ML20085K419
| ML20085K419 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 10/01/1991 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20085K416 | List: |
| References | |
| NUDOCS 9110310068 | |
| Download: ML20085K419 (4) | |
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 99TO FACILITY OPERATING LICENSE NO. NPF-10 AND AMENDMENT NO. 88-TO FACILITY OPERATING LICENSE NO. NPF-15 SOUTHERN CALIFORNIA EDISON COMPANY SAN DIEGO GAS AND ELECTRIC COMPANY THE CITY OF RIVERSIDE, CALIFORNIA THECITYOFANgElh, CALIFORNIA SAN ONOFRE NUCl. EAR GENERATING STATION, UNITS 2 AND 3 DOCKET NOS. 50-361 AND 50-362
1.0 INTRODUCTION
By. letter dated June 17, 1991, Southern California Edison Company (SCE or the licensee)submittedarequestforchangestotheTechnicalSpecifications(TS) for San Onofre Nuclear Generating Station, Units 2 and 3.
The licensee for SONGS Units 2 and 3 proposed changes to plant Technical Specification (TS) 3/4.7.1.2, "Auxilia_ry Feedwater System." Specifically, the licensee proposed to identify that the AFW system performs a dual function in an event which reqaires SG isolation and secondary heat removal.
Currently, TS 3/4.7.1.2 addresses the operability requirements of the Emergency Feedwater Actuation
Also, a new section is being proposed to address the operation of the AFW system--in Mode 4 L
when the SGs are being used for. decay heat removal, as well as a clarification j
to Surveillance Requirements 4.7.1.2J.b.1 and 4.7.1.2.1.b.2 L
2.0 EVALUATION The licensee proposes to revise the TS to address the dual function of the
-AFW system in an event which' requires SG isolation and secondary heat removal;-
The EFAS and the-MSIS are Engineered Safety Feature Actuation Systems (ESFAS) designed to' assist the AFW system in performing its dual function.
EFAS is designed to automatically initiate AFW system flow to the SG when the level is low resulting from a loss of main feedwater. The MSIS is designed to isolate E
steam and feedwater lines to mitigate the consequences of a Main Steam Line-
~ Break (MSLB) or Main Feedwater Line Break (MFLB) accidents by isolating the af_fected SG. An EFAS signal is generated-by a two-out-of-four logic system l _
.which requires one of the following combinations before an EFAS signal is
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generated:-
L 1.
Low SG level coincident with no low pressure for that SG; or b
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2.
. Low SG level coincident with a pre-set differential prossure between the two SGs with higher pressure associated with the SG to be fed.
AFW flow tn the SG is controlled by two trains of valves on discharge piping for three AFW pumps. These AFW valves have three safety functions associated with this design:
1.
They close on an MSIS, 2.
They open on an EFAS signal, and 3.
They cycle open/ closed to control the level of the intact SG af ter EFAS is initiated.
However, valves that receive an EFAS signal are unable to close upon receipt of an MSIS because an EFAS signal overrides an MSIS. Therefore, during certain planned maintenance or upon EFAS subsystem actuation, the valves are not available to close on an MSIS. This has resulted in several entries into TS 3.0.3 during testing because the current TS is not provided with operability and action statements related to ope, ibility of the MSIS.
To avoid entry into TS 3.0.3 during ESFAS functional testing, the licensee has proposed limiting conditions of operation (LCO) to TS 3/4.7.1.2 for AFW valves. The LC0 requires that all manual AFW valver be in.ne correct position and automatic valves each be capable of being opened and closed except for the following:
1.
Bypass control valves HV-4762 and HV-4763 need only be capable of being closed.
2.
Steam turbine driven AFW pump steam supply isolation valves HV-8200 and HV-8201 and turbine stop valve HV-4716 need only be capable of being opened.
3.
Manual crosstie valves 1305MU634 and 1305MU635 may be open in Mode 3 provided a minimum 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> has elapsed since reactor shutdown.
