ML20101S656

Safety Evaluation Supporting Amends 29 & 18 to Licenses NPF-10 & NPF-15,respectively

ML20101S656
Person / Time
Site:	San Onofre
Issue date:	01/09/1985
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20101S645	List: ML20101S644 ML20101S656
References
TAC-54730, TAC-54731, NUDOCS 8502050575
Download: ML20101S656 (4)

Text

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UNITED STATES 8

NUCLEAR REGULATORY COMMISSION o

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SAFETY EVALUATION i

AMENDMENT NO. 29 TO NPF-10 AMENDMENT NO. 18 TO NPF-15 SAN ONOFRE NUCLEAR GENERATING STATION, UNITS 2 & 3 DOCKET NOS. 50-361 AND 50-362

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Introduction l

Southern California Edison Company (SCE), on behalf of itself and the other i

licensees, San Diego Gas and Electric Company, the City of Riverside, California, and The City of Anaheim, California has submitted several applications for license amendments for San Onofre Nuclear Generating Station, Units 2 and,3.

One such request, Proposed Change Number 135, or PCN-135, dated April 27, 1984, involves the control room toxic gas isolation system setpoints. Specifically, I

Technical Specification 3/4.3.2 requires that the engineered safety features actuation system (ESFAS) instrumentation channels be operable, and defines a

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number of functional tests and response time tests that must be periodically conducted in order to assure operability. Table 3.3-4 of this-technical i

specification defines the ESFAS. instrumentation trip values for the toxic j

gas isolation system (TGIS). The TGIS is actuated by greater than allowable 4

concentration of toxic gas (i.e., chlorine, ammonia, butane / propane, or carbon i

dioxide) in the nonnal control room air supply duct. Upon receipt of a TGIS signal, the control room heating, ventilation, and air conditioning (HVAC) system is automatically isolated. The FSAR analysis indicates that adequate protection for the control room operators will be provided if the toxic gas concentration in the control room during the first two (2) minutes after the 1

detector responds is less than the protective action limit for toxic gas j

concentration. The proposed change would make the following revisions to Table 3.3-4:

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(1) The allowable values for chlorine concentration would be increased from less than or equal to 6.2 ppm to less than or equal to 15.0 ppm.

With an allowable value for chlorine limited to less than or equal to l

15.0 ppm, the high chlorine trip value would be. increased from le.ss l

than' or equal to 6.0 ppm to less than or equal to 14.3 ppm.

(2) The allowable values for ammonia concentration would be increased from less than or equal to 44.7 ppm to less than or equal to 100 ppm. With an allowable value for ammonia limited to less than or equal to 100. ppm, the high ammonia trip value would be increased from less than or equal to 42.4 ppm to less than or equal to 97 ppm.

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_(3) The allowable values for butane / propane concentration would be increased from less than or equal to 89.3 ppm to less than or equal to 200 ppm.

With an allowable value for butane / propane limited to less than or equal to 200 ppm, the high butane / propane trip value would be increased from less-than or equal to 84.8 ppm to less than or equal to 193 ppm (4) The allowable value for carbon dioxide concentration would be deleted (the present value is less than or equal to 4275.0 ppm). Therefore the high carbon dioxide trip value would also be deleted (the present value is less than or equal to 4061.3 ppm).

Evaluation The staff has reviewed the proposed changes to Technical Specification 3/4.3.2, Table 3.3-4.

Based on a review in accordance with the guidelines of Regulatory Guide 1.78 and Standard Review Plan (SRP) Sections 2.2.3 and 6.4,'the staff concludes that these changes meet the requirements of General Design Criterion

'19 of 10 CFR Part 50, Appendix A, and are acceptable.

The licensees' evaluation addresses the exter' to which the toxic gas monitor setpoints could be raised or deleted and stili provide adequate protection for the control room operators. The toxic gases considered are chlorine, ammonia, propane, butane and carbon dioxide. The proposed change revises the set point from 6.0 ppm to 14.3 ppm for chlorine, 42.4 ppm to 97 ppm for ammonia, and 84.8 ppm to 193 pon for butane / propane. The proposed change deletes the requirement to actuate the TGIS on carbon dioxide. These modifications will help reduce the number of spurious TGIS actuations currently being experienced at San Onofre Units 2 and 3.

