ML20215J051

Safety Evaluation Supporting Proposed Rev to Tech Spec 3/4.10.4 Re Reactor Coolant Loops to Replace Refs in Reactor Protection Sys P-7 Permissive w/P-10 Permissive

ML20215J051
Person / Time
Site:	Wolf Creek
Issue date:	06/19/1987
From:	WOLF CREEK NUCLEAR OPERATING CORP.
To:
Shared Package
ML20215J012	List: ML20215J009 ML20215J051 ML20215J063
References
NUDOCS 8706240304
Download: ML20215J051 (6)

Text

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i ATTAclDiENT I SAFETY EVALUATION l

l 8706240304 070619 PDR ADOCK 050004G2 PDR P

SAFETY EVALUATION This application for amendment revises Wolf Creek Generating Station (WCGS), ,

Unit No. 1, Technical Specification 3/4.10.4, Reactor Coolant Loops, I replacing references to the Reactor Protection System P-7 permissive with the P-10 permissive.

Background

Technical Specification 3/4.10.4, Reactor Coolant Loops, is a special test exception which allows requirements to be suspended provided certain criteria are met. One of the requirements which may be suspended is Technical Specification 3.4.1.1 during the performance of startup and PHYSICS TESTS in MODE 1 or 2 provided:

1) The THERMAL POWER does not exceed the P-7 Interlock Setpoint, and

2) The Reactor Trip Setpoints are on the OPERABLE Intermediate and Power Range channels are set less than or equal to 25% of RATED THERMAL POWER.

The proposed technical specification revision would replace the P-7 Interlock Setpoint with the P-10 Interlock Setpoint where P-7 is listed in Technical Specification 3/4.10.4 Limiting Condition for Operation and Surveillance Requirements.

Interlock P-7 is a Reactor Protection System permissive that unblocks certain Reactor Trips when going above 10 percent power. P-7 is derived from a bistable circuit that is fed from P-10 and P-13. Either P-10 or P-13 will trip the P-7 bistable. The presence of P-10 allows a manual block of the power range (low setpoint) reactor trip, the intermediate range reactor trip, and intermediate rod stops. P-10 is also used as a back-up to block the source range reactor trip. The P-13 permissive provides a signal when the turbine is greater than 10 percent power. The permissive is generated when one-of-two turbine impulse pressure channels indicates greater than 10 percent power.

Technical Specifications presently require both the P-10 and P-13 permissives to be OPERABLE whenever this specification is being used for low power physics testing. This amendment request would require only the P-10 permissive to be OPERABLE. This change would reduce the amount of surveillence testing required prior to entering this technical speci fica tion .

Evaluation The P-7 permissive is derived from a bistable circuit indicating greater than ten percent power as measured by either first stage turbine pressure or nuclear-power range level. The turbine power input is supplied by P-13 and the nuclear power range input is supplied permissive P-10. Permissive P-7 defeats the automatic block of the following:

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. Attachm:nt I to ET 87-0219 Page 2 of 3 June 19, 1987

1) Pressurizer low pressure trip

2) Pressurizer high level trip

3) Reactor Coolant Pump undervoltage and underfrequency trips

4) Reactor coolant low flow trip in more than one loop The F-10 permissive is used to bypass the intermediate range high flux and power range low setpoint trips during an approach to power. It also serves as a backup for P-6 by automatically blocking out the source range high voltage and provides one of the two inputs to P-7. P-10 is derived from a bistable circuit indicating greater than ten percent power as measured by the' power range nuclear instruments. In order to block the intermediate range high flux power range low setpoint trips, the reactor must be above ten percent nuclear power.

The P-13 permissive provides a signal when the turbine is greater than 10 percent power. The permissive is generated when one-of-two turbine impulse pressure channels indicates greater than ten percent power. The P-13 permissive is the other one of the two inputs to P-7 Low power physics testing involves tests run on the reactor following a refueling outage. During this testing the turbine is left on the turning gear and not 'used. Therefore, the P-13 signal is always at zero.

