ML20128C565

Safety Evaluation of Util 831104 Response to Generic Ltr 83-28,Item 1.2 Re post-trip Review (Data & Info Capability). Licensee post-trip Review Data & Info Capabilities Acceptable

ML20128C565
Person / Time
Site:	North Anna
Issue date:	06/14/1985
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20128C551	List: ML20128C547 ML20128C565
References
GL-83-28, NUDOCS 8507030621
Download: ML20128C565 (12)

Text

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION VIRGINIA ELECTRIC AND POWER COMPANY ,.

NORTH ANNA POWER STATION UNITS 1 AND 2 DOCKET NOS. 50-338, 50-339 .

GENERIC LETTER 83-28, ITEM 1.2 - POST-TRIP REVIEW (DATA AND INFORMATION CAPABILITY)

I. INTRODUCTION On February 25, 1983, both of the scram circuit breakers at Unit 1 of the Salem Nuclear Power Plant failed to open upon an automatic reactor trip signal from the reactor protection system. This incident occurred during the plant start-up and the reactor was tripped manually by the operator about 30 seconds after the initiation of the automatic trip signal. The failure of the circuit breakers has been determined to be related to the sticking of the under voltage trip attachment. Prior to this incident, on February 22, 1983, at Unit 1 of the Salem Nuclear Power Plant, an automatic trip signal was generated based on steam generator low-low level during plant start-up. In this case, the reactor was tripped manually by the operator almost ,

coincidentally with the automatic trip. Following these incidents, on February 28, 1983, the NRC Executive Director for Operations (ED0), directed

, the staff to investigate and report on the generic implications of these .

occurrences at Unit 1 of the Salem Nuclear Power Plant. The results of the l

staff's inquiry into the generic implications of the Salem unit incidents are reported in NUREG-1000, " Generic Implications of the ATWS Events at the Salen Nuclear Power Plant." As a result of this investigation, the Commission

! (fE) requested (by Generic Letter 83-28 dated July 8,1983) all licensees of operating reactors, applicants for an operating license, and holders of 8507030621 850614 PDR ADOCK 05000338 P PDR

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construction permits to respond to certain generic concerns. These concerns are categoriznd into four areas: (1) Post-Trip Review, (2) Equipment 4

Classification and Vendor Interface, (3) Post-Maintenance Testing, and (4) Reactor Trip System Reliability Improvements.

The first action item, Post-Trip Review, consists of Action Item 1.1,

" Program Description and Procedure" and Action Item 1.2, " Data and Information Capability." This safety evaluation (SE) addresses Action Item 1.2 only.

II. REVIEW GUIDELINES The following review guidelines were developed after initial evaluation of the various utility responses to Item 1.2 of Generic Letter 83-28 and incorporate the best features of these submittals. As such, these review guid,elines in effect represent a " good practices" approach to post-trip review. The staff has reviewed the licensee's response to Item 1.2 against these guidelines:

A. The equipment that provides the digital secuence of events (SOE) record and the analog time history records of an unscheduled shutdown should provide a reliable source of the necessary information to be used in the post-trip review. Each plant variable which is necessary to determine the cause and progression of the events following a plant trip should be monitored by at least one recorder (such as a sequence-of-events recorder or a plant process computer) for digital parameters; and strip

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charts, a plant process computer or analog recorder for analo'g (time history) variables. Performance characteristics guidelines for SOE and time history recorders are as follows:

Each sequence of events recorder should be capable of detecting and recording the sequence of events with a sufficient time discrimination capability to ensure that the time responses associated with each monitored safety-related system can be ascertained, and that a determination can be made as to whether the time response is within acceptable limits based on FSAR Chapter 15 Accident Analyses. The recommended guidelines for the SOE time discrimination is approximately 100 milliseconds. If current SOE recorders do not have this time discrimination -

capability, the licensee should show that the current time discrimination capability is sufficient for an adequate

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reconstruction of the course of the reactor trip and post-trip events. As a minimum, this should include the ability to adequately reconstruct the transient and accident scenarios presented in Chapter 15 of the plant FSAR.

Each analog time history data recorder should have a sample interval small enough so that the incident can be accurately reconstructed following a reactor trip. As a minimum, the licensee should be able to reconstruct the course of the transient and accident sequences evaluated in the accident analysis of

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Chapter 15 of the plant FSAR. The recommended guidelin,e for the sample interval is 10 seconds. If the time history equipment does not meet this guideline, the licensee should show that the time history capability is sufficient to accurately reconstruct the transient and accident sequences presented in Chapter 15 of the FSAR. To support the post-trip analysis of the cause of the trip and the proper functioning of involved safety related equipment, each analog time history data recorder should be capable of updating and retaining information from approximately 5 minutes prior to the trip until at least 10 minutes after the trip.

