ML20077K834

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

ML20077K834
Person / Time
Site:	Oconee
Issue date:	04/06/1983
From:	Held J ENERGY, INC., LAWRENCE LIVERMORE NATIONAL LABORATORY
To:	Alberthal G NRC
Shared Package
ML16152A268	List: ML20077K834
References
CON-FIN-A-0250, CON-FIN-A-250, TASK-2.B.1, TASK-TM TAC-44300, TF-384-0823A, TF-384-823A, NUDOCS 8306130286
Download: ML20077K834 (6)

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'g LAWRENCE LIVERMORE LABORATORY hSZ4 Selected Operating Reactor Issues Program II Reactor Coolant System Vents (NUREG-00737 Item II.B.1.)

. NRC FIN A0250 - Project 9 FINAL TECHNICAL EVALUATION REPORT FOR OCONEE 1, 2, AND 3 Docket Numbers 50-269, 50-270, and 50-287 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.

NRC Lead Engineer - Gus Alberthal NOTICE "This report was prepared as an-account of work sponsored by the United States Government. Neither the United States nor the United States

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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 is PDR d.- _ TF-384/0823a

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Docket Numbers 50-269,50-270, and 50-287 TECFNICAL EVALUATION REPORT

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ON REACTOR COOLANT SYSTEM VENTS FOR OCONEE I,2, APO 3 l

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. INTKODUCTION The requirements for reactor coolant system high point vents are stated in paragrap (cX3Xiii) of 10 CFR 50.44, " Standards for Combustible Gas Control System in Water Cooled Power Reactors," and are further described in Standard Review Pl

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Section S.4.12, " Reactor Coolant System High Point Vents," and item li.B.I of NUREG-0737,"Clorification of TMI Action Plan Requirements." In response to these previous requirements, the D*e Power Corrpcny has submitted information in i

References I through 4 in support of the vent system on Units I,2, and 3 of the Oconee Nuclear Station. .

EVALUATION .

The function of the reactor coolant system (RCS) vent system is to vent nonconde gases from the high points of the RCS to unre that core cooling during na circulat:on will not be inhibited. Oconee I,2, ud 3 provide venting capability from th

' high points of the reactor vessel heod and both RCS hot legs with high point The existing power operated relief volve (PORV) con be used to vent the (HPVs).

The noncondensible gases,. steam, and/or liquids vented from the hot legs pressurizer.

' are separately piped to the basement of the reactor building where they are rele The reactor vessel head vent the discharge air stream of the reactor building coolers. ,

ties into one of 'the hot leg HPVs downstream of the hot leg vent volves. Each pat the HPVs is designed to vent one half of the RCS volume per hour. The additio HPVs has not introduced any new piping whose size is not encompassed by existin break onolyses, and hence, the licensee's compliance with 10 CFR 50.I.5, " Accepta Criterio for Emergency Core Cooling Systems for Light Water Nuclear Power Rea is not offected by the installation of the HPVs.

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s Enclosure 7 9

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The HPV paths f rom the reoctor vessel head and the RCS hot leg high points each contoin

- two solenoid-operated volves in series which are remotely controlled from the main Positive indication of volve position, sensed by limit switches in the control room.

solenoid volves, is also provided in the main control room. A degree of redundancy has been provided by powering each HPV path from o different emergency power train to ensure that RCS venting capability from at least one hot leg high point is maintained.

Volve seat leckoge from the RCS through the HPV volves w. be dcict:-hcd rith tha current procedures described in Oconee Technical Specification 3.1.6. The PORV con operated manually from the Integrated Control System (ICS) Cabinets odjacent to t main control room. The PORV is powered from o Class IE emergency panel and has on ocoustical monitoring system which provides positive position indication and actuates on The PORV block volve receives power from o alarm in the main control room.

non-lood-shed rnotor control center that derives its power from Class IE switchgear. '

Controls and positive position indication for the PORV block volve are also in the main control room. The power supply and position indication provisions for the PORV and block volve have been previously accepted by the NRC (Reference 5).

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The" portion of each HPV path up to and including the second normally closed vol a part of the reactor coolant pressure boundary and thus must meet reactor coo pressure boundary requirements. Consistent with the origiddl (and previou piping design criteria presented in Section 1.c.3, Vol. I of the Oconee FSAR, all of which is one Inch and smaller in diameter, is designated Class 111 (USAS The portion of the HPV paths up to and including the second normally closed vol designed for pressures and temperatures corresponding to the RCS design p fernperature. In addition, the vent system materials are Type 304 stainless ste fabricated and tested in occordance with Section til of the ASME Bo Vessel Code. The HPVs are also occeptably separated and protected from miss However, the HPVs are not the dynamic effects of postulated piping ruptures.

specifically designed to withstand potential dynamic loods ossociated with w from the starting of reactor coolont pumps (RCPs). Therefore the licensee must eit analyze the HPVs for these dynamic loods or develop and implement All portions of operat instructions that prohibit starting of the RCPs when the HPVs are open.

in the HPVs are seismically designed to withstand the safe shutdown eartiquoke, However, SRP Section 3.2.1 states occordance with Seismic Category I requirements.

that structures, systems, and components that are important to safety must be as Seismic Category I items and identified in on accepicble manner. Although th Enclosure 7 gl 3/TER/P-18 Page 2 of 5

are designed to acceptable seismic criterio, the licensee has not verified that the portion  !

l of the vent system that is part of the reactor coolant pressure boundary hos been _

occeptably identified and classified Seismic Category 1. We therefore conclude that the design of the portion of the HPVs up to and including the second normally closed volve conforms to oil reactor coolant pressure boundary requirements, including 10 CFR 50.55a and the applicable portions of General Design Criterio I, 2, 4,14, 30, and 31,,with two confirmatory items. First, the licensee must pre, vide eth-c nn analysis of the dynamic icods of water slugs potentially resulting from storting the RCPs or prohibit starting the RCPs with the HPVs open. Second, the licensee must. confirm the classificction of the reactor coolant pressure boundary portion of the vent system os Seismic Category 1. The

> licensee has further ascertained that the essential operation of other safety-related systems will not be impaired by postulated failures of HPV components, with one exception. The licensee hos not justified the use of a design pressure of 500 psig for the piping downstream of the second solenoid volve in each HPV path. This is on open item.

