ML20052E920

Proposed Changes to Tech Specs to Provide Addl Assurance of Availability of Redundant Reactor Decay Heat Removal Capabilities

ML20052E920
Person / Time
Site:	Point Beach
Issue date:	05/03/1982
From:	WISCONSIN ELECTRIC POWER CO.
To:
Shared Package
ML20052E910	List: ML20052E909 ML20052E920
References
TAC-42114, TAC-42115, NUDOCS 8205110539
Download: ML20052E920 (10)

Text

_ _ _ _ _ _ _ _ _ _ - - _ _ _ _ _ _ _

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

1 Objective To specify those limiting conditions for operation of the Reactor Coolant

. System which must be met to ensure safe eactor operation.

Specification A. OPERATIONAL COMPONENTS

1. Coolant Pumps

a. At least one reactor coolant pump or the residual heat removal system shall be in operation when a reduction is made in th boron concentration of the reactor coolant.

J

b. When the reactor is critical and above 1% of rated power except for natural circulation tests, at least one reactor coolant pump shall be in operation.

c. (1) Peactor power shall not be maintained above 10% 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 10% of rated power.

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 generator and either reactor coolant pump l

8205110539 820503 PDR ADOCK 05000266 15.3.1-1 p PDR s

(c)- Residual Heat Removal Loop (A) *

(d) ' Residual Heat Removal Loop (B)*

(2) If the conditions of . specification (1) above cannot be met, corrective action to return a second decay heat removal method to operable status as soon as possible shall be initiated immediate.ly.

(3) At.least one of the above decay heat removal methods shall be in operation except when required to be secured for testing.

(4) If no decay heat removal method is in operation, all opera-tions causing an increase in the reactor decay heat load or  !

a reduction in reactor coolant system boron concentration l

snall be suspended. Corrective actions to return a decay  !

i heat removal method to operation shall be initiated immediately.

(5) One of the twc operable decay heat removal methods may be temporarily out of service to meet surveillance require-  ;

I ments.

b. Reactor Coolant Temperature Less Than 140*F .

1 (1) Both residual heat remval loops shall be operable except l as permitted in items (3) or (4) below or 15.3.8. A.4.  ;

I (2) If no residual heat removal loop is in operation, all operations causing an increase in'the reactor decay heat load or a reduction in reactor coolant system boron con-l centration shall be suspended. Corrective actions to l

l return a decay heat removal method to operation shall be l

initiated immediately.

l-(3) One residual heat removal loop may be out of service when the reactor vessel head is removed and the refueling cavity flooded.

! (4) One of the two operable decay heat removal methods may be temporarily out of service to meet surveillance

( requirements.

• Mechanical and electrical design provisions of the residual heat removal system I afford the necessary flexibility to allow an operable residual heat removal r ' loop to consist of the RHR pump from one loop coupled with the RHR heat exchanger l from the other loop and to allow the normal or emergency power source to be inoperable or tied together when the reactor coolant temperature is less than 200'F.

l 15.3.1-2 L

4. Pressurizer Safety Valves

a. At least one pressurizer safety valve shall be operable whenever the reactor head is on the vessel or the Reactor Coolant System shall be open to atmosphere.

b. Both pressurizer safety valves shall be operable whenever the reactor is critical.

5. Pressurizer Po*er Operated Relief Valves (PORV) and PORV Block Valves

a. Two PORV's and their associated block valves shall be operable (1) If a PORV is inoperable, the PORV shall be restored to an operable condition within one hour or the associated block valve shall be closed.

(2) If a PORV block valve is inoperable, the block valve shall be restored to an operable condition within one hour or the block valve shall be closed with power removed from the block valve, otherwise the unit shall be in hot shutdown within the next six hours.

6. The pressurizer shall be operable with at least 100 KW of pressurizer heaters available and a water level greater than 10% and less than 95% during steady-state power operation. At least one bank of pressurizer heaters shall be supplied by an emergency bus power supply.

Basis When the boron concentration of the reactor coolant system is to be reduced, the process must be uniform to prevent sudden reactivity changes in the reactor. Mixing of the reactor coolant will be sufficient to maintain a vniform boron concentration if an least one reactor coolant pump or one residual heat removal pump is running while the change is taking place.

The residual heat removal pump will circulate the primary system volume in l

l approximately one-half hour. The pressurizer is of little concern because of the lower pressurizer volume and because pressurizer boron concentration normally will be higher than that of the rest of the reactor coolant.

