ML20128G111

SER of Util Response to Generic Ltr 83-28,Item 1.2 Re post-trip Review (Data & Info Capability).Response to Item 1.2 Complete & Acceptable

ML20128G111
Person / Time
Site:	Mcguire, Catawba, McGuire, 05000000
Issue date:	06/21/1985
From:	NRC
To:
Shared Package
ML20128G098	List: ML20128G094 ML20128G111
References
GL-83-28, NUDOCS 8507090050
Download: ML20128G111 (10)

Text

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ENCLOSURE 1 SAFETY EVALUATION REPORT FOR GENERIC LETTER 83-28, ITEM 1.2 - POST-TRIP REVIEY (DATA AND INFORMATION CAPABILITY)

CATAWBA AND MCGUIRE NUCLEAR STATIONS, UNITS 1 AND 2 DOCKET NOS.: 50-369, 50-370, 50-413, 50-414 I. INTRODUCTION On February 25, 1983, both of the scram circuit breakers at Units 1 and 2 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 Units 1 and 2 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 Directer for Operations (ED01, directed the staff to investigate and report on the generic imolications of these occurrences at Units 1 and 2 of the Salem Nuclear Power Plant. The results of the staff's inquiry into the generic imolications of the Salem unit incidents are ,

reported in MUREG-1000, " Generic Implications of the ATWS Events at the Salem Nuclear Power Plant." As a result of this investigation, the Commission (NRC) reouested (by Generic Letter 83-28 dated July 8, 1983) all licensees of operating reactors, applicants for an operating license, and holders of 8507090(H50 850621 9 DR ADOCK 050

construction permits to respond to certain generic concerns. These concerns are_ categorized into four areas: (1) Post-Trip Review, (2) Eouipment Classification and Vendor Interface, (3) Post-Maintenance Testing, and (a) 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 report (SER) addresses Action Item 1.2 only. .

6 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 ircorporate the best features of these submittals. As such, these review guidelines in effect represent a " good practices" approach to post-trip review. We have reviewed the licensee's response to Item 1.2 against these

-guidelines:

A. Tne 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 olant variable which is necessary to determine the cause and progression of the events following a olant 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 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 discriminatis* 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 transiert l

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 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 five minutes prior to the trip until at least ten 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.

S. The secuence 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-trio 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 o# 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 ccmplete 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 shcw 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 hardcooy, (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 frcm all unscheduled shutdowns orovides a valuable reference scurce 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 comparisons of subsequent events.

III. EVALUATION AND CONCLUSION By letters dated November 4,1983, Duke Power Company provided information regarding its post-trip review program data and information capabilities for Catawba and McGuire Nuclear Stations. We have evaluated the licensee's submittals 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 23, 1985. A brief description of the licensee's responses and the staff's evaluation of the responses against each of the review guidelines are provided below:

A. The licensee has described the performance characteristics of the equipment used to record the sequence of events and time history data needed for post-trip review. Based on our review, we find 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-trio review. Based on our review and on information obtained during our telephone review, we find that the parameters selected by the licensee include most of those identified in Table 1. The licensee does not record all of the sequence of events

parameters recommended in Section II B. We find that control rod position is not recorded for all rods; this information is only available in a control room display. Safety injection flow is not

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recorded on the sequence of events recorder; however, pump and valve status are recorded. Feedwater flow and steam flow (trip parametersi are not recorded; however..the licensee states that these are not trip parameters for the plants. All of the time history parameters listed in Section II B are recorded by the licensee. We find that alternative data sources for those parameters not recorded on the sequence of events recorder are available for the post-trip review.

Consequently, we find that the licensee's selection of parameters meets the intent of the guidelines described in Section II B 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 our review and on information obtained during our telephone review, we find that this information is being presented in a readable and meaningful format, and that the storage, retrieval and presentation conforn to the guidelines of Section II C.

D. The licensee has informed us that the data and information used during post-trip reviews will be retained for no more than six years. We find

that the licensee's program for data retention does not conform to the guidelines of Section II D, which recommend that information gathered during a post-trip review be retained for the life of the plants.

3ased on our review, we conclude that with the exception of the record retention period for data and information used in post-trip reviews, the licensee's post-trip review data and internation capabilities for Catawba and McGuire fluclear Stations Units 1 and 2 are acceptable. We recommend that the data and information used during post-trip reviews be retained for the life of the plants.

TABLE 1 PWR PARAMETER LIST SOE Time History Recorder ' Recorder Parameter /Sfanal (1)x Reactor Trip (1) x Safety In,iection 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 ,YSIV 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/0ff) x PORY Position (1) Trio parameters (2) Parameter may be monitored by either an SOE or time history recorder.

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

-eouipment status recorded on an SOE recorder.

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