ML061310295

SONGS, Unit 3, Technical Specifications, Request to Shutdown Cooling Line Vent Line

ML061310295
Person / Time
Site:	San Onofre
Issue date:	05/06/2006
From:	Plant Licensing Branch III-2
To:
Kalyanam N
Shared Package
ML061310164	List: ML061310169 ML061310295
References
TAC MD1446
Download: ML061310295 (1)

Text

San Onofre 2&3 FSAR Updated COMPONENT AND SUBSYSTEM DESIGN and pressure have been reduced to approximately 350'F and 376 lb/in. 2 a, the SCS is put into operation.

In their shutdown cooling function. the LPSJ pumps take suction from one of the two RCS bot legs. Heat is removed by circulating this flow through the shutdown cooling heat exchangers (SCHXs). The cooled flow returns to the RCS through four LPSI headers connected to the cold legs. Plant cool-down rate is controlled by flow control valves which permit proportioning the amount of shutdown cooling flow passing through the heat exchangers and heat exchanger bypass line. The SCS reduces reactor coolant temperature to refueling temperature and maintains this temperature during refueling operations.

The SCHXs are also used during the recirculation mode following a loss-of-coolant incident for containment spray purposes, as discussed in subsections 6.2.2 and 6.5.2.

The SCS is used in conjunction with steam generator atmospheric dump and emergency feedwater to cool down and depressurize the RCS following a small break LOCA (see section 6.3).

No components of the SCS for Unit 2 are shared by Unit 3.

5.4.7.1.2 Design Criteria In addition to the functional requirements of paraoraph 5.4.7.1.1, the following design requirements form the design basis for the SCS-A. The functional requirements defined in paragraph 5.4.7.1.1 must be met assuming the failure of a single active component.

B. No single active failure will allow overpressurization of the SCS. Positive isolation from the RCS is provided whenever the RCS is above the shutdown cooling initiation pressure of 376 lb/in.2 a (pressurizer). Isolation valves with appropriate interlocks are provided on the SCS suction line for this purpose. The valves and interlocks are discussed in paragraph 5.4.7.2.2.

Overpressure protection from the safety injection tanks is discussed in paragraph 6.3.2.2.1.

The SCS is provided with appropriate relief valves for overpressure protection. Design basis for pressure relief capacity is discussed in paragraph 5.4.7.2.2.

C. No single aztik' failure preventc' .+/-t asc one t-V24 offthe A RC= from= being alige _An cpcrAt f- the :onrrel rooem ekithr 0arhing a nenal p]anE seeldown or ffowi accident. A faIure made&-sP Wndest;c analysie of th SC -Sirprvi ded in al-A 5.4-38 Amended: June 2005 T1 E02B052