ML20036C073
| ML20036C073 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 06/04/1993 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20036C072 | List: |
| References | |
| NUDOCS 9306110293 | |
| Download: ML20036C073 (6) | |
Text
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UNITED STATES
[ h[%hj NUCLEAR REGULATORY COMMISSION t
WASHINGTON. D.C. 20556-0001 ggu /
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.106TO FACILITY OPERATING LICENSE NO. NPF-10 bHD AMENDMENT NO. 95 TO FACILITY OPERATING LICENSE NO. NPF-15 SOUTHERN CALIFORNIA EDISON COMPANY SAN DIEGO GAS AND ELECTRIC COMPANY THE CITYJF RTVE'";IDE. CALIFORNIA THE CITY OF ANAHEIM. CALIFORNIA SAN ONOFRE NUCLEAR GENERATING STATION. UNITS 2 AND 3 DOCKET NOS. 50-361 AND 50-362
1.0 INTRODUCTION
By letter dated December 24, 1992, Southern California Edison Company, et al.
(SCE or the licensee) submitted a request for changes to the Technical Specifications (TS) for San Onofre Nuclear Generating Station, Unit Nos. 2 and 3.
The proposed changes would revise TS 3/4.4.1.4.1, " Cold Shutdown - Loops Filled," TS 3/4.4.1.4.2, " Cold Shutdown - Loops Not Filled," TS 3/4.9.8.1,
" Shutdown Cooling and Coolant Circulation-High Water Level," TS 3/4.9.8.2,
" Shutdown Cooling and Coolant Circulation-Low hter Level," and associated Bases. This will allow for the use of Containment Spray (CS) pumps in place of Low Pressure Safety Injection (LPSI) pumps to perform Shutdown Cooling (SDC) during Modes 5 and 6 of operation.
The licensee has stated that these proposed modifications would provide flexibility for the operation and the maintenance of the SDC and SFP cooling systems and components during outages; would facilitate outage planning; and would potentially reduce the refueling outage duration by approximately 5 days.
2.0 EVALUATION The SDC system is used to remove heat from the reactor coolant system (RCS) during shutdown and post-shutdown periods. During normal plant operation major components of the SDC syrtem (the LPSI pumps and the SDC heat exchangers) are aligned for emergency core cooling and containment cooling functions. The LPSI system is not needed for emergency core cooling in Modes 5 and 6 and therefore is available to provide SDC.
In their SDC function the LPSI pumps take suction from RCS hot leg number 2.
Heat is removed by circulating this flow through the SDC heat exchangers.
The cooled flow 9306110293 930604 PDR ADOCK 05000361 P
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returns to the RCS through at least two of the four LPSI headers connected to the cold legs.
l Currently, the SDC system at the San Onofre Nuclear Station, Units 2 and 3, may be aligned to be used as an alternate means of cooling the spent fuel pool (SFP) provided that the reactor vessel is in a full core offload condition.
When the SDC system is aligned in the SFP cooling configuration, each 100%.
capacity SDC/SFP cooling train consists-of one LPSI pump, one SDC heat exchanger, and the associated flow path to and from the SFP.
Each train is powered by a separate safety grade source of AC power.
The proposed plant modifications detailed in the licensee's letter dated December 24, 1992, will add two basic changes to the operation of the SDC system. The first change will provide the capability to substitute a CS pump for a LPSI pump on either or both trains to provide SDC flow, provided that the reactor coolant system is fully depressurized and vented in accordance with TS Section 3.4.8.3.1.b.
The second change will remove the restriction of requiring the reactor core to be fully offloaded before the SDC system can be utilized as a means for cooling the spent fuel pool.
Plant modifications to support these operational modes is planned for the Cycle 7 refueling outages for each unit.
To support the requested TS changes, the licensee provided the following revisions to the description of the SDC the Updated Final Safety Analysis Report (UFSAR):
l 1)
Revision to Section 9.1.3.2 of the UFSAR (shaded area indicates new text).
