ML20126L744
| ML20126L744 | |
| Person / Time | |
|---|---|
| Site: | Hatch  |
| Issue date: | 07/18/1985 |
| From: | NRC |
| To: | |
| Shared Package | |
| ML20126L742 | List: |
| References | |
| GL-83-28, NUDOCS 8508010006 | |
| Download: ML20126L744 (10) | |
Text
ENCLOSURE 1 SAFETY EVALUATION REPORT FOR i
GENERIC LETTER 83-28, ITEM 1.2 - POST-TRIP REVIEW (DATA AND INFORMATION CAPA8ILITY)
EDWIN 1. HATCH NUCLEAR PLANT UNITS 1 AND 2 DOCKET NOS.: 50-321, 50-366 1.
INTRODUCTION On February 25, 1983, both of the scram circuit breakers at Unit 1 of th Salem Nuclear Power Plant failed to open upon an automatic re e
i rp signal from the reactor protection system.
1his incident occt.rred during the plant start-up and the reactor was tripped manually by the op u
seconds after the initiation of the automatic trip signal.
The failure of the circuit breakers has been determined to be relate c ng 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 sig generated based on steam generator low-low level during plant 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 impli:ations of th ese occurrences at Unit 1 of the Salem Nuclear Power Plant.
The results of the staff's inquiry into the generic implications of the Salem unit inci reported in NUREG-1000, " Generic Implications of the ATWS Even Nuclear Power Plant."
As a result of this investigation, the Commission (NRC) requested (by Generic Letter 83-26 dated July 8, 1983) al censees of operating reactors, applicants for an operating license, and holders of i
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construction pemits to respor.d to certain generic con: erns.
These concerns are ce'tesqrized into four are:is:
-()) Post-Trip Review. (2) Equi;wnent Classification and Vendor Ir,terface, (3) Post-Maintenance Te
,and (4)ReactorTripSystemheliab,ility.Inrsvements.
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The first action item, F,ost-Trip 9eview, consists of Action Item 1
" Program Descri,ntion and ProceJum" ano Action Item 12 4
" Data and Infomation Caj sbility."
Thissafetyevaluationreport(SER)tddresses Action Item I.2 only.
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REVIEW GUIDE!.INES Jhe following review glidelinek Mre eveloped after initial eval uation of the vario,", utility responses to l tem 1.2 of Generic Letter 83 28 anc '
.ine:orpora $ the best features of these submittals.
s, As such, these reviev 9
guidelines in eff+;t represent a " good practices" approach t review.
We have reviewed the licensee's response to Item 1.2 again gui.'.el ir.es ;
ee A.
Theequipmentthatprovidesthedigitalsiguenceelevents(SOE r
nnd tbf analog time history records of.an't:nschtduled shutdown provide a reliable source of the necessary informtfon to be us lost-trip regiew.
Each plant variable which if necessary to determine 1
thecauseandprogressionoftheevents(911bwfngap;lanttri p should be mclitorehLy9tleastonerecorder(sur.h'ast.styuencte-of-events recorder'<,r's plant process cor.pi.ter) for d9 ital prbneters; a
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charts, a plant process coinputer or analog recorder for history) variables., Performance characteristics guidelines fo r SOE and time history recorders' are as follows:
' Each sequence cf events recorder should be capa and recording the sequence of events with a sufficient time discriminationcapabilitytoensurethatthetimeresponses assocMc:1 with each monitored safety-related system can be ascertained, and that a determination can be made as to wh the time response is within acceptable limits based on FSA Chapter 15 Accident Analyses.
The recomended guidelines for the
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SOE time discrimination is approximately 100 milliseconds If i
cur ent SOE recorders do not have this time discrim
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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 a
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events.
1 e a minimum this should include the ability to k
adequately recbnstruct the transient and accident scenario
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Each analog time history data recorder should have a sa i
interval small enough so that the incident can be accuratel 4
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y reconstructed fo11 wing a reactor trip.
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As a minimum, the s
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g and accident sequences evaluated in the accident analysis of i
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l Chapter' M. of the plant FSAR.
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The recomended guideitne for the T
sample interval is 10 seconds.
j If the time history equipment does not' neet this guideline, the licensee should show that the s
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,j ? history capability is sufficient to accurately reconstruct the
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r transient and accident sequences presented in Chapter 15 of t
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FSAR.
e To support the post-trip analysis of the cause of the trip andbe proper functioning of involved safety relate i
each analog time history data recorderishould be capable of i
i updat.inj and retaining infomation from>approximately five j
, prior 'to the trip until at least ten minutes after the trip.
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All equipment used to record sequence of events and time h
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s ory infomation should be powered from a reliable and i
non-interruptible p~ wer source.
o The power source used need not be safety related.
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I B.
The sequence of everts and tine! history recording equipme t n should monitor sufficient digital and anckog parameters, respectively
, to assure that the course of the recctor trip and post-trip events can b t
i, reconstructed.
e The parameters monitored'should provide sufficient infomation to detsemine the root cause of 'the unscheduled shutdown, the
, progression of the reactor trip, and the responsed of the plant parameters and protection and safety systems to the unscheduled 7 shutdowns.
