ML20010E207

Proposed Tech Specs 2.2 & 2.3,limiting Setpoints for Five Electromagnetic Relief Valves

ML20010E207
Person / Time
Site:	Oyster Creek
Issue date:	08/27/1981
From:	JERSEY CENTRAL POWER & LIGHT CO.
To:
Shared Package
ML20010E202	List: ML20010E201 ML20010E204 ML20010E207
References
NUDOCS 8109030202
Download: ML20010E207 (3)

Text

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2.2-1 7 .

2.2. SAFETY LIMIT - REACTOR COOLANT SYSTEM PRESSURE Applicability: Applies to the limit on reactor coolont system pressure.

Obj ec t ive : Preserve the integrity of the reactor coolant system.

Specification: The reactor coolant system pressure shall not exceed 1375 psig whenever irradiated t'uel is in the reactor vessel. f Bases: The reactor coolant system (1) represents an important barrier in the prevention of the uncontrolled release of fission products.

It is essential that the integrity of this system be protected by establishing a pressure limit to be observed whenever there is irradiated fuel in the reactor vessel.

The pressure safety limit of 1375 psig was derived from the de-sign pressures of the reactor pressure vessel, coolar t piping, and isolation condenser. The respective design pressures are 1250 psig at 5750F, 1200 psig at 5700F and 1250 psig t.t 575 F.

The pressure satety limit was chosen as the lower of tl e pres-sure transients permitted by the applicable design codes: ASME Boiler and Pressure Vessel Code Section I for the pressure t~

vessel, ASME Boiler and Pressure Vessel Code Section III for the isolation condenser and the ASA Piping Code Section B31.1 '

for the reactor coolant systcm p.,ing. The ASME Code permits pressure transients up to LO% over the design pressure (110% x 1250 = 1375 psig) and the ASA Code permits pressure transients up to 15% over the design pressure (115% x 1200 =

1380 psig).

The design basis for the reactor pressure vessel makes evident the substantial margin of protection against failure at the safety pressure limit of 1375 psig. The vessel has t een de-signed for a general membrane stress no greater than 20,000 psi at an internal pressure of 1250 psig and temperature of 575 F; this is more than a factor of 2 below the yield strength of 42,300 psi at this temperature. At the pressure limit of 1375 psig, the general membrane stress increases to 21.000 psi, still almost a factor of 2 below the yield strength.

The reactor coolant system piping provides a comparable margin of protection at the established pressure safety limit.

The normal operating pressure of the reacto coolant system is 1020 psig. An over-pressurizat ion analysis 2)is performed each cycle to assure the pressure safety limit is not exceeded. The reactor fuel cladding can withstand pressures up to the safety limit, 1375 psig, without co11apsing(3) . Finally, reactor sys-tem pressure is continuously monitored in the control room during reactor operation on the 1600 psi full scale pressure recorder with an error of < 1% and a recorder time response a 02 second.

REFERENCES (1) FDSAR, Volume I, Sect ion IV .

(2) License Application Amendment 76.

(3) FDcAR, Volume I, Section III-2.3.3 A=aaM= ant %M 8109030202 810827 PDR ADOCK 05000219 P FDR -

2.3-2 1

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FUNCTION LIMITING SAFETY SYSTEM SETTINGS 1

1

2) Neutron Flux, Control Rod Block For recirculation flow. W Z. 61 x 10 6lb/hr:

4. ( [1. 34 x 10-6} W + 24. 3) percent of rated neutron flux when total peaking factors in all fuel types are less than or equal to those in Specification 2.1.A.1, or The lowest value of:

4. ( [1. 3'. x 10-6} W + 24. 3 o PF percent of rated neut ron flux f rom among those calculated for each fuel type with total peaking facters, PF7 PFo, where PPo = peaking factor in Specification 2.1.A.1 For recirculation flow, W > 61 x 106 lb/hr:

f 106 percent of rated neutron flux when total peaking factors in all fuel types are less than or equal to those in Specification 2.1.A.1, or The lowest value of t 106 [ PFo ) percent PF of rated neutron flux from anong those calculated for each fuel type with total peaking factors, PF >PF o, where PF o

=

peaking factor in Spoeification 2.1.A.1

[ 3) Reactor Iligh Pressure, Scram 3 1060 psig.

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4) Reactor High Pressure, Relief 2 valves 3 1070 psig Valves Initiation 3 valves _4 1090 psig

5) Reactor liigh Pressure, Isola-

-- 1060 psig with time delay 4. 15 seconds, tion Condenser initiation

6) Reactor liig'i Pressure, 4 0 1212 psig Safety Valve Initiation 4 0 1221 psig i

I 4 0 1230 psig -+U si l 4 0 1239 psig l

l l Amendment No.

1 i

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2.3-5 For operation in the startup mode while the reactor is at low f pressure, the IRM scram setting of 15% of rated power provides 22% thermal margin between the maximum power and the safety limit, 18.3% of rated. The margin is adequate to accommodate anticipated maneuvers associated with power plant startup. There are a few possible sources of rapid reactivity input to the sys-tem in the low power low flow condition. Effects of increasing pressure at zero or low void content are minor, cold water fron sources available during startup is not much colder than that already in the system. temperature coefficients are small, and control rod patterns are constrained to be uniform by operating procedures backed up by the rod worth minimizer. b' orth of in-dividual rods is very low in a uniform rod pattern. Thus, of all possible sources of reactivity input, uniform control rod withdrawal is the most probable cause of significant power rise.

Because the flux distribution associated with uniform rod with-drawals does not involve high local peaks, and because several rods must be moved to change power by a significant percentage of rated, the rate of power rise is very slow. Generally the heat flux is in near equilibrium with the fission rate. In an assumed uniform rod withdrawal approach to the scram level, the rate of power rise is no more than five percent of rated per minute, and the IRM system would be more than adequate to assure a scram before the power could exceed the safety limit. The IRM scram remains active until the mode switch is placed in the run position at which time the trip becomes a coincident IRM upscale, APRM downscale scran. The Reactor Protection System is designed such that reactor pressure must be above 825 psig to success-fully transfer into the RUN mode, thus assuring protection for the fuel cladding safety limit.

The settings on the reactor high pressure scran, anticipatory scrams, react'or coolant system relief valves and isolation con-denser have been established to assure never reaching the rcactor coolant system pressure safety limit as well as assuring the sys-tem pressure does not exceed the range of the fuel cladding integrity safety limit. In addition, the APRM neutron flux scram and the turbine bypass system also provide protection for these safety limits, e.g., turbine trip and loss of electrical load transients (8). In addition to preventing power operation above 1060 psig, the pressure scram backs up the other scrams for these transients and other seam line isolation type transients. With the addition of the anticipatory scrams, the transient analysis for operation at 1930 FNt shows that the turbine trip with failure of the bypass system transient is the worst case transient with respect to peak pressure. Analysis of this transient shows that the relief valves limit the peak pressure well below the 1250 psig l range of applicability of the fuel cladding integrity safety limit and the 1375 psig reactor coolant system pressure safety limit.

Actuation of the isolation condenser during these transients re-moves the reactor decay heat without further loss of reactor coolant thus protecting the reactor water level safety limit.

Amendment No.