ML20072S074

Application for Amend to License DPR-35 Re Proposed TS Change to Standby Gas Treatment & Control Room High Efficiency Air Filtration Sys Requirements

ML20072S074
Person / Time
Site:	Pilgrim
Issue date:	09/06/1994
From:	Oliver L BOSTON EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20072S077	List: ML20072S074 ML20072S086
References
94-099, 94-99, NUDOCS 9409130410
Download: ML20072S074 (7)

Text

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10CFR50.90 G l Boston Edison Pdgom Nuclear Power Staton Rocky HJi Road Plymouth, Massachusetts 02360 l L. J. OHvier Vice President Nuclear operations and station Onector September 6,1994 l

l BECo Ltr. #94-099 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 Docket No. 50-293 License No. DPR-35 Proposed Technical Specification Change to Standby Gas Treatment and the Control Room Hiah Efficiency Air Filtration System Reauirements The Boston Edison Company (BECo) proposes changes to Pilgrim Nuclear Power Station Technical Specification sections 3.7.B.1.a, 3.7.B.1.c, 3.7.B.1.e, 3.7.8.2.a, and 3.7.B.2.c. The proposed change also adds new sections 3.7.B.1.f and 3.7.B.2.e. These sections require both trains of the Standby Gas Treatment (SGTS) and Control Room High Efficiency Air Filtration System (CRHEAF) to be operable for the initiation of fuel movement and during fuel handling

, operations involving irradiated fuel. The proposed change supports a planned sequence of safety systems maintenance and/or refurbishment during refueling outages._

This change is proposed as a Cost Beneficial Licensing Action (CBLA) because the change j l

allows scheduling such as to reduce refueling outage duration. This was demonstrated during '

j Pilgrim's Refueling Outage #9 by employing this proposed change as technical specification relief.

1 Attachment A, " Comparison of Existing and Proposed Requirements for SGTS and CRHEAF" summarizes existing and proposed requirements. This proposed change makes permanent i NRC approved temporary relief and compensatory measures issued as Amendment #144 on December 16,1992.

A l

130.!.18 9409130410 940906 .

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The requested changes are described in Attachment B. Revised technical specification pages are included in Attachment C, and existing pages marked up to show the proposed changes I are included in Attachment D. A si:igle line diagram depicting a portion of the station electrical 4.16 KV and 480 V distribution system is included as Attachment E.

fOfn . J. Olivier Commonwealth of Massachusetts)

Country of Plymouth)

Then personally appeared before me, L. J. Olivier, who being duly sworn, did state that he is Vice President - Nuclear Operations and Station Director of Boston Edison Company and that i he is duly authorized to execute and file the submittal contained herein in the name and on behalf of Boston Edison Company and that the statements in said submittal are true to the best of his knowledge and belief.

My commission expires: OM f /97 _ .M . [A l

ETB/PMK/nas/TS/ STANDBY cc: Mr. R. Eaton, Project Manager Division of Reactor Projects - l/II I Mail Stop: 14D1 U. S. Nuclear Regulatory Commission 1 White Flint North 11555 Rockville Pike Rockville, MD 20852 U.S. Nuclear Regulatory Commission Region I 475 Allendale Road King of Prussia, PA 19406 Senior Resident inspector Pilgrim Nuclear Power Station Mr. Robert M. Hallisey, Director Radiation Control Program l Center for Communicable Diseases Mass. Dept. of Public Health 305 South Street  ;

Jamaica Plain, MA 02130

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ATTACHNENT A COMPARIS0N OF EXISTING AND PROPOSED TECHNICAL SPECIFICATION REQUIREMENTS FOR SGTS AND CRHEAF PROPOSED TECH SPECS PROPOSED TECH SPECS EXISTING TECH SPEDS DURING REFUELING IF DURING REFUELING IF EQUIPMENT DURING REFUELING *B" SAFETY BUS 0.0.5 "A" SAFETY BUS 0.0.5 "A" SGTS/CRHEAF ALL NECESSARY NORMAL AND 1 NORMAL AND 2 OUT OF 3 I NORMAL POWER SOURCE EMERGENCY POWER SOURCES EMERGENCY POWER SOURCES, AS LISTED BELOW:

NORMAL NORMAL NORMAL

- STARTUP TRANSFORMER - STARTUP TRANSFORMER - STARIUP TRANSFORMER OR OR OR ,

- UNIT AUXILIARY (BACK- - UNIT AUXILIARY (BACK- - UNIT AUXILIARY (BACK-FEED MODE) FEED MODE) FEED MODE)

EMERGENCY EMERGENCY "A" EDG -

"A" EDG AND EITHER

- S/D TRANSFORMER ~

OR

- BLACKOUT D/G "B" SGTS/CRHEAF ALL NECESSARY NORMAL AND 1 NORMAL AND 2 OUT OF 3 EMERGENCY POWER SOURCES 1 NORMAL POWER SOURCE EMERGENCY POWER SOURCES, AS LISTED BELOW: AS LISTED BELOW:

NORMAL NORMAL NORMAL

- STARTUP TRANSFORMER - STARTUP TRANSFORMER - STARTUP TRANSFORMER OR OR OR '

