ML20217M367

LAR 98-07 to License NPF-86,modifying Tech Specs 3.7.6, Control Room Emergency Makeup Air & Filtration Subsystem

ML20217M367
Person / Time
Site:	Seabrook
Issue date:	03/27/1998
From:	Feigenbaum T NORTH ATLANTIC ENERGY SERVICE CORP. (NAESCO)
To:
Shared Package
ML20217M338	List: ML20217M330 ML20217M367 ML20217M377
References
NUDOCS 9804080083
Download: ML20217M367 (4)

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s This License Amendment Request is submitted by North Atlantic Energy Service Corporation pursuant to 10 CFR 50.90 and 10 CFR 50.4. The following information is enclosed in support of this License Amendment Request:

. Section 1 -

Introduction and Safety Assessment for Proposed Changes

. Section 11 -

Markup of Proposed Changes

. Section 111 -

Retype of Proposed Changes

. Section IV -

Determination of Significant Hazards for Proposed Changes

. Section V - Proposed Schedule for License Amendment issuance and Effectiveness

. Section VI -

Environmentalimpact Assessment Swom and Subscribed Tinf

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W T ~ Notary Public Executive Vice President l ,

and Chief Nuclear Officer I

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INTRODUCTION AND SAFETY ASSESSMENT OF PROPOSED CHANGES i

l. A. Introduction License Amendment Request (LAR) 98-07 proposes to modify.the action requirements as l presently contained in Technical Speci6 cation 3.7.6, " Control Room Emergency Makeup Air l and Filtration". Currently, the action for both trains of Control Room Emergency Makeup Air and Filtration Subsystem (CREMAFS) inoperable in Modes 5 and 6 requires the suspension of all operations involving core alterations or positive reactivity changes. The proposed change will modify the existing requirement by eliminating the restriction of suspending positive reactivity changes.

The proposed change to eliminate the positive reactivity restriction in Modes 5 and 6 with both '

trains of CREMAFS inoperable is consistent with similar actions in NUREG-1431 " Standard Technical Specifications Westinghouse Plants".

B. Safety Assessment of Proposed Changes l BACKGROUND l The function of the Control Room Emergency Makeup Air and Filtration Subsystem (CREMAFS) is to remove particulate and gaseous activity from the control room atmosphere following a core damage event with subsequent release. Currently, the Technical Specification l for the CREMAFS also includes the cooling function of the Control Room Air Conditioning  ;

i Subsystem (CRACS), which is required both for habitability purposes and for maintaining an appropriate equipment service environment.

The CREMAFS is required to be operable during all modes of operation. Presently, when both trains of CREMAFS are inoperable in Modes 5 and 6, Technical Specification 3.7.6 ACTION b l . requires the suspension of all operations involving positive reactivity changes or core alterations.

However, a shutdown required per Technical Specification 3.0.3, as a result of both trains of CREMAFS inoperable in Modes 1 through 4, would prevent cooling the plant down to a stable' temperature in Mode 5 without violating the literal requirements of Technical Specifications.

A similar event to this occurred in December of 1997 and was reported to the NRC in LER 97-18

" Control Room Emergency Makeup Air and Filtration Subsystem inoperability." On December 16,1997, the plant entered Technical Specification 3.0.3 and commenced a plant shutdown due l to both trains of the CREMAFS being inoperable per Technical Specification 3.7.6. At the time of the event, the plant was in Mode 4 transitioning towards a restart, following an unrelated outage. Technical Specification 3.0.3 was exited upon reaching Mode 5, where Technical i

Specification 3.7.6 has an applicable ACTION for both trains of CREMAFS inoperable in Mode 5.

During the cooldown into Mode 5, control room operators reduced the Reactor Coolant System (RCS) temperature from 200 to approximately 180-190 degrees Fahrenheit to ensure the that plant was maintained in a stable condition. The action requirements for Technical Specification 3.7.6 in Mode 5 require the suspension of all operations involving positive reactivity changes and core alterations. Compliance with this action statement would prevent a cooldown below Page1 l

200 degrees Fahrenheit. Based on this, the operators borated the RCS to offset the positive reactivity change associated with the cooldown. The net result of the boration was a negative reactivity change which satisfied the intent of Technical Specification 3.7.6. Throughout the remainder of Mode 5 operation, control room personnel maintained RCS temperature in a stable band. It was subsequently determined that the cooldown actions did not meet the literal requirements of suspending "all" positive reactivity changes, of which the cooldown constituted a positive reactivity addition. Therefore, this event was determined to be reportable pursuant to 10 CFR 50.73(a)(2)(i)(B) as a condition prohibited by the plant's Technical Specifications.

