ML20079G883

ECCS Repts (F-47):TMI Action Plan Requirements,Peach Bottom Atomic Power Station,Units 2 & 3, Technical Evaluation Rept

ML20079G883
Person / Time
Site:	Peach Bottom
Issue date:	11/24/1982
From:	Ludington B, Overbeck G, Vosbury F FRANKLIN INSTITUTE
To:	Chow E NRC
Shared Package
ML20079G888	List: ML20079G883
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-C5506-208-2, TER-C5506-208-209, NUDOCS 8212010075
Download: ML20079G883 (15)

Text

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TECHNICAL EVALUATION REPORT I ECCS REPORTS (F-4 TMI ACTION PLAN REQUIREMENTS l

PHILADELPHIA ELECTRIC COMPANY  ;

PEACH BOTTOM ATOMIC POWER STATION UNITS 2 AND 3 NRC DOCKET NO. 50-277, 50-278 FRC PROJECT C5506 FRC ASSIGNMENT 7 NRC OONTRACT NO. NRC-03-81-130 FRC TASKS 208, 209 Preparedby a, y, o,,,y,eg Franklin Research Center Author: F. W. Vosbury 20th and Race Streets B. Ludington Philadelphia, PA 19103 FRC Group Leader: G. J. Overbeck Prepared for a Nuclear Regulatory Commission Lead NRC Engineer: E. Chow Washington, D.C. 20555 November 24, 1982 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 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, 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:

Llwlu)di A1 L'1 Principal Author Group Leader

/fW h a Dep'artment Ol[ector/

Date: //- / 7- & A Date-

• U~" cate: s i - 24.- P t 4 .

1

. ._ . .;.. Franklin Research Center XA Copy Has Been Sent fo.PDR ~

A Division of The Franklin Institute je- - n.. .. r__,, 1 w 03 ms) us.:ooo I c O7

TER-C5506-208/209 l CONTsuTS l*

Section Title Page 1 INTRODUCTION . . . . . . . . . . . . . 1

l. 1.1 Purpose of Review . . . . . . . . . . . 1 1

1.2 Generic Background. . . . . . . . . . . 1 1.3 Plant-Specific Background . . . . . . . . . 2 l 2 REVIEN CRITERIA. . . . . . . . . . . . . 3 f 3 TECHNICAL EVALUATION . . . . . . . . . . . 4 l

3.1 Review of Completeness of the Licensee's Report . . . 4 l

3.2 Comparison of ECC System Outages with Those of Other Plants . . . . . . . . . . 4 i

3.3 Review of Proposed Changes to Improve the l 9 Availability of ECC Equipment . . . . . . . .

l 4 CONCLUSIONS. . . . . . . . . . . . . . 10 l

I 5 REFERENCES . . . . . . . . . . . . . . 11 l

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This Technical Evaluation Report was prepared by Franklin Research Center under a contract with the U.S. Nuclear Begulatory Commission (Office of Nuclear Reactor Regulation, Division of Operating Reactors) for technical assistance in support of NBC operating reactor licensing actior.s. The technical evaluation was conducted in accordance with criteria established by l the Nac.

Mr. G. J. Overbeck, Mr. F. W. Vosbury, and Mr. B. W. Ludington i

contributed to the technical preparation of this report through a subcontract with WESTEC Services, Inc. .

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1. IHTRODUCTION 1.1 PURPOSE OF REVIDI S is technical evaluation report (TER) documents an independent review of the outages of the emergency core cooling (ECC) systems at Philadelphia Electric Company's (PECD) Peach Bottom Atomic Power Station Units 2 and 3.

The purpose of this evaluation is to determine if the Licensee has submitted a report that is complete and satisfies the requirements of mI Action Item II.K.3.17, " Report on Outages of Baergency Core-Cboling Systems Licensee Report and Proposed Technical Specification Changes."

1.2 GENERIC BACKGROUND Pollowing the tree Mile Island Unit 2 accident, the Bulletins and Orders Task Pbres 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. Bere 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.

Therefore, to ensure that the small break LOCA analyses are consistent with the actual plant response, the Bulletin and Orders Task Pbres recommended in NUREG-0626 [1], " Generic Evaluation of Feedwater Transients and Small Break Ioss-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. The report should also include the cause of the outage (e.g., controller failure or spurious isolation) . The outage data for 4

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TER-C5506-208/209 ECC components should include all outages for the last five years of operation. Se end result should be the quantification of historical unreliability due to test and maintenance outages. 21s will establish if a need cxists for cumulative outage requirements in technical specifications."

