ML20076F248

Selected Operating Reactor Issues Program II RCS Vents (NUREG-0737,Item II.B.1), Final Technical Evaluation Rept for Nine Mile Point 1

ML20076F248
Person / Time
Site:	Nine Mile Point
Issue date:	04/06/1983
From:	Held J ENERGY, INC., LAWRENCE LIVERMORE NATIONAL LABORATORY
To:	Alberthal G NRC
Shared Package
ML17054A011	List: ML20076F248
References
CON-FIN-A-0250, CON-FIN-A-250, RTR-NUREG-0737, RTR-NUREG-737, TASK-2.B.1, TASK-TM TAC-44387, TF-383-0823A, TF-383-823A, NUDOCS 8306080040
Download: ML20076F248 (6)

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Selected Operating Reactor Issues Program II -

Reactor Coolant System Vents (HUREG-00737, Item II.B.l. )

NRC FIN A0250 - Project 9

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. FINAL TECHNICAL EVALUATION REPORT FOR NINE MILE POINT 1

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Docket Number 50-220 NRC TAC Number 44387 Prepared by J. T. Held of Energy Incorporated - Seattle (Subcontract

- 4324401) for Lawrence Livermore National Laboratory under contract to the NE: Office of Nucl6ar Reactor Regulation; Division of Licensing.

NOTICE "1his report was prepared ts an account of work sponsored by the United States Government. Neither the United States nor the United States Department of Energy, nor any of their employees, nor any of their contractors, subcontractors, or their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for

the accuracy, completeness or usefulness of any information, apparatus, product or process disclosed, or represents that its use would not infringe privately-owned rights."

XA Copy Has Been Sent._tof_DR TF-383 0823a April 6,1983 v@?* 40 f e.oversety o: California P.O. Sox G8 Livermore. California 94550 C Telephone (415) 4221100 ~a Tws 910 :25 8339 UCLL LVMR

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% I TEC!-NCAL EVALUATION REPORT .

ON REACTOR COOLANT SYSTEM VENTS FOR NINE MILE POINT I INTRODUCTION The requirements for reactor coolant system high point vents'are stated in paragraph (cX3Xiii) of 'lo 'CFR 50.44, "StorJeds for Combustible Gas Control System in Light _. -

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Water Cooled Power Reactors," and ani further described in Standard Review Plan (SRP)

Section 5.4.12,' "Reactori Coolant' ~ System High Point Vents," and item 11.B.1 cf NUREG-0737," Clarification of TMI Action Plan Requirements." in response to these and .

previous requirements, the Niagara Mohawk Power Corporatien has submitted information in References I through 5 Iri, support of the vent system on Nitie Mile Point Unit 1. s :=.- '.Y '

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EVALUATION

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The function of the reactor coolant system (RCS) vent system is io vent noncondensible gases from the high points of the RCS to assure that core cooling during natural circulation will not be inhibited. The Boiling Water Reactor (BWR) Owners' Group has submitted documentation (References 6 through 9) on how the RCS venting requirements are met in General Electric (GE) BWRs. The BWR Owners' Group position has been endorsed by the licensee. .

In accordance with the BWR Owners' Group position, the means of ven' ting noncondensible gases from the reactor pressure vessel at Nine Mile Point I are six 6-inch power-operated, safety-related electromatic relief volves which alone provide adequate venting. Eoch relief volve is provided with positive position indication in the main control room derived from individual occustic monitors and' is operable from the main control room. In addition, the licensee has statec that no protection system that is necessary to maintain adequate core cooling, with the exception of the emergency condensers, requires remote venting since none is susceptible to the bui! dup of a large ornount of noncondensible gas that could cause o foss of function of the system.

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The licensee has modified the emergency cond:;nser vent system to provida venting capability from the high point of the primary side of each of the four emergency .

cond'ensers to the suppression pool. Previous LOCA analyses have considered and found occeptoble pipe breaks equivalent in size to a break in the new emergency condenser vent path. Hence, the licensee's previously demonstrated compliance with 10 CFR 50.46,

" Acceptance Criteria for Emergency Core Cooling Systems for Light Water Nuclear Power Reactors," is not offected and remains acceptable. A degree of redundoney has been provided by powering the emergency condenser vent volves and the electmmatic relief volves from different emergency buses and powering the air-operated and i

motor-operated emergency ' condenser vent volves from separate DC and AC power a .

trains. A.

We have reviewed the licensee's modified emergency condenier vent system design to .

assure on acceptably low probability exists for inadvertent or irreversible octuation of the vent system. The common discharge path from the emergency condensers to the suppression pool has two AC-powered mator-opemted volves in series and a DC-powered air-operated block volve is located on each branc'h' ipstream coming from the two bcriks

[ of emergency condensers. These volves all receive emergency power, are individually operable from the main control room, and are provided with. position indication in the main control room. Valve position indication is provided by way of position indication switches located on the volve stems. The air-operated block volves fail to the closed l position in the event of loss of power. The previously existing discharge path th'at discharges to a main steam line downstream of the main steam isolation volve is provided with two cir-operated feil-closed automatic isolation volves to prevent inadvertent l venting outside containment under accident condit' ions. The licensee has stated that all displays and controls added to the main control room os a result of emergency condenser modifications will be considered in the human factors analysis required by NUREG-0737 Item 1.D.1, " Control-Room Design Reviews," in order to reduce the potential for operator error. We therefore find that no single active component failure or human error should result in inadvertent opening or failure to close offer intentional opening of the emergency condenser vent.

