ML20138J075

Proposed Tech Specs,Relocating Control of Standby Liquid Control Relief Valve Setpoint in TS 4.4.A.2.a & Associated Bases

ML20138J075
Person / Time
Site:	Cooper
Issue date:	05/05/1997
From:	NEBRASKA PUBLIC POWER DISTRICT
To:
Shared Package
ML20138J073	List: ML20138J069 ML20138J075
References
NUDOCS 9705080009
Download: ML20138J075 (9)

Text

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1 LIMITING CONDITIONS FOR OPERATION SURVEILLANCE REQUIREMENTS i

3.4 STANDBY LIOUID CONTROL SYSTEM 4.4 STANDBY LIOUID CONTROL SYSTEM Aeolicability: Apolicabilitvr j l

Applies to the operating status of Applies to the surveillance require- l the Standby Liquid Control (SLC) ments of the Standby Liquid Control System. (SLC) System. l Obiectiver Obiectivei To verify the OPERABILITY of the SLC l To assure the OPERABILITY of a sys- System.

tem with the capability to SHUTDOWN l the reactor and maintain the SHUT-DOWN condition without the use of control rods.  ;

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Snecificatiorg Snecifigation:

A. Normal System Operation A. Normal System Operation l

During periods when fuel is in the The OPERABILITY of the SLC System l l 1. reactor and prior to startup from a shall be shown by the performance of I Cold Condition, the Standby Liquid the following tests:

Control System shall be operable, except as specified in 3.4.B below. 1. At least once each 3 months each This system need not be operable subsystem shall be tested for OPERA- l when the reactor is in the Cold BILITY by recirculat;c'; demineral- 4 Condition and all control rods are ized water to the test tank and l fully inserted and Specification verifying each pump develops a flow 3.3.A is met. rate 2 38.2 gpm at a discharge pres- ,

sure 2 1300 psig. j

2. At least once during each OPERATING CYCLE:

a. ^%rk th:t th: :tting: Of th Cub l cycter relief f 1 ecc cre l E 0 ' P

ic00 peig and the f21 f e r "i ! !-

-rere! at P1 1300-prig, a

b. Manually initiate the system, except explorive valves, and pump boron i solution from the SLC Storage Tank l l through the recirculation path.

Verify each pump develops a flow  :

rate 2 38.2 gpm at a discharge pressure 2 1300 psig. After pumping baron solution the system will be flushed with demineralized water.

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STANDBY LIOUID CONTROL SYSTEM e  !

j A. The Standby Liquid Control (SLC) System consists of two, distinct subsystems, l 4 each containing one positive displacement pump and independent suction from the

' SLC storage tank, and discharge to a common injection header through parallel l explosive valves. The purpose of the SLC System is to provide the capability l 4

of bringing the reactor from RATED POWER to a cold, xenon-free SHUTDOWN  ;

CONDITION assuming that none of the withdrawn control rods can be inserted. l

{ To meet this objective, the system is designed to inject a quantity of boron that produces a concentration of 660 ppm of boron in the reactor pressure l l vessel in less than 125 minutes. -The 660 ppm concentration in the reactor l

pressure vessel is required to bring the reactor from RATED POWER to a 3.0 l

[ percent ok suberitical condition, considering the hot to cold reactivity j

! difference, xenon poisoning, etc. The time requirement for inserting the boron

solution was selected to override the rate of reactivity insertion caused by f cooldown of the reactor following the xenon poison peak. ,

I The conditions under which the SI.c System must provide shutdown capability are

[ identified in Limiting Conditions for Operation. If no more than one OPERABLE j control rod is withdrawn, the basic shutdown reactivity requirement for the

! core is satisfied and the SLC System is not required. Thus, the basic

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reactivity requirement for the core is the primary detenninant of when the SLC System is required.

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4 l B. Only one of the two SLC subsystems is needed for operating the system. One l j inoperable subsystem does not immediately threaten shutdown capability, and i reactor operation can continue while the inoperable subsystem is being l_ repaired. The seven day completion time is based on the availability of an OPERABLE sabaystem capable of performing the intended SLC system function and

the low probability of a Design Basis Accident (DBA) or severe transient occurring concurrent with the failure of the Control Rod Drive (CRD) system to shut down the plant.

