ML19345E593
| ML19345E593 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 08/24/1977 |
| From: | Bixel D CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Desiree Davis Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8102050255 | |
| Download: ML19345E593 (2) | |
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Consumers e
po\\"C Company o.n.r.: on.c.s: ms w.st MicNgan Aventee. Jackson MecfWgen 49201 e Area Code S17 788-0550 N
August 2h, 1977
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l,UCy Director of Nuclear Reactor Regulation y M L>
Att: Mr Don K Davis, Acting Branch Chief Q
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Operating Reactor Branch No 2 r
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Washington, DC 20555 DOCKET 50-155, LICENSE DPa. BIG ROCK POINT PLANT - 900#
CLA2S CORE SPRAY VALVES By letter dated April 19, 1976 Consumers Power Company was required to provide a modified overpressure protection analysis of the core ring spray reactor pressure boundary valves (check valve CV-T and isolation valve MC-7051) based on the lover design ratings of these valves. The method used by Consumers Power Company to meet this requirement is to ensure that the valves are able to withstand the prescure t
transient imposed by the most limiting overpressurization event.
The most limiting overpressurization event for Big Rock Point is the safety valve sizing event (turbine trip vithout bypass) as specified in the General Electric Report " Anticipated Transients Without Scram Study for Big Rock Point Power Plant" (NEDE-21065 dated October 1975). This assumed event postulated the following:
Peak reactor vessel pressure vould be 1587 psig for approximately three (3) a.
seconda. At that point, the relief valves vould cpen and pressure vould begin to decay, stabilizin6 at a reactor vessel temperature and pressure of 582 F and 1350 psig (hot shutdown conditions).
b.
Peak containment pressure of 57 7 psig and te=perature of 286 F is reached approximately ten minutes after event initiation.
If it were assumed that downstream isolation valve M0-7061 vere open at the ini-tiation of the event (a hishly unlikely occurrence since it is a normally clcsed valve) check valve CV-T would be subject to full transient pressure of 1587 psig for approximately three seconds. This pressure transient is not considered to be impulsive at the valve due to the damping effect of the static fluid stream (h-inch piping approxi=ately h0 feet in length). Transient temperature would peak at 60h F but, as indicated on the attached curve, valve CV-T would con-servatively be subjected to lho F temperatures. Thus, for this limitin$ event,
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check valve CV-T and isolation valve M0-7051 =ust be able to withstand a pressure of 1587 psig at a temperature of lho F.
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AliSI B 16.5-1973, Table 2.1 indicates that a 900-pound cast carbon A 216 Gr WCB valves must be designed to withstand 2142 psi at 1h0 F.
Chapman Valve Pressure Te=perature Ratings stipulate that valves CV-7 and MO-7051 are designed for 2136 psig at 140 F.
Further, after the primary relief valves have opened and system pressure decreases while containment pressure ir. creases, the conservative assumption is that the valves reach 286 F at a pressure of 1350 psis ten minutes after event initiation. ANSI B 16.5 specifies a pressure capability of 1978 psi and Chap =an valve data specifies pressure capability of 2056 psig at this temper-ature.
Thus, it is concluded that check valve CV-7 and isolation valve MO 'iO51 can ade-quately withstand the effects of the most limiting overpressuri::ation event.
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David A Bixel Nuclear Licensing Administrator CC: JGKeppler, USURC
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NRC DISTRIBUTION Foo PART 50 DOCKET MATERIAL T t:
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DATE OF OCCUME NT Consumers Power Company 8/24/77 Mr. Don K. Davis Jackson, Michigan DATE RECEIVED David A. Bixel 8/29/77 ETTER O NOTO RIZE D FROP INPUT FORM NUMBER OF CO*tES RECEnv50 R t24N AL UNCLASiFISO
$ g 9 N Cg COPY DESCZt?Tl!N E N CLOSU R E Consists of i.. formation concerning class core spray valves.....
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PLANT NAME: Big Rock Point RJL 8/29/77 SAFFTY FOR ACTION /INFORMATION BRANCH CHIEF: (7)
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