ML20023B062
| ML20023B062 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 12/10/1982 |
| From: | Overbeck G, Ludington B, Vosbury F Franklin Research Ctr, Franklin Institute |
| To: | Chow E Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20023B063 | List: |
| References | |
| CON-NRC-03-81-130, CON-NRC-3-81-130, RTR-NUREG-0737, RTR-NUREG-737, TASK-2.K.3.17, TASK-TM TER-C5506-303, TER-C5506-303-1, NUDOCS 8212140392 | |
| Download: ML20023B062 (13) | |
Text
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TECHNICAL EVALUATION REPORT ECCS REPORTS (F-47)
TMI ACTION PLAN REQUIREMENTS YANKEE ATOMIC ELECTRIC COMPANY YANKEE R0WE NUCLEAR POWER STATION NRC DOCKETNo.50-029 FRC PROJECT C5506 FRC ASSIGNMENT 7 NRC CONTRACT NO. NRC-03-81 130 FRC TASK 303 Ptsparedby F. W. Vosbury Franklin Research Center Author:
G. J. Overbeck l
20th and Race Streets B. W. Ludington Philadelphia, PA 19103 FRC Group Leader:
G. J. Overbeck Prepared for Nuclear Regulatory Commission Lead NRC Engineer:
E. Chow Washington, D.C. 20555 XA Copy Has Been Sent fo PDR This report was prepared as an account of work sponsored by an agency of the United States Govemment. Neither the United States Govemment nor any agency thereof, or any of their employees, makes any warranty, expressed or implied, or assumes any legal liability or responsibility for any third party's use, or the results of such use, of any information, appa-ratus, p.oduct or process disclosed in this report, or represents that its use by such th!rd party would not infringe privately owned rights.
Prepared by:
Reviewed by:
Approved by:
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brincipal Author
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TER-C5506-303 1
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i CONTENTS l
Section Title Page i
1 INTRODUCTION 1
l 1.1 Purpose of Review.
1 1.2 Generic Background.
1 1.3 Plant-Specific Background.
2 2
M fBTTERTA_
3 3
TECHNICAL EVALUATION 4
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Review of completeness of the Licensee l's Report 3.1 4
3.2 Comparison of ECC System Outages with those of Other Plants.
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3.3 Review of Proposed Changes to Improve the Availability of ECC Muipment.
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4 CONCLUSIONS.
8 5
REFERENCES.
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TER-C5506
'3 FOIU!MORD This Technical Evaluation Report was prepared by Franklin Research Center under a contract with the U.S. Nuclear FAjulatory Commission (Office of Nuclear Reactor Regulation,' Division of Operating Reactors) for technical assistance in support of NBC. operating reactor licens'ing actions. The technical evaluation was cond'ucted in accordance with criteria established by the NBC.
nr. u.~s. overbeck, nr.-- r. w. vesbury, ana nr. 3. w. Ludington contributed to the technical preparation of this report through a subcontract i
with WESTEC Services, Inc.
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TEA-C5506-303 1.
INTRODUCTION k
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1.1 PURPOSE OF REVIEW P
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. This techni' cal evaluation report (TER) documents an independent review of the outages of the emergency core cooling (ECC) systems at Yankee Atomic Electric Company's (YABC) Yankee Bowe Nuclear Power Station. Se purpose of th1Is evaluation is to determine if the Licensee has subeitted a report that is complete and satisfies the requirements of TMI Action Item II.K.3.17, " Report
'IOutages of Daergency Core-Cooling Systems Licensee Report and Proposed c
Technical. Specification Changes."
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1.2' GENERIC BACEGROUlm l
Pellowing the Sree' Mile Island Unit 2 accident, the Bulletins and Orders Task Force reviewed nuclear
- steam supply system (NSSS) vendors' small break lon-of-coolant accident (IOCA) analyses to ensure that an adequate basis existed for developing guidelines for small break I d emergency procedures.
