ML20077K150

ECCS Repts (F-47),TMI Action Plan Requirements, Davis-Besse Nuclear Power Station,Unit 1, Technical Evaluation Rept

ML20077K150
Person / Time
Site:	Davis Besse
Issue date:	11/24/1982
From:	Vosbury F FRANKLIN INSTITUTE
To:	Chow E NRC
Shared Package
ML20077K153	List: ML20077K150
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-C5506-273, NUDOCS 8212010152
Download: ML20077K150 (14)

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l TECHNICAL EVALUATION REPORT

'S REPORTS (F-47)

.CTION PLAN REQUIREMENTS O EDISON COMPANY

-BESSE NUCLEAR POWER STATION UNIT 1 KET NO. 50-346 FRC PROJECT C5506 FRC ASSIGNMENT 7

, rRACT NO. NRC-03-81 130 FRC TASK 273 E. W..Vosbury lesearch Center Atthor: G. J. Overbeck lace Streets B. W. Ludington bla, PA 19103 FRC Group Leader: G. J. Overbeck for agulatory Commission Lead NRC Engineer: E. Chow in, D.C. 20555 November 24, 1982 E

G.as prepared as an account of work sponsored by an agency of the United States

'f Neither the United States Govemment nor any agency thereof, or any of their l

makes any warranty, expressed or implied, or assumes any legal liability or reyfor any third party's use, or the results of such use. of any information, appa-raht or process disclosed in this report, or represents that its use by such third patot infringe privately owned rights.

Pr6: Reviewed by: Approved by:

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Dati 7/03 Date' ' ~ # 3- Date: Il~ Z b'~~ Y L 4

XA Copy Has Been Sent to PDR ..

Franklin Research Center -

A Division of The Franidin institute The Benjamn Franksn Parkwey. Phala Pa. 19103 (215)448 1000 l 80 % ol5 o .- . - - - - - - - - - - - - - - - - - - - -

i TE3M:5506-273 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 CONCLUSIONS. . . . . . . . . . . . . . . 9 5 REFERENCES . . . . . . . . . . . . . . 10 4

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TER-C5506-273 FORNIORD This hchnical Evaluation Report was prepared by Franklin Research Center under a contract with the U.S. melear Regulatory Cosumission (Office of kclear Reactor Regulation, Division of Operating Reactors) for technical assistance in support of NBC operating reactor licensing actions. Se technical evaluation was conducted in accordance with criteria established by the NBC.

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

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2 TER-C5506-273

1. INTRODUCTION 1.1- PURPOSE OF REVIEN

. Sis technical evaluation report (TER) documents an independent review of r 4 -

the outages of the emergency core cooling (ECC) systems at Toledo Edison

. Company's (TE) Davis-Besse Nuclear Power Station Unit 1. 2e 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.E.3.17, " Report on Outages of Energency Core-Cooling Systems Licensee Report and Proposed h chnical Specification Changes."

1.2 GENERIC BACIGROUND Following 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 (I4CA) analyses to ensure that an adequate basis existed for developing guidelines for small break LOCA caergency 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. Bowever, the technical specifications t

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 ECC systems for which substantial outages might occur within the limits of the present technical specification. B erefore, to ensure that the small break LOCA analyses are consistent with the actual plant response, the Bulletin and Orders Task I'bece recommended in NUREG-0626 [1], " Generic Evaluation of Feedwater Transients and N- Small Break Ioss-of-0)olant 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. Se report should also include the cause of the outage (e.g., controller failure or spurious isolation) . The outage data for

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TER-C5506-273 ECC components should include all outages for the last five years of operation. Se end result shculd be the quantification of historical unreliability due to test and maintenance outages. B is will establish 4 4 if a need exists for cumulative outage requirements in technical

, specifications."

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Later, the recommendation was incorporar.ed into NUREG-0660 (2], "NBC Action Plan Developed as a assult of the 1MI-2 Accident," for all light water reactor plants as 1MI Action Item II.E.3.17. In NUREG-0737 [3], "Clarifica-tion of 1MI Action Plan Requirements," the NBC staff 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:

i "The report should contain (1) outage dates and duration of outages; (2) cause of the outager (3) ECC systems or components involved in

-1:he outages and (4) corrective action taken."

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1.3 PLANT-SPECIFIC BACKGROUND

j. On February 24, 1981 [4], TE submitted a report in response to E

NUREG-0737, Item II.E.3.17, " Report on Outages of Baergency Core-Cooling Systems Licensee Report and Proposed Technical Specification Changes." The report submitted by TE covered the period from May 27, 1977 to December 31, 1980 for Davis-Besse Unit 1.  % July 30, 1982 [5], TE submitted a second report in response to a request ' .r additional information concerning diesel generator outages, surveillance testing, preventive maintenance and outage

! durations. The second report covered the same period described in the first report. TE did not include any recommendations in its reports to improve the availability of ECC system components.

