ML20079G930

ECCS Repts (F-47),TMI Action Plan Requirements,Northern States Power Co,Praire Island Nuclear Generating Plant Units 1 & 2, Technical Evaluation Rept

ML20079G930
Person / Time
Site:	Prairie Island
Issue date:	12/06/1982
From:	Ludington B, Overbeck G, Vosbury F FRANKLIN INSTITUTE
To:	Chow E NRC
Shared Package
ML20079G933	List: ML20079G930
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-C506-290-291, TER-C5506-290-2, TER-C5506-290-291, NUDOCS 8212090146
Download: ML20079G930 (15)

Text

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TECHNICAL EVALUATION REPORT ECCS REPORTS (F-47)

TMI ACTION PLAN REQUIREMENTS NORTHERN STATES POWER COMPANY

. PRAIRIE ISLAND NUCLEAR GENERATING PLANT UNITS 1 AND 2 NRC DOCKET NO. 50-282, 50-306 FRC PROJECT C5506 FRC ASSIGNMENT 7 NRC CONTR ACT NO. NRC-03-81-130 FRCTASKS 290, 291 Preparedby y, y, ya,y,q Frank!!n 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 Decernber 6,1982 This report was prepared as an account of work sponsored by an agency of the United States Govemment. Neither the United States Government nor any agency thereof, or any of their employees, makes any warranty, expressed or implied, or assumes any legal liability or i

j 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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' Principal Author /

1. ~,de '1 Group' Leader EW Department Dire / tor [/

Date- '1 /7 71 Date. /2-3-Ba- Date: 31-4 O XA Copy Has Been Sent foJ4 Franklin Research Center

- A Division of The Franklin Institute The s n,arrun FrankEn Partnway. PMa Pa. 19103 (215)448 1000 1ra 499f.L46, J

TER-C5506-290/291 conn NTS Section Title Page 1 INTRODt%: TION . . . . . . . . . . . . . 1 1.1 Purpose of Review . . . . . . . . . . . 1 1.2 Generic Background. . . . . . . . . . . 1 1.3 Plant-Specific Background . . . . . . . . . 2 2 BBVIEW CRIERIA. . . .' .' . . . . . . . . 3 3 WCHNICAL 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 . . . . . . . . 6 4 COICLUSIONS. . . . . . . . . . . . . . 9 5 IEFERENCES . . . . . . . . . . . . . . 10 I

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6 TER-C5506-290/291 roREwoRD This Technical Evaluation Report was prepared by Franklin Research Center under a contract with the U.S. Nuclear Regulatory Consaission (Office of Nuclear Reactor Regulation, Division of Operating Reactors) for technical assistance in support of NRC operating reactor licensing actions. Tha technical evaluation was conducted in accordance with criteria established by the NBC.

Mr.~G. J. Oeerbeck, Mr. F. W. Vosbury, and Mr. B. W. Ludington contributed to the technical preparation of this report through a subcontract with WES12C Services, Inc.

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1. INTRODUCTION 1.1 PURPO S OF REVIEW Win technical evaluation report (TER) documents an independent review of the outages of the emergency core cooling (ECC) systems at Northern States and Power Company's (NSP) Prairie Island Nuclear Generating Plant Units 1 rnd 2.

The purpose of this evaluation is to determine if the Licensee has submitted a report that is complete and satisfies the requirements of 1MI Action Item II.K.3.17, " Report on Outages of Emergency Core-Cooling Systems Licensee Report and Proposed Mchnical Specification Changes." ~

1.2 GENERIC BACEGROUND Pollowing the Three Mile Island Unit 2 accident, the Bulletins and. Orders Task Force reviewed nuclear steam supply system (NSSS) vendors' small break loss-of-coolant accident (IOCA) 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. Mere is concern not only about the HPCI system, but also about all ECC systems for which substantial outages might occur within the limits of the present technical specification. Merefore, to ensure that the small break LOCA analyses are consistent with the actual plant response, the Bulletin and Orders Task Force reconnended in NUREG-0626 [1], " Generic Evaluation of Feedwater Transients and Small Break Ioss-of-Coolant Accidents in GB-Designed Operating Plants and Near-Mrs 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. Se report should also include the cause of the outage I

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I TER-C5506-290/291 (e.g., controller failure or spurious isolation) . Se outage data for ECC components should include all outages for the last five years of operation. S e end result should be the quantification of historical unreliability due to test and maintenance outages. m is will establish if a need exists for cumulative outage requirements in technical specifications."