- UNIT AUXILIARY (BACK- - UNIT AUXILIARY (BACK- - UNIT AUXILIARY (BACK-FEED MODE) FEED MODE) FEED MODE)

EMERGENCY EMERGENCY "B" EDG- -

"B" EDG AND EITHER

- S/D TRANSFORMER OR

- BLACK 0UT D/G

ATTACHMENT B l

Proposed Chanaes The proposed changes to Sections 3.7.B.1.a,3.7.B.1.c, 3.7.B.1.e,3.7.B.2.a and 3.7.B.2.c reference new sections 3.7.B.1.f and 3.7.B.2.e. The new section provides an exception to )

entering the LCO during refueling by requiring only one train of the Standby Gas Treatment System (SGTS) and one train of the Control Room High Efficiency Air Filtration System (CRHEAF) to meet the strict Technical Specification interpretation of operable prior to or during activities involving irradiated fuel movement or operations conducted over irradiated fuel with 4 the train's emergency power source out of service.

Reason for Chance This change is proposed as a Cost Beneficial Licensing Action (CBLA) because, as was demonstrated during Refueling Outage #9, it can reduce outage duration by allowing fuel i movement during schedule periods current technical specifications would forbid. l l

The Pilgrim Station Technical Specifications require both trains of the SGTS and CRHEAF systems to be operable during irradiated fuel handling operations. In addition, the definition of

" operable" requires both normal and emergency electrical power sources be available to support the SGTS and CRHEAF function (s).

During refuelings we use an outage work management concept for Pilgrim Station that takes an entire equipment loop of out service for maintenance activities. The outage work management concept conflicts with Technical Specifications when handling irradiated fuel because removal of an equipment loop makes the related emergency electric power source (diesel generator and associated 4kV bus) unavailable to supply power to the associated trains of SGTS and CRHEAF. The existing LCO allows a 7 day period to restore the system to operable or discontinue activities involving irradiated fuel. The proposed change addresses this conflict by allowing irradiated fuel activities to commence and continue for a period greater than 7 days with the emergency power source out of service.

Safety Considerations The SGTS is one of four subsystems of the Secondary Containment System (SCS). The other subsystems are the Reactor Building, the Reactor Building Isolation and Control System (RBICS), and the main stack. The SCS surrounds the refueling facilities and is designed to provide primary containment for the postulated refueling accident.

The SCS uses four different features to mitigate the consequences of a postulated fuel handling accident. The first feature is a negative pressure barrier which minimizes the ground level release of fission products by exfiltration. The second feature is a low leakage containment volume which provides a holdup time for fission product decay prior to release.

The third feature is the removal of particulates and iodines by filtration prior to release. The fourth feature is the exhausting of the secondary containment atmosphere through an elevated release point which aids in dispersion of the effluent by atmospheric diffusion.

Each of the features is provided by a different combination of subsystems: the first by the Reactor Building, the RBICS, and the SGTS exhaust fans; the second by the Reactor Building and the RBICS; the third by the SGTS filters; and the fourth by the main stack.

The safety objective of the SCS is to limit the release of radioactive materials to the environs ensuring offsite doses from a postulated DBA will be below the guideline values of 10CFR100.

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l The safety design bases of the SCS satisfying this safety objective states that the SCS shall be designed to be sufficiently leaktight to allow the Standby Gas Treatment System (SGTS) to i reduce the Reactor Building pressure to a minimum subatmoshperic pressure of 0.25 inches of i water, under neutral wind conditions, when the SGTS fans are exhausting Reactor Building atmosphere at a maximum of 4,000 ft 3/ min.

PNPS Technical Specifications Bases state that only one of the two Standby Gas Treatment I Systems is needed to maintain the secondary containment at a 0.25 inch of water negative l pressure upon containment isolation. During outages we intend to maintain at least one train l of SGTS operable with both normal and emergency safety related power sources available, I satisfying the need for secondary containment. The other train will be available using normal l power sources but will not have an emergency backup source.

SGTS is only required for fuel handling accidents during refueling operations. During refueling operations the most limiting postulated event is the worst case fuel handling accident coincident with a loss of offsite power and a random failure of a SGTS component in the train being fed from the emergency diesel generator. The probability of this combination of events i is extremely low. l We have restncted fuel movement for 5 days following reactor shutdown to provide decay time for the irradiated fuel.

The CRHEAF system's safety function is to maintain Control Room habitability after an event that releases radioactive material. During fuel movement operations, damage to irradiated fuel would be the event CRHEAF addresses. ,

I The compensatory measures described below apply to both SGTS and CRHEAF. These compensatory measures give added assurance SGTS and CRHEAF will not be needed or will perform their design function although one train will not be operable within the strict application of existing Technical Specification requirements.

Compensatory Measures

. Fuel movement will not occur until 5 days following reactor shutdown. ,

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. Fuel movement will not occur until the reactor vessel is flooded up to elevation 114' to i provide an enlarged coolant inventory. l

. The train of SGTS and CRHEAF without its safety-related bus and without its ,

emergency diesel generator will have power supplied from a normal offsite source via a j non safety-related bus. The normal offsite sources consist of either the Startup  !

