ML20079Q695

Selected Operating Reactor Issues Program Ii:Rcs Vents (NUREG-0737,Item II.B.1), Final Technical Evaluation Rept

ML20079Q695
Person / Time
Site:	Crystal River
Issue date:	03/14/1983
From:	Held J ENERGY, INC., LAWRENCE LIVERMORE NATIONAL LABORATORY
To:	Alberthal G Office of Nuclear Reactor Regulation
Shared Package
ML20079Q696	List: ML20079Q695
References
CON-FIN-A-0250, CON-FIN-A-250, RTR-NUREG-0737, RTR-NUREG-737, TASK-2.B.1, TASK-TM TAC-44363, TF-370-0817A, TF-370-817A, NUDOCS 8306080106
Download: ML20079Q695 (6)

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. . Enclosure 2 LAWRENCE LIVERMORE LABORATORY s

Selected Operating Reactor Issues Program II Reactor Coolant System Vents (NUREG-00737, Item II.B.l.)

NRC FIN A0250 - Project 9 -

FINAL TECHNICAL EVALUATION REPORT FOR CRYSTAL RIVER 3 Docket Number 50-302 NRC TAC Number 44363 Prepared by J. T. Held of Energy Incorporated - Seattle (Subcontract 4324401) for Lawrence Livermore National Laboratory under contract to the NRC Office of Nuclear Reactor Regulation, Division of Licensing, ee~

NRC Lead Engineer - Gus Alberthal NOTICE

• • This report w s prepared as 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 liabihty or respon-sibility for the accuracy, completeness or usefulness of any information, apparatus, product or process disclosed, or represents that its use i

would not infringe privately-owned rights.

U aS Been&nt to PDR TF-370/0817a March 14, 1983 N

5 t40 0to g Universitr of California P.O. Bos 308 Livermore, California 945 ~ e W9t400-16ModeuJI" * *LW L LVMR

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bockst-Number 50-302 NRC TAC Number 44363 TECFNICAL EVALUATION REPORT ON REACTOR COOLANT SYSTEM VENTS FOR CRYSTAL RIVER 3 INTRODUCTION The requirements for reactor coolant system high point vents are stated in paragraph (cX3Xiii) of 10 CFR 50.44, " Standards for Combustible Gas Control System in Light Water Cooled Power Reactors," and are further described in Standard Review Plan (SRP)

Section 5.4.12, " Reactor Coolant System High Point Vents," and item II.B.I of NUREG-0737," Clarification of TMI Action Plan Requirements." In response to these and previous requirements, Florida Power Corporation has submitted information in References I through 4 in support of the vent system on Crystal River Unit 3.

EVALUATION -

The function of the high point vent system is to vent noncondensible gases from the high points of the reoctor coolant system (RCS) to assure that core cooling during natural circulation will not be inhibited. The Crystal River 3 high point vent system provides venting capability from high points of the pressurizer and both RCS hot legs. However, the Crystal River 3 high point vent system does not include o reactor vessel head vent as required by 10 CFR 50.44 (cX3Xiii). Until on occeptoble reactor vessel head vent is designed and installed, this is on open item.

The noncondensible gases, steam, ond/or liquids vented from either the pressurizer or the hot legs are separately piped and discharged directly to the containment atmosphere.

Flow restriction orifices in each vent path limit the flow from o pipe rupture or from inodvertent octuation of the vent system to less than the copobility of the reactor coolont makeup system. Hence, the licensee's compliance with 10 CFR 50.46, "Acceptonce Criteria for Emergency Core Cooling Systems for Light Water Power Reactors,"hos not been offected by the addition of the high point vent system.

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e The vent paths from the pressurizer and the RCS hot leg high. points to the containment atmosphere each contain two solenoid-operated volves in series which are remotely controlled from the main control room. The licensee has indicated that positive indication of volve position is provided in the main control room with open/ closed status lights. However, the licensee has not provided sufficient informatian r=aardino the

_ method of volve position detection to verify acceptability._ This is o confirmatory item.

A degree of redundancy hos been provided by powering each hot leg vent path from o different emergency bus to ensure that RCS venting capobility from at least one hot leg high point is maintained. The vent system also includes flow elements with associated indication in the main control room to detect volve seat leokoge from the reactor coolont system through the vent system isolation volves.

The portion of each high point vent path up to and including the second normally closed volve forms a port of the reoctor coolant pressure boundary, and thus must meet reactor coolant pressure boundary requirements. The licensee has stated the vent system is designated Seismic Category I in compliance with Regulatory Guide 1.29. The licensee has also classified the piping and volves up to and including the second normally closed volve os Sofety Class I in compliance with 10 Cf R 50.55o and Regulatory Guide 1.26.

The vent system is designed for pressures and temperatures corresponding to the RCS design pressure and temperature. In oddition, the vent system materials are compatible ,

with the reoctor coolont chemistry and will be fabricated and tested in occordance with the requirements of the ASME Boiler and Pressure Vessel Code for Class I and Class 2 components. The vent system is also acceptobly protected from missiles and the dynamic effects of postulated piping ruptures. We therefore conclude that the design I

ond construction of the portion of the high point vent system up to and including the second normally closed volve conforms to all reactor coolant pressure boundary requirements, including 10 CFR S0.550 and the applicable portions of General Design Criteria 1,2,4,14,30, and 31. The licensee has further ascertained that the essential operation of safety-related systems will not be impaired by postulated failures of high point vent system components.