All equipment used to record sequence of events and time history information should be powered from a reliable and non-interruptible power source. The power source used need not be safety related.

B. The sequence of events and time history recording equipment should monitor sufficient digital and analog parameters, respectively, to assure that the course of the reactor trip and post-trip events can be reconstructed. The parameters monitored should prcvide sufficient information to determine the root cause of the unscheduled shutdown, the progression of the reactor trip, and the response of the plant parameters and protection and safety systems to the unscheduled shutdowns. Specifically, all input parameters associated with reactor trips, safety injections and other safety-related systems as well as output parameters sufficient to record the proper functioning of these

systems should be recorded for use in the post-trip review. The parameters deemed necessary, as a minimum, to perform a post-trip review that would determine if the plant remained within its safety limit design envelope are presented in Table 1. They were selected on the basis of staff engineering judgment following a complete evaluation of utility submittals. If the licensee's SOE recorders and time history recorders do not monitor all of the parameters suggested in these tables, the licensee should show that the existing set of monitored parameters are sufficient to establish that the plant remained within the design envelope for the accident conditions analyzed in Chapter 15 of the plant FSAR.

C. The information gathered by the sequence of events and time history recorders should be stored in a manner that will allow for data

. retrieval and analysis. The data may be retained in either hardcopy, ,

(e.g., computer printout, strip chart record), or in an accessible l memory (e.g., magnetic disc or tape). This information should be presented in a readable and meaningful format, taking into consideration good human factors practices such as those outlined in NUREG-0700.

D. Retention of data from all unscheduled shutdowns provides a valuable reference source for the determination of the acceptability of the plant vital parameter and equipment response to subsequent unscheduled shutdowns. Information gathered during the post-trip review is to be

retained for the life of the plant for post-trip review conipa'risons of subsequent events.

III. EVALUATION AND CONCLUSION By letter dated November 4,1983, Virginia Electric and Power Company provided infonnation regarding its post-trip review program data and information capabilities for North Anna Power Station Units 1 and 2. The staffhasevaluatedtheIicensee'ssubmittalagainstthereviewguidelines described in Section II. Licensee deviations from the Guidelines of Section II were reviewed with the licensee by telephone on May 23, 1985. A brief descrip- -4 tion of the licensee's responses and the staff's evaluation of the response ,

against each of the review guidelines is provided below:

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A. The licensee has described the perfonnance characteristics of the equipment used to record the sequence of events and time history data needed for post-trip review. Based on the staff's review, the staff finds that the sequence of events and time history recorder characteristics con-form to the guidelines described in Section II A, and are acceptable.

B. The licensee has established and identified the parameters to be monitored and recorded for post-trip review. Based on the staff's review and on information obtained during the telephone review, the staff finds that the parameters selected by the licensee include most of those identi-fied in Table 1. The licensee does not record all of the sequence of events and time history parameters as recorrunended in Section IIB. However, the staff

finds that the licensee has alternative data sources for those parameters not recorded on the sequence of events recorders and time his' tory recorders. These include: (1) an alarm printer, (2) the SPDS with hard copy capability, and (3) strip chart recorders with non-interruptible power supplies. Consequently, the staff finds the licensee's selection of parameters meets the intent of the guidelines described in Section IIB and is, therefore, acceptable.

C. The licensee has described the means for storage and retrieval of the information gathered by the sequence of events and time history recorders, and for the presentation of this information for post-trip review and analysis. Based on the staff's review, the staff finds that this information will be presented in a readable and n:aningful format, and that the storage, retrieval and presentation conform to the guidelines

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of Section II C.

D. The licensee's submittal indicates that the data and information used during post-trip reviews will be retained in an accessible manner for the life of the plant. Based on the staff's review, the staff finds that the licensee's progr6m for data retention conforms to the guidelines of Section II D, and is acceptable.

Bcsed on the staff's review, the staff concludes that the licensee's post-trip review data and information capabilities for North Anna Power Station linits 1 and 2 are acceptable.