We have reviewed the licensee's HPV design to assure on acceptably low probability exists for inadvertent or irreversible octuation of the vent system. Eoch HPV path has two solenoid-operated volves in series. Each volve hos a power switch that (1) removes ,

power from the volves in each HPV path during normal operation to prevent inadvertent

} operation, and (2) minimizes the probability of isolation failure due to hot shorts la the control switches. Valve position indicator lights, which operate independently of the power switch position, will olert operators in the event of an open volve. Each volve also r j hos a separate piubbutton control to actuate the volve, with a spring return to interrupt power and close the volve. The HPV volves oil receive emergency Class IE power and fail to the closed position in the event of loss of power. Operator access to the ICS Cobinets for manual operation of the,PORV is limited by administrative controls to provide resistance to inadvertent operation. The PORV vent path from the pressurizer is protected from potential irreversible octuation since the PORV and block volve are powered from different power sources. The licensee has stated that displays and controls added to the main control room by 'he installation of t,he HPVs will be considered in the human factors analysis during the " Control Room Design Review" required by NUREG-0737 Item 1.D.I. We therefore find that no single octive component failure or human error should result in inadvertent opening or failure to close offer intentiono!

opening of the HPVs and the PORV pressurizer high point vent.

I gl3/TER/P-18 Enclosure 7 Poge 3 of 5

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l We have also evoluoted the. licensee's word description of the locations where the HPVs normally discharge to the containment atmosphere in t'he reoctor building basement (References I and 4). Since he HPV discharges are directed to the discharge air streams of the reoctor building coolers at opposite sides of the reactor building, good mixing with the containrnent 'otmosphere is assured to prevent the occumulation or pocketing of high concentrations of hydrogen *mcomplionce with 10 CFR 50.44, " Standards for Combustible Gas Control ' System in Light Water Cooled Power Reactors." Additionally, these locations are such that operation of safety-related systems would not be impacted by the discharge of the anticipated mixtures of steam, liquids, and noncondensible gases.

The design provides for individual test and open/ closed indication of each HPV volve, and the licensee has stated that operability testing of the HPV volves will be performed in accordance with subsection lWV of Section XI of the ASME Code for Category B volves during each scheduled refueling outoge.

i CONCLUSION We conclude that the design of the Oconee I,2, and 3 RCS vent system, which includes the HP.Vs and PORV pressurizer high point vent system, is sufficient to effectively vent noncondensible gases from the reoctor coolont system without leading to on unocceptoble increase in the probobility of a LOCA or a challenge to containment integrity, meets the design requirements of NUREG-0737 Item II.B.I and the applicable portions of General Design Criterio I, 2,4,14,30, and 31, and conforms to the requirements of paragraph (cX3Xiii) of 10 CFR S0.44, wRh one exception conceming the design pressure of piping downstream of the second solenoid volve in each HPV path. The justification of the j design pressure for these sections of piping is on open item. We therefore recommend following resolution of this gen item that the Oconee I, 2, and 3 RCS vent system design be found acceptable wRh the following confirmatory items. Either the dynamic loods on the HPVs from storting the RCPs must be analyzed or operating procedures to prohibit storting the RCPs while the HPVs are open must be developed. Also, the licensee must verify that the portion of the HPVs that is part of the reactor coolant pressure boundary is classified Seismic Category I. In oddition, it should be noted that the following items were excluded from the scope of our review: seismic ond environmental qualification of the HPVs, the RCS vent system operating guidelines and procedures, and required modifications to the plant technical specifications and in-service inspection program for the RCS vent syste.m.

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REFERENCES

1. Letter, W.O Parker, Jr. (Duke Power Company) to H.R. Denton (NRC), providing information conceming NUREG-0578 requirernents, dated January 2,1980.

. 2. Luitec, W.O. Pc. iter, Jr. (Dit<a Pnwer Cornpony) to H.R. Denton (NRC), "Oconee Nuclear Station, Docket Nos. 50-269, -270, 287," dated April 2,1980.

3. Letter, W.O. Parker, Jr. (Duke Power Company) to H.R. Denton (NRC), providing information conceming the design and operation of the RCS high point vent system, dated June 29,1981.

4. Letter, W.O. Parker, Jr. (Duke Power Compmy) to H.R. Denton (NRC), "Oconee Nuclear Station, Docket Nos. 50-269, -270, -287," dated March 26,1982.

5. Letter, R.W. Reid (NRC) to W.O. Parker, Jr. '(Duke Power Company), with enclosure,

'A' Items of NRC "Ev,aluation of Licensee's Compliance with Category Recommendations Resulting from TMI 2 Lessons Leomed," dated April 7,1980.

Enclosure 7 gl3/TER/P-18 Poge 5 of 5

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