ML20196J004

Proposed Revised TS Bases for Section 3.5.F,correcting Volume of Water Available in Refuel Cavity & Dryer/Separator Pool When Flooded to Elevation 114 Ft & Revising Torus Water Volume to Reflect Volume Above Min Pump NPSH

ML20196J004
Person / Time
Site:	Pilgrim
Issue date:	07/22/1997
From:	BOSTON EDISON CO.
To:
Shared Package
ML20196J000	List: ML20196H997 ML20196J004
References
NUDOCS 9708010246
Download: ML20196J004 (2)

Text

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BASES:

., V 3.5 - CORE AND CONTAINMENT COOLING SYSTEMS (Cont) ,

E. Automatic Depressurization System (ADS)

The limiting conditions for operating the ADS are derived from the Station Nuclear Safety Operational Analysis (FSAR Appendix G) and a detailed functional analysis of the ADS (FSAR Section 6).  !

This specificaticzn ensures the operability of the ADS under all conditions for which the

automatic or manual depressurization of the nuclear system is an essential response to l

station abnormalities.

l The nuclear system pressure relief system provides automatic nuclear system l depressurization for small breaks in the nuclear system so that the low pressure coolant injection (LPCI) and the core spray systems can operate to protect the fuel barrier.

Because the Automatic Depressurization System does not provide mak'eup to the reactor primary vessel, no credit is taken for the steam cooling of the core caused by the system actuation to provide further conservatism to the CSCS. Performance

analysis of the Automatic Depressurization System is considered only with respect to its l depressurizing effect in conjunction with LPCI or Core Spray. There are four valves l provided and each has a capacity of 800,000 lb/hr at a reactor pressure of 1125 psig.

The allowable out of service time for one ADS valve is determined as 14 days because of the redundancy and because of HPCI operability; therefore, redundant protection for

the core with a small break in the nuclear system is still availa?

The ADS test circuit permits continued surveillance on the operable relief alves to assure that they will be available l' required.

F. Minimum Low Pressure Coolina and Diesel Generator Availability The purpose of Specification F is to assure that adequate core cooling equipment is available at all times. If, for example, one core spray were out of service and the diesel which powered the opposite core spray were out of service, only 2 LPCI pumps would be available. It is during refueling outages that major maintenance is performed and

, during such time that alllow pressure core cooling systems may be out of service. This-l specification provides that should this occur, no work will be performed on the primary system which could lead to draining the vessel. This work would include work on certain control rod drive components and recirculation system. Specification F allows removal of one CRD mechanism while the torus is in a drained condition without compromising core cooling capability. The available core cooling capability for a I potential draining of the reactor vessel while this work is performed is based on an l estimated drain rate of 300 gpm if the control rod blade sealis unseated. Flooding the l refuel cavity and dryer / separator pool to elevation 114'-0" corresponds to approximately 305,000 gallons of water and will provide core cooling capability in the event leakage from the control rod drive does occur. A potential draining of the reactor vessel (via l l control rod blade leakage) would allow this water to enter into the torus and after approximately 243,000 gallons have accumulated, the torus would be able to serve as ]

l l

a common suction header. This would allow a closed loop oporation of the LPCI

- system and the core spray system (once re-aligned) to the torus. In addition, the other

! core spray system is lined up to the condensate storage tanks which can supplement i the refuel cavity and dryer / separator pool water to provide core flooding, if required.

i Specification 3.9 must also be consulted to determine other requirements for the diesel j generators.

1 i Revision 197 i Amendment No.15,109r435,140,15e B3/4.5-5 I

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97000io PDR A g % $93

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BASFS:

., '. 3.6 - CORE AND CONTAINMENT COOLING SYS e EMS (Cont)

G. Deleted H. Maintenance of Filled Discharae Pioe if the discharge piping of the core spray, LPCI system, HPCI, and RCIC are not filled, a water hammer can develop in this piping when the pump and/or pumps are started. An analysis has been done which shows that if a water hammer were to occur at the time at which the system were required, the system would still perform its design function.

However, to minimize damage to the discharge piping and to ensure added margin in the operation of these systems, this Technical Specification requires the discharge lines to be filled whenever the system is in an operable condition.

An acceptable method of ensuring that the lines are full is to vent at the t,t,n points.

The monthly frequency is based on the gradt,al nature of void buildup in the ECCS piping, the procedural controls, and operating experience.

4.5 CORE AND CONTAINMENT COOLING SYSTEMS SURVEILLANCE FREQUENCIES The testing interval for the core and containment cooling systems is based on industry practice, quantitative reliability analysis, judgment and practicality. The core cooling systems have not been designed to be fully testable during operation. For example, in the case of the HPCI, automatic initiation during power operation would result in pumping cold water into the reactor vessel which is not desirable. Complete ADS testing during power operation causes an undesirable loss-of-coolant inventory. To increase the availability of the core and containment cooling systems, the components l which make up the system; i.e., instrumentation, pumps, valves, etc., are tested )

frequently. The pumps and motor operated valves are tested in accordance with ASME B&PV Code,Section XI (IWP and IWV, except where specific relief is granted) to assure their operability. The frequency and methods of testing are described in the PNPS IST program. The PNPS IST Program is used to assess the operational readiness of pumps and valves that are safety-related or important to safety. Wnen components are tested and found inoperable the impact on system operability is determined, and corrective action or Limiting Conditions of Operation are initiated. A simulated automatic actuation test once each cycle combined with code inservice testing of the pumps and valves is deemed to be adequate testing of these systems.

The surveillance requirements provide adequate assurance that the core and l containment cooling systems will be operable when required.

Revision 197 Amendment No. Se, 135,149,157 B3/4.5-6