ML20077K823

Selected Operating Reactor Issues Program Ii:Rcs Vents (NUREG-0737,Item II.B.1), Final Technical Evaluation Rept for Salem 1 & 2

ML20077K823
Person / Time
Site:	Salem
Issue date:	02/23/1983
From:	Held J ENERGY, INC.
To:	Alberthal G Office of Nuclear Reactor Regulation
Shared Package
ML18089A399	List: ML20077K823
References
CON-FIN-A-0250, CON-FIN-A-250, RTR-NUREG-0737, RTR-NUREG-737, TASK-2.B.1, TASK-TM TAC-44405, TAC-44406, TF-343-0809A, TF-343-809A, NUDOCS 8306080112
Download: ML20077K823 (6)

Text

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ENCLOSURE 2 g

Lawrence Livermore National. Laboratory A

s Selected Operating Reactor Issues Program II Reactor Coolant System Vents lNtiRE(A)0737, Item II.B.1. )

NPC FIN A0250 - Project 9 FINAL TECHNICAL EVALUATION REPORT FOR SALEM 1 -AND 2 Docket Numbers 50-272 and 50-311 NRC TAC Numbers 44405 and 44406 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 "Tbh report was prepared as an account of work spon.ored by the United States Government.

Neither the United Staics not 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 atsumes any legal liability or respon-sibility for the accuracy, completeness or usefulness of any information, apparatus, product or process disclosed, or represents that its use would not infringe privately-owned nghts."

M %y Hos Bean Sent to PDR TF-343/0809a February 23, 1983 7

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Docket Numbers 50-272 and 50-311

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NRC TAC Numbers 44405 ond 44406 i

TECHNICAL EVALUATION REPORT ON REACTOR COOLANT SYSTEM VENTS FOR SALEM I AND 2 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,"Clorification of TMI Action Plan Requirements." In response to these and previous requirements, the Public Service Electric and Gas Company has submitted information in References I and 2 in support of the vent system on Units I and 2 of the Salem Nuclear Generating Station. _

EVALUATION The function of the high point vent system is to vent noncondens.ible gases from the high points of the reactor coolant system (RCS) to assure that core cooling during natural circulation will not be inhibited. The Solem I and 2 reactor vessel head vent system provides venting capability from the reactor vessel head, while the pressurizer con be vented through the existing power operated relief volves (PORVs). The noncondensible gases, steam, and/or liquids vented from either the reactor vessel head or the pressurizer are piped and discharged to the pressurizer relief tank (PRT). The reactor vessel head vent system is designed to vent a volume of gas opproximately equal to one half of the RCS volume in one hour. ,A flow restriction orifice, however, limits the flow from o pipe rupture or from inadvertent actuation of the reactor vessel head vent system to less than the capability of the reactor coolont makeup system. Hence, the licensee's compliance with 10 CFR 50.46, " Acceptance Criteria for Emergency Core Cooling Systems for Light Water Power Reactors," has not been offected by the oddition of the reactor vessel head vent system.

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The vent path from the reactor vessel head to the PRT contains two parallel sets of two normally closed solenoid-operated valpe's in series which are remotely controlled from

, the main control room. Eoch of the two solenoid-operated vent volves in series in each set is powered from one of two redundant vital DC buses. The two parcliel sets of volves are cross-connected downstream of the first normally closed volves, so reactor vessel head venting capability will be maintained in the event of failure of one of the vital DC buses. Indication of volve position, derived from limit switches located in all four l

reoctor vessel head vent valves, is provided in the main control room. NRC has previously determined that each PORV and PORV block valve also has positive position indication in the main control room (Reference 3). The PRT has pressure, temperature, and level indications and alarms in the main control room'which con be used to detect valve seat teokoge from the reactor coolarit system through the reactor vessel head vent system volves and the PORVs. Valve seat leakage from the PORVs con also be detected by the temoerature display and alarm provided in the main control room for the common pressurizer header. '

The portion of the recetor vessel head vent system up to and including the second -

normcIly closed volve forms a part of the reactor 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 valves up to and including the second normally closed valve os ' Safety Class 2 in complionce with 10 CFR 50.55a and Regulatory Guide 1.26. The vent system is designed for pressures and temperatures corresponding to the RCS -design pressure and temperature. . The piping and volves are stainless steel and are compatible with the reactor coolant chemistry. In addition, the vent system is acceptably protected from missiles and the dynamic effects of postulated piping ruptures. However, the licensee has not verified that the reactor vessel head vent system materials will be fabricated and' tested in accordance with the requirements of SRP Section 5.2.3 or other occeptable standards. We therefore conclude that the design and construction of the portion of the reactor vessel head vent system up to and including the second normally closed valve conforms to all geactor coolant pressure boundary requirements, including 10 CFR 50.550 and the cpplicable portions of General Design Criteria I, 2,4,14,30, and 31, contingent on verification of acceptable material fabrication and testing provisions. The licensee has further ascertoimd that the essential operation of other safety-related systems will not be impaired by postulated failures of vent system components.