During these reviews, a concern developed about the assumption of the worst single failure. Typically, the small break LOCA' analysis for boiling water reactors (BWRs) assumed a loss of the high pressure coolant injection (HPCI) system as the worst single failure. However, the technic &l specifications permitted plant operation for substantial periods with the HPCI system out of service with no limit on the accumulated outage time. There is concern not only about the HPCI system, but also about all BCC systems for which substaa-tial outages might occur within the limits of the present technical specifica-tion. M erefore, to ensure that the small break LOCA analyses are consistent with the actual plant response, the Bulletin and Orders Task Force reconsended in NUREGHT626 (1],' " Generic Evaluation of Feedwater Transients and Small Break I;
Ioss-of-Coolant Accidents in GE-Designed Operating Plants and Near-Tern l
Cperating License Applications," that licensees of General Electric (GE)-designed NSSSs do the following:
" Submit a report detailing outage dates and lengths of the outages for all BCC Jystems. Se report should also include the cause of the outage (e.g., controller failure or spurious isolation). Se outage data for BCC ccaponents should include all outages for the last five years of nkjin Research Center 3.h of The Fm Wuesuse '
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TER-C5506-303 operation. The end result should be the quantificction of historical unreliability due to test and maintenance outage's. This will establish if a need exists for cumulative outage roquirements in technical specifications."
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I,ater, the 'rer==andation was incorporated into NUREG-0660 [2], "NBC U
Action Plan DevelopN as a~ Result of the TMI-2 Acciddnt," for all light water c
e reactor plants as TMI Action Item II.K.3.17.
In NUREG-0737 [3],
" Clarification of TMI Action Plan 'Dquirements," the NBC staff expanded the Action Item to include all lightwater reactor plants and added a requirement that licensees propose Eidnges that will improve and control availability of ECC systems and components.- In addition, the contents of the reports to be submitted by the Eicensees were further clarified as follows:
"The report s$ould contain (1) outage dates and duration of outages;
. (2).cause of the astager -(3)EC systems or m=pna==ts involved in the outage; and (4) corrective action taken."
1.3 PLANT-SPECIFIC BACKGROUND On January 1, 1981 [4], YAEC submitted a report in response to s
N.,
NUREC-0737, Item II.K.3.17, " Report on Outages of Ehergency Core-Cooling Systems" Licensee Report and Proposed Technical Specification Changes." The
- report submitted by YAEC covered the period from January 1,1976 to December 31, 1980 for Yankee Bowe Nuclear Power Station. On September 17, 1982 [5]
YABC submitted a second report in response to an NRC request for additional
.information regarding surveillance testing and preventive maintenance. The
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second report covered the same period described in the first report. YABC did not propose any changes to improve or control availability of ECC systems.
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TEarC5506-303 2.
REVIEN CRITERIA The Licensee's response to NUREG-0737, Item II.K.3.17, was evaluated against criteria provided by the NBC in a letter dated July 21, 1981 [6]
l outlining Tentative Work Assignment F.
Provided as review criteria in l
Reference 5, the.NRC stated that the Licensee's response should contain the following information:
1.
A report detailing outage dates, causes of outages, and lengths of outages for all BCC systems for the last 5 years of opera,.. ion. mis report was to include the BCC systems or components involved and corrective actions taken. Test and maintenance outages were to be included.
2.
A quantification of the historical unavailability of the BCC systems
- and components-due D-test and unintenance outages.
3.
Proposed changes to improve the availability of ECC systems, if necessary.
The type of information required to satisfy the review criteria was clarified by the NRC on August 12, 1981 [7]. Auxiliary systems such as component cooling water and plant service water systems were not to be considered in determining the unavailability of ECC systems. Only the outages of the diesel generators were to be included along with the primary ECC system outages. Finally, the "last five years of operation" was to be loosely interpreted as a continuous 5-year period of recent operation.
On July 26, 1982 [8], the NBC further clarified that the purpose of the review was to identify those licensees that have experienced higher ECC system outages than other licensees with similar NSSSs. Se need for improved reliability of diesel generators is under review by the NBC. A Diesel Generator Interim Reliability Program has been proposed to effect improved performance at operating plants. As a consequence, a comparison of diesel generator outage information within this review is not required.
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TECHNICAL EVALUATION 3.1 REVIEW OF COWLETENESS OF THE LICENSEE'S REPORT The ECC systems at YABC's Yankee Rowe Nuclear Power Station consist of the following four separate systems:
o accumulators o high pressure safety injection (HPSI) o low pressure safety injection (LPSI) o refueling water storage tank (RNST).
YABC also provided information on'the emergency diesel generators.
