ML063320115

E-Mail from Peck to Wang - Cvvy MSIV Operability Question

ML063320115
Person / Time
Site:	Callaway
Issue date:	01/03/2005
From:	Peck M NRC Region 4
To:	Gramm R, Wang A Office of Nuclear Reactor Regulation
References
FOIA/PA-2006-0230
Download: ML063320115 (2)

Text

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,Miroe aueStioNpd e page 1e From: Michael S. Peck To: Alan Wang; Robert Gramm Date: 1/3/05 10:04AM

Subject:

ACT: CWY MSIV Operability Question Wang & et al:

Thank you, Michael Peck, SRI The Callaway Plant has one MSIV on each main steam line. Each MSIV has two independent.

trains of closing solenoids. Technical Specification 3.7.2 provide the Callaway Plantwith an 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> actionto restore an inoperable MSIV. Surveillance Requirement SR 3.7.2 requires each MSIV to close in less than 5 seconds. The bases for Surveillance Requirement 4.7.2 stated that each actuator train was required to close each MSIV in less than 5 seconds.

FSAR Section 10.3.1.1, Safety Design Bases stated:

SAFETY DESIGN BASIS THREE - Component redundancy is provided so that (MSIV) safety functions can be performed, assuming a single active component failure coincident with the loss of offsite power (GDC-34).

MAIN STEAM ISOLATION VALVES AND BYPASS ISOLATION VALVES - One MSIV and associated bypass isolation valve (BIV) is installed in each of the four main steam lines outside the containment and downstream of the safety valves. The MSIVs are installed to prevent uncontrolled blowdown from more than one steam generator. The valves isolate the nonsafety-related portions from the safety-related portions of the system. The valves are bidirectional, double disc, parallel slide gate valves. Stored energy for closing is supplied by accumulators which contain a fixed mass of high pressure nitrogen and a variable mass of high pressure hydraulic fluid. For emergency closure, a solenoid is energized which causes the high pressure hydraulic fluid to be admitted to the top of the valve stem driving piston and also causes the fluid stored below the piston to be dumped to the fluid reservoir. Two separate pneumatic/

hydraulic power trains are provided. Electrical solenoids for the separate pneumatic/hydraulic power trains are energized from separate Class IE sources. If both trains of control power are lost, the MSIVs will fail as is. The valves are designed to close between 1.5 to 5 seconds against the flows associated with line breaks on either side of the valve, assuming the most limiting normal operating conditions prior to occurrence of the break. Valve closure capability is tested in the manufacturer's facility by pressurizing the valve body and closing the valve twice, each time with a different set of actuator controls. Preservice and inservice tests are also performed as discussed in Sections 10.3.4.2 and FSAR Section 10.3.3, SAFETY EVALUATION, stated:

Information in this record was deleted inaccordance with the Freedom of Information Act, exemptions _ ' u zIr/d e- r c6P,(, ..

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'tacel'L: "1Vt.roe- .lack 7 MSiv Operability Question.wpd Page 2 SAFETY EVALUATION THREE - As indicated by Table 10.3-3, no single failure will compromise the (MSIV) system's safety functions. All vital power can be supplied from either onsite or offsite power systems, as described in Chapter 8.0.

FSAR Section7.3.7.1.2, Design Bases, stated:

The design bases for the main steam and feedwater isolation actuation system are provided in Section 7.3.8. The design bases for the remainder of the main steam and feedwater isolation system are that the system isolates the main steam and feedwater when required, and that no single failure can prevent any valve from performing its required function. See Section 7.3.8 for additional discussion.

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