Principal Contributor:

J. J. Kramer, DHFS

TABLE 1 PWR PARAMETER LIST

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4 SOE Time History

• Recorder Recorder Parameter / Signal (1) x Reactor Trip (1)x Safety Injection x Containment Isolation (1) x Turbine Trip x Control Rod Position (1) x x Neutron Flux, Power x x Containment Pressure (2) Containment Radiation x Containment Sump Level (1)x x Primary System Pressure (1)x x Primary System Temperature (1)x Pressurizer Level -

(1) x Reactor Coolant Pump Status (1) x x Primary System Flow (3) Safety Inj.; Flow, Pump / Valve Status -

x MSIV Position x x Steam Generator Pressure (1) x x Steam Generator Level (1) x x Feedwater Flow (1) x x Steam Flow

SOE Time History Recorder Recorder Parameter / Signal (3) Auxiliary Feedwater System: Flow, Pump / Valve Status x AC and DC System Status (Bus Voltage) x Diesel Generator Status (Start /Stop, On/Off) x PORV Position (1) Trip parameters (2) Parameter may be monitored by either an SOE or time history recorder. _

(3) Acceptable recorder options are; (a)systemflowrecordedonanSOE l '. recorder, (b) system flow recorded on a time history recorder, or (c) -

l equipment status recorded on an SOE recorder.

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TABLE 1 BWR PARAMETER LIST SOE Time History Recorder Recorder Parameter / Signal x Reactor Trip x Safety Injection x Containment Isolation x Turbine Trip x Control Rnd Position x(1) x Neutron Flux, Power x (1) Main Steam Radiation (2) Containment (Dry Well) Radiation x(1) x Drywell Pressure (Containnent Pressure)

(2) Suppression Pool Temperature x(1) x Primary System Pressure x (l') x Primary System Level -

x MSIV Position x (1) Turbine Stop Valve / Control Valve Position x Turbine Bypass Valve Position x Feedwater Flow x Steam Flow (3) Recirculation; Flow, Pump Status x(1) Scram Discharge Level x(1) Condenser Vacuum

SOE Time History Recorder Recorder Parameter / Signal x AC and DC System Status (Bus Voltage)

(3)(4) Safety Injection; Flow, Pump / Valve Status x Diesel Generator Status (on/0ff, Start /Stop)

(1): Trip parameters (2): Parameter may be recorded by either an SOE or time history recorder.

(3): Acceptsble recorder options are: (a) system flow recorded on an SOE recorder, (b) system flow recorded on a time history recorder, or (c) equipment status recorded on an SOE recorder. .

(4): Includes recording of parameters for all applicable systems from the following: HPCI, LPCI, LPCS, IC, RCIC.

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Mr. W. L. Stewart North Anna Power Station Virginia Electric & Power Company Richard M. Foster, Esq. Atomic Safety and Licensing Appeal Musick, Williamson, Schwartz, Board Panel leavenworth & Cope, P.C. U.S. Nuclear Regulatory Commission P. O. Box 4579 Washington, DC 20555 ,

Boulder, Colorado 80306 Regional Administrator Michael H. Maupin, Esq. USNRC, Region II Hunton, Williams, Gay and Gibson Office of Executive Director P. O. Box 1535 for Operations Richmond, Virginia 23212 101 Marietta Street N.W., Suite 2900 Atlanta, Georgia 30323 Mr. W. T. Lough Virginia Corporation Comission Mr. E. W. Harrell Division of Energy Regulation P. O. Box 402 P. O. Box 1197 Mineral, Virginia 23117 Richmond, Virginia 23209 A Old Dominion Electric Cooperative Ellyn R. Weiss, Esq. c/o Executive Vice President Sheldon, Hannan, Roisman and Weiss Innsbrook Corporate Center j Wa ing on 5 5 556 en e irg a 060 Mg. J. H. Ferguson Mr. Richard C. Klepper

' Executive Vice President - Power Board of Supervisors .

Virginia Electric and Power Co. Louisa County Courthouse Post Office Box 26666 P. O. Box 27 Richmond, Virginia 23261 Louisa, Virginia 23093 Mr. Anthony Gambardella -

Office of the Attorney General Supreme Court Building 101 North 8th Street Richmond, Virginia 23219

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Resident Inspector / North Anna c/o U.S. NRC Senior Resident Inspector Route 2, Box 78 Mineral, Virginia 23117 Mrs. Margaret Dietrich Route 2, Box 568 Gordonsville, Virginia 22042 Mr. Paul W. Purdom Environmental Studies Institute Drexel University 32nd and Chestnut Streets Philadelphia, Pennsylvania 19104

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