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LIMITING CONDITIONS FOR OPERATION SURVEILLANCE REQUIREMENTS 3.4 STANDBY LIOUID CONTROL SYSTEM 4.4 STANDBY LIOUID CONTROL SYSTEM Apolicability; Anolicability:

Applies to the operating status of Applies to the surveillance require-the Standby Liquid Control (SLC) ments of the Standby Liquid Control System. (SLC) System.

Obiective:

Obiectivet To verify the OPERABILITY of the SLC To assure the OPEPABILITY of a sys- System.

tem with the capability to SHUTDOWN the reactor and maintain the SHUT- t DOWN condition without the use of control rods.

Specifica? ion. Snecification:

A. Normal System Operation A. Normal System Operation

1. During periods when fuel is in the The OPERABILITY of the SLC System reactor and prior to startup from a shall be shown by the performance of l Cold Condition, the Standby Liquid the following tests:

Control System shall be operable, except as specified in 3.4.B below. 1. At least once each 3 months each This system need not be operable subsystem shall be tested for OPERA-when the reactor is in the Cold BILITY by recirculating demineral-l Condition and all control rods are ized water to the test tank and fully inserted and Specification verifying each pump develops a flow 3.3.A is met. rate 38.2 gpm at a discharge pres-sure 1300 psig.

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2. At least once during each OPERATING

! CYCLE:

a. Manually initiate the system, except ,

explosive valves, and pump boron '

solution from the SLC Storage Tank through the recirculation path.

Verify each pump develops a flow rate 38.2 gpm at a discharge pressure 1300 psig. After pumping boron solution the system will be flushed with demineralized water.

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STANDBY LIOUID CONTROL SYSTEM l j A. The Standby Liquid Control (SLC) System consists of two, distinct subsystems, j each containing one positive displacement pump and independent suction from the i

. SLC storage tank, and discharge to a common injection header through parallel ,

]' explosive valves. The purpose of the SLC System is to provide the capability i of bringing the reactor from RATED POWER to a cold, xenon-free SHUTDOWN t i CONDITION assuming that none of the withdrawn control rods can be inserted. l i To meet this objective, the system is designed to inject a quantity of boron l l that produces a concentration of 660 ppm of boron in the reactor pressure l 2 vessel in less than 125 minutes. The 660 ppm concentration in the reactor a pressure vessel is required to bring the reactor from RATED POWER to a 3.0 ,

1 percent Ak suberitical condition, considering the hot to cold reactivity

difference, xenon poisoning, etc. The time requirement for inserting the boron ,

solution was selected to override the rate of reactivity insertion caused by I i cooldown of the reactor following the xenon poison peak.

b i The conditions under which the SLC System must provide shutdown capability are i identified in Limiting conditions for Operation. If no more than one OPERABLE j control rod is withdrawn, the basic shutdown reactivity requirement for the

! core is satisfied and the SLC System is not required. Thus, the basic reactivity requirement for the core is the primary determinant of when the SLC.

System is required.

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B.

Only one of the two SLC subsystems is needed for operating the system. One i inoperable subsystem does not immediately threaten shutdown capability, and ,

I reactor operation can continue while the inoperable subsystem is being repaired. The seven day completion time is based on the availability of an 3 OPERABLE subsystem capable of performing the intended SLC system function and j the low probability of a Design Basis Accident IDBA) or severe transient occurring concurrent with the failure of the Control Rod Drive (CRD) system to 4 shut down the plant.

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4 ENCLOSURE

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1 In the unlikely event the suction piping temperature could not be I maintained above the adjusted solution saturation temperature *, due to complete failure of the heating system and excessively cold weather conditions outside the i

, reactor building, the following operating procedures will be followed. The tank j outlet valve would be temporarily closed and the solution drained from the pump suction line and replaced with domineralized water. This represents no new operating procedures as the system is designed to operate in this manner when it is

, being tested using the test tank, and no credit is taken for the storage of sodium pentaborate in the suction lines. M j Each positive displacement pump is capable of injecting the required I weight of solution into the reactor in 82 to 116 minutes, independent of the amount

, of solution in the tank (within the required volume range of 3132 gal.9 16% and

