ML19289C197
| ML19289C197 | |
| Person / Time | |
|---|---|
| Site: | Indian Point  |
| Issue date: | 11/28/1978 |
| From: | Schwencer A Office of Nuclear Reactor Regulation |
| To: | Berry G POWER AUTHORITY OF THE STATE OF NEW YORK (NEW YORK |
| References | |
| NUDOCS 7812140351 | |
| Download: ML19289C197 (6) | |
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UNITED STATES 1
NUCLEAR REGULATORY COMMISSION 3*
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November 28, 1978 Docket No. 50-286 Power Authority of the State of New York ATTN:
Mr. George T. Berry General Manager and Chief Engineer 10 Columbus Circle New York, New York 10019 Gentlemen:
RE: CONTAINMENT PURGING DURING NORMAL PLANT OPERATION A number of events have occurred over the past several years whicn directly relate to the practice of containment purging during nomal plant operation. During recent months, two specific events have occurred which have raised several questions relative to potential failures of automatic isolation of the large diameter purge pene-trations which are used during power operation. On July 26, 1978, the Northeast Nuclear Energy Company reported to the NRC such an event at Millstone Unit No. 2, a pressurized watar reactor located in New London County, Connecticut. On September 8, 1978, the Public Service Electric and Gas Company reported a similar event at Salem Unit No.1, a pressurized water reactor located in Salem County, New Jersey.
During a review of operating procedures on July 25, 1973, the licensee discovered that since May 1, 1978, intermittent containment purge operations had been conducted at Millstone Unit No. 2 with the safety actuation isolation signals to both inlet and outlet redundant containment isolation valves (48 inch butterfly valves) in the purge inlet and outlet penetrations manually overridden and inoperable.
The isolation signals which are required to automatically close the purge valves for containment integrity were manually overridden to allow purging of containment with a high radiation signal present.
The manual override circuitry designed by the plant's architect / engineer defeated the high radiation signal and all other isolation signals to these valves. To manually override a safety actuation signal, the operator cycles the valve control switch to the closed position and then to the open position. This action energized a relay which blocked the safety signal and allowed manual operation independent of any safety actuation signal. This circuitry was designed to permit reopening these valves after an accident to allow manual operation of certain safety equipment.
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2 On September 8,1978, the staff was advised that, as a matter of routine, Salem Unit No. I has been venting the containment through the containment ventilation system valves to reduce pressure.
In certain instances this venting has occurred with the containment high particulate radiation monitor isolation signal to the purge and pressure-vacuum relief valves overridden. Override of the containment isolation signal was accomplished by resetting the train A and B reset buttons. Under these circumstances, six valves in the containment vent and purge systems could be opened with a high particulate isolation signal present. This override was performed after verifying that the actual containment particulate levels were acceptable for venting. The licensee, after further investigation of this practice, determined that the reset of the particulate alarm also bypasses the containment isolation signal to the purge valves and that the purge valves would not have auto-matically closed in the event of an emergency core cooling system (ECCS) safety injectior, signal.
These events and information gained from recent licensing actions have raised several concerns relative to potential failures affecting the purge penetration valves which could lead to a degradation in cor,tainment integrity and, for PWR's, a degradation in ECCS performance. Should a loss-of-coolant accident (LOCA) occur dui',g purging there could be insufficient containment backpressure to assure proper operation of the ECCS. As the practice of containment purging during normal operation has become more prevalent in recent years, we have required that applicants for construction permits or operating licenses provide test results or analyses to demonstrate the capability of the purge isolation valves to close against the dynamic forces of a design basis LOCA.
Some licensees have Technical Specifications which prohibit purging during plant operation pending demorstration of isolation valve operability.
In light of the above, we request that you provide within 30 days of receipt of this letter your commitment to cease all containment purge during operation (hot shutdown, hot standby, startup and power operation) or a justification for continuing purging at your facility. Specifically, provide the following information:
. (1) Propose an amendment to the plant Technical Specifications based upon the enclosed model Technical Specification, or (2)
If you plan to justify limited purging, you must propose a Technical Specification change limiting purging during operation to 90 hours0.00104 days <br />0.025 hours <br />1.488095e-4 weeks <br />3.4245e-5 months <br /> per year as described in the enclosed Standard Review Plan Section 6.2.4, Revision 1.