DESCRIPTION OF TECHNICAL SPECIFICATION CilANGE REQUEST Presently, the requirements for CREMAFS and CRACS are combined and contained in Technical Specification 3.7.6 based on operating mode. The proposed license amendment will modify the action requirements as presently contained in Technical Specification 3.7.6, " Control Room Emergency Makeup Air and Filtration" Currently, the action for both trains of CREMAFS inoperable in Modes 5 and 6 requires the suspension of all operations involving core alterations or positive reactivity changes. The proposed change will modify the existing requirement by eliminating the restriction of suspending positive reactivity changes.

SAFETY ASSESSMENE The system description and safety analysis for the control room area ventilation are provided in Sections 6.5.1 and 9.4.1 of the Updated Final Safety Analysis Report (UFSAR). The area ventilation serves two basic functions: (1) to protect the control room environment from external airborne concerns (e.g., radioactive gases or particulate, etc.) and (2) to maintain the temperature in the control room within a range needed to allow operators and the control room equipment to perform properly.

The first function, protecting the control room environment from external airborne problems, depends heavily on the CREMAFS. By ensuring proper filtration and proper pressurization, in-leakage into the control room is controlled as is the quality of the control room air. Calculations were performed based on the availability of this system to ensure that the post-event atmosphere will allow the operators to safely function in the control room.

The second function, maintaining the temperature in the control room within a range needed to allow operators and equipment to perform properly, is achieved primarily by the CRACS. This system is conservatively sized to handle the worst heat load condition postulated based on normal conditions, accident conditions and conservative meteorology. The actual load can vary greatly. Temperature changes in the control room are gradual even under degraded conditions.

Time is available to find alternate solutions to cool the control room.

Presently, Technical Specification 3.7.6 " Control Room Emergency Makeup Air and Filtration Subsystems" includes the operability requirements for both the CREMAFS and the CRACS.

The CREMAFS functions to protect the control room environment from external airborne concerns (e.g., radioactive gases or particulate, etc.). The CRACS functions to maintain the temperature in the control room within a range needed to allow operators and the control room equipment to perform properly.

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l The proposed license amendment will modify the action requirements as presently contained in  :

Technical Specification 3.7.6, " Control Room Emergency Makeup Air and Filtration" l

Currently, the action for both trains of CREMAFS inoperable in Modes 5 and 6 requires the suspens' ion of all operations involving core alterations or positive reactivity changes. The proposed change will modify the existing requirement by eliminating the restriction of suspending positive reactivity changes.

The Seabrook Station UFSAR Section 15.4.6 analyzes chemical and volume control system malfunctions that could result in a decrease in the reactor coolant system boron concentration for all modes of operation. The results of the analysis conclude that for dilutions during cold shutdown or refueling there is adequate time for the operator to terminate an unplanned boron ,

dilution event prior to the loss of all shutdown margin. Following the termination of the dilution flow, the reactor will be in a stable condition with no fuel damage. No radiological consequences have been calculated for this postulated event since no fuel or clad damage is predicted.

i There are no presently evaluated positive reactivity or boron dilution accidents that credit the 8 CREMAFS to mitigate its consequences or provide radiological protection. The positive reactivity restriction in Modes 5 and 6 is overly restrictive in that it does not allow cooldown below 200 F when Mode 5 is entered as a result of both trains of CREMAFS being inoperable l nor does it allow RCS temperature to vary while in Modes 5 and 6. The restriction is also I redundant to Technical Specification 3.1.1.2 " Reactivity Control Systems Shutdown Margin-Ty less than or equal to 200 F" in Mode 5 and Technical Specification 3.9.1 " Refueling Operations Boron Concentration" in Mode 6. Technical Specification 3.1.1.2 action, with

shutdown margin less than the limit in the Core Operating Limits Report or with the RCS boron l concentration less than 2000 ppm boron, requires immediate and continued boration until the l

restoration of the required shutdown margin or boron concentration. Similarly, Technical {

Specification 3.9.1 actions require suspension of core alterations or positive reactivity changes,  !

in addition to immediate and continued boration until the restoration of the required shutdown f margin (Km) or boron concentration while in Mode 6. Sufficient shutdown margin ensures that (1) the reactor can be made suberitical from all operating conditions, (2) the reactivity transients associated with the postulated accident conditions are controllable within acceptable limits and (3) the reactor will be maintained sufficiently suberitical to preclude inadvertent criticality in the i shutdown condition. The above referenced reactivity control system specifications provide the l necessary protection for postulated reactivity addition accident conditions. Maintaining shutdown margin within acceptable limits will allow for deliberate evolutions (such as snall changes in temperature and boron concentration), without adversely affecting the net core

! reactivity.

l The proposed change to eliminate the positive reactivity restriction in Modes 5 and 6 with both trains of CREMAFS inoperable is consistent with similar actions in NUREG-1431 " Standard Technical Specifications Westinghouse Plants".

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