ML18053A477

Proposed Tech Specs,Revising Secondary Sys Safety Valve Setpoint Tolerances

ML18053A477
Person / Time
Site:	Palisades
Issue date:	08/04/1988
From:	CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:
Shared Package
ML18053A476	List: ML18053A475 ML18053A477
References
NUDOCS 8808110264
Download: ML18053A477 (2)

Text

ATTACHMENT {

Consumers Power Company Palisades Plant Docket 50-255 August 4, 1988 1 Page OC0788-0079-NL02

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.. -'..,.)~ . ', _,. 3. 1 PRIMARY coo~ SYSTEM (Contd) 3.1. 7 Primary and Secondary Safety Valves Specifications

a. The reactor shall not be made critical unless all three pressurizer safety valves are operable with their lift settings maintained between 2500 psia and 2580 psia (+/- 1%).

b. A minimum of one operable safety valve shall be installed on the pressurizer whenever the reactor head is on the vessel.

c. Whenever the reactor is in power operation, a minimum of 23 secondary I system safety valves shall be operable with their lift settings I between 985 psig (+/- 30 psig) and 1025 (+/- 3%) psig. I Basis The primary and secondary safety valves pass sufficient steam to limit the primary system pressure to 110 percent 1 ~f design (2750 psia) following a complete loss of turbine generator load without simultaneous reactor trip while operating at 2650 MWt.

The reactor is assumed to trip on a "High Primary Coolant System Pressure" signal. To determine the maximum steam flow, the only other pressure relieving system assumed operational is the secondary system safety valves. Conservative values for all system parameters, delay times and core moderator coefficient are assumed. Overpressure protection is provided to the portions of the primary coolant system which are at the highest pressure considering pump head, flow pressure drops and elevation heads.

If no residual heat were removed by any of the means available, the amount of steam which could be generated at safety valve lift pressure would be less than half of one valve's capacity. One valve, therefore, provides adequ~te defense against overpressurization when the reactor is subcritical.

The total relief capacity of the 24 secondary system safety valves is 6

11.7 x 10 lb/h. This is based on a steam flow equivalent to an NSSS power level of 2650 MWt at the nominal 1000 psia valve lift pressure.

At the power rating of 2530 MW , a relief capacity of less than 6 t 11.2 x 10 lb/h is required to prevent overpressurization of the secondary system of loss of load conditions, and 23 valves provide 6 (1 2) relieving capability of 11.2 x 10 lb/h. '

2 The overpressurization analysis for the loss of load event( ) supports I the specified secondary safety valve lift pressure tolerance. ASME I B&PV Code Section 1986 edition,Section XI, subsection IWV-3500, I specifies ANSI/ASME OM-1-1981 requirements which allow the specified I tolerances in the lift pressures of the safety valves. I References (1) FSAR, Sections 4.3.4 and 4.3.7.

(2) ANF-87-150(NP) Volume 2, Section 15.2.1. I 3-25 Amendment No. 'J,l OC0788-0079-NL02