Consequently, P-10 is the only signal to P-7 while the plant is performing this Technical Specification. By completing the surveillance requirements for P-10 P-7 is ensured of being functional. Performing the surveillance requirments for P-13 for this Technical Specification requirement when it is not used for an input to P-7 is unnecessary.

The proposed change does not increase the probability of occurrence or the consequences of an accident or malfunction of equipment important to safety previously evaluated in the Safety Analys11 Report. This amendment will only eliminate surveillance requirements fc. P-13 while operating under this l Technical Specification. Since P-13 will not input into P-7 with the turbine left on the turning gear and not used, performing these surveillance .

requirements does not affect the reliability of the circuit which will trip the P-7 bistable.

The proposed change does not create the possibility of an accident or .

malfunction of a different type than any evaluated previously in the Safety Analysis Report. No additional plant equipment is being added nor will any l existing plant equipment be operated in a manner inconsistent with existing requirements. The proposed amendment does not change any setpoints related ,

l to nuclear safety. i The proposed change does not affect the margin of safety as defined in the

! basis for any technical specification. This amendment only eliminates the need to perform the surveillance requirements for P-13 while the plant is

, operating under this Technical Speci fica tion. The setpoints remain I

unchanged.

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, Attachstnt I to ET 87-0219 Page 3 of 3

.Juna'19,'1987

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Conclusion' Based on the' above discussion and the considerations presented in Attachment II, ; the ' proposed revision to Technical: . Specification - 3/4.10.4 .does not.

increase the probability of occurrence.or. the consequences of an accident or malfunction'of ~ equipment.important to safety 'previously evaluated in the g

Safety Analysis;' Report;- or create the possibility for an~ accident or malfunction of a different type than any previously evaluated in~ the Safety Analysis. Report; or reduce the margin of safety. as defined in the basis for -

any Technical Specification. Therefore, the proposed revision does not adversely affect' or . endanger. the health and safety of the general public or ,

involve- a significant safety hazard.  ;

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i ATTACHMENT II f

SIGNIFICANT HAZARDS CONSIDERATION i

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'* - 'SIGNIFICANT HAZARDS CONSIDERATION This application for amendment revises Wolf Creek Generating Station, Unit No ~1,. Technical Specification 3/4.10.4, Reactor Coolant Loops, replacing

. references to the . Reactor Protection System P-7 permissive with the P-10 permissive.

1. The proposed change does not involve a significant increase in the-probability or consequences of an accident previously . evaluated.

The proposed amendment would only eliminate . surveillance.

requirements for P-13 which have no effect on plant operation while using this . Technical Specification. With the turbine off line, P-13 does not provide an input into P-7. This leaves P-10 as the only input which can trip the P-7 bistable.

2. The proposed change does not create the possibility of a new or 6ifferent. kind of accident from any previously evaluated. . There are no new failure modes or mechanisms associatedL with the proposed changes. No. additional plant equipment is . being ladded nor will any existing plant equipment be operated in a manner inconsistent with existing requirements. . The proposed change-does-not change any.setpoints related to nuclear safety.

3. The. proposed change does not involve a significant reduction in a '

margin of safety. The proposed amendment does not affect ' any -

technical specification margin of safety. This amendment only eliminates the need to perform the surveillance. requirements for P-13 while the plant is operating under this Technical Specification. The proposed change does not alter the manner in which safety limits and limiting safety system setpoints are determined.

Based on the above discussions and those presented in Attachment I,_ it has been determined that the requested Technical. Specification revision does not.

involve a significant increase in the probability or consequences of an accident or other adverse condition over previous evaluations; or create the possibility.of a new or different kind of accident or condition over

-previous evaluations; or involve a significant reduction in a margin of sa fety. There fore , the requested license amendment does not involve a significant hazards consideration.

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