Transformer or Unit Auxiliary Transformer (Back-feed Mode). j

. Prior to and during fuel movement, the Station Blackout (SBO) Diesel Generator or the Shutdown Transformer will be required to be operable. This will provide another source of emergency power to the safety-related bus still in service, should normal sources of offsite power become available.

Determination of No Sionificant Hazards Consideration The Code of Federal Regulations (10CFR50.91) requires licensees requesting an amendment to provide an analysis, using the standards in 10CFR50.92, that determines whether a significant hazards consideration exists. The following analysis is provided in accordance with Page 2 of 4

10CFR50.91 and 10CFR50.92 for the proposed amendment to Technial Specification sections 3.7.B.1 and 3.7.B.2.

1. The operation of Pilgrim Station in accordance with the proposed amendment will not involve a significant increase in the probability or consequences of an accident l previously evaluated.

Technical Specifications 3.7.B.1 and 3.7.B.2.e restrict the movement of irradiated fuel when only one train of SGTS or one train of CRHEAF are operable. Irradiated fuel ,

movement may not Degin and may only continue for seven days when the Limiting l Condition of Operation is entered. '

Removing these restrictions during refueling operations does not involve a significant increase in the probability or consequences of an accident previously evaluated because compensatory measures will be in place.

When sections 3.7.B.1.f and 3.7.B.2.e are invoked fuel movement will not commence '

until 5 days following plant shutdown and reactor vessel will be flooded-up to elevation 114'. The 5 day period provides decay-time before irradiated fuel movement begins.

Flooding-up to elevation 114' provides an enlarged inventory reducing the possibility of a loss-of-coolant event exposing fuel such that radioactive gasses are produced, an event SGTS and CRHEAF are designed to mitigate.

Other compensatory measures include requiring the SBO diesel or the shutdown transformer to be operable prior to and during the fuel movement. This adds defense-in-depth by making available another power supply to the in-service safety-related bus.

Also, the substitution of a non-safety power supply to the SGTS and CRHEAF

" inoperable" systems while their safety-grade bus is out-of-service for maintenance will provide offsite power to the " inoperable" train. While this electrical supply is not safety-grade, it is reliable and capable of powering the SGTS and CRHEAF systems. The components of the " inoperable" trains will be available with power from an altemate power source. The compensatory connection to the non-safety grade bus gives adder' confidence these trains can perform the design function although they are not

" operable" as defined by Technical Specifications.

Operating Pilgrim in accordance with this proposed change does not involve a significant increase in the probability or consequence of an accident previously .

analyzed because compensatory measures will be in force to: restrict the l commencement of irradiated fuel handling or new fuel handling over the spent fuel or i core until 5 days following reactor shutdown; provide a reliable source of power to the

" inoperable'" SGTS and CRHEAF systems; provide an enlarged coolant inventory to i protect irradiated fuel from the effects of an inadvertent draindown of the vessel; and provide an additional source of emergency power to the active SGTS and CRHEAF systems by ensuring the operability of the SBO diesel generator or the Shutdown Transformer.

2. The operation of Pilgrim Station in accordance with the proposed amendment will not create the possibility of a new or different kind of accident from any accident previously evaluated.

Planned maintenance activities require removing a safety-related bus and emergency diesel generator powering a train of SGTS and CRHEAF from service The redundant trains are not affected. The affected trains of SGTS and CRHEAF will be connected to a non-safety bus, allowing them to operate but not allowing them to be considered Page 3 of 4

operable under the purview of Technical Specifications. The proposed change allows refueling activities to commence with one train of SGTS and CRHEAF fully operable and the other train available but not powered by its safety grade bus and associated emergency diesel generator. Compensatory measures will be in effect during refueling activities involving this configuration. The proposed changes do not create the possibility of a new or different kind of accident from the fuel-drop accident previously analyzed. Therefore, operating Pilgrim in accordance with this change will not create the possibility of a new or different kind of accident from any accident previously analyzed.

3. The operation of Pilgrim Station in accordance with the proposed amendment will not involve a significant reduction in the margin of safety.

SGTS and CRHEAF contribute to the margin of safety during fuel handling by mitigating the consequences of a fuel-handling event. Allowing an exception to the requirement of both trains of SGTS and CRHEAF operable prior to or during fuel movement activities does not involve a significant reduction in the margin of safety because the first line of defense, the other SGTS and CRHEAF trains, will be operable. ,

The redundant trains will also be powered and operable in all ways except the l

" operable" concept required by Technical Specification.

Hence, the actual condition of the equipment allows it to meet its design function except under the strict Technical Specification interpretation of operable, and the described compensatory measures that will be in effect when the exception is ]

employed, constrain the potentialimpact on the margin of safety caused by using the exception; therefore, operating Pilgrim in accordance with this proposed Technical Specification request does not involve a significant reduction in the margin of safety.

This proposed change has been reviewed and recommended for approval by the Operations Review Committee, and reviewed by the Nuclear Safety Review and Audit Committee. l l

Schedule of Chance This change will be implemented within 30 days following BECo's receipt of its approval by the NRC.

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