ML20076C403

ECCS Repts (F-47) TMI Action Plan Requirements,Millstone Nuclear Power Station,Unit 2, Technical Evaluation Rept

ML20076C403
Person / Time
Site:	Millstone
Issue date:	01/27/1983
From:	Ludington B, Overbeck G, Udington B, Vosbury F FRANKLIN INSTITUTE
To:	Chow E NRC
Shared Package
ML20076C406	List: ML20076C403
References
CON-NRC-03-80-130, CON-NRC-3-80-130, RTR-NUREG-0737, RTR-NUREG-737, TASK-2.K.3.17, TASK-TM TER-C5506-282, NUDOCS 8302020165
Download: ML20076C403 (14)

Text

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TECHNICAL EVALUATION REPORT ECCS REPORTS (F-47)

TMI ACTION PLAN REQUIREMENTS NORTHEAST NUCLEAR ENERGY COMPANY MILLSTONE NUCLEAR POWER STATION UNIT 2 A

NRC DOCKET NO. 50-336 FRC PROJECT C5506 FRC ASSIGNMENT 7 NRC CONTRACTNC NRC-03-81-130 FRC TASK 282 Prepared by

. F. W. Vosbury Franklin Research Center Author: G. J. Overbeck 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 i

January 27, 1983 l XA Copy Has Been Sent fiPDR .

l This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, or any of their (mployees, 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, product or process disclosed in this report, or represents that its use by such third party would not infringe privately owned rights.

Prepared by: Reviewed by: Approved by:

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TER-C5506-282 CONTENTS Section - Title Page 1 INTRODUCTION . . . . . . . . . . . . . 1 1.1 Purpose of Review . . . . . . . . . . . 1

. 1.2 Generic Background. . . . . . . . . . . 1 1.3 Plant-Specific Background . . . . . . . . . 2 2 REVIEW CRITERIA. . . . . . . . . . . . . 3 3 TECHNICAL EVALUATION . . . . . . . . . . . 4 3.1 Review of Completeness of the Licensee's Report . . . 4 3.2 Comparison of ECC System Outages with Those of Other Plants.- . . . . . . . . 4 3.3 Review of Proposed Changes to Improve the Availability of ECC Equipment . . . . '. . . . 8 4 COtCLUSIONS. . . . . . . . . . . . . . 9 5 REFERENCES . . .. . . . . . . . . . . . 10 l

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TER-C5506-282 FOREWORD Tnis Technical Evaluation Report was prepared by Franklin Resaarch Center under a contract with the U.S. Nuclear Regulatory Commission (Office of Nuclear Reactor Regulation, Division of Operating Reactors) for technical assistance in support of NRC operating reactor licensing actions. The technical evaluation was conducted in accordance with criteria established by the NRC.

Mr. G. J. Overbeck, Mr. F. W. Vosbury, and Mr. B. W. Ludington contributed to the technical preparation of this report through a subcontract with WESTEC Services, Inc.

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1. INTRODUCTION 1.1 PURPOSE OF REVIEW This technical evaluation report (TER) documents an independent review of the outages of the emergency core cooling (ECC) systems at Northeast Nuclear

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Energy Company's (NNEC) Millstone Nuclear Power Station Unit 2. The purpose of this evaluation is to determine if the Licensee has submitted a report that is complete and satisfies the requirements of TMI Action Item II.K.3.17,

" Report on Outages of Bnergency Core-Cooling Systems Licensee Report and Proposed M chnical Specification Changes."

i 1.2 GENERIC BACKGROUND Following the t ree Mile Island Unit 2 accident, the Bulletins and Orders Task Force reviewed nuclear steam supply system (NSSS) vendors' small break loss-of-coolant accident (LOCA) analyses to ensure that an adequate basis existed for developing guidelines for small break LOCA 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 technical specifications permitted plant operation for substantial periods with the HPCI system out of service with no limit on the accumulated outage time. tere is concern not only about the HPCI system, but also about all ECC systems where substantial outages might occur within the limits of the present technical specification.

Werefore, ensure that the small break LOCA analyses are cons'istent with the actual plant response, the Bulletin and Orders Task Perce recommended in NUREG-0626 [1] , " Generic Evaluation of Feedwater Transients and Small Break Loss-of-Coolant Accidents in GE-Designed Operating Plants and Near-Term Operating 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 ECC systems. Be report should also include the cause of the outage (e.g. , controller failure or spurious isolation) . W e outage data for 4 MJ Franklin Research Center A Dmmon of The Fransen Insetute

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4 SCC components should include all outages for the last five years of operation. The end result should be the quantification of historical unreliability due to test and maintenance outages. This will establish if a need exists for cumulative outage requirements in technical specifications."