We have reviewed the licensee's high point vent system design to assure on acceptobly low probability exists for inodvertent or irreversible octuation of the vent system. Eoch vent path has two solenoid-operated volves in series and each volve has on individual and independent control switch. The volves all receive emergency Class IE power and foil to the closed position in the event of loss of power. Power is removed from the vent volves

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- during normal operation by opening selected breakers, ond on automatic olarm in the main control room is activated if both volves in a vent path are in the open position. J Furthermore, the licensee has stated that all displays and controls located in the main _

f control room 'due to addition of the high point vent system will be considered in the I human factors analysis required by NUREG-0737 Item 1.D.I, " Control-Room Design Reviews," in order to reduce the potential for operator error. _However, the Crystal

_ River 3 high point vent system design includes Torget Rock solenoid-operated volves, 7

which may be susceptible to o common mode failure in that anaration of on upstream

_volve may cause the dnwnstream volve to ooen temoororiiv. It was recommended in Reference 5 that plants with Target Rock volves evoluote their vent systems ono present their conclusions including any design changes necessary to minimize the probability of on inodvertent vent system actuation. We therefore find that no single active component failure or humon error should result in inodvertent opening or irreversible operation (i.e.,

failure to close offer intentional opening) of the high point vent system, contingent on a satisfactory evoluotion per Reference 5 for Crystal River 3.

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We have also examined the locations where the vent system normally discharges to the containment atmosphere. Based on drawings and a description provided by the licensee, these locations are in creas that will provide good mixing with the containment l otmosphere to prevent the occumulation or pocketing of high concentrations of hydrogen in compliance with 10 CFR 50.44, " Standards for Combustible Gas Control System in l Light Water Cooled Power Reactors." Additiono!!y, these locations are such that operation of safety-related systems would not be impocted by the discharge of the onticipated mixtures of steam, liquids, and noncondensible gases.

The licensee hos stated that provisions to test the operability of the vent system volves are a port of the design and that the solenoid volves have been tentatively identified as Category B vcives. We find this occeptable contingent on a commitment by the licensee that the vent system solenoid volves will be fested in accordance with Sub'seciion 155fV o[ ~

Section XI of the ASME Code for Category B volves. _ Also, the licensee hos not stated that the RCS vent volves will be exercised during eold shutdown or refueling ini'eod of

.every three months. This is a confirmatory item.

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CONCLUSION We conclude that the Crystal River 3 high point vent system design is sufficient to effectively vent noncondensible gases from the reactor coolant system without leading to an'unocceptable increase in the probability of a LOCA or o challenge to containment integrity, meets the requirements of NUREG-0737 Item II.B.1, and conforms to the requirements of porograph (cX3Xiii) of 10 CFR 50.44, with one exception concerning the required reactor vessel heod vent as noted above. We therefore recommend following resolution of this open item that the Crystal River 3 high point vent system design be found occeptable with the following three confirmatory items. First, the licensee must provide sufficient design information to allow determination of the acceptobility of the volve position indication provisions. Second._ the Torget Rock solenoid-operated volve problem ri6ted above must be satisfactorily resolved. g, _the final provisions for operability testing of the vent system solenoid volves must be confirmed, including o i

commitment by the licensee to exercise the vent volves during cold shutdown or_

refuelina rather than every three months in cecordance with the requirements of

. subsection IWV of Section XI of the ASME Code for Category B volves. It should also be noted that the following items were excluded from the secpe of our review: seismic and environmental qualification of the high point vent system, high point vent system operating guidelines and procedures, and required modifications to the plant technical

specifications and in-service inspection program for the high point vent system.

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REFERENCES

1. Letter, P.Y. Boynard (Florido Power Corporation) to H.R. Denton (tRC), " Crystal River Unit 3, Docket No. 50-302, . Operating License No. DPR-72," with Attachment IV, " Venting Design Criterio," dated Jonvory 11, 1980.

2. Letter, G.C. Moore (Florido Power Corporation) to H.R. Denton (NRC), " Crystal River Unit. 3, Docket No. 50-302, Operating License No. DPR-72, Short-Term Lessons Learned Recommendations," dated April i 1,1980.

3. Letter, P.Y. Boynard (Florida Power Corporation) to D.G. Eisenhut (NRC), " Crystal

- River Uhit 3, Docket No. 50-302, Operating License No. DPR-72, NUREG 0737 -

Item II.B.1, Reactor Coolont System Vents," dated July 1,1981.

4. Letter, D.G. Mardis (Florida Power Corporation) to J.F. Sto!z (NRC), " Crystal River Unit 3, Docket No. 50-302, Operating License No. DPR-72, NUREG-0737; Item II.B.1, Reactor Coolant System Vents Additional information," dated March 9,1982.

5. NRC Memorandum, T.P. Speis (Division of Systems integration) to T.M. Novak (Division of Licensing), " Unintentional Lifting of Solenoid Operated Pilot Volves in RCS Vent System," dated March 9,1982.

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