"The shutdown cooling system is a safety related, seismically qualified system which is powered by a class 1E electrical system. The ccoling capacity of 1 train of the shutdown cooling system is sufficient to maintain the spent fuel pool temperature lower than th: : pent fuel p:01 Eihi6sTiiilitified!6fjths5spihY f661})3olscooling system.
During : full 00r: OfflEid~ff55' TEE'FEict M:::eT~
Whentcomp6hihisTofithe shutdown cooling system are not required Mjbit0PERABLE bst'echnicaQspediffiffoh 5: :per:ble for re::ter cer: :: liEg h trainfof the shutdown cooli t:
ingsystem(consistingofatleast1LPSIpu)mp.enlone i:ontainmisEs^pFlyjuip,1 heat exchanger, flow path to and from the SFP, is;l or
'thi isi5disfsd Diesel Generator)0theIfiiEf6tRiNslinmay be aligned to cool the spent fuel
$peaterith'antoWe~quallto! 23 ?fsetyiboVe sthe?resstorkf)iRisiff fsisiitiMidiel ddltishillEddFI6biMODEI6 Nit 1 arigE!the?SDCisystes f
- (cohsisting orstlleast;2[p0mpss(eithe#1ELPS!! pump %ndilsCS5umR6te24CS puka s ) ;D14sDCi he atWe h ange r gfl of path s stoj andif romlthel RCS RandiSFPis and Ethi riactoricotal" ))1@eneryof)lmaQejaljgnidjtojcjolj}othjthegPla_n,dJhe ~"~~
associated (Dies 2)
Revision to Section 9.1.3.3 of the UFSAR.
"The shutdown cooling system, if available, may be used as an alternative
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. means of cooling the spent fuel pool wher. the full :cre h rencved frc: the rc:: tor vc:::1. This covers the possibility referred to under the remarks column of table 9.1-3."
To support use of the proposed SDC system, as outlined in the UFSAR change described above, the licensee proposes to make the following changes to the TS:
TS 3/4.4.1.4.1 1)
Add a third footnote to the " Shutdown Cooling train" as it appears in items (a.3), (a.4) and (b) of the LC0 to allow for use of CS pumps in place of LPSI pumps to provide SDC flow beginning no sooner than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after the reactor is suberitical and provided the reactor coolant system is fully depressurized and vented in accordance with TS 3.4.0.3.1.b.
2)
Revise the first footnote in the present TS to recognize that the CS pump may be providing SDC flow.
3)
Revise the associated Bases of TS 3/4.4.1.4.1 to document the basis for the above TS changes.
TS 3/4.4.1.4.2 1)
Add a third footnote to the " Shutdown Cooling train" as it appears in items (a.3), (a.4) and (b) of the LC0 to allow for use of CS pumps in place of LPSI pumps to provide SDC flow beginning no sooner than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after the reactor is subcritical and provided the reactor coolant system is fully depressurized and vented in accordance with TS 3.4.8.3.1.b.
2)
Revise the second footnote in the prest.nt TS to recognize that the CS pump may be providing SDC flow.
3)
Revise the associated Bases of TS 3/4.4.1.4.2 to document the basis for the above TS changes.
TS 3/4.9.8.1 1)
Add a footnote to the LC0 to allow use of CS pumps in place of LPSI pumps to provide shutdown cooling flow.
2)
Revise the associated Bases of TS 3/4.9.8 to document the basis for the above TS changes.
TS 3/4.9.8.2 1)
Add a footnote to the LCO to allow use of CS pumps in place of LPSI pumps to provide shutdown cooling flow.
. m.