Later, the recommendatian was incorporated into NUREG-0660 (2], "NBC Action Plan Developed as a Result of the '11tI-2 Accident," for GE-designed l NSSSs as '1?tI Action Item II.K.3.17. In NUREG-0737 [3], " Clarification of TMI Action Plan Requirements," the NBC staff expanded the action item to include all light water reactor plants and added a requirement that licensees propose changes that will improve and control availabil'ity of ECC systems and components. In addition, the contents of the reports to be submitted by the licensees were further clarified as follows:

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

1.3 PLAlff-SPECIFIC BACKGROUND On January 16, 1981 (4), NSP submitted a report in response to NUBEG-0737, Item II.K.3.17, " Report on Outages of Emergency Core-Cooling

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Systems Licensee Report and Proposed Technical Specification Changes." We report submitted by NSP covered the period from January 1,1976 to December 31, 1980 for Prairie Island' Units 1 and 2. NSP did not propose any changes to control and improve the availability of specific ECC equipment.

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2. REVIEW CRITERIA I l

The Licensee's response to NUREG-0737, Item II.K.3.17, was evaluated against criteria providad by the NBC in a letter dated July 21, 1981 [5]

outlining Tentative Work Assignment F. Provided as review criteria in Reference 5, the NBC 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 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 > v==*= due .to test anc. maintenance outages.

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

The type of ip oemation required to satisfy the review criteria was clarified by the NRC on August 12, 1981 [6]. Auxiliary sy4tems 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 [7], 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 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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3. WCHNICAL EVALUATION 3.1 MVIEW OF COMPLEENESS OF THE LICENBE'S REPORT The ECC systems at NSP's Prairie Island Units 1 and 2 consist of the following four separate systems:

o accumulators o safety injection

• system (SIS; high head) o residual heat removal (RHR) system (low head safety injection) o refueling water storage tank (RNST) .

For each ECC system outage event, NSP provided the outage dates, the

. duration...and a sufficient deacciption. to.discera .the corrective action taken. Maintenance and surveillance testing activities were included in the BCC system outage data. 'the results of NSP's review were provided for the period from January 1, 1976 to December 31, 1980 for Prairie Island Units 1 and 2.

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

3.2 COMPARISON OF ECC SYSTEM 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 (IJtRs) 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. Tne purpose of the technical specification maximum allowable outage times is to

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. TER-C5506-290/291 prevent extended plant operation without sufficient ECC system protection.

Se maximum allowable outage time, specified per event, tends to' limit the 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 [8], is the proba-bility of a system being in a failed state when required. However, for this review, a detailed unavailability analysis was not required. Instead, a prelim-inary 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 operational Mode 1 was cons'idered. Sis 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 addition, an ECC system was considered down whenever an ECC system component was unavailable due to any cause. I i

It should be noted that the ratio calculated in this manner is not a true measure of the ECC system unavailability, since cutage 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.

l In addition, the actual ECC system unavailability is a function of planned and {

unplanned outages of essential' support systems as well as of planned and unplanned outages of primary BCC 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. We inclusion of all outage events assumed to be true ECC system outages tends to overestimate the una.vailability, while the exclusion of support i

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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 four ECC systems (accumulators, SIS, RER, RWST) were identified from the outage information in Refstence 4 and are shown in number of days and as percentage of plant operating time per year in Tables 1 and 2 for Prairie Island Units 1 and 2, respectively. W e accumulators and RWST were not included in the tables because these systema did not have any outages. Outages that occurred during

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noncoerational periods were eliminated, as were those caused by failures or tent and maintenance of support systems. Data on plant operating conditions were obtained from the annual reports,'*maclear Power Plant Operating Experience" (9-12), and from monthly reports, " Licensed Operating Beactors Status Cummary Rep:'rts" [13]. The outage periods for each category were calculated b/ summing the individual outage durations.