Later *he recosmaendation was incorporated into NUREG-0660 [2], "NBC Action Plad Developed as a Result of the M-2 Accident," for GE-designed NSSSs as M Action Item II.K.3.17. In NUREG-0737 [31, " Clarification of M 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 availability of ECC systems and compnnents. In addition, the contents of the reports to be submitted by the liconi.ees were further clarified as follows:

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

1.3 PLANT-SPECIFIC BACKGROUND #

On January 5, 1981 [4], PECD submitted a report'in response to NUREG-0737, Item II.K.3.17, " Report on Outages of Baergency CorWiing Systems Licensee Report and Proposed '14chnical Specification Chances." The report submitted by PECO covered the period from January 1,1975 to September 1,1980 for Peach '

Botton Atomic Power Station Units 2 and 3. PECO listed several modifications to ECC systems to improve availability that have already been accomplished.

• However, in their report, the Licensee did not propose any further

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2. REVIDt CRITERIA The Licensee's response to NUREG-0737, Item II.E.3.17, was evaluated against criteria provided by the NRC in a letter dated July 21, 1981 [5]

outlining Tentative Work Assignment F. Provided as review criteria in 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 ECC systems for the last 5 years of operation. mis report was to include the ECC systems or components involved and corrective actions taken. Test and maintenance outages were to be included.

2. A quancification of the historical unavailability of the ECC systems and mapanant m due to test and maintenance outages.

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

The type of information required to satisfy the review critaria was clarified by the NBC on August 12, 1981 (6]. Auxiliary systems such as component cooling water and plant service water systems were r.ot 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.

l On July 26, 1982 [7], the NRC further clarified that the purpose of the 1

review was to identify those licensees that have experienced higher ECC syston outages than other licensees with similar NSS5s. me need for improved reliability of diesel generators is under review by the NBC. A Diesel i Generator Interim Reliability Program has been proposed to effect improved 1

l performance at operating plants. As a consequence, e comparison of diesel generator outage information within this review is not required.

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3. TECHNICAL EVALUATION 3.1 REVIDt OF COMPLETENESS OF THE LICENSEE'S REPORT I The ECC systems at PECO's Peach Bottom Atomic Power Station Units 2 and 3 I consist of the following four separate systems:

o high pressure coolant injection (EPCI) system o automatic depressurization system (ADS) o core spray (CS) system o low pressure coolant injection (LPCI) mode of the residual heat l removal (RER) system.

! In Rafarance 4, PECD also included data on standby diasal generators and the reactor coolant isolation cooling (RCIC) system. Ihe latter is a non-safety-related high pressure system available for high pressure injection. Although the RCIC system mitigates the consequences of a loss of normal feedwater, this system is not required to prevent coro damage and -

therefore is not considered to be an ECC system.

For each ECC system outage event, PECX) 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. Sie results of PECI)'s review were provided for the period from January 1,1975 to September 1,1980 for Units 2 and 3.

Based on the preceding discussion, it is concluded that PECO has submitted a report which fulfills the requiremer,ts of review criterion 1 without exception.

3.2 COMPARISON OF ECC SYSTEM OUTAGES WITH THOSE CF 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 (LEES) under the technical specifications. Planned outages for 4 dNU Franklin Research Center 4 om or w en

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TER-C5506-208/209 periodic maintenance and testing are not reportable as LERs. S e technical specifications identify the type and quantity of ECC equipment required as well as tne maximum ~ allowable outage times. If an outage exceeds the maximum 4

allowable time, then the plant operating mode is altered to a lower status

, consistent with the available ECC system components still operational. Se purpose of the technical specification maximum allowable cutage times is to

. prevent extended plant operation without sufficient ECC system protection.

The maximum allowable outage time, specified per event, tends to limit the unavailability of an ECC syst:en. 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 WASE-1400 (8], is the probability of a system being in a failed state when required. However, 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 ECC system downtime to the numbe'r 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 considered. This simplifying assumption is reasonable given that the period of tism 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.