The staff evaluated these proposed UFSAR changes, and the associated proposed changes to the TS, for the acceptability of utilizing CS pump (s) in lieu of LPSI pump (s) for SDC and SFP cooling purposes, and for-the ccceptability of using the proposed SDC system to provide cooling to both the reactor vessel and the spent fuel pool at the same time. The staff's evaluation is detailed below.
r The CS pumps can deliver more cooling flow than the LPSI pumps, and their i
power supply, safety class, and connecting piping and valves are of equivalent quality to the existing LPSI pumps. To prevent the possibility of over-pressurizing the SDC system due to the higher discharge head of tha CS pumps, the proposed TS will require that the RCS be fully depressurized 1..a vented before the CS pumps can be aligned to the SDC system. This requirement will also prevent the CS pumps from being aligned to the SDC system during those operational modes when the CS pumps provide a containment atmosphere cooling safety function.
In Modes 1, 2, and 3 operation, the manually operated valves in the cross-connection lines will be in the locked-closed positions, thus segregating the CS system from the SDC system. The proposed use of the CS pumps tt
- eform shutdown cooling functions has been evaluated to verify that sufficient capacity to remove decay heat will be available for all single active failtres. Shutdown cooling by the CS pumps will only be performed when the RCS is vented and the reactor coolant is equal to or less than 200*F.
For this situation, only one complete train is required to provide sufficient decay heat removal capability.
No electrical or instrumentation setpoints will be added, deleted, or revised due to the proposed modifications, and no TS setpoints or automatic trip functions will be modified. The staff concludes that the CS pumps will perform their intended function when aligned to the SDC system, and no adverse impact to the plant will result from the proposed plant modifications.
The new SDC system operational configuration proposed by the licensee will be capable of providing cooling to both the fuel in the reactor vessel and fuel in the spent fuel pool at the same time, and takes advantage of the extra two pumps available for SDC system usage. This operational configuration is not allowed by the existing TS and requires staff review and approval before it can be implemented. The staff considers this operational configuration to be acceptable because:
i 1)
This SDC system configuration can only be utilized when the reactor refueling cavity water level is equal to or greater than 23 feet above the reactor flange. This large heat sink provides adequate time for the operators to initiate emergency procedures if a failure of a SDC train should occur, t
2)
The combined heat load from the fuel in the RCS and the spent fuS is well within the heat removal capacity of the two SDC trains required to operable, and; 3)
Outage planning is used to mimimize risk during shutdown and to optimize s1fety system availability.
If the results of the outage assessment a
k u.
4 indicates a higher risk probability than is desired, compensatory measures are implemented. Components are not removed from service until their maintenance activities are ready to be initiated.
The licensee has revised the administrative controls to reflect the use of SDC system for reactor core and SFP cooling during Modes 5 or 6.
Based on its review, the staff finds the licensee's revist..s to the SFP cooling administrative controls acceptable. As part of its normal inspection activities, the staff will review th6 establishment and implementation of procedures and operator training for use of the new SDC system configuration.
Based on its review, the staff concludes that the licensee has adequately-demonstrated that the SDC and the SFP cooling systems will continue to meet their design safety basis functions and satisfy the requirements of GDC 34 and GDC 44, respectively. The staff, therefore, finds the licensee's proposed plant modifications to the SDC system and the associated proposed TS changes, revisions to UFSAR, and administrative controls acceptable as stated in its December 24, 1992 letter.
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the California State official was notified of the proposed issuance of the amendment. The State official had no comments.
4.0 ENVIRONMENTAL CONSIDERATION
The amendments change a requirement with respect to the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and changes surveillance requirements. The NRC staff has determined that the amendments involve 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 that the amendments involve no significant hazards considera-tion, and there has been no public comment on such finding (58 FR 8786).
Accordingly, the amendments meet 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 of the amendments; S.O CONCLUSION The Commission has concluded, based on the considerations discussed above, that (1) there is reasonable assurance that the health and safety of the
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public will not be endangered by operation in the proposed manner, (2) such i
activities will be conducted in compliance with the Commission's regulations, i
and (3) the issuance of the amendment will not be inimical to the comon defense and security or to the health and safety of the public.
l, Principal Contributor: David Shum i
Date: June 4, 1993 I
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