In its rationale for the LCO requirements for the AFW valves, the licensee stated that, bypass control valves HV-4762 and HV-4763 only safety-related function is to close on an MSIS and therefore need only be capable of being closed. The licensee also stated that, although steam supply valves HV-8200 and HV-8201 close on an MSIS, this function is not relied upon in the accident analysis because they fail open upon a loss of nonsafety-grade compressed air.
Therefore, the down-stream check valves are credited for isolating the intact steam supply from the failed steam supply under MSLB or MSLB conditions.
It should be noted that the licensee requires both steam supply valves HV-8200 and HV-8201 to be operable for the steam supply line to be operable.
The licenree stated that San Onofre Units 2 and 3 have nne steam supply fed from two steam generators, thus both steam supply valves must be operable. Also incorporated in the proposed TS change is an action statement which states, if an automatic l
valve, in any flow path, is incapable of closing upon receipt of an MSIS the affected valve or its block valve must be closed within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />; and if there is a luss of flow pathis), the affected unit must enter one of the current action statenents in TS 3/4.7.1.2. This action statement clearly states that testing l
pursuant to TS 3.3.2 does not constitute entry into this action statement.
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. The proposed TS change also modifies Surveillance Requirements 4.7.1.2.1.b.1 and 4.7.1.2.1.b.2 as well as adding a new Surveillance Requirement 4.7.1.2.1.b.(3).
Changes to 4.7.1.2.1.b.1 and 4.7.1.2.1.b.2 are strictly editorial to clarify the surveillance program.
Surveillance Requirement 4.7.1.2.1.b.2 has been edited to clarify that only the motor driven AFW pumps start automatically upon receipt of an EFAS test signal.
The steam driven pump is not started at-this time because the EFAS actuation test is performed during cold shutdown and no steam is available to drive the pump.
Surveillance Requirement 4.7.1.2.1.b.1 is edited to clarify that the flow path's operability as well as the pump's operability must be verified monthly.
The new surveillance requirement 4.7.1.2.1.b.(3) will be added to demonstrate operability by verifying that each automatic valve in the flow path must be in its isolation position on an MSIS with the exception of HV-8200 and HV-8201.
The original TS is silent to the issues addressed by the proposed TS changes.
LCO and surveillance requirements for the flow paths and AFW valves were not included in the original TS. The proposed changes are intended to ensure that the flow path and AFW valves are operable as well as the AFW pumps, and address the dual function of the AFW system (EFAS and MSIS).
Additionally, the licensee hcs proposed to add a new TS section which addresses the operation of the AFW system in Mode 4 when the SGs are being used fcr decay heat removal. Tne existing AFW TS section is renumbered to be 3/4.7.1.2.1 and the new section is 3/4.7.1.2.2.
The licensee states that the addition of the new section documents the current practice of maintaining the operability of the AFW system components required to support SG heat removal capability in Mode 4 This is implicitly in accordance with TS 3.4.1.3 and thus found acceptable.
l Based on its review of the proposed TS changes to TS 3/4.7.1.2, " Auxiliary Feedwater" and the new TS Section 3/4.7.1.2.2 for removal of decay heat in Mode 4, the staff concludes that the proposed changes meet the requirements of 10 CFR Part 50, Appendix A, General Design Criteria (GDC) 34 and a4 and meet the acceptance criteria of Standard Review Plan Section 10.4.9.
Therefore, the l
proposed changes, as outlined in the June 17, 1991, submittal, are acceptcble.
3.0 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 i
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 bazards consideration, and there has been no public comment on such finding (56 FTs 31443). Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 1
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4 51.22(c)(9).
Pursuant to 10 CFR 51.22(b) no environmental impact statement or
- 1 environmental assessment need be prepared in connection with the issuance of the amendments.
4.0 CONCLUSION
The Commission has 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, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributors:
.S. Flanders L. Kokajko Date: Cctcter 1, 1991 l-I e
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