ML20086U023

Safety Evaluation Supporting Amends 123 & 112 to Licenses NPF-10 & NPF-15,respectively

ML20086U023
Person / Time
Site:	San Onofre
Issue date:	07/26/1995
From:	NRC (Affiliation Not Assigned)
To:
Shared Package
ML20086U016	List: ML20086U023
References
NUDOCS 9508030238
Download: ML20086U023 (4)

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i SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT N0.123TO FACILITY OPERATING LICENSE NO. NPF-10 AND AMENDMENT NO.117TO 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 ON0FRE NUCLEAR GENERATING STATION. UNITS 2 AND 3 DOCKET NOS. 50-361 AND 50-362

1.0 INTRODUCTION

By letter dated August 26, 1994, 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 (SONGS).

The proposed changes would revise TS 3.7.5, " Control Room Emergency Air Cleanup System," to (1) add " movement of irradiated fuel assemblies" to the modes for which this limiting condition for operation (LCO) applies, and (2) provide an LC0 3.0.4 exception for Modes 5 and 6 and a defueled configuration.

2.0 EVALUATION The LCOs in TS 3.7.5 define the operability requirements for the control room emergency air cleanup system (CREACUS) for all modes.

This system provides a protected environment from which operators can control the plant following an uncontrolled release of radioactivity or toxic gas.

2.1 ProDosed Chanaes to the APPLICABILITY and ACTION statements TS 3.7.5 presently applies to all operational modes, but not to movement of irradiated fuel assemblies. Mode 6 (refueling) is characterized as the operational mode when fuel is in the reactor vessel.

Movement of irradiated fuel inside or outside containment when no fuel is in the vessel is not covered by this definition.

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.- The SONGS Units 2 and 3 Updated Final Safety Analysis Report (UFSAR),

Section 15.7.3.4, " Design Basis Fuel Handling Accidents," describes the consequences of a fuel-handling accident inside containment and inside the fuel-handling building.

Since the fuel-handling accident is considered a limiting fault, it is postulated that a fuel assembly is dropped during refueling operations, breaching the cladding of the fuel pins and releasing the volatile fission products contained in the gap region of the fuel pin.

Radiation doses to control room personnel following a postulated fuel handling accident are based on the same shielding, ventilation, atmospheric dispersion, and dose model assumptions used for the loss-of-coolant accident.

Buildup of activity in the control room is based on the 2-hour release of activity following the accident.

In calculating the doses, outside air intake through the control room heating ventilation, and air-conditioning system (emergency mode of operation) is assumed for the 2-hour duration of the accident.

l 1he additional requirement proposed for the Applicability statement--that two l

trains of CREACUS be operable during movement of irradiated fuel--covers the consequences of a fuel-handling accident when there are no assemblies in the core, including (1) when fuel is moved in the fuel-handling building, (2) when l

the last fuel assembly is moved from the vessel (defueling) to the transfer canal inside containment, and (3) when the first fuel assembly is moved from the transfer canal to the vessel (fuel loading).

The proposed change would also revise the Action statement by adding the words "or defueled configuration when moving irradiated fuel assemblies" after Modes 5 or 6.

These words are added for consistency with the proposed Applicability statement. This change clarifies the action to be entered if i

the LC0 is not met in a defueled configuration during movement of irradiated fuel assemblies.

The proposed change would also revise Action b) by adding the words "or movement of irradiated fuel assemblies." Action b) requires that if both trains of CREACUS are inoperable or not capable of being powered by an operable emergency power source, the licensee must suspend all operations involving core alterations or positive reactivity changes. The proposed change clarifies that movement of irradiated fuel must also be suspended.

These changes are conservative in that they place additional requirements on the operability of CREACUS during movement of irradiated fuel.

These changes are consistent with the accident analyses described in the UFSAR.

Based on these considerations, the staff finds the requested changes acceptable.

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Based on an oral discussion between the staff and the licensee, the applicability statement in TS 3.7.5 that currently reads, " Units 2 and 3 in MODE 5 or 6..." has been changed to read, " Units 2 or 3 in MODE 5 or 6...".

This is an editorial change to clearly indicate that the ACTIONS under this statement apply whenever either unit is in Mode 5 or 6.

This will avoid the possible misinterpretation that both units need to be in Modes 5 or 6 before l

the ACTIONS apply,

, 2.2 Proposed Exception to LC0 3.0.4 for TS 3.7.5 TS 3.0.4 prohibits entry into an operational mode or other specified condition unless the conditions of the LCO are met.

Therefore, Mode 6 cannot be entered frcm a defueled configuration unless both trains of CREACUS are operable.

The i

current TS provide critical path restrictions to refueling outages. When maintenance and surveillance activities are performed on the system during outages, the activities must be terminated for mode changes and later reestablished, adding to the time that the system is in a degraded condition.

The proposed revision to add an exception to TS 3.0.4 when entering Modes 5 or 6 or a defueled configuration would allow one train of the system to remain inoperable during the mode change from defueled configuration to Mode 6, from Mode 6 to Mode 5, from Mode 5 to Mode 6, from Mode 6 to defueled configuration, and from Mode 4 to Mode 5.

Allowing one train of CREACUS to be inoperable during the mode changes described above has no safety effect.

The transition from Mode 6 to the defueled configuration occurs when the last fuel assembly remaining in the core is being removed; during such an evolution, current TS 3.0.4 requires both CREACUS trains to be operable.

This requirement also applies during the transition from the defueled configuration to Mode 6, i.e., when there are no fuel assemblies in the core, and an irradiated fuel assembly is being moved into the core.

The only credible event during these transitions is the design-basis fuel-handling accident.

This fuel handling accident is the same design basis accident for evolutions involving the movement of an irradiated fuel assembly during Mode 6, to which the requirements of TS 3.7.5 apply.

TS 3.7.5 requires one operable train of CREACUS for such an event.

The design basis accident described above is covered by the proposed revision to the Applicability statement discussed in Section 2.1.

With the addition of "or during movement of irradiated fuel assemblies" to the Applicability statement, operability of at least one train of CREACUS will be ensured prior to the start of movement of irradiated fuel.

Entering Mode 5 from Mode 6 consists of fully tightening the last reactor vessel head closure bolt.

This evolution has no safety significance from the point of view of isolating the control room from a potential radiation or gas release and can be excepted from TS 3.0.4.

The threshold of entering Mode 6 i

from Mode 5 consists of untightening at least one reactor vessel head closure bolt. This evolution has no safety significance from the point of view of isolating the control room from a radiation or toxic gas release and can be excepted from TS 3.0.4.

Entering Mode 5 from Mode 4 consists of decreasing reactor coolant system temperature to less than or equal to 200 degrees F by initiating shutdown cooling. This evolution has no safety significance from the point of view of isolating the control room from a radiation or toxic gas release.

The current TS allow one train of CREACUS to be inoperable for up to 7 days during all modes based on the ability of one train of CREACUS to provide control room isolation following design-basis accidents.

The mode changes discussed above have no significance relative to the releases and no effect on the ability of CREACUS to perform its function.

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, Based on the considerations discussed above, the staff finds the exception to TS 3.0.4 when entering Modes 5, 6, and defueled configuration acceptable.

3.0 STATE CONSULTATION

i 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. 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 +.ne amendments involve no significant hazards consideration, and there has been no public comment on such finding (59 FR 55891).

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.

5.0 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 amendments will not be inimical to the common defense and security or to the health and safety of the public.

Principal Contributor: Donna Skay Date:

July 26, 1995

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