Obcerved outage times of various ECC systems at Prairie Island Units 1 and 2 were compared with those of other IWRs. Based on this comparison, it was concluded that the historical unavailability of the accumulators, RWST, SIS, and RHR system has been consistent with the performance of those systems throughout the industry. We observed unavailability was less than the industrial mean for all four ECC systems, assuming that the underlying unavailability is distributed lognormally. We outage. times were also consistent with existing technical specifications.

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3.3 REVIEW OF PROPOSED CHANGES 'IO IMPROVE THE AVAILABILITY OF ECC EQUIPHENT In Reference 4, NSP did not propose any changes to improve the avail-l ability of ECC systems and components.

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'litR-C5506-290/291 Fable 1. Outage Times for Prairie Island thit 1*

Days of Flant SIS 145R Year Operation Outage in Dags, Outage'in Days 1976 283.4 0.0 0.0 1977 310.8 1.3 0.8 (0.4 % ) (0.3%)

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. 1978 333.8 0.0 0.0 1979 266.9 0.0 1.3 (0.5%)

4 1980 289.9 0.0 2.0 (0.7 % )

'Ibtal 1484.8 1.3 3.6

(< 0.1% ) (0.2%)

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• Numbera in parentheses indicate system outage time as a percentage of total Plant operating time.

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TER-C5506-290/291 Table 2. Outage Times for Prairie Island Unit 2*

Days of Plant SIS IqER Year Operation Outage in Days Outage in Days l

1976 277.4 0.0 0.6 (0.2%)

1977 325.5 0.0 0.0 1978 388.7 0.0 0.9 (0.3%)

1979 361.1 0.0 1.9 (0.5%)

1980 302.2 0.2 2.6

(< 0.1% ) (0.9%)

Total 1604.9 0.2 6.0

(< U .1% ) (0.4%)

• Numbers in parentheses indicate system outage time as a percentage of total plant operating time.

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4. cot!CLUSIONS Northern States Power Company (NSP) hag submitted a report for Prairie Island Itaclear Generating Plant Units 1 and 2 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* NS'P has fulfilled the requirements of NUREG-0737, Item II.K.3.17. In addition, the historical unavailability of the ECC systems has been-consistent with the performance of those systems throughout the industry. Se observed unavailability was less than the industrial mean for all ECC systems. Se outage times were also consistent with existing technica1 specifications.

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5. MFEM NCES

1. NUM G-0626

" Generic Evaluation of Feedwater Transients and Small Break Ioss-of-Coolant Accidents in GE-Designed Operating Plants and Near-Mrs Operating License Applications" NBC, January 1980

2. NUM G-0660 "NRC Action Plan Developed as a Result of the 'IMI-2 Accident" NBC, March 1980

3. NUEG-0737

" Clarification of '1W. Action Plan Requirements" NBC, October 1980

4. L. O. Mayer (MSP)

.Lettet tokecket. ot M1ane Anactot Regulation

Subject:

WUMG-0737 Item II.E.3.17, Report on Outages of Emergency Core-cooling Systema January 16, 1981

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

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

Subject:

Contract No.

NRC-03-81-13 0, M ntative Assignment F NRC, July 21, 1981

6. NRC Meeting between NBC and FRC.

Subject:

C5506 Tentative Work Assignment F, Operating Reactor PORV and ECCS Outage Reports August 12, 1981

7. NBC -'

Meeting between NRC and FRC.

Subject:

Resolution of Review Criteria and Scope of Nork July 26, 1982 8 NASE-1400

" Reactor Safety Study" NRC, October 1975

9. NUMG-0366

, "Welear Power Plant Operating Experience 1976" NBC, December 1977

10. NURG-0483

" W clear Power Plant Operating Experience 1977" NRC, February 1979 ranidin Research Center A Ohemen of The FranhAn ineshale

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11. NUMG-0618 "Wclear Power Plant Operating Experience 1978" NBC, December 1979

12. NUMG/CR-1496

, "Wclear Power Plant Operating Experience 1979"

. NRC, May 1981

. 13. NUMG-0020

" Licensed Operating Reactors Status Summary Report" .

Volum,e 4, Mas.1 through 12, and Volume 5, No.1 NRC, December 1980 through January 1981

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