The portion of each emergency condenser vent path up to and including the second normally closed volve forms a part of the reactor coolant pressure boundary, and thus must meet reactor coolant pressure boundary requirements. The licensee has stated that l

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tha modified vent system is. designed to safety and seismic critoria consistent with the original system design, which is Seismic Category 1. The em:rgsncy condens r vtnt system is designed for pressures and temperatures corresponding to the RCS design  !

pressure and ternperature. In addition, newly installed vent system materials are consistent with the original system design. Valve seat leakage from the modified emergency condenser vent will be directed to the suppression pool and detected by existing methods for the detection of unidentified reactor coolant pressure boundary leakage. We therefore conclude that the design and construction of the modified portion of the emergency condenser vent system up to and including the second normally closed volve conforms to all applicable reactor coolant pressure boundary requirements.

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The errergency condenser vent system discharges to the suppression pool at a point below the minimum water level. Hence, no safety-related equipment will be adversely impacted by its use. Also, the occumulation of combustible concentrations of gases is precluded by an inerted atmosphere. ~

The design of the emergency condenser vents provides for individual test and open/ closed indication of each valve. However, the licensee has not committed to include the ,

emergency ccridenser vent valves in his pump and valve in-service inspection prognam and lir it volve exercising to cold shutdown or refueling rather than every three months.

This is a confirmatory iterii.

CONCLUSION We conclude, based on the applicability of the BWR Owners' Group position to Nine. Mile Point I cnd our specific review of the Nine Mile Point I design, that the existing systems and the licensee's modifications to the emergency condenser vents at Nine Mile Point I are sufficient to vent noncondensible gases from the.RCS and emergency condensers without leading to on unocceptable increase in the probability of a LOCA or a challenge to containment integrity, meets the design requirements of NUREG-0737 Item 11.B.I, and conforms to the requirements of paragraph (c)(3Xiii) of 10 CFR 50.44. We therefore recommend that the Nine Mile. Point i RCS venting capabilit'y be found acceptable with the following confirmatory item. The licensee must commit to exercise the emergency condenser vent valves during cold shutdown or refueling in accordance with the requirements of subsection IWV of Section XI of the ASME Code for Category B vcives.

In addition, it should be noted that the following items were excluded from the scope of i

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our review: seismic and environmental qualification of the RCS vent system, RCS vent systcm operating guidslines and procedures, and requirzd modifications to tha plant

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technical specifications and in-service inspection program for the RCS vent systern.

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. 1. Lettar, G.K. Rhode (Niagoro Mohawk Power Corporation) to D.G. Eisenhut (NRC),

- dated October 18, 1979, with Attachment, "Toble I, Nine Mile Point Unit I Commitment to Meet NUREG-0578 Requirements."

2. Letter, D.P. Dise (Niogoro Mohawk Power Corporation) to H.R. Denton (NRC),

dated Decernber 31, 1979, with Enclosure, "NUREC-0578 Recommendation, Reactor Coolant System Venting."

3. Letter, D.P. Dise (Niagoro Mohawk Power Corporation) t'o D.Ci. Eisenhut (NRC),

dated March 31, 1981, with Enclosure, "TMI Action Plan Item No. II.B.I, Reactor

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Coolant System Vents."

4. Letter, D.P. Dise (Niogoro Mohawk Power Corporation) to D.B. Vossallo (NRC), ,

dated March 16, 1982, with Enclosure, "Reques+ for Additional information, Nine Mile Point I, NUREG-0737 Item !!.B.'l Reactor Coolant System Vents."

S. Niagoro Mohawk Power Corporation Drawing No. C-180!7-C, "Nine Mile Pbint Nuclear Station - Emergency Cooling System, P&l Diagram," Rev.14 dated September 16, 1981. ,

6. Letter, T.D. Keenan (BWR Owners' Group) to D.C. Eisenhut (NRC), "BWR Owners' Group Positions on NUREG-0578," dated October 17,1979. ,

7. Letter, D.B. Waters (BWR Owners' Group) to NRC (Attn: D.G. Eisenhut),

" Preliminary Clarification of TMI Action Plan Requirements - BWR Owners' Group Comments," dated October 8,1980.

8.. General Electric Report NEDO-24708A, Revision I, " Additional Information i Required for NRC Staff Generic Report on Boiling Water Reactors," dated December 1980.

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9. Letter, D.B. Waters (BWR Owners' Group) to NRC (Attn: D.G. Eisenhut),

"NUREG-0660/0737 Requirement 11.B.1: Reactor Coolant System Vents," dated April 24,1981.

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