ML20206F880

Exemption from Requirements of 10CFR50,App R,Subsection Iii.L Re Capability to Achieve Cold Shutdown in 72 H. Alternative Shutdown Capability Should Be Able to Achieve Cold Shutdown Conditions in 205 H

ML20206F880
Person / Time
Site:	Rancho Seco
Issue date:	05/19/1986
From:	Miraglia F Office of Nuclear Reactor Regulation
To:	SACRAMENTO MUNICIPAL UTILITY DISTRICT
Shared Package
ML20206F869	List: ML20206F865 ML20206F880 ML20206F907
References
TAC-53444, NUDOCS 8606250017
Download: ML20206F880 (3)

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7590-01 UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION I

l In the Matter of

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SACRAMENTO MUNICIPAL UTILITY

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Docket No. 50-312

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i DISTRICT

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(Rancho Seco Nuclear Generating Station)

EXEMPTION I.

Sacramento Municipal Utility District (the licensee) is the holder of Facility Operating License No. DPR-54 which authorizes the operation of the Rancho Seco Nuclear Generating Station (the facility) at steady-state power r-levels not in excess of 2772 megawatts thermal. The facility is a pressurized water reactor (PWR) located at the licensee's site in Sacramento i

County, California. The license provides, among other things, that it is subject to all rules, regulations and Orders of the Nuclear Regulatory 4

Commission (the Commission) now or hereafter in effect.

l II.

i On November 19, 1980, the Commission published a revised Section 10 CFR 50.48 and a new Appendix R to 10 CFR 50 regarding fire protection featu'res of ruclear power plants (45 FR 76602). The revised Section 50.48 and Appendix R j

became effective on February 17, 1981. Section li: of Appendix R identifies specific fire protection requirements in fifteen subsections, A through 0.

This exemption relates to Subsection III.L which requires, in part, that the alternative-or dedicated shutdown capability provided for a specific fire area be able to achieve cold shutdown conditions within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> without the I

l use of offsite power.

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. 7590-01 III.

By letter dated February 28, 1985, as supplemented by letter dated November 7, 1985, the licensee requested exemption from the specific requirement of III.L which requires that alternative or dedicated shutdown be able to achieve cold shutdown conditions within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. The acceptability of the request is addressed below.

Subsection III.L.1 of Appendix R to 10 CFR 50 states, in part, that the alternative shutdown capability shall be able to achieve cold shutdown i

conditions within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.

Further, Subsection III.L.3 of Appendix R states that the alternative shutdown capability must accommodate post-fire conditions where offsite power is available and where offsite power is not i

available for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. Thus, the alternative shutdown capability must be able to achieve cold shutdown conditions within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, independent of l.

offsite power. The licensee has requested an exemption from the 72-hour i

requirement for achieving cold shutdown independent of offsite power.

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The design of the Rancho Seco Nuclear Generating Statio6 is such that pressurizer spray capability is dependent upon operation of the reactor j

coolant pumps which, in turn, require offsite power. Without pressurizer i

l spray availability, depressurization of the reactor and subsequent cooldown i

would be determined by the rate of heat loss from the pressuri7er to the I

containment environment. Additionally, the licensee has imposed a further restriction to cooldown in order to avoid formation of steam in the upper head. Usino this cooldown restriction and a conservative analysis, the licensee calculated that 205 hours0.00237 days <br />0.0569 hours <br />3.38955e-4 weeks <br />7.80025e-5 months <br /> would be required to achieve cold shutdown conditions,' assuming offsite power was unavailable.

i For plant cooldown, the auxiliary feedwater (AFW) system in conjunction 4

with the atmospheric dump valves provides initial decay heat removal i

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7590-01 independent of offsite power. The AFW system utilizes one electric driven and one tandem steam and electric driven feedwater pump. The AFW pumps take suction from the condensate storage tanks. The onsite reservoir, which can be manually valved into the suction side of the ArW pumps, serves as the backup source of water. When the condensate storage tank is isolated from the AFW system, water from the reservoir flows by gravity to the suction side of the AFW pumps. Therefore, no additional pumps are reouired. The AFW pumps can be powered by the emergency diesel generators. The licensee stated that the diesel generators have onsite fuel available for 175 to 250 hours0.00289 days <br />0.0694 hours <br />4.133598e-4 weeks <br />9.5125e-5 months <br /> of continuous operation and that additional supply of oil can be brought onsite by tanker trucks from local supplies.

For long term heat removal, the decay heat system will be utilized. The decay heat removal pumps can be powered by the diesel generators.

Since the capability to achieve cold shutdown utilizing onsite power is available during the time period proposed by the licensee without any adverse effects on the reactor, we find the licensee's cooldown time period acceptable.

IV.

Accordingly, the Commission has determined that, pursuant to 10 CFR 50.12, this exemption is authorized by law, will not present an undue risk to the public health and safety, and is consistent with the common defense and security. The Comissior. further determines that special circumstances, as provided in 10 CFR 50.12(a)(2)(ii), are present justifying the exemption, namely the application of the regulation in the particular

. 7590-01 circumstance is not necessary to achieve the underlying purpose of the rule:

to require that the alternative or dedicated shutdown capability be able to achieve cold shutdown conditions independent of offsite power and without any adverse effects on the reactor. Specifically, as noted,above. the licensee has demonstrated, using conservative analyses, the capability of achieving

' cold shutdown in 205 hours0.00237 days <br />0.0569 hours <br />3.38955e-4 weeks <br />7.80025e-5 months <br /> with alternate shutdown utilizing only onsite i

power without any adverse effects on the reactor. This leads the staff to conclude that requiring alternative or dedicated shutdown capability to be able to achieve cold shutdown conditions within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> (rather than 205 hours0.00237 days <br />0.0569 hours <br />3.38955e-4 weeks <br />7.80025e-5 months <br /> as r-requested by the licensee) is not necessa y to assure no adverse effects on the reactor. Accordingly, the Commission hereby grants an exemption as described in Section III above from Subsection III.L of Appendix 2 to 10 CFR 50 to the extent that the alternative shutdown capebility shall be able to achieve cold shutdown conditions in 205 hours0.00237 days <br />0.0569 hours <br />3.38955e-4 weeks <br />7.80025e-5 months <br />.

Pursuant to 10 CFR 51.32, the Commission has determined that the issuance of the exemption will have no significant inpact on the environment (51 FR 6054).

This Exemption is effective upon issuance.

FOR THE NUCLEAR REGULATORY COMMISSION Jzu2k A

Frank J. Miraglia, Director Division of PWR Licensing-B Dated at Bethesda, Maryland, this 19th day of May 1986.

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