ML20128C252

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

ML20128C252
Person / Time
Site:	Fort Calhoun
Issue date:	06/13/1985
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20128C228	List: ML20128C225 ML20128C252
References
GL-83-28, NUDOCS 8507030520
Download: ML20128C252 (10)

Text

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UNITED STATES fog g[ g NUCLEAR REGULATORY COMMISSION W A5HINGTON, D. C. 20555 t j

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REA DMAHA PUBLIC POWER DISTRICT FORT CALHOUN STATION UNIT I -

DOCKEI NO. 50-285 POST-TRIP REVIEW GENERIC LETTER 83-28, ITEM 1.2 a I. INTRODUCTION _

On February 25, 1983, both of the scram circuit breakers at Unit I of the Salem Nuclear Power Plant failed to open upon an automatic reactor f This incident occurred during the signal from the reactor protection system. b t 30 plant start-up and the reactor was tripped manually by the operator a r The failure of seconds after the initiation of the automatic trip signal. f the i g r

the circuit breakers has been detemined to be related 22,1983, to the stick ngt o Prior to this incident, on February &

under voltage trip attachment. i at Unit 1 of the Salem Nuclear Power Plant, an automatic In trip signal w generated based on steam generator low-low level during plant star this case, the reactor was tripped manually by the operator almost Following these incidents, on coincidentally with the automatic trip.

the NRC Executive Director for Operations (EDO), directed February 28, 1983, the staff to investigate and report on the generic implications of these The results of the occurrences at Unit 1 of the Salem Nuclear Power Plant.

staff's inquiry into the generic implications of the Salem unit inciden the Salem reported in NUREG-1000, " Generic Implications of the ATWS Even As a result of this investigation, the Comission Nuclear Power Plant."

(NRC) requested (byGenericLetter83-28datedJuly8,1983)a operating reactors, applicants for an operating license, and ho '

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construction permits to respond to certain generic concerns. These concerns are categorized into four areas: (1) Post-TripReview,(2) Equipment 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 end incorporate the best features of these submittals. As such, these review guidelines 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 sequence 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 detennine thecauseandprogressionoftheeventsfollowingaplanttripshouldbe monitored by at least one recorder (such as a sequence-of-events recorder or a plant process computer) for digital parameters; and strip

charts, a plant process computer or analog recorder for analog (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

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discrimination capability is sufficient for an adequate 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

Chapter 15 of the plant FSAR. The recommended guideline for the sample interval is 10 seconds. If the time history equipment does not meet this guideline, the licensee should show that the time 1

history capability is sufficient to accurately reconstruct the l 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 infomation from approximately 5 minutes prior to the trip until at least 10 minutes after the trip.

l 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 l 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 provide 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

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l l systems should be recorded for use in the post-trip review. The parameters deemed necessary, as a minimum, to perfom a post-trip review that would detemine 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 I 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 is sufficient to establish that the plant remained within the design l

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 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

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l retained for the life of the plant for post-trip review comparisons of subsequent events.

III. EVA!.UATION AND CONCLUSION By letter dated November 4,1983, the Omaha Public Power District provided infomation regarding its post-trip review program data and infonnation capabilities for Fort Calhoun Station Unit 1. The staff has evaluated the licensee's submittal against the review guidelines described in Section II.

Licensee deviations from the Guidelines of Section II were reviewed with the licensee by telephone on May 28, 1985. A brief description of the licensee's responses and the staff's evaluation of the response against each of the review guidelines is provided below:

A. The licensee has described the performance characteristics of the equipment used to record the sequence of events and tim.: history data f needed for post-trip review. Based the staff's our review and on infor-mation obtained during the telephone review, the staff finds that the sequence of events and time history recorder characteristics conform 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 infomation obtaineo during the telephone review, the

staff finds that the parameters selected by the licensee include all of those identified in Table 1 and conform to the guidelines described in Section II B and are, therefore, acceptable.

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C. The licensee has described the means for storage and retrieval of the infonnation gathered by the sequence of events and time history recorders, and for he presentation of this infonnation for post-trip

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review and analysis. Based on the staff's review, we finds that this in-fonnation will be presented in a readable and meaningful format, and that g 2, the storage, retrieval and presentation confonn to the guidelines of 9

Section II C.

D. The licensee has confirmed 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 telephone review, the staff finds that the licensee's program for data retention confonns to the guidelines of Section II D, and is acceptable.

Based on the staff's review, the staff concludes that the licensee's post-trip N

review data and infonnation capabilities for Fort Calhoun Station Unit I are acceptable.

Principal Contributor:

R. W. Froelich, DHFS

TABLE 1 PWR PARAMETER LIST 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 4

(1) Trip parameters (2) Pareneter may be monitored by either an SOE or time history recorder.

(3) Acceptable 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.

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Mr. R. L. Andrews Omaha Public Power District Ft. Calhoun Station, Unit No. 1 Harry H. Voigt, Esq.

LeBoeuf, Lamb, Leiby & MacRae -

1333 New Hampshire Avenue, NW Washington, DC 20036 Mr. Jack Jensen, Chairman Washington County Board of Supervisors Blair, Nebraska 68023 Metropolitan Planning Agency ATTN: Dagnia Prieditis

'7000 West Center Road Omaha, Nebraska 68107 Mr. Larry Yandell U.S. NRC Resident Inspector Post Office Box 309 Fort Calhoun, Nebraska 68023 Mr. Charles B. Brinkman, Manager Washington Nuclear Operations C-E Power Systems 7910 Woodmont Avenue Bethesda, Maryland 20814 Regional Administrator USNRC, Region IV Office of Executive Director for Operations 611 Ryan Plaza Drive, Suite 1000 Arlington, Texas 76011 9

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