4414 gal.0 11.5%), and the pump rate (within the specified Tech. Spec. limits of a minimum of 38.2 gpm). The pump and system design pressure between the explosive valves and the pump discharge is 1460 psig. MEiiilisMElijji@i~nsodijiii5iEEMW4

. K5~C6hfgTf5MSEil4Eguiiip34fDi(65Es~siiM456iistiH5ID$MYM3171[Cf6dIT4116iiFiblWNi1Wi!W RNIEuYMEERIEWIKUEWEnWI5E#k%WXtTiGpdiiiiEWEEMEEsi$iEHsiBiiSiiHW4 SSIM66sl@ The two relief valves are set fe. mini-- mi 1+56 yeiv .nd a full j ec-mol Lien y..eene cf 1000 yeiv f43766isif5ElfiM)ilitiX11EliI4W166 To prevent '

bypass flow from one pump in case of relief valve failure in the line from the other pump, a check valve is installed downstream of each relief valve line in the pump discharge pipe.

The two explosive-actuated injection valves provide assurance of opening )

when needed and ensure that boron will not leak into the reactor even when the pumps j are being tested.

Each explosive valve is closed by a plug in the inlet chamber. The plug l is circumscribed with a deep groove so the end will readily shear cff when pushed with the valve plunger. This opens the inlet hole through the plug. The sheared end is pushed out of the way in the chamber; it is shaped so it will not block the i ports after release.

The shearing plunger is actuated by an explosive charge with dual ignition primers, inserted in the side chamber of the valve. Ignition circuit continuity is monitored by a trickle current, and an alarm occurs in the control room if either circuit opens. Indicator lights show which primary circuit opened.

To service a valve after firing, a six-inch length of pipe (spool piece) must be removed immediately upstream of the valve to gain access to the shear plug.

The SLC system is actuated by separate, keylock on-off switches for each pump on the control room console. The use of keylock switches assures that switching from the "offa position is a deliberate act. Starting Pump A will open explosive valve 14A and close the inboard isolation valve of tihe Reactor Water Clean Up (RWCU) system to prevent loss or dilution of the boron. Similarly, starting Pump B will open explosive valve 14B and close the outboard isolation valve of the RWCU system. Separate switches for each pump allows both pumpc to operate simultaneously to inject the boron.

• The sdjusted saturation temperature is equal to the actual saturation temperature plus 10*F.

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l USAR The low-level setpoint for the SLC storage tank, iu based on the minimum

! weight of sodium pentaborate in solution at the design solution concentration of l 15.0 weight percent The high levd setpoint is selected to provide an adequate ,

operating region between the high and low alarm setpoints to minimize the frequency 1 of tank servicing. l l

cooldown of the nuclear system will rnquire a minimum of several hours j to remove the thermal energy stored in the reactor, cooling water, and associated

! equipment and to remove most of the radioactive decay heat. The controlled limit  !

for the reactor vessel cooldcwn is 100*F per hour, and normal operating temperature ,

is approximately 550*F. Usually, using the main condenser and various shutdown l cooling systems to shut down the plant will require 10 to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> before the

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reactor vessel is opened and much longer to reach room temperature (70'F); this is the condition of maximum reactivity and, therefore, the condition that requires the maximum concentration of boron.

The specified boron injection rate is limited to the range of 7 to 50 ppm per minute. The lower rate assures that the boron gets into the reactor in about two hours, considerably quicker than the cooldown rate. The upper limit injection rate assures that there is sufficient mixing so the boron does not recirculate through the core in uneven concentrations that could possibly cause nuclear power to rise and fall cyclically.

The SLc system equipment necessary for injection of neutron absorber solution into the reactor is designed as class I (seismic) for withstanding the specified earthquake loadings (see Section XII and Appendix C). Nonprocess equipment such as the test tank is designed as class II (seismic). The system piping and equipment are designed, installed, and tested in accordance with I requirements stated in Appendix c. 1 The SLC system is required to be operable in the event of a loss of normal station power. Therefore the pumps, valves, and controls are powered from the standby a-c power supply in the absence of normal power. The pumps and valves are powered and controlled from separate buses and circuits so that a single electrical failure will not prevent system operation. l The SLC system and pumps have sufficient pressure margin, .e Le um ellcal 2.i- .elle! ,elv. ..iLiuv ..ny. e 100 Lv 1000 v.ig, to assure solution injection into the reactor at anticipated ATWS pressures (near 1100 psig), which are above the normal pressure of approximately 1030 psig in the bottom of the reactor. 4 W#7d$fdllE51MfDsWsEssWMF84fEi$MEpiif5Df1MsiisIdER36sETyhsEE7sliiW6issi@k I NEpur6ENETsiEs55sNErstipitsd7BEisfaluuaI1rfEWWssuMNit1%EIMAYpsliiN#15#s EsNsliTEGETsip5EEsdYiiiYiEaaTWsiiirguFayfugwa:56EigspEisgtsg w it15 5 E ni5ssaD M )