Specification 15.3.1.A.1 requires that a sufficient number of reactor coolant pumps be operable to provide core cooling. The flow provided in each case will keep DNSR well above 1.30 as discussed in FFDSAR, Section 14.1.9.

Therefore, cladding damage and release of fission products to the reactor coolant 15.3.1-3

will not occur. Heat transfer analyses III show that reactor heat equivalent to 10% of rated power can be removed with natural circulation only; hence the specified upper limin of 1% rated power without operating pumps provides a substantial safety factor.

Item 15.3.1.A.l.c.(2) permits an orderly reduction in power if a reactor coolant pump is lost during operation between 10% 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 minimum DNB ratio increases at lower flow since the maximum enthalpy rise does not increase above its normal full-flow 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 available. Operability of a steam generator for decay heat removal includes 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 core alterations

[

l in progress. In this condition, the reactor vessel is essentially a fuel storage pool and removing a RHR loop from service provides conservative condi-tions should operability problems develop in the other RHR loop. Also, one decay heat removal method may be temporarily out of service du'e to surveillance testing, calibration, or inspectio.7 requirements. The surveillance procedures i follow administrative controls which allow for timely restoration of the decay heat removal method to service if required.

l (1) FSAR Section 14.1.6 (2) FSAR Section 7.2.3 15.3.1-3a f

w Each of the pressurizer safety valves is designed to relieve 288,000 lbs.

per hour of saturated steam at setpoint. If no residual heat is removed f by any of the means available, the amount of steam which could be generated at safety valve relief pressure would be less than half the valves' capacity.

One valve, therefore, provides adequate defense against overpressurization.

Below 350*F and 400 psig in the Reactor Coolant System, the residual heat f removal system can remove decay heat and thereby control systes temperature and pressure.

l l

l l 15.3.1-3b l

t

safety injection system are in the open position.

g. All valves, interlocks, and piping associated with the above components and required to function during accident conditions, are operable.

h. During conditions of operation with reactor coolant system pressure in. excess of 1,000 psig, the source of AC power shall be removed from the accumulator isolation valves MOV-841 A and B at the motor control center and the valves shall be open.

i. Power may be restored to MOV-841 A and B for the purpose of valve testing or maintenance providing the testing and maintenance is completed and power is removed within four hours.

2. During power operation, the requirements of 15.3.3.A.1, Items b and c, may be modified to allow one of each of the following components to be inoperable at any one time. If the system is not restored to meet the requirements of 15.3.3. A.1 within the time period specified, the reactor shall be placed in the hot shutdown condition. If the requirements of 15.3.3.A.1 are not satisfied within an additional 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />, the reactor shall be placed in the cold shutdown condition.

a. One accumulator may be isolated for a period of up to one hour to permit a check valve leakage test. Before isolating an accumulator, the other accumulator isolation valve shall be checked open.

l b. One safety injection pump may be out of service, provided the pump is restored to operable status within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. The other i

I safety injection pump shall be tested to demonstrate operability i

prior to initiating repair of the inoperable pump.

c. Any valve in these systems required to function during accident l

conditions, may be inoperable provided repairs are ccmpleted within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. Prior to initiating repairs, all valves in the system that provide the duplicate function shall be tested to demonstrate operability.

15.3.3-2

3. During power operation, the requirements of 15.3.3.A.1, Items d and e, may be modified to allow one of each of the following components to be inoperable at any one time. If the component is not restored to meet the requirements of 15.3.3.A.1 within the time specified, the reactor shall be placed in the hot shutdown condition. If the requirements of 15.3.3.A.1 are not satisfied within an additional 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />, the reactor shall be maintained in a condition with reactor coolant temperatures between 500 and 350'F. ,

a. One residual heat removal pump may be out of service, provided the pump is restored to operable status within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. The other residual heat removal pump shall be tested to demonstrate operability prior to initiating repair of the inoperable pump.

b. One residual heat exchanger may be out of service for a period l

of no more than 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />.

c. Any valve in the system, required to function during accident conditions, may be inoperable provided repairs are-completed within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. Prior to initiating repairs, all valves in

! the system that provide the duplicate function shall be tested to demonstrate operability, i

i l

i u

r l

l

{ 15.3.3-2a i

_ _ _ . ~ - . . _ , _ _ . . _ , _ _ _

l l

Assuming the reactor has been operating at full rated power for at least 100 days, the magnitude of the decay heat decreases as follows after initiating hot shutdown.

