ML20055G317
| ML20055G317 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 07/10/1990 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20055G316 | List: |
| References | |
| NUDOCS 9007230039 | |
| Download: ML20055G317 (4) | |
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UNITED STATES:
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g-NUCLEAR REGULATORY COMMISSION i
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WASHINGTON, D. C. 20b55 4
\\**U SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION l
RELATED T0 AMENDMENT NO. 89.TO FACILITY OPERATING LICENSE NO. NPF-10 AND AMENDMENT NO.79 TO FACILITY OPERATING LICENSE NO. NPF-15 SOUTHERN CALIFORNIA EDISON COMPANY.
SAN DIEGO GAS AND ELECTRIC COMPANY THE CITY OF RIVERSIDE, CALIFORNIA THE CITY OF ANAHEIM, CALIFORNIA SAN ONOFRE NUCLEAR GENERATING STATION, UNIT NOS. 2 AND 3 I
DOCKET NOS. 50-361 AND 50-362 l
1.0 INTRODUCTION
l By letter dated August 18, 1989, Southern California Edison Company. et al.,
1 (SCE or the licensee) requested changes-to the Technical S)ecifications for i
L Facility Operating License Nos. NPF-10 and NPF-15 that aut1orize operation of San:0nofre Nuclear Generating Station Unit Nos. 2 and 3 (SONGS 2/3) in San Diego Count California. The licensee has proposed to-add Technical.
y Specification-(y,).3/4.7.1.6,'" Atmospheric Dump Valves," (ADV) which docu-K TS ments the. operability.and surveillance: requirements for the ADVs. The
,4 Technical Specification fulfills the licensee's commitment-to establish L
an ADV Technical Specification. The proposed TS would establish the 4
limiting conditions for operation-(LCO), associated action statements,
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surveillance requirements, and bases for the ADVs.
. Based upon the staff's review of the August 18, 1989 submittal, the staff i
had several telephone. discussions with the-licensee regarding the amendment
-application.
Specifically, the staff requested modifications to the amend-ment package in regard to the remote operating capability and the. surveil-
' lance requirements of the ADVs.
On May 31, 1990, the licensee supplemented.
the original submittal which addressed the concerns of the staff. The addi-tional submittal did not affect the proposed no significant hazards consid-eration determination as previously noticed.
n, 2.0 EVALUATION
'The atmospheric dump valves provide a safety grade method for cooling the plant to the shutdown cooling entry condition in the event that the prefer-red heat sink via the steam bypass system is not available. They may also be utilized during normal plant startup and cooldowns when either a vacuum l
in the condenser-or the steam bypass control system is not available. The L
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E ADVs are equipped with pneumatic controllers to permit control of the cooldown rate,~and are capable of being operated remotely from the control room, and locally with manual han6 wheels.
Two ADVs are provided to-meet single failure assumptions following an event-that' renders one steam generator unavailable for reactor coolant system (RCS) heat' removal. The ADVs.are not assumed to be used until-the operator takes action to cool down the plant, generally _30 minutes fol-lowing event initiation.
Postulated events that could render one steam generator unavailable for RCS heat removal are main steam line break, feedwater line break, and a steam generator tube rupture. To conduct a plant cooldown following such an event, at least one ADV must remain available.
Failure to meet the LCO could result in the inability to cool the plant to shutdown cooling entry conditions following an event in which the condenser is unavailable for use with the steam bypass-system.
The )roposed TS establishes the requirements for ensuring the reliability of t1e ADYs, in order to secure a controlled cooldown over a: wide range of transients and that the ADVs close upon actuation of main steam iso-lationsignal(MSIS).- The proposed TS requires'that the ADVs be operable at all times in Modes 1, 2, 3 and in Mode 4 when the steam generators are
'being used for decay heat removal, if any one of the ADVs becomes inoperable, an action would then be taken to restore it to. operable status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. 'If the' inoperable ADV cannot be restored within the specified time period, or if both ADVs are inoperable, the plant will be placed in at least hot standby within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in hot shutdown and on shutdown cooling within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
If the backup nitrogen gas system capacity is less than 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />, the capacity must.be restored wi.in 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or the ADV will be declared inoperable. With one ADV inoperable in Modes 2, 3 or 4 (when steam generators are being used for 3
decay heat removal), the provisions of TS 3.0.4.are not applicable.
Since the ADVs are subject to inservice testing, the frequency of the TS L
surveillances is based on-the length of a fuel cycle. The TS will require L
that both ADVs be demonstrated operable at least once per refueling L
interval.
In order to perform a controlled cooldown of RCS, the ADVs L
must be able to be opened and-throttled through their full opening from either the control room or the local handwheel. The surveillance require-ments.will verify that the ADVs will open in modulate mode using the backup nitrogen supply system. -With a MSIS test signal present, the ADVs will be verified to actuate to their isolation position, and that they l
will open in modulate / override mode. Additionally, both ADVs will be demonstrated operable with operation of the valves locally. This redundancy ensures;the reactor coolant system can be cooled down such that the shutdown cooling can be placed-in service. The operability and surveillance require-ments will ensure that the ADVs are tested through a full control cycle at least once per fuel cycle.
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The ADVs are operated from the unit's instrument cir system. However, nitrogen can be supplied to the ADVs by a seismic Category I pressurized gas supply in case instrument air is unavailable. The backup nitrogen capacity is controlled to a minimum accumulator pressure of 1050 psig, which includes allowances for seven days worth of leakage and uncertainty in the nitrogen consumption rates. This pressure represents enough backup nitrogen capacity for a minimum of 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> of pneumatic ADY operation.
This is based on the time needed to reach shutdown cooling condition during a small' break loss of coolant accident and is consistent relative to the-emergency operating procedures.
The proposed TS addition is consistent with the Branch Technical Position (BTP) RSB 5-1, " Design Recuirements of the Residual Heat Removal System";
10 CFR 50, Appendix R; anc Section 5.4.7 of the Standard Review Plan, NUREG-800, " Residual Heat Removal (RHR) System." SONGS 2/3 have both met the requirements for Class 2 plants under BTP RSB S-1, as indicated in the February 24, 1988 NRC letter forwarding the safety evaluation of the natural circulation cooldown tests at SONGS 2/3. Local manual operating capability can be relied upon for longer term cooldowns or for shutdown from outside the control room, where the ADVs would be required. The safety evaluation states in paragraph g; "That the atmospheric dump valves could be manually operated in the event the nitrogen supply to these valves should'become depleted." Therefore, if instrument air and nitregen supply were: lost, the ADVs could be manually operated.
Therefore, based upon the information presented, the staff concludes that the proposed addition to the Technical Specifications regarding the ADVs is acceptable.
3.0 CONTACT WITH STATE OFFICIAL The NRC staff has advised the State of California of the proposed determination of no significant hazards consideration.
No comments were received.
4.0 ENVIRONMENTAL CONSIDERATION
The amendments involve changes in requirements with respect to the instal-i lation or use of a faci'lity component located within the restricted-areas as defined in 10 CFR Part 20 and changes in surveillance requirements.
The staff has determined that the amendments involve no significant increase in.the amounts, and no significant change in the types, of any-1 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 considerat'on and there has been no public comment on such finding. Accord hgly, the amendments meet the eli criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9)gibility Pursuant to 10 CFR 51.22(b) no environmental impact statement or environ-mental assessment need be prepared in connection with the issuance of the amendments.
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S '. 0 CONCLUSION We have 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 amendments will not be inimical i
to the common defense'and security or to the health and safety of the
-l public.
Principal contributors: Arny Almond 1
Lawrence E. Kokajko Dated: July 10, 1990 l.
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