ML20101L656
| ML20101L656 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 02/28/1996 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20101L640 | List: |
| References | |
| NUDOCS 9604040144 | |
| Download: ML20101L656 (4) | |
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UNITED STATES E
NUCLEAR REGULATORY COMMISSION f
WASHINGTON, D.C. 20686 4 001 i
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR RECULATION RELATED TO AMENDMENT NO. 128 TO FACILITY OPERATING LICENSE N0. NPF-10 AND AMENDMENT NO. 117 TO FACILITY OPERATING LICENSE NO. NPF-15 SOUTHERN CALIFORNIA EDISON COMPANY SAN DIEGO GAS AND ELECTRIC COMPANY THE CITY OF RIVERSIDE. CALIFORNIA l
THE CITY OF ANAHEIM. CALIFORNIA 1
SAN ONOFRE NUCLEAR GENERATING STATION. UNITS 2 AND 3 DOCKET NOS. 50-361 AND 50-362
1.0 INTRODUCTION
By letter dated October 14, 1992, as supplemented by letter dated December 18, 1995, 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 3/4.7.5, " Control Room Emergency Air Cleanup System" and their associated Bases by clarifying unit mode entry requirements, revising the test duration for the control room emergency air cleanup system (CREACUS), deleting requirements for duct heaters and diverting valves, and modifying their associated Bases to be consistent with the existing system and proposed amendment changes.
The December 18, 1995, supplemental letter provided additional clarifying information and did not change the initial no significant hazards consideration determination, which was published in the Federal Reaister on March 3, 1993 (58 FR 12267).
2.0 BACKGROUND
The CREACUS is responsible for maintaining control room habitability during an uncontrolled radioactive release as required by 10 CFR 50 Appendix A, General Design Criterion (GDC) 19, which limits the control room personnel radiation exposure to 5 rems or less to the whole body for the duration of the accident.
GDC 61 requires that systems that may contain radioactivity:be designed to ensure adequate safety under normal and postulated accident conditions and that they be designed with appropriate containment, confinement, and filtering 2
systems.
Further guidance is provided by Regulatory Guide 1.52, " Design, j
Testing, and Maintenance Criteria for Post Accident Engineered-Safety-Feature Atmosphere Cleanup System Air Filtration and Adsorption Units of Light-Water-i Cooled Nuclear Power Plants." The system is also required to be designed such 9604040144 960228 DR ADOCK 05000361 PDR
that appropriate inspection and testing can be performed to confirm its integrity, capability, and operability as stated in GDC 41, 42, and 43.
The CREACUS design for San Onofre Units 2 and 3 consists of two redundant emergency filtration trains, each equipped with an emergency ventilation supply unit and an emergency air conditioning (recirculation) unit.
TS Surveillance Requirement 4.7.5.b currently requires verification of CREACUS operability at least once per 31 days by initiating flow through the HEPA i
filters and charcoal adsorbers for a minimum of 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> with the heaters on.
The time duration is set to 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> to ensure that any moisture accumulated in the charcoal adsorbers is removed to guarantee maximum adsorber efficiency.
The efficiency of the adsorber is assured by maintaining incoming air to the i
emergency air conditioning unit charcoal adsorbers to less than 70 percent relative humidity (RH).
3.0 EVALUATION i
The licensee has reevaluated the need for heaters in the CREACUS.
The i
i function of the heaters is to heat the incoming air stream to reduce the stream's RH below 70 percent before the air reaches the filters and adsorbers credited in the dose analysis. The licensee has concluded that the heaters are not needed for the CREACUS to perform its intended safety function. This i
conclusion is based on (1) the heaters in the emergency ventilation supply unit do not perform a safety function since the filters in this unit are not i
credited in the dose analysis, and (2) the heaters are not needed to maintain 1
the RH below 70 percent at the filters in the emergency recirculation unit, which are credited in the dose analysis.
The analysis to support the conclusion that the RH will be less than 70 percent is based on the following assumptions and CREACUS system I
parameters. The bounding operability impact of the emergency recirculation ESF filters is considered during the winter conditions. Theoutsideagkeup i
4 air for control room envelope pressurization at a flow rate of 2050 ft / min is assumed to be at 100 percent RH for the bounding winter conditions. When this air stream mixes with the recirculated air from the control room at a flow 3
rate of 33655 ft / min and at 70*F and 50 percent RH, the resulting air mixture that enters the emergency recirculation filters is well below 70 percent RH during the bounding conditions. This air mixture is then passed through the cooling coil and is heated up to 70*F and 50% RH due to the normal control room heat loads (electrical cabinets and personnel).
The staff reviewed the licensee's analysis and concluded that RH of the incoming air to the emergency air conditioning charcoal adsorbers will be maintained below 70 percent assuring adsorber efficiency during the accident conditions. Therefore, the staff concludes that the CREACUS can perform its intended safety function without heaters.
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,. The conversion of the time duration in TS 4.7.5.b from 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> to 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> provides reasonable assurance that system operability will be verified.
In addition, the licensee has demonstrated through conservative analysis that operation of the CREACUS for 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> every 31 days is sufficient to remove any moisture buildup inside the filter housing and ductwork in communication with the ESF filters.
l The proposed change deleting Surveillance Requirement 4.7.5.e.5 is consistent with the removal of requirements in surveillance requirement 4.7.5.b, since the heaters are no longer credited.
l The proposed deletion of Surveillance Requirement 4.7.5.c.1 is being made to reflect the existing design of the CREACUS. This surveillance requirement originated in the CE Standardized TS (NUREG-0212) and was intended for plants where the control room emergency air cleanup system is integrated with the I
normal air conditioning system. This surveillance requirement was l
inadvertently included in the San Onofre TS at the time of licensing, and its j
deletion is acceptable to the staff.
The proposed addition to TS 3/4.7.5 of the phrase, "Each Unit shall enter applicable ACTIONS separately," will clarify to the operators the actions i
i required when the units are in different operational modes. This change does not otherwise affect the TS requirements, and is acceptable to the staff.
i The proposed changes to Section 3/4.7.5 of the Bases accurately reflect the design and test requirements of the CREACUS, and are acceptable to the staff.
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4.0 STATE CONSULTATION
l 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.
5.0 ENVIRONMENTAL CONSIDERATION
The amendments change a requirement with resper.t to the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and change surveillance requirements. The NRC staff has detemined that the amendments involve no significant increase in the amounts, and no significant change in the types, of any effluents that may be reltased 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 consideration, and there has been no public comment on such finding (58 FR 12267). Accordingly, the amendments meet the. eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR j
51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendments.
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6.0 CONCLUSION
The Commission has concluded, based on the considerations discussed above, 1
that (1) there is reasonable assurance that the health and safety of the l
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 Contributor:
E.A. Brown Date:
l February 28, 1996 i
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