Your justification must include a demonstration (by test or by test and analysis similar to that required by Standard Review Plan 3.9.3) of the ability of the containment isolation valves to close under postulated design basis accident conditions. Within thirty days of receipt of this letter, you are requested to provide a schedule for completion of your evaluation justifying continuation of limited purging during power operation.
(3)
If yoa plan to justify unlimited purging you need not propose a Technical Specification change at this time. You must, however, provide the basis for ourging and a schedule for responding to the issues relating to purging during normal operation as described in the enclosed Standard Review Plan Section 6.2.4, Revision 1, and the associated Branch Technical Position CSB 6-4.
As discussed in these documents, purging during normal operation may be permitted if the purge isolation valves are capable of closing against the dynamic forces of a design basis loss-of-coolant accident. Also, basis for unlimited purging must include an evaluation of the impact of purging during operation on ECCS performance, an evaluation of the radiological consequences of any design basis accident requiring containment isolation occurring during purge operations, and an evaluation of containment purge and isolation instrumentation and control circuit designs. Within thirty days of receipt of this letter, you are requested to provide a schedule for completion of your evaluation justifying continuation of unlimited purging during power operation.
Pending completion of the NRC staff review of the justification for continued purging in (2) or (3) above, you should commit to either cease purging or limit purging to an absolute minimum, not to exceed 90 hours0.00104 days <br />0.025 hours <br />1.488095e-4 weeks <br />3.4245e-5 months <br /> per year.
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The staff believes that both the Millstone and Salem events resulted from lack of proper management control, procedural inadequacies, and possible design deficiencies. While the containment atmosphere was properly sampled and the purging (venting) discharges at both facilities were within regulatory requirements, the existing plant operating procedures approved by the licensee's management did not adequately address the operability of the purge valves and the need for strict limitations on (or prohibition of) overriding a safety actuation closure signal. The requirements for valve operability were not discussed and the related Technical Specifi-cations were not referenced in the procedures. Design deficiencies probably contributed to the events as the safety actuation bypass condition is not annunciated nor is a direct manual reset of the safety actuation signal available. Consequently, we have developed the position specified below to assure that the design and use of all override circuitry in your plant is such that your plant will have the protection needed during postulated accident conditions.
Whether or not you plan to justify purging, you should review the design of all safety actuation signal circuits which incorporate a manual override feature to ensure that overriding of one safety actuation signal does not also cause the bypass of any other safety actuation signal, that sufficient physical features are provided to facilitate adequate administrative controls, and that the use of each such manual override is annunciated at the system level for every system impacted. Within thirty days of receipt of this letter, you are requested to provide (1) the results of your review of override circuitry and (2) a schedule for the development of any design or procedural changes imposed or planned to assure correction of any non-conforming circuits. Until you have reviewed circuitry to the extent necessary to verify that operation of a bypass will affect no safety functions other than those analyzed and discussed on your docket, do not bypass that signal. Our Office of Inspection and Enforcement will verify that
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Sincerely, Original Signed By A. Schwencer, Chief Operating Reactors Branch #1 Division of Operating Reactors
Enclosures:
l.
Model Technical Specification 2.
Standard Review Plan 3.
Branch Technical Position CSB 6-4 cc: w/ enclosures See next page DISTRIBUTION Docket File NRC PDR Local PDR ORBI Rdg A. Schwencer C. Parrish Project Manager M. M1ynczak W. Russell I&E (3)
D. Eisenhut 0 ELD B. Grimes f
TERA J. Buchanan ACRS (16)
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Power Authority of the State 6-Of New York cc:
White Plains Public Library Power Authority of the State of 100 Martine Avenue New York White Plains, New York 10610 Environmental Programs J. W. Blake, Ph.D.
Leonard M. Trosten, Esquire Director LeBoeuf, Lamb, Leiby & MacRae 10 Columbus Circle 1757 N Street, NW New York, New York 10019 Washington, D.C.
20036 Theodore A. Rebelowski Anthony Z. Roisman USNRC Natural Resources Defense Council P. O. Box 38 917 - 15th Street, NW Buchanan, New York 10511 Washington, D.C.
