ML20091S160

Proposed Tech Specs Re Positive Moderator Temp Coefficient

ML20091S160
Person / Time
Site:	Seabrook
Issue date:	08/28/1995
From:	NORTH ATLANTIC ENERGY SERVICE CORP. (NAESCO)
To:
Shared Package
ML20091S159	List: ML20091S156 ML20091S160
References
NUDOCS 9509080012
Download: ML20091S160 (2)

Text

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REACTIVITY CONTROL SYSTEMS ,

BASES, B0 RATION CONTROL 3/4.1.1.3 MODERATOR TEMPERATURE COEFFICIENT (Continued)

The surveillance recuirements for measurement of the MTC at the i beginning and near the enc of the fuel cycle are adequate to confirm that the MTC remains within its limits since this coefficient changes slowly due 3rincipally to the reduction in RCS boron concentration associated with fuel

)urnup.

The cycle specific upper MTC limit in the COLR is determined during the  ;

design of each cycle. The upper MTC limit provides assurance of compliance i with the ATWS Rule and the basis for the Rule by limiting core damage '

frequency from an ATWS event below the target of 1.0 x 10 4 per reactor year established in SECY-83-293. The COLR limit will also assure that the core ,

will have an MTC less positive than -8 PCM/DEG F for at least 95% of the cycle time at full power.

Prior to initial operation above 5% RATED THERMAL POWER after each fuel I loading, the MTC is measured as recuired by Surveillance Requirement l 4.1.1.3.a. A measurement bias is cerived from the difference between test  !

measurement and test prediction. All predicted values of MTC for the cycle  :

are conservatively corrected based on measurement bais. The corrected ,

predications are then compared to the maximum upper limit of Technical Specification 3.1.1.3. Control rod withdrawal limits are established, if required, to assure all corrected values of predicted MTC will be less positive than the limit specified in the COLR, and the maximum upper limit required by Technical Specification 3.1.1.3.

3/4.1.1.4 MINIMUM TEMPERATURE FOR CRITICALITY l

4 This specification ensures that the reactor will not be made critical with the Reactor Coolant System average temperature less than 551' F. This limitation is required to ensure: (1) the moderator temperature coefficient is within its analyzed temperature range. (2) the trip instrumentation is within its normal operating range, (3) the pressurizer is capable of being in an OPERABLE status with a steam bubble, and (4) the reactor vessel is above its minimum RT, temperature, t

3/4.1.2 BORATION SYSTEMS The Boron Injection System ensures that negative reactivity control is available during each mode of facility operation. The components required to perform this function include: (1) borated water sources. (2) charging pumps, (3) separate flow paths. (4) boric acid transfer pumps, and (5) an emergency power supply from OPERABLE diesel generators.

With the RCS in MODES 1, 2. or 3. a minimum of two boron injection flow paths are required to ensure single functional capability in the event an assumed failure renders one of the flow paths inoperable. The boration

capability of either flow path is sufficient to provide a SHUTDOWN MARGIN as specified in the CORE OPERATING LIMITS REPORT from expected operating conditions after xenon decay and cooldown to 200*F. The maximum expected SFARR00K - UNIT 1 B 3/4 1-2 Amendment No. 9. 33 9509080012 950828 PDR ADOCK 05000443  !

._P. . _ _ DR. _

, REACTIVITY CONTROL SYSTEMS BASES 3/4.1.2 BORATION SYSTEMS (Continued) boron capability requirement occurs at E0L from full power equilibrium xenon conditions and requires 22.000 gallons of 7000 ppm borated water from the boric acid storage tanks or a minimum contained volume of 477.000 gallons of 2000 ppm borated water from the refueling water storage tank (RWST).

The limitation for a maximum of one centrifugal charging pump to be OPERABLE and the Surveillance Requirement to verify all charging pumps except the required OPERABLE pump to be inoperable in MODES 4. 5. and 6 provides assurance that a mass addition pressure transient can be relieved by operation of a single PORV or an RHR suction relief valve.

As a result of this, only one boron injection system is available. This is acceptable on the basis of the stable reactivity condition of the reactor, the emergency power supply requirement for the OPERABLE charging pump and the additional restrictions prohibiting CORE ALTERATIONS and positive reactivity changes in the event the single injection system becomes inoperable.

The boron capability required below 200*F is sufficient to provide a SHUTDOWN MARGIN as specified in the CORE OPERATING LIMITS REPORT after xenon decay and cooldown from 200* F to 140' F. This condition requires a minimum contained volume of 6500 gallons of 7000 ppm borated water from the boric acid storage tanks or a minimum contained volume of 24.500 gallons of 2000 ppm borated water from the RWST.

The contained water volume limits include allowance for water not available because of discharge line location and other physical characteristics.

The limits on contained water volume and boron concentration of the RWST also ensure a pH value of between 8.5 and 11.0 for the solution recirculated within containment after a LOCA. This pH band minimizes the evolution of iodine and minimizes the effect of chloride and caustic stress corrosion on mechanical systems and components.

The OPERABILITY of one Boron Injection System during REFUELING ensures that this system is available for reactivity control while in MODE 6.

The limitations on OPERABILITY of isolation provisions for the Boron Thermal Regeneration System and the Reactor Water Makeup System in Modes 3. 4,

5. and 6 ensure that the boron dilution flow rates cannot exceed the value assumed in the transient analysis.

3/4.1.3 MOVABLE CONTROL ASSEMBLIES )

The specifications of this section ensure that: (1) acceptable power distribution limits are maintained. (2) the minimum SHUTDOWN MARGIN is maintained, and (3) the potential effects of rod misalignment on associated accident analyses are limited. OPERABILITY of the control rod Josition indicators is required to determine control rod positions and t1ereby ensure compliance with the control rod alignment and insertion limits. Verification that the Digital Rod Position Indicator agrees with the demanded position SEABROOK - UNIT 1 B 3/4 1-3 Amendment No. 9

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