Per each ECC system outage event, YABC provided the outage dates, the duration, and the cause, plus sufficient description to discern the corrective action taken. Maintenance and surveillance testing activities were included in the ECC system outage data. The results of YABC's s;eview were provided for the period from January 1, 1976 to December 31, 1980 for the Yankee Bowe plant.
Based on the preceding discussion, it has been established that YAEC has submitted a report which fulfills the requirements of review criterion 1 without exception.
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3.2 COMPARISON OF ECC SYSTEN OUTAGES WITH THOSE OF OTHER PLANTS The outages of ECC systems can be categorized as (1) unplanned outages due to equipment failure or (2) planned outages due to surveillance testing or preventive maintenance. Unplanned outages are reportable as Licensee Event Reports (LERs) under the technical specifications. Planned outages for periodic maintenance and testing are not reportable as LERs. The technical specifications identify the type and quantity of ECC equipment required as well as the maximum allowable outage times.
If an outage exceeds the maximum
' allowable time, then the plant operating mode is altered to a lower. status consistent with the available ECC system components still operational. The purpose of the technical specification maximum allowable outage times is to prevent extended plant operation without sufficient ECC system protection.
The maximum allowable outage time, specified per event, tends to limit the
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TER-C5506-303 unavailability of an ECC' system. Bowever, there is no cumulative outage time limitation to prevent repea'ted planned and unplanned outages from accumulating extensive BCC system downtime.
Unavailability, as defined in general terms in MASE-1400 [9], is the probability of'a system being in a failed state when required. Bowever, for this review, a detailed unavailability analysis was not required. Instead, a l
preliminary estimate of the unavailability of an ECC system was made by calculating the ratio of the BCC system downtime to the number of days that the plant was in operation during the last 5 years. To simplify the tabula-tion of operating time, only the -period when the plant was in operational Mode 1 was considered. This simplifying aar.umption is reasonable given that the period of time that a plant is starting up, shutting down, and coollag down is l
semil compared to the time it is operating at power. In addition, an ECC system was considered down whenever an ECC system component was unavailable due to any cause.
It should be noted that the ratio calculated in this manner is not a true measure of the ECC system unavailability, since outage events are included that appear to compromise system performance when, in fact, partial or full function of the system would be expected. Full function of an ECC system would be expected if the design capability of the system exceeded the capacity required for'the system to fulfill its safety function. For example, if an ECC system consisting of two loops with multiple pumps in each loop is designed so that only one pump in.each loop is required to satisfy core cooling requirements, then an outage of a single pump would not prevent the system from performing its safety function.
In addition, the actual ECC system unavailability is a function of planned and unplanned outages of essential support systems as well 1
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as of planned and unplanned outages of primary BCC system components.
In l-l accordance with the clarification discussed in Section 2, only the effects of outages associated with primary BCC system components and emergency diesel generators are considered in this review. The inclusion of all outage events assumed to be true BCC system outages tends to overestimate the unavailability, while the exclusion of support system outages tends to underestimate the unavailability, of ECC systems and components.' Only a nklin Research Center A Chesen of The Frenten insususe
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4 TE3K5506-303 detailed analysis of each BCC system for each plant could improve the confidence in the calculath result. Such an analysis is beyond the intended scope of this report.
The planned and unplanned (forced) outage times for the four ECC systems (accumulators, HPSI, LPSI, and RWST) and the emergency diesel generators were l
identified from the outage information in References 4 and 5 and are shown in number of days and as percentage of plant operating time per year'in Table 1 for the Yankee Bowe plant. Outages that occurred during nonoperational periods were eliminated, as were those caused by failures or test and maintenance of support systems. Data on plant operating conditions were obtained from the annual reports, " Nuclear Power Plant Operating Experience"
[10-13), and from raonthly reports, " Licensed Operating Reactors Status Summary Reports"- (14]. Se Temmining outages were 1 segregated into planned and unplanned outages based on YABC's description of the causes. The outage periods for each category were calculated by summing the individual outage d,urations.
Observed outage times of various BCC systems at the Yankee Rowo plant were compared with those o'f other PWRs. Based on this comparison, it was 4
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concluded that the historical unavailability of the accumulators, HPSI, LPSI, l
l and RNST systems has been consistent with the performance of those systems throughout the industry. The observed unavailability was less than the industrial mean for all BCC systems, wasuming that the underlying unavailability is distributed lognormally. The outage times were also consistent with existing technical specifications. The diesel generators were not included in this comparison.
