ML20141E548

Proposed Tech Specs Allowing Single Reactor Coolant Pump Operation W/Power Above 3.5%

ML20141E548
Person / Time
Site:	Point Beach
Issue date:	02/14/1986
From:	WISCONSIN ELECTRIC POWER CO.
To:
Shared Package
ML20141E521	List: ML20141E516 ML20141E548
References
TAC-57555, TAC-57556, NUDOCS 8602250278
Download: ML20141E548 (4)

Text

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j as actuated by either high current, low supply voltage or low electrical fre-i quency, or by a manual control switch. The significant feature of the breaker j trip is the frequency setpoint, 55.0 HZ, which assures a trip signal before the

[ pump inertia is reduced to an unacceptable value. The high pressurizer water

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level reactor trip protects the pressurizer safety valves against water relief.  ;

! The specified setpoint allows adequate operating instrument error (2) and -

! transient overshoot in level before the reactor trips.

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i The low-low : steam generator water level reactor trip protects against loss of [

feedwater flow accidents. The specified setpoint assures that there will be j sufficient water inventory in the steam generators at the time of trip to allow l for starting delays for the auxiliary feedwater system.I9)

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Numerous reactor trips are blocked at low power where they are not required [

for protection and would otherwise interfere with normal plant operations, f

The prescribed setpoint above which these trips are unblocked assures their j availability in the power range where needed. Specifications 15.2.3.2.A(1)

] and 15.2.3.2.C have 1% tolerance to allow for a 2% deadband of the P10 '

l bistable which is used to set the limit of both items. The difference

betweenthenominalandmaximumallowedvalue(orminimumallowedvalue)is j to account for "as measured" rack drift effects.

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] Sustained operation with only one pump will not be permitted above 3.5 percent power. If a pump is lost while operating between 3.5 percent and 50 percent j power, an orderly and immediate reduction in power level to below 3.5 percent is i j allowed. The power-to-flow ratio will be maintained equal to or less than unity, .

J which ensures that the minimum DNB ratio increases at lower flow because the i

1 maximum enthalpy rise does not increase above the maximum enthalpy rise which  !

occurs during full power and full flow operation.  ;

I References t

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(1) FSAR 14.1.1 (4) FSAR 14.3.1 (7) FSAR 3.2.1 j (2) FSAR, Page 14-3 (5) FSAR 14.1.2 (8) FSAR 14.1.9 (3) FSAR 14.2.6 (6) FSAR 7.2, 7.3 (9) FSAR 14.1.11 Wh P

15.2.3-7 I

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s 15.3 LIMITING CONDITIONS FOR OPERATION l

15.3.1 REACTOR COOLANT SYSTEM Applicability Applies to the operating status of the Reactor Coolant System.

i Objective To specify those limiting conditions for operation of the Reactor Coolant System l which must be met to ensure safe reactor operation.

Spacification A. OPERATIONAL COMP 0NENTS

1. Coolant Pumps *

a. When the reactor is critical, except for tests, at least one reactor coolant pump shall be in operation.

(1) Reactor power shall not be maintained above 3.5% of rated

' power unless both reactor coolant pumps are in operation.

(2) If either reactor coolant pump ceases operating, immediate power reduction shall be initiated under administrative control as necessary to reduce power to less than 3.5% of rated power.

l (3) If both reactor coolant pumps cease operating and power is i

greater than 3.5% of rated power, reactor shutdcwn shall j commence imediately and the reactor trip breakers opened within one hour,

b. When the reactor is subcritical and the average reactor coolant temperature is greater than 350*F except for tests, at least one reactor coolant pump shall be in operation. -

(1) Both reactor coolant pumps may be deenergized provided:

a. No operations are permitted that would cause dilution of the reactor coolant system boron concentration,

b. Core outlet temperature is maintained at least 10'F below saturation temperature, and

c. The reactor trip breakers are open.

c. At least one reactor coolant pump or residual heat removal system shall be in operation when a reduction is made in the ~b'6FoIn con-centration of the reactor coolant.

2. Steam Generator *

a. One steam generator shall be operable whenever the average reactor

coolant temperature is above 350*F.

'3 . Components Required for Redundant Decay Heat Removal Capability *

a. Reactor coolant temperature less than 350*F and greater than 140*F.

(1) At least two of the decay heat removal methods listed shall be operable.

(a) Reactor Coolant Loop A, its associated steam generator and either reactor coolant pump (b) Reactor Coolant Loop B its associated steam genera *or and either reactor coolant pump applicauie only when one or more fuel assemblies are in the reactor vessel.

I 15.3.1-1

t Specification 15.3.1.A.1 requires that at least one reactor coolant pump must be operating whenever the average reactor coolant temperature is above 350 F unless the listed restrictions are established. This is required so that the FSAR zero power transients (rod withdrawal from subcritical and rod ejection) are addressed j from conservative conditions. With the reactor subcritical, with required shut-down margin, and with the trip breakers open, a single rod ejection will not result in criticality being reached. With the reactor subcritical and the average reactor coolant temperature above 350*F, a single reactor coolant pump provides sufficient decay heat removal capability. Heat transfer analysesII) show that reactor heat equivalent to 3.5% of the rated power can be removed with natural circulation only.

Items 15.3.1.A.1.a.(2) permits an orderly reduction in power if a reactor coolant pump is lost during operation between 3.5% and 50% of rated power.

Above 50% power, an automatic reactor trip will occur if either pump is lost.

The power-to-flow ratio will be maintained equal to or less than 1.0, which ensures that the mininum DNB ratio increases at lower flow since the maximum enthalpy rise does not increase above its normal full-ficw maximum value.(2)

Specification 15.3.1.A.3 provides limiting conditions for operation to ensure that redundancy in decay heat removal methods is provided. A single reactor coolant loop with its associated steam generator and a reactor coolant pump or a single residual heat removal loop provides sufficient heat removal capacity for removing the reactor core decay heat; however, single failure considerations require that at least two decay heat removal methods be avail-able. Operability of a steam generator for decay heat renoval includas two sources of water, water level indication in the steam generator, a vent path to atmosphere, and the Reactor Coolant System filled and vented so thermal convection cooling of the core is possible. If the steam generators are not available for decay heat removal, this Specification requires both residual heat removal loops to be operable unless the reactor system is in the refueling shutdown condition with the refueling cavity flooded and no operations in progress which could cause an increase in reactor decay heat load or a decrease in boron concentration, in this condition, the reactor vessel is essentially l

a fuel storage pool and removing a RHR loop from service provides conservative conditions ',hould operability problems develop in the other RHR loop. Also, one residual heat removal loop may be temporarily out of service due to 15.3.1-3b

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restricts leakage so that, in the event of a pipe break or isolation valve failure, makeup water for the leakage can be provided by a single coolant charging pump. If a RCGVS vent path from either the pressurizer or reactor vessel head is inoperable, Specification 15.3.1.A.7.c requires the remotely operable valves in that inoperable path to be shut with power renoved. If a vent path from the common header to the pressurizer relief tank or contain-ment atmosphere is inoperable, the isolation valve in that path must b! shut but reactor operations may continue. If both vent paths to or both vent paths from the common header are inoperable, the RCGVS is inoperable and the steps in specification 15.3.1.A.7.d must be taken.

(1) FSAR Section 14.1.11.

(2) FSAR Section 7.2.3.

15.3.1-3d