\

Time After Shutdown Decay Heat % of Rated Power 1 min. 3.6 )

30 min. 1.55 'I 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> 1.25 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> 0.7 q 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> 0.4 N

• Based on ANS 5.1-1979, " Decay Heat Power in Light-Water Reactors" Thus, the requirement for core cooling in case of a postulated loss-of-coolant ,

1 accident while in the hot shutdown condition is significantly reduced below the requirements for a postulated loss-of-coolant accident during power oper- .f ation. Putting the reactor in the hot shutdown condition significantly reduces the potential consequences of a loss-of-coolant accident, and also allows more free access to some of the engineered safety system components in order to effect repairs. s 1

Failure to complete safety injection system repairs within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> of going to the hot shutdown condition is considered indicative of a requirement for major maintenance and, therefore, in such a case, the reactor is to be put into the cold shutdown condition. However, when the failures involve the residual heat removal system, in order to insure redundant means of decay heat removal, the reactor system should remain in a condition with reactor coolant temperatures between 500 and 350 F so that the reactor coolant loops and associated steam generators may be utilized for redundant decay heat removal.

With respect to the core cooling function, there is some functional redundancy for certain ranges of break sizes.( }

The containment cooling function is provided by two independent systems:

(a) fan coolers and (b) containment spray which, with sodium hydroxide addition, provides the iodine removal function. During normal power operation, only three of the four fan coolers are required to remove heat lost from equipment 15.3.3-8

7_

O and piping within the containment.(3) In the event of a Design Basis Accident, any one of the following combinations will provide sufficient cooling to reduce contairuaent pressure: (1) four fan coolers (2) two containment spray

~

pumps, (3) two fan coolers plus one containment spray pump.(0) Sodium hydroxide addition via one spray pump reduces airborne iodine activity sufficiently to limit off-site doses to acceptable values. One of the four fan coolers is permitted to be in 'perabic o when the reactor is made critical and during power operation.

The component' cooling system is different from the other systems discussed above in that the components are so located in the Auxiliary Building as to be accessible for repair after a loss-of-coolant accident. One component cooling water puma together with one component cooling heat exchanger can accommodate the. heat removal load on one unit either following a loss-of-coolant accid'en.t'or during normal plant shutdown. If during the postaccident phase the component cooling water supply is lost, core and containment cooling could be maintained until repairs were affected.(5)

A total of six service water pumps are installed, only three of which are required to operate during the injection and recirculation phases of a post-ulated loss-of-coolant accident, in one unit together with a hot shutdown condition in the other unit.

References (1) FSAR Section 3.2.1 (2) FSAR Secticn 6.2 (3) FSAR Section 6.3.2 (4) FSAR Section 6.3 (5) FSAR Section 9.3.2 l (6) FSAR Section 9.6.2 15.3.3-9 L _

15.3.8 REFUELING AND SPENT FUEL ASSEMBLY STORAGE Applicability Applies to operating ~1imitatio.3 during refueling operations and to operating limitations concerning the movement of heavy loads over or into the spent fuel-storage pools.

Objective '

To ensure that no incident could occur during refueling operations or during auxiliary building crane operations that would affect public health and safety.

Specifications A. During refueling operations:

1. The equipment hatch shall be closed and the personnel locks shall be capable of being closed. A temporary third door.on the outside of the personnel lock shall b.e in place whenever both doors in a personnel lock are open (except for initial core loading).

2. Radiction levels in fuel handling areas, the containment, and spent fuel storage pool shall be monitored continuously.

3. Core suberitical neutron flux shall be continuously monitored by at least two neutron monitors, each with continuous visual indication in the control room and one with audible indication in the containment available whenever core geometry _is being changed. When core geometry is not being changed at least one neutron flux monitor shall be in service.

4. At least one residual heat removal loop shall be in operation.

$$ wever,ifrefuelingoperationsareaffectedbytheresidualheat removal loop flow, the operating residual heat removal loop may be removed from operation for up to one hour per eight hour period.

5. During reactor vessel head removal and while loading and unloading fuel from the reactor, a minimum boron concentration of 1800 ppm shall be maintained in the primary ccolant system.

15.3.8-1