3.3 REVIEW OF PROPOSED CHANGES TO IMPROVE THE AVAILABILITY OF ECC EQUIPMENT In References 4 and 5, YABC did not propose any changes to improve the availability of BCC systems and components.
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>m Table 1.
Planned and unplanned (porced) Outage Times f Yankee Bowe mclear Power Station
- K3 2$?
~3 Accu.ulators BPSI LPSI RNOT Diesel Generators Days of Plant Outage in Days Outage in Days Outage in Days Outage in Days Outage in Days
- r Year Operation Forced Planned Forced Planned Forced Planned Forced Planned Forced Planned
(?
R 1976 328.6 0.33 0.0 0.97 0.0 0.44 0.0 7.33 0.0 0.0 0.0 3
(0.14)
(0.3%)
(0.14)
(2.2%)
1977 269.7 0.0 0.0 1.06 0.0 1.18 00 0.0 0.0 0.13 0.0 (0.4%)
(0.4 t)
(<0.14) j, 1978 295.6 0.33 0.0 0.33 0.0 0.33 0.0 0.0 0.0 0.0 0.0 I
(0.1%)
(0.It)
(0.1% )
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l' (0.14) 1979 297.9 0.23 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1980 02.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 votal 1373.s 0.es 0.0 2.36 0.0 1.es 00 7.33 0.0 0.13 0.0 (0.14)
(0.20)
(0.2t)
(0.6% )
(<0 14)
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TER-C5506-303 4.
CONCLUSIONS Yankee Atomic Electric Company (YABC) has submitted a report for Yankee Bowe Nuclear Power Station that contains (1) outage dates and duration of outages, (2) causes of the outages, (3) ECC systems or components involved in the outages, and (4) corrective actions taken. It is concluded that YABC has fulfilled the requirements of NUREG-0737, Item II.E.3.17.
In addition, the historical unavailability of the accumulators, high pressure safety injection, low pressure safety injection, and refueling water storage tank systems has been consistent with the performance of those systems throughout the industry. The observed unavailability was less than the industrial mean for all ECC systems. The outage times were also consistent with existing tar hair m1 vifications.
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TER-C5506-303 5.
REFERENCES 1.
" Generic Evaluation of Feedwater Transients and naall Break Ioss-of-Coolant Accidents in GE-Designed Operating Plants and Near-Tern Operating License Applications" NBC, January 1980 2.
NUR8G-0660 "NBC Action Plan Developed as a Result of the 'DtI-2 Accident" NBC, March 1980 3.
" Clarification of TMI Action Plan Requirements" NRC, October 1980 4.
J. A. Ray (YABC)
Letter to m. S..mismahnt (Director, Jiv1 Slop 4 of LiceASing, NEC) subject:
Submittal of Informatic.n Required by NURBG-0737 l
YABC, January 1, 1981 5.
J. A. Kay (YABC)
Letter to D. M. Crutchfield (Chief, Operating Reactors Branch 5, NRC)
Subject:
Submittal of Additional Information Required by NUREG-0737 YABC, September 17, 1982 6.
J. N. Donohew, Jr. (NBC)
Letter to Dr. S. P. Carfagno (FRC)
Subject:
Contract No. NRC-03-81-130, Tentative Assignment F July 21,1981 7.
NRC Meeting between NRC and FRC.
Subject:
C5506 Tentative Work Assignment F, Operating Reactor PORV and BCCS Outage Reports August 12, 1981 8.
NRC Meeting between NRC and FRC.
Subject:
Resolution of Review Criteria and Scope of Work July 26, 1982 9
WASE-1400
" Reactor Safety Study" NRC, October 1975 10.
" Nuclear Power Plant Operating Experience 1976" NRC, December 1977 _nklin Res,ea_rch._ Center
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- 11. NUREG-0483 "maclear Power Plant Operating Experience 1977" N E, February 1979 i
12.
NUREG-0618 "maclear Power Plant Operating Experience 1978" NE, December 1979 13.
NUREG/CR-1496 "Bhaclear Power Plant Operating Experience 1979" NE, May 1981 14.
" Licensed Operating Reactors Status Summary Report" i
volume 4, Nos. 1 through 12, and volume 5, No. 1 NE, December 1980 through January 1981 i
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