and surveillance testing require-ments for the ECCS. One of the surveillance tests (TS 4.5.2.e.3) requires verification that the ECCS miniflow valves close within a speci-fied period of time (currently 50.7 seconds for Unit 3; 40.7 seconds for Unit 2) upon manual actuation from the control room. The proposed change would require verification that the ECCS miniflow isolation valves close automatically on a RAS test signal coincident with a con-tainment sump level high signal. The required response time is specified in Table 3.3-5.
The current technical specification requires verification that the ECCS miniflow isolation valves close within a specified time (50.7 seconds for Unit 3, 40.7 seconds for Unit 2) following manual actu-ation. However, the time interval between RAS and the valve closure time is undefined. The proposed change will require that the valves close automatically within 50.7 seconds on a RAS coincident with high containment sump level for both Units 2 and 3.
The proposed require-ment to automatically close within 50.7 seconds of a RAS is more re-strictive since the existing specification does not require automatic closure and does not define a closure time relative to the occurrence of a RAS. Therefore, the proposed change constitutes additional limi-tations not currently in the technical specifications.
Based on the above evaluation, the staff finds that the proposed changes of technical specifications constitute an additional limitation and control not presently included in the technical specifications which improve safe plant operation. Therefore, the staff concludes that the proposed changes to the technical specifications are acceptable.
Contact With State Official The NRC staff has advised the Chief of the Radiological Health Branch, State Department of Health Services, State of California, of the proposed deteminations of no significant hazards consideration. No comments were received.
-r r_,_
w m-..
v_,.---.--__-
.,_me,__.%,.-.._,-__.,.,.,,,..__,-.---y-
_ _ _ _. - _ _ _. _ _ _ _ _ _. _ - - -... _ _ - -. _ ~
Environmental Consideration These amendments involve changes in the installation or use of facility components located within the restricted area. The staff has detennined that the amendments involve no significant increase in the amounts of any effluents that may be released offsite and that there is no significant increase in individual or cumulative occupccion radiation exposure. The Comission has previously issued proposed findings that the amendments involve no significant hazards consideration, and there has been no public comment on such findings.
Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR Sec. 51.22(c)(9). Pursuantto10CFR51.22(b),
no environmental impact statement or environmental assessment need to be prepared in connection with the issuance of these amendments.
Conclusion Based upon our evaluation of the proposed changes to the San Onofre Units 2 and 3 Technical Specifications, we have concluded that:
there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and such activities will be conducted in compliance with the Commission's regulations and the issuance of the amendments will not be inimical to the common defense and security or to the health and safety of the public. We, therefore, conclude that the proposed changes are acceptable, and are hereby incorporated into the San Onofre 2 and 3 technical specifications.
Dated: September 9, 1986
(
l l
l l
e,
ISSUANCE OF AMENDMENT N0. 55 TO FACILITY OPERATING LICENSE NPF-10 AND AMENDMENT N0. 44 TO FACILITY OPERATING LICEhSE NPF-15 SAN ONOFRE NUCLEAR GENERATING STATION, UNITS 2 AND 3 DISTRIBUTION d ocket File Kn-361/36 D NRC PDR Local PDR PRC System NSIC PBD7 Reading JLee(10)
HRood WJones LChandler, OGC - Bethesda CMiles HRDenton RHVollmer JRutberg AToalston RDiggs, LFMB Edordan LHarmon MVirigilo TBarnhart(8)
JPartlow BGrimes
)
I
_ _ _ _ _ _ _ _ _ _. _ _ _, _, _ _,..., _ _ _ _ _ _ _ _.., _ _. _. _ -