Later the recommendation was incorporated into NUREG-0660 [2] , "NRC Action Plan Developed as a Result of the TMI-2 Accident," for GE-designed NSSSs as TMI Action Item II.K.3.17. In NUREG-0737 [3] , " Clarification of 'IMI Action Plan Requirements," the NRC staff expanded the Action I em to include all light water reactor plants and added a requirement that licensees propose changes that will improve and control availability of ECC systems and components. In addition, the contents of the reports to be submitted by the licensees were further clarified as follows:

"The report should contain (1) outage dates and duration of outages; (2) cause of the outage; (3) ECC systems or components involved in the outage; and (4) corrective action taken."

1.3 PLANT-SPECIFIC BACKGROUND On December 31, 1980 [4] and March 4, 1981 [5], NNEC submitted reports in d

response to NUREG-0737, Item II.K.3.17, " Report on Outages of Emergency Core-Cooling Systems Licensee Report and Proposed Technical Specification Change s. " The reports submitted by NNEC covered the period from January 1, 1976 to December 31, 1980 for Millstone Nuclear Power Station Unit 2. On August 16, 1982 [6], NNEC submitted a third report in response to an NBC l request for additional information concerning surveillance testing and preventive maintenance. This report covered the same period described in the earlier reports. NNEC did not provide any recommendations to improve and control availability of ECC systems.

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2. REVIEW CRITERIA The Licensee's response to NUREG-0737, Item II.K.3.17, was evaluated against criteria provided by the NRC in a letter dated July 21, 1981 [7]

outlining Tentative Work Assignment F. Provided as review criteria in Reference 5, the NRC stated that the Idcensee's response should contain the following information:

1. A report detailing outage dates, causes of outages, and lengths of outages for all ECC systems for the last 5 years of operation. This report was to include the ECC 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 ECC systems and components due to test and maintenance outages.

3. Proposed changes to improve the availa,bility of ECC systems, if necessary. .

The type of information required to satisfy the review criteria was clarified by the NRC on August 12, 1981 [8]. Auxiliary systems such as component cooling water and plant service water systems were not to be considered in determining the unavailability of ECC Gystems. 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, l'982 '[9], the NRC 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. The need for improved reliability of diesel generators is under review by the NRC. 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, uQDsr.nklin Rese.rch center A OMaan of The Franhen insatute

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3. TECHNICAL EVALUATION 3.1 REVIEW OF COMPLETENESS OF THE LICENSEE'S REPORT The ECC systems at NNEC's Millstone Unit 2 consist of the following five separate systems:

o safety injection (SI) tanks o chemical and volume control system (CVCS) o high pressure safety injection (HPSI) o low pressure safety injection (LPSI) o refueling water stcrage tanks (RWST) .

In References 4, 5, and 6, NNEC also included the containment spray system and standby diesel generators. The containment spray system is a

. containment heat removal system as well as a fission product cleanup system.

But because the containment spray system is not an emergency core cooling system, its outages are not considered in this review.

For each ECC system outage, NNEC provided the date, the duration, a brief description, and the cause, with sufficient details to indicate the corrective action taken. In establishing the type of event that constitutes an ECC system outage, NNCC indicated that an outage was included if it required I

taking an ECC system or component out of service, whether for planned maintenace, unplanned maintenance, or surveillance testing.

NNEC's review encompassed the period from January 1, 1976 to December 31, 1980 for Millstone thit 2.

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Based on the preceding discussion, it has been established that NNEC has submitted a report which fulfills the requirements of review criterion 1 without exception.

l l ' 3.2 COMPARISON OF ECC SYSTEM OUTAGES WITH THOSE OF;CFfHER PLANTS i

te 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 l Reports (LERs) under the technical specifications. Planned outages for

periodic maintenance and testing are not reportable as LERs. We technical I

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TER-C5506-282 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 i

unavailability of an ECC system. However, there is no cumulative outage time limitation to prevent repeated planned and unplanned outages from accumulating extensive ECC system downtime.

Unavailability, as defined in general terms in WASH-1400 [10], is the probability of a system being in a failed state when required. However, for Instead, a  !

this review, a detailed unavailability analysis was not required.

preliminary estimate of the unavailability of an ECC system was made by calculating the ratio of the ECC system downtime to the number of days that the plant was in operation during the last 5 years. To simplify the tabulation of operating time, only the period when the plant was in l

operational Mode 1 was considered. This simplifying assumption is reasonable given that the period of time that a plant is starting up, shutting down, and cooling down is small compared to the time it is operating at power. In I

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 I

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TER-C5506-282 essential support systems as well as planned and unplanned outages of primary ECC system components. In accordance with the clarification discussed in Section 2, only the effects of outages associated with primary ECC system components and emergency diesel generators are considered in this review. The.

inclusion of all outage events assumed to be true ECC 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 detailed analysis of each ECC system for each plant could improve the confidence in the calculated result. Such an analysis is beyond the intended scope of this report.