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We have reviewed the licensee's reactor vessel head vent system design to assure on occeptably low probability exists for inadvertent _or irre_versible octuation of the vent system. Eoch vent path from the reactor vessel head includes two normally closed solenoid-operated vent volves in series from which power is removed during normal operation. Eoch reactor vessel head volve otso has on individual key-locked control l

switch, with both visual and audible valve position indications in the control room. In addition, each solenoid-operated vent volve is powered from one of two redundant vital DC buses and fails to the closed position in the event of loss of power. Furthermore, the liensee has stated that all displays and controls located in the main control room due to oddition of the reactor vessel head vent system will be considered in the human factors analysis in occordance with NUREG-0700 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 reactor vessel head vent system. However, reactor vessel head vent volve position indication is powered from the some power supply which supplies control power. If the licensee's intention is to remove control power by opening the breakers rather than locking out power to the valves by the key-lock switches, positive volve position indication will be l lost. Until the licensee verifies that the control power breakers will not be maintained open during normal operation or the licensee provides on acceptable alternative method -

of continuous, direct volve position indication, this is on open item.

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We have also examined the location where the reactor vessel head vent system and PORVs would discharge to the containment atmosphere through the PRT rupture disc.

Based on a description provided by the licensee (Reference 2) this crea is adequately ventilated following on cecident and will provide good mixing with the containment atmosphere to prevent the occumulation or pocketing of high concentrations of hyorogen in compliance with 10 CFR 50.44, " Standards for Combustible Gas Control System in Light Water Cooled Powei Reactors." Additionally, this location is such that operation of safety-related systems would not be impacted by the discharge of the anticipoted mixtures of steam, liquids, cod noncondensible gases.

The design provides for individual test and open/ closed indication of each volve, and the

!!censee has stated that operability testing of the reactor vessel head vent volves, PORVs, and PORV block volves will be performed in accordance with Subsection IWV of Section XI of the ASME Code for Category B volves. However, the licensee has not 2c/TER-P-25

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. stated that the reactor vessel head vent volves will be exercised during cold shutdown or refueling rather than every three months. This is a confirmatory item. NRC has previously determined that the operability testing provisions for the PORV and bled <

volves are acceptable (Reference 3).

CONCLUSION We conclude that the Salem I and 2 RCS vent system design, consisting of the reactor vessel head vent system and existing PORVs, is s'ufficient to effectively vent noncondensible gases from the reactor coolant system without leading to on unocceptable increase in the probability of a LOCA or o challenge to containment integrity, meets the requirements of NUREG-0737 Item II.B.I and the opplicable portions of General Design Criterio I, 2,4,14,30, and 31, and conforms to the requirements of paragraph (cX3Xiii) of 10 CFR 50.44 with one exception concerning positive volve position indication as noted above. We therefore recommend following resolution of this open item that the Solem I and 2 RCS vent system design be found acceptable with the following two confirmatory items. The material fabrication and testing provisions for the portions of the reactor vessel head vent system that form part of the reactor coolant pressure boundary must be determined to be acceptable, and the licensee must commit to exereira the reactor vessel head vent volves during cold shutdown or refueling rather than every

• three months in accordance 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 scope of our review: seismic and environmental qualification of the RCS vent system, RCS vent system operating guidelines and procedures, and required modifications to the plant technical specifications and in-service inspection program for the RCS vent system. -

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. REFERENCES

1. Letter, R.L Mitti (Public Service Electric and Gas Company) to F.J. Miraglia (NRC),

" Reactor Coolant System Vents, No. 2 Unit, Salem Nuclear Generating Station, Occket No. 50-311," dated June 30,1981

2. Letter, E.A. Liden (Public Service Electric and Gas Company) to S.A. Varga (NRC),

" Reactor Coolant System Vents (Item II.B.1), Units I and 2, Salem Nuclear Generating Station, Docket No. 50-272 and 50-311," dated April 28,1982

3. Letter, S.A. Varga (NRC) to F.W. Schneider (Public Service Electric and Gas Company)," Category A Items of TMI Lessons Learned," dated March 21,1981 9 .

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