ML20199D421

SER on Util 831104 & 860423 Responses to Generic Ltr 83-28, Item 1.2 Re post-trip Review Data & Info Capabilities.Data & Info Capabilities Acceptable

ML20199D421
Person / Time
Site:	Summer
Issue date:	06/09/1986
From:	NRC
To:
Shared Package
ML20199D413	List: ML20199D410 ML20199D421
References
GL-83-28, NUDOCS 8606200304
Download: ML20199D421 (9)

Text

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

SUMMER NUCLEAR STATION DOCKET NO. 50-395 I. INTRODUCTION On February 25, 1983, both scram circuit breakers at Unit 1 of the Salem Nuclear Power Plant (SNPP) 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 detemined to be related to the sticking of the undervoltage trip attachment. On February 22, 1983, during start-up of SNPP, Unit 1, an automatic trip signal occurred as the result of steam generator low-low level. 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 (EDO) directed the staff to investigate and report on the generic implications of these occurrences. The results of the staff's inquiry into these incidents were reported in NUREG-1000, " Generic Implications of ATWS Events at the Salem Nuclear Power Plant." As a result of this investigation, the Commission requested (by Generic Letter 83-28 dated July 8,1983) all licensees of operating reactors, applicants for an operating 4 license, and holders of construction permits to respond to certain generic concerns. These concerns are categorized into four areas: (1) Post-Trip r

Review, (2) Equipment Classification and Vendor Interface, (3) Post-Maintenance l

Testing, and (4) Reactor Trip System Reliability Improvements.

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8606200304 860609 l PDR ADOCK 05000395 P

PDR _

2-e The first action item, Post-Trip Review, consists of Action Item 1.1, " Program Description and Procedure" and Action Item 1.2, " Data and Infomation Capability." This safety evaluation report (SER) 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 guidelines in effect represent a " good practices" approach to post-trip review. We have re-viewed the applicant'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 infomation 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 charts, l a plant process computer or analog recorder for analog (time history) i

variables. Performance characteristics guidelines for SOE and time history recorders are as follows

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l' o 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 reconnended 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 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.

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o 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 l

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• . i analysis of Chapter 15 of the plant FSAR. The reconnended 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 retcining information from approximately five minutes prior to the trip until at least ten minutes after the trip.

o 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 Class IE.

4 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 provide sufficient information to determine the root cause of the unscheduled shutdown, the progression of the reactor trip, and the response of the plant 1

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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 para-meters deemed necessary, as a minimum, to perform 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 utility submittals; If the licensee's SOE recorders and time history recorders do not monitor all of the parameters suggested in these tables the licen-

. see should show that the existing set of monitored parameters are suffi-cient to establish that the plant remained within the design envelope for the accident conditions analyzed in Chapter 15 of the plant FSAR.

. . C. The infomation 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., com-puter printout, strip chart record), or in an accessible memory (e.g.,

magnetic disc or tape). This information should be presented in a read-able and meaningful femat, 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 comparisons of subsequent events.

III. EVALUATION AND CONCLUSION By letters dated November 4,1983 and April 23, 1986, South Carolina Electric &

Gas Company provided information regarding its post-trip review program data and information capabilities for Sunner Nuclear Station. We have evaluated the licensee's submittals against the review guidelines described in Section II.

Deviations from the Guidelines of Section II were discussed with representatives of the licensee by telephone on March 26, 1986. A brief description of the licensee's responses and the staff's evaluation of the response against each

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of the review guidelines follows:

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 of the licensee's submittals and our telephone conversation, we find that the sequence of events recorder and time history recorder characteristics conform to the guidelines described in Section II A, and are acceptable.

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B. The licensee has established and identified the parameters to be monitored and recorded for post-trip review. Based on our review, we find 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 therefore are acceptable. -

C. The licensee described the means for storage and retrieval of the infomation 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, we find that this information will be presented in a readable and meaningful fomat, and that the storage, retrieval and presentation conform to the guidelines of Section II C.

D. The licensee's submittal of April 23, 1986 indicates that the data and

. . infomation used during post-trip reviews are being retained in an accessible manner for the life of the plant. Based on this infomation, we find that the licensee's program for data retention confoms to the guidelines of Section !! D, and is acceptable.

Based on our review of the licensee's submittals and our telephone conversa-tion with the licensee, we conclude that the licensee's post-trip review data and infomation capabilities for Sumer Nuclear Station are acceptable.

Principal Contributors:

Joel J. Kramer, Electrical, Instrumentation and Control Systems Branch, DPLA Jon B. Hopkins, PWR Project Directorate #2, DPLA

TABLE 1 PWR PARAMETER LIST t

SOE Time History Fecorder Recorder r arameter/ 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

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(2) Containment Radiation x Containment Sump Level (1)x x Primary System Pressure (1)x x Primary System Temperature (1)a Pressurizer Level (1)x Reactor Coolant Pump Status l-

, (1)x x Primary System Flow (3) Safety inj.; Flow. Pump / Valve Status

.x MSIV Position x x Steam Generator Pressure l

(1)x x Steam Generator Level

(1)x x Feedwater Flow l

l (1)x x Steam Flow I

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SOE Time History Recorder Recorder {

. Parameter / Signal j (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 PORY Position (1) Trip parameters (2) Parameter may be monitored by either an SOE or time history recorder.

(3) Accep*able recorder options are; (a)systemflowrecordedonanSOE recorder. (b) system flow recorded on a time history recorder, or (c) equipment status recorded on an SOE recorder.

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