ML17037B589

Letter Regarding Use of the Recirculation Pump Trip to Mitigate the Consequences of an Anticipated Transient Without Scram and Request for Additional Information

ML17037B589
Person / Time
Site:	Nine Mile Point
Issue date:	05/15/1978
From:	Lear G Office of Nuclear Reactor Regulation
To:	Dise D Niagara Mohawk Power Corp
References
Download: ML17037B589 (10)

Text

0 HN g 5 1978 DISTRIBUTION:

Docket 11AY 5 1S78 NRC PDR Local PDR Docket No. 50-220 ORB83 Rdg

'Lear S Sheppard VRooney Niagara Mohawk Power Corporation RCl ark ATTN: Hr. Donald P. Disc OELD Vice President - Engineering OI&E (3) 300 Erie Boulevard Hest DEisenhut Syracuse, New York 13202 TPAbernathy A fi~<sAA4 JRBuchanah 6~4~

Gentlemen: ACRS (16)

RDiggs RE: NINE HILE POIilT File Me are reviewing your letter dated October 4, 1976, which discusses your use of the recirculation pump trip {RPT) to r~itigate the consequences of an Anticipated Transient Hithout Scram {ATMS). To continue our review we need to compare your design with certain criteria described in the Enclosure. Therefore, please provide the following information:

1. Your detailed point-by-point description of how your RPT meets the criter ia of Enclosure l. Identify all instances in which you believe you do not conform to the criteria and either propose modifications to meet the criteria, or justify your design as an acceptable al ternative.

2. Provide complete logic diagrams and electrical schematics for the RPT.

3. Propose any plant Technical Specification changes which should result from the RPT and provide a schedu'le for implementation.

If some of the above information has already been submitted, please provide a specific reference. You are requested to supply one signed original and 39 copies of your response within 60 days of the receipt of this letter.

Sincerely, Original sign41d bV George Lear, Chief Operating Reactors Branch P3 D ivision of 0p ratin g React ors

Enclosure:

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Niagara Mohawk Power Corporation'c:

Eugene B. Thomas, Jr., Esquire LeBoeuf, Lamb, Leiby 5 MacRae 1757 N Street, N. W.

Washington, D. C. 20036 Anthony Z. Roisman Natural Resources Defense Council 917 15th Street, N. W.

Washington, D. C. 20005 Oswego County Office Building 46 E. Bridge Street Oswego, New York 13126

4l ENCLOSURE 1 CRITERIA FOR RECIRCULATION PUMP TRIP RPT IN OPERATING BWR'S A. General Functional Re uirement The RPT system shall automatically initiate the appropriate action whenever the conditions monitored by the system reach a preset level.

B. Inde endence and Inte rit The RPT system and components shall be independent and separate

-from components and/or'ystems that initiate the anticipated transient(s) being analyzed and diverse from the normal scram system (postulated to fail) to minimize the probability of the ATWS disabling the operation of the mitigating system. Diversity can be achieved by incorporating as many of the following methods as is practicable:

(1) Use of components from different manufacturers.

(2) Use of electromechanical devices versus electronic devices.

(3) Use of energized versus deenergized trip status. (For some components, such as relays, this alone may not be acceptable).

(4) Use of AC versus DC power sources.

(5) Use of sensors employing different principles f'r measuring the same parameters.

Tests and/or analyses shall be performed to demonstrate that the function of the RPT system and components will not be disabled as a consequence of the ATWS event being analyzed.

C. RPT S stem Interaction with Control S stems and Scram S stems Any control systems or control equipment and components that are used for both normal control functions and as part of the RPT system shall be classified as part of the RPT system and shall meet all the requirements for the RPT system, including independence from the scram system. For shared components, test and/or analyses shall be performed to demonstrate that no credible failures exist in the portions of the control systems which interface with the shared system that could disable the RPT system.

E ui ment uglification The RPT system equipment and components shall be tested to verify that the system will provide, on a continuing basis, its functional capability under conditions relevant to the postulated ATWS, including extremes of conditions (as applicable) relating to environment, which are expected to occur in the lifetime of a plant.

Periodic Surveillance and Preventative Maintenance Testin and Calibration Periodic surveillance and preventative maintenance tests and calibration requirements shall be identified to provide continuing assurance that the RPT system, including sensors and actuated equipment, is capable of functioning as designed and that system accuracy and performance have not deteriorated with time and usage. These requirements shall be particularly directed toward the detection of those failures or degradation of accuracy and performance which would not otherwise be likely to be detected during the course of normal operations. Integrated system testing shall also be performed to verify overall system performance. The frequency of testing and calibration shall be determined and justified in accordance with the availability and reliability requirements of the system.

ualit Assurance A quality assurance program in conformance with the requirements of 10 CFR 50 Appendix 8 shall be applied to the RPT system design and equipment.

Administrative Controls Administrative controls shall be established to control the access to all set point adjustments, calibration and test points.

Information Readout The RPT system shall be designed to provide the operator with accurate, complete and timely information regarding its status.

For those functions, including operations, test or maintenance, and calibration, which require direct operator inter action, human engineering factors such as information displays (e.g.,

display formats, layout and controls) and functional controls (e.g., methods, location and identification) shall be included in the design.

~II i i bli The design shall include measures which enhance maintainability to reduce mean-time-to-repair and to assure the continued availability and reliability the system for the life of the of plant. The system design shall include features which facilitate the recognition, location, replacement, repair and/or adjustment of malfunctioning equipment, and components or modules.

J. Availabilit and Reliabilit Two options are provided. Fulfilling the requirements of either (1) or (2) below will provide the reliability appropriate for the RPT system.

~0tion 1 The RPT system shall satisfy all requirements for a safety system in the nuclear power plants of IEEE-279, dated 1971 and supplemented by paragraph (A) through (I) above.

~0tion 2 The RPT system shall satisfy (A) through (I) above and in addition for all initiating events except loss of offsite power shall have a calculated unavailability of approximately 10 3 per demand at the 50% confidence level. Reliability calculations similar to the reactor safety study (WASH 1400) shall include consideration of human errors, comon-mode failures and test and maintenance outages. Applicable failure rates from the Reactor Safety Study shall be used unless similar analyses are performed using more current data base. For loss-of-offsite-power transients, the unavailability limit is 5 x 10 2 at the 505 confidence level.