The planned and unplanned (forced) outage times for the ECC systems (SI tanks, CVCS, HPSI, LPSI, and RNST) and for the standby diesel generators were identified from the outage information in References 4, 5, and 6 and are shown i in number of days and as percentage of plant operating time per year in Table 1 for Millstone Unit 2. Outages that occurred during non-operational periods J

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" (11-14], and from monthly reports, " Licensed Operating Reactors Status Summary Reports" (15] .

l Additional information on outages of the SI tanks and RNST was obtained in a letter dated December 29, 1982 (16]. The remaining outages were segregated i into planned and unplanned outages on tne basis of NNEC's description of the cause. The outage periods for each category were calculated by s'umming the individual outage durations.

Observe,d outage times of various ECCS systems at Millstone Unit 2 were compared with those of other PWRs. Based on this comparison, it was concluded that the historical unavailability of the SI tanks, CVCS, HPSI, LPSI, and RWST has been consistent with the performance of those systems throughout the industry and consistent with existing technical specifications. The observed unavailability was less than one standard deviation above the industrial mean for all the ECC systems, assuming the underlying unavailability is distributed lognormally. The diesel generators were not included in this comparison.

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TER-C550 6-282 3.3 REVIEW OF PROPOSED CHANGES TO IMPROVE THE AVAILABILITr OF ECC EQUIPMENT In References 4, 5, and 6, NNEC did not propose any changes to improve the availability of ECC systems and components..

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4. CONCLUSIONS Northeast Nuclear Energy Company (NNEC) has submitted a report for Millstone Nuclear Power Station Unit 2 that contains (1) outage dates and durations, (2) causes of the outages, (3) ECC systems or components involved in the cutages, and (4) corrective action taken. It is concluded that NNEC h s fulfilled the requirements of NUREG-0737, Item II.K.3.17. In addition, the historical unavailability of the safety injection tanks, chemical and volume control system, high pressure safety injection, low pressure safety injection, and refueling water storage tank has been consistent with the performance of those systems throughout the industry and consistent with existing technical specifications. The observed unavailability was less than one standard deviation above the industrial mean for all ECC systems.

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5. REFERENCES

1. NUREG-0626 i

" Generic Evaluation of Feedwater Transients and Small Break Loss-of-Coolant Accidents in GE-Designed Operating Plants and Near-Term Operating License Applications" NRC, January 1980

2. NUREG-0660 "NRC Action Plan Developed as a Result of the TMI-2 Accident" NRC, March 1980

3. NUREG-0737

" Clarification of TMI Action Plan Requirements" NRC, October 1980 2

4. W. G. Council (NNEC)

Letter to D. G. Eisenhut (Director, Division of Licensing, NRC)

Subject:

Submittal of Information Required by NUREG-0737 NNEC, December 31, 1980

5. W. G. Council (NNEC)

Letter to D. G. Eisenhut (Director, Division of Licensing, NRC)

Subjcet: Submittal of ECCS Outage Information NNEC, March 4, 1981 t 6. W. G. Council (NNEC)

Letter to R. A. Clark (Chief, Operating Reactors Branch 3, NRC)

Subject:

ECCS Outages, NUREG-0737, Item II.k.3.17 NNEC, August 16, 1982

7. J. N. Donohew, Jr. (NBC)

Letter to Dr. S. P. Carf agno (FRC) .

Subject:

Contract No.

l NRC-03-81-130, Tentative Assignment F NBC, July 21, 1981

8. NRC Meeting between NRC and FRC.

Subject:

C5506 Tentative Work Assignment F, Operating Reactor PORV and ECCS Outage Reports

August 12, 1981

9. NHC Meeting between NRC and FRC.

Subject:

Resolution of Review Criteria '

and Scope of Work July 26, 1982

10. WASH-l'400

" Reactor Safety Study"

NRC, October 1975 l

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11. -NUREG-0366

" Nuclear Power Plant Operating Experience 1976" NRC, December 1977

12. NUREG-0483

" Nuclear Power Plant Operating Experience 1977" NRC, February 1979

13. NUREG-0618

"!Mclear Power Plant Operating Experience 1978" NRC, December 1979

14. NUREG/CR-1496

" Nuclear Power Plant Operating Experience 1979" NRC, May 1981

15. NUREG-0020

" Licensed Operating Reactors Status Summary Report" Volume 4, Nos.1 throu9h 12, and Volume 5, No.1 NRC, December 1980 through January 1981

16. W. G. Counsil (NNEC)

Letter to R. A. Clark (Chief, perating Deactor Branch 3, NRC)

Subject:

Additional Infor' nation, ECCS Outages, Millstone Unit 2 NNEC, December 29, 1982 9

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