Increasing the setpoint to the proposed values for chlorine and ammonia could lead to a control room concentration exceeding the long tern exposure limits defined in SRP 6.4 without an alarm or other safety systems ~ actuation. This could be possible in the event of a maximum concentration-duration type acci-dent identified in Regulatory Guide 1.78. However, because the odor threshold values for chlorine and ammonia are lower than the long term exposure limits, the control room operators with proper training can be expected to take effec-tive~ safety measures. SCE, in response to a staff request, has committed (by j

letter dated November 9,1984) to implement a procedural requirement to j

-manually actuate the TGIS in the event that an airborne irritant is detected by the control room staff.

For a maximum concentration accident, independent assessments by the licensees and staff indicate that the control' room operators would have at least two minutes (the'value reconnended in Regulatory Guide 1.78 and SRP 6.4) following i

an ' alarm to don self-contained breathing apparatus before the concentration reaches protective action levels for annonia and chlorine.

j' In the assessment of the time-dependent toxic gas concentration at the control room. air intake for carbon dioxide, there is about a two minute period in which j

the concentrations resulting from a maximum release accident exceed the toxic limit. However, as soon as the " puff" passes, this concentration drops below i

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. the toxic limit.

In the event of a maximum concentration-duration type acci-dent, the concentration exceeds the long term exposure limit but not for more than an hour.: On this basis the staff concurs with the licensees that protec-4 tion of the control room operator from a postulated carbon dioxide release i

on-site is not required.

For hydrocarbons, i.e., butane and propane, the detector setpoint is low enough that an accident involving a release of these. chemicals would not pose a problem i

for the operators. This conclusion is based upon independent assessments by both the licensees and staff..

Based on the submittal and the implementation of the licensees'. commitment to

-institute procedures requiring control room isolation following detection of an airborne irritant by the control room operators, the staff concludes that i

proposed change PCN-135 meets the guidelines of Regulatory Guide 1.78, SRPs

_2.2.3 and 6.4, and 10 CFR Part 50, Appendix A. General Design Criterion 19, and is, therefore, acceptable.

j Contact With State Official The NRC staff has advised the Chief of the Radiological Health Branch, State Department of Health Services, State of California, of the proposed determina-l tions of no significant hazards consideration. No coments were received.

i-Environmental Consideration l

These amendments involve changes in the installation or use of facility com-ponents located within the restricted area. The staff has determined that the amendments involve no significant increase in the amounts of any effluents that may be released offsite and that there is no significant increase in individual or cumulative occupation radiation exposure. The Comission has previously issued proposed findings that the amendments involve no significant hazards consideration, and there has been no public comment on such findinos.

Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR Sec. 51.21(c)(9).

Pursuant to 10 CFR 51.22(b) i no environmental ' impact statement or environmental assessment need to prepared in connection with the issuance of these amendments.

i Conclusion Based upon our evaluation of the proposed changes to the' San Onofre Units 2 and 3 Technical Specifications, we have concluded that:

there is reasonable assurance that the health and safety of the public will not be endangered by 4

operation in the' proposed manner, and such activities will be conducted in compliance with the Commission's regulations and the issuance of this amend-i ment will not be inimical to the comon defense and security or to the health and safety'of the public. We, therefore, conclude that the proposed changes-are acceptable Dated: January-9, 1985 i

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January 9, 1985 4

ISSUANCE OF AMENDMENT NO. 29 TO FACILITY OPERATING LICENSE NPF-10

- AND AMENDMENT NO.18 TO FACILITY OPERATING LICENSE NPF-15 SAN ONOFRE NUCLEAR GENERATING STATION, UNITS 2 AND 3 DISTRIBUTION g0ocket: File:.504361/36 C 1 NRC PDR 1

Local PDR 4

PRC System NSIC LB#3 Reading J. Lee (20)

H. Rood T. Novak J. Saltzman, SAB L. Chandler, OELD C. Miles H. Denton J. Rutberg A. Toalston W. Miller, LFMB N. Grace E. Jordan L. Harmon D. Brinkman, SSPB T.Barnhart(4) i i

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