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 reired for the system to fulfill its safety function. For example, if an ECC system consisting of two loops with multiplc pumps in each loop is designed so that only one pump in each loop is required to satisfy core i cooling requirements, then an outage of a single pump would not prevent the p# bi} Franidin Research Center u> .en.r .r

i TER-C5506-208/209 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 as planned and unplanned outages of primary ECC system components. In accordance with the clarification discussed in t,

Section 2, only the effects of outages associated with primary ECC system components and emergency diesel generators are considered in this review. The i 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 end components. Only a detailed analysis of each ECC system for each plant could improve the confi-4 dance in the calculated result. Such an analysis is beyond the intended scope of this report.

The pimined 2nd unplanned (forced) autage times for the four ECC systems (HPCI, ADS, CS , and RRR) and the standby diesel generators were idaientified from the outage information in Reference 4 and are shown in number of days and as percentage of plant operating time per year in Tables 1 and 2 for the Peach Bottom Units 2 and 3, respectively. Outages that occurred during nonopera-i tional periods were eliminated as well as 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"

[9-12], and from monthly reports, " Licensed Operating Reactors Status Summary Reporta" [13] . The remaining outages were segregated into planned and i unplannad outages based on an interpretation of PECD's description of the causes. The outage periods for each category were calculated by sunsing the individual outage durations. Included for informational purposes are the RCIC system outage data.

Observed outage times of various ECC systems at Peach Bottom Units 2 and f'

l 3 were compared with those of other BWRs. Based on this comparison, it was concluded that the historical unavailability of the NPCI, ADS, CS, and RER l

systems has been consistent with the performance of those systems throughout the industry. The observed unavailability was less than the industrial mean for HPCI, ADS, and CS for both units and for the RER system of Unit 3, and less

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• TER-C5506-208/209 than about one standard deviation above the industrial mean for the RER system for Unit 2, assuming that the underlyins unavailability is distributed lognormally. me outage times were also consistent with existing technical specifications. Se outage times of the standby diesel generators and the ICIC systems were not included in this comparison. 1 3.3 REVIEW OF PRWOSED CHANGES TO IMPROVE THE AVAILABILITY OF ECC EQUIPME:1T In Reference 4, PECO indicated that reveral modifications had been performed on the ECC systems at Peach Botton Units 2 and 3 to increase ECC availability. These included improvements to HPCI and diesel generator control systems, RER/LPCI heat exchanger integrity, and a new motor operator for the RER/LPCI injectiori valve. PECO did not make any new recommendations in Reference 4.

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4. GNCLUSIONS Philadelphia Electric Company (PECO) has submitted a report for Peach

• ' Botton Unita 2 and 3 which 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 PECO has

, fulfilled the requirements of NUREG-0737, Item II.K.3.17.

In addition, the historical unavailibility of the HPCI, ADS, CS, and RER systems has been consistent with the performance of those systems throughcut the industry.  % observed unavailability was less than the industrial mean for HPCI, ADS, and CS for both units and for the RER system for Unit 3, and less than about one standard deviation above the industrial mean for the RER system for Un.it 2. S e outage tians were also ~ a=4=tsat with existing technical specifications.

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5. REFERENCES

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

• - NUREG-0626 l

2. "NBC Action Plan Developed as a Result of the DG-2 Accident" NRC, March 1980  !

NUREG-0660

3. " Clarification of TMI Action Plan Requirements" NRC, October 1980 NUREG-0737

4. S. L. Daltroff (PECO)

Letter to Director of Licensing, D. G. Eisenhut.

Subject:

Report on Outage of Emergency Core Cooling Systems January 5,1981

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

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

Subject:

Contract No.

NBC-0 3-81-13 0, Tentative Assignment F

• July 21, 19 81

6. NBC Meeting between NBC and FRC.

Subject:

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

7. NRC Meeting between NBC and FBC.

Subject:

Resolution of Review Criteria and Scope of Work July 26,1982

8. " Reactor Safety Study" NBC, October 1975 WASE-1400

9. " Nuclear Power Plant Operating Experience 1976" NRC, December 1977 NUREG-0366 A

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10. " Nuclear Power Plant Oparating Experience 1977" NBC, February 1979 NUREG-0483

11. " Nuclear Power Plant Operating Experience 1978" NRC, December 1979 NUREG-0 618

12. " Nuclear Power Plant Operating Experience 1979" Nac, May 1981 NUREG/CR-1496

13. " Licensed Operating Reactors Status Summary Report" Volume 4, Nos. I through 12, and Volume 5, No.1 NHC, December 1980 througn January 1981 NUREG-0020 l

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