Specifically, all input parameters associited with reactor x
trips,issfety injections and other se;fety-related syste 4
i' ms as well as output parameters sufficient to record the proper functioning of th s s
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. systems should be recorded for use in the post-trip review The parameters deemed necessary, as a minimum, to perfom a post that would determine if the plant remained within its safet review y limit design envelope are presented in Table 1.
They were selected on the basis of staff engineering judgment following a complete ev l a uation of
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utility submittals.
If the licensee's SOE recorders and time history recorders do not monitor all of the parameters suggested in thes the licensee should show that the existing set of monitored a es parameters are sufficient to establish that the plant remained within the desi envelope for the accident conditions analyzed in Chapter 15 of th gn FSAR.
e plant C.
The infomation gathered by the sequence of events and ti me history recorders should be stored in a manner that will allow f retrieval and analysis.
The data may be retained in either hardcopy, (e.g., computer printout, strip chart record), or in an a ccessible memory (e.g., magnetic disc or tape).
This information should be presented in a readable and meaningful format, taking into consid eration good human tactors practices such as those outlined in NUREG 0 D.
Retention of data from all unscheduled shutdowns provides a valuable reference source for the detemination of the acceptability of th e plant vital parameter and equipment response to subsequent unschedu shutdowns.
Infomation gathered during the post-trip review is to be
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. i retained for the life of the plant for post-trip review comparisons subsequent events.
III.
EVALUATION AND CONCLUSION By letters dated November 7,1983 and February 29, 1984, Georgia Power Company provided information regarding'its post-trip review pro and information capabilities for Edwin I. Hatch Nuclear Plant Units 1 We have evaluated the ifcensee's submittal against the review guidel described in Section II.
Licensee deviations from the Guidelines of Se II were reviewed with the licensee in a meeting on June II
, 1985, and by phone on June 12, 1985.
A brief description of the licensee's responses and the staff's evaluation of the response against each of the revi ew guidelines is provided below:
A.
The licensee has described the perfomance characteristics of th equipment used to record the sequence of events and time histo needed for post-trip review.
The licensee's submittals contained no infomation on time discrimination between events for the seque events recorders. By telephone on June 12, 1985, the licensee stat that the time discrimination between events is 16.7 m The staff, therefore, finds that the sequence of events recorder characteristics conform to the guidelines in Section II A, and are acceptable.
The time history recorder characteristics conform to these guidelines, except for the post-trip duration of five minutes During
-our meeting and phone call with the licensee, the licensee stated that
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. they sanple all of the time history parameters at five second i
- ntervals, which is superior to our guideline of ten seconds, and that co nuously running strip chart recorders are available for the period bey e
post-trip recording duration of five minutes.
In view of these characteristics, we find that the licensee's post-trip duration i acceptable.
B.
The licensee has established and identified the parameters to e
monitored and recorded for post-trip review. Based on our review, of the licensee's submittals and on information obtained during ur meeting and phone call with the licensee, we find that the paramete by the licensee include all but one of those identified in T bl e
a e 1.
The licensee stated that while Turbine Bypass Valve Position is recorded on a sequence of event recorder, there are indirect indication Flow and Reactor Pressure) in the control room which
, when combined with special procedures, provide the desired information.
The staff finds this alternative acceptable.
The licensee does not record all of the sequence of events a history parameters in the specific renner recommended in Tabl me e 1.
However, based upon information provided by the licensee du i r ng our meeting and phone call, we find that the licensee has alternat a
sources for those parameters not recorded on the sequence of ev recorders and time history recorders.
These include: (1) an alarm printer, (2) the SPDS with hardcopy capability, and (3) strip cha
. recorders with non-interruptible power supplies.
Consequently, we find that the licensee's selection of parameter 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 retriev information gathered by the sequence of events and time his recorders, and for the presentation of this information for pos review and analysis.
Based on our review, we find that this information will be presented in a readable and meaningful format, and tha storage, retrieval and presentation conform to the guidelines of Section II C.
D.
The licensee's submittals did not indicate that the d rmation used during post-trip reviews is retained in an accessible manner the life of the plant.
During our meeting and phone call with the licensee, the licensee stated that this data and inforvation is r ned in an accessible manner for the life of the plant.Therefore, we find that the licensce's program for data retention conforms to the guidelines of Section II D, and is acceptable.
Based on our review, we conclude that the licensee's post-trip re i v ew data and information capabilities for Edwin I. Hatch Nuclear Plant Un are acceptable.
Dated: July 18, 1985 Principal Contributor:
J. Kramer
-9 TABLE 1 BWR PARAMETER LIST SOE Recorder Time History Recorder
_ Parameter / Signal x
Safety injection x
Containment Isolation x
Control Rod Position x (1) x Neutron Flux, Power x(1)
Main Steam Radiation (2)
Containment (Dry Well) Radiation x (1) x (2)
Drywell Pressure (Containment Pressure)
Suppression Pool Temperature x (1) x Primary System Pressure x (1) x Primary System f.evel 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 i
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. SOE Time History Recorder Recorder
.Pa rameter/ Signal x
AC and DC System Status (Bus Voltage)
(3)(4)
Safety Injection; Flow, Pump / Valve Status x
Diesel Generator Status (on/Off, Start /Stop)
(1) Trip parameters (2)
Parameter may be recorded 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.
(4)
Includes recording of parameters for all applicable systems from the following: HPCI, LPCI, LPCS, IC, RCIC.
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