5s1WMIEEisEWdsuTELT6sasWiiRf6FYp6sHWsidiWTsisashE9pEspMppisleffsEtiiRWs HINGinTh6ErffWsHRE6HisifskriduisEt6ErisisidEEHbHhsifopsisEWiBEEsiRui 6sWssi@iistp6Ih@sfiffdsEf6iiREsstFT The SLC system positive displacement pumps cannot overpressurize the nuclear system because the nuclear system relief and safety valves begin to relieve pressure above approximately 1080 to 1100 peig.

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While both pumps may be operated simultaneously, only one of the two l standby liquid control pumps is needed for system operation pursuant to the original design basis for the system. If one pump is found to be inoperable, there is no l immediate threat to shutdown capability, and reactor operation can continue during I repairs. The period while one redundant component upstream of the explosive valves may be out of operation should be consistent with the very small probability of failure of both the control rod shutdown capability and the alternate component in the SLC system, together with the fact that nuclear system cooldown takes several

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< l i between the check valves. Position indicator lights in the control room indicate that the local valve is closed for tests or open and ready for operation. Leakage <

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1 from the reactor through the first check valve can be detected by opening the arme j test connection when the reactor is pressurized.

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! The test tank contains domineralized water for approximately i i three minutes of pump operation. Domineralized water is available for refilling or j i flushing the system. 1

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Should the boron solution ever be injected into the reactor, either i I

l intentionally or inadvertently, then after making certain that the normal reactivity l

controls will keep the reactor subcritical, the boron is removed from the reactor  !

4 coolant system by flushing for gross dilution followed by operating the RWCU syetem. y l There is practically no effect on reactor operations when the boron concentration -]

l has been reduea4 below approximately 50 ppm.  !

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The concentration of the sodium pentaborate in the solution tank is )

determined periodically by chemical analysis.

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! 9.6 Nuclame Safety Ocarational Rmanir===nts j NOTE: Limiting Conditions for Operation and surveillance testing j requirements stated and listed in this subsection are based on analyses performed j at the time of original license application. For current information refer to the

Technical specifications.

j Table III-9-1 presents the nuclear safety operational requirements for the SLC system for each BWR operating state. The entries in this table represent 3 an extension of the plant-wide BWR systems analysis of Appendix G to the components j of the SLC system.

i j The limiting conditions for operations (LCOs) of the SLc system listed i below were included in the original FsAR. Section 3.4 of the CNS Technical j specifications contains Loos which may differ or be in addition to the following Loos.

1. The SLC system shall be operable at any time that more than one operable control rod is withdrawn.

2. At all times when the SLC system is required to be operable the following conditions shall be mets

a. The boron concentration in the liquid control solution shall be maintained s required in the Technical specifications.

b. The volume of liquid control solution in the SLC tank shall be maintained as required in the Technical specifications.

c. 'The temperature of the liquid control solution shall be maintained above the curve presented in Figure III-9-3,

3. If one SLC system pumping loop becomes inoperable at a time when the system is required to be operable, the reactor can remain in operation provided that repairs are accomplished within seven days.

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, ATTAdigENT 3 LIST OF NRC COMMITMENTS i

Correspendence No: NLS970093 The following table identifies those actions committed to by the District in this document. Any other actions discussed in the submittal represent intended or planned actions by the District. They are described to the NRC for the NRC's

' information and are not regulatory commitments. Please notify the Licensing Manager at C'aoper Nuclear Station of any questions regarding this document or any associated regulatory commitments.

COMMITTED DATE COMMITMENT OR OUTAGE None i

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l PROCEDURE NUMBER O.42 { REVISION NUMSER 4 l PAGE 8 OF 9 l {

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