20005 Paul S. Shemin, Esquire Assistant Attorney General State of New York Department of Law Two World Trade Center New York, New York 10047 Sarah Chasis, Esquire Natural Resources Defense Council 122 East 42nd Street New York, New York 10017 Mr. George M. Wilverding Licensing Supervisor Power Authority of the State of New York 10 Columbus Circle New York, New York 10019 Mr. P. W. Lyon Manager - Nuclear Operations Power Authority of the State of New York 10 Columbus Circle New York, New York 10019 Mr. J. P. Bayne, Resident Manager Indian Point 3 Nuclear Power Plant P. 0. Box 215 Buchanan, New York 10511
NUREG.75/087 p aaca,
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U.S. NUCLEAR REGULATORY CCMMISSION o
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STANDARD REVIEW PLAN
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OFFICE OF NUCLEAR REACTOR REGULATION CCNTAI MENT ISOLAT!CN SYSTEM SECTICM 6.2.4 SEVIEW QESPONSIBILITIES Primary - Containment Systems Branch (CSS)
Secondary - Accicent Analysis Branch (AAS)
[nstrumentation and Control System 3 ranch (IC58) l Mechanical Engineering Branch (MES)
Structural Engineering Branch (SEB)
Reactor Systems Branch (958)
Pewer Systems Branch (PSB) 1.
AAEAS OF REvtEW The design objective of the containment isolation system is to allow the normal or emer-gency passage of fluids througn the containment coundary.hile paeservirq tre soility of the boundary to prevent or limit the escape of fission products that may result frca This SRP section, therefore, is concerred witn tre isolation of postulated accidents.
fluid systems which penetrate the containment boundary, including the design and testing requirements for isolation Darriers and actuators. Isolation Darriers include valves, closed piping systems, and blind f!anges.
The CSS reviews the information presented in the applicant's safety analysis report (SAR) regarding containee9t isolation provisions to assure conformance with the requirements of General Cesign Criteria 54, 55. 56 and 57.
The CSB review covers the following aspects of containment isolation:
1.
The sesign of containment isolation provisions, including:
The number and location of isolation valves, i.e.,
the isolatten <alve arrange-a.
ments and the physical location of isolation valves with respect to the containment.
The actuation and control features 'or isolation <alves.
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The positions of isolation valves for ncrsal olant coersting conditions (includ-c.
in the event of valve ocerator ing shutdown), post-accicent conditions, and power failures.
3.
The valve actuation signals.
The basis for selection of closure times of isolation <alves.
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USNRC STAND ARO REVIEW PLAN
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The mechanical redundancy of isolation devices.
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The acceptability of closed piping systees inside containment as isolation barriers.
2.
The protection provided for containment isolation provisions against loss of function from missiles, pipe. Nip, and earthquakes.
3.
The environmental conditions inside and outside the containment that were considered in the design of isolation barriers.
4.
The design criteria applied to isolation barriers and piping.
5.
The provisions for detecting a possible need to isolate remote-manual-centmiled systems, such 45 engineered safety features systems.
5.
The design provisions for and technical specifications pertaining to operability and leakage rate testing of the isolation barriers.
7.
The calculation of containment atmosphere released prior to isolation valve closure for lines that provide a direct path to the environs.
PS8 has primary responsibility for the qualification test program for electric valve operators, and the ICSB has primary responsibility for the qualification test program for the sensing and actuation instrumentation o* the plant protection system located both inside and outside of containment. The MES has review responsibility for the qualifica-tion test program to demonstrate the performance and reliability of containment isolation valves. The MES and SES have review responsibility for mechanical and structural design j
of the containment isolation provisions to ensure adeouate protection against missiles, pice whip, and earthquakes. The AAB reviews the radiological dose consequence analysis for the release of containment atmosphere prior to closure of containment isolation valves in lines that provide a direct path to the environs. The R58 reviews the closure time for containment isolation <alves in lines that provide a direct path to the environs, witn ecspect to the prediction of onset of accident induced fuel failure.
II. ACCEPTANCE CRITERIA The general design criteria establish requirements for isolation barriers in lines pene-trating the primary containment boundary. In general, two isolation barriers in series are required to assure that the isolation function is satisfied assuming any single active failure in the containment isolation provisions.
The design of the containment isolation provisions will be acceptable to CSB if the following criteria are satisfied:
1.
General Design Criteria 55 and 56 reautre that lines that penetrate the primary con-tainment boundary and eitner are part of the reactor coolant pressure coundary or Rev. I s.2.5-2