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2. .REVIEN CRITERIA The Licensee's response to NUREG-0737, Item II.E.3.17, was evaluated

. against criteria provided by the NBC in _a letter dated July 21, 1981 [6]

- outlining Tentative Work Assignment F. Provided as review criteria in Beforence 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 2 _ outages for all ECC systems for the last 5 years of operation. Bis

. report was to include the ECC systems or components involved and

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corrective actions taken. Test and maintenance outages were to be included.

2. A quantification of the historical unavailability of the ECC systems

.and P*= due. to test and asiatenance outages.

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

The type of information required to satisfy the review crii.eria was

, clarified by the NBC on August 12, 1981 [7]. Auxiliary systems such as i c 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 L -. interpreted as a continuous 5-year period of recent operation.

On July 26, 1982 [8], the NRC further clarified that the purpose of the l 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 NaC. A Diesel Generator Interim Beliability Program has been proposed to effect improved

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

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TER-C5506-273 l- 3. TECHNICAL EVALUATION

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l 3.1 REVIEN OF COMPLETENESS OF THE LICENSEE'S REPORT

. The ECC systems at TE's Davis-Besse Unit 1 consist of the following four l separate systems:

. o core flood tank l'

o high pressure injection (HPI) 7 r' o low pressure injection (LPI) o borated water storage tank (BNST) .

l TE stated that all unplanned equipment outage events are reported as

, r.1, an.. . 3yant Reports U.EBs) ...Bar. mach JCC system outage avan 4 TE provided reference to the LER data which included the outage dates and the cause, plus sufficient description to discern the corrective action taken. Monthly estimates of the time required for maintenance and surveillance testing activities were included in the ECC system' outage submittal. Se results of TE's review were provided for the period from May 27, 1977 to December 31, 1980 for Davis-Besse Unit 1.

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Based on the preceding discussion, it is concluded that TE has submitted a report which fulfills the requirements of review criterion 1 without

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3.2 COMPARISON OF ECC SYSTM OUTAGES WITH THOSE OF OTHER PLANTS Se outages of ECC systems can be categorized as (1) unplanned outages due l to equipment failure or (2) planned outages due to surveillance testing or preventive maintenance. Unplanned outages are reportable as LERs under the

, technical specifications. Planned outages for periodic maintenance and j testing are not reportable as LERs. Me technical specifications identify the type and quantity of ECC equipment required as well as the maximum allowable I

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. me purpose of the technical specifica-l ranidin Research Center A Onamen af The Fransen buense t

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tion maximum allowable outage times is to prevent extended plant operation 7

j without sufficient ECC system protection. The 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

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i planned and unplanned outages from acen=utating extensive ECC system downtime.

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Unavailability, as defined in general terms in NASE-1400 [9], 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 calcu-h' lating 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 considered. ,

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. Mis =i=a14 4'ying - _ ^ 4 .is x===a==ht= 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 j 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 3:C system would be expected if the design capability of the system exceeded the capacity required for the system to fulfill its safety functien. Ibr 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

l. as of planned and unplanned outages of primary ECC system components. In I' 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., me inclusion of all outage events gn. p -ww,g.n--. , y -

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1 l 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. mly a detailed analysis of each ECC system for each plant could improve the confidence in the calculated result. asch an analysis is beyond the intended scope of this report.

p The planned and unplanned (forced) outage times for the four ECC systems ll (core flood tank, HPI, LPI, and BNST) were identified from the outage l 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 Davis-Besse Unit i 1. Outages that occuraed during nonoperational periods were eliminated as l' well as those caused by failures or test and maintenance of support systems.

Data on plant operating conditions were obtained from the annual reports, "macLear JIouer _Jtiant ?-=*h Esperience" (10-23], .and.from imenehty reports, i- " Licensed Operating Reactors Status Summary Reports" (14]. The remaining l

outages were segregated into planned and unplanned outages based on an TE's description of the causes. The outage periods for each category were ,

cale41ated by summing the individual outage durations.

Observed outage times of various ECC systems at Davis-Besse Unit 1 were compared with those of other IWRs. Based on this comparison, it was concluded that the historical unavailability of the core flood tank, HPI, LPI, and BWST systems has been consistent with the performance of those systems throughout the industry. The observed unavailability was less than the industrial mean for the core flood tank and BNST, and less than about one standard deviation above the mean for the HPI and LPI systems, assuming that the underlying i unavailability is distributed lognormally. The outage times were also consistent with existing technical specifications.

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$j" Core Flood HPI LPI BWST Outage in Days Outage in Days Outage in Days Outage in Days ,

i R Days of Plant S Year Operation Forced Planned Forced Planned Fbrced Planned Pbrced Planned f9 1977 a k

1978 177.8 0.0 0.0 0.0 1.7 0.0 1.7 0.0 0.0 (1.0%) (1.0%)

1979 172.6 0.0 0.0 0.0 1.7 0.0 1.7 0.0 0.0 4s (1.0 6 ) - (1.0%)

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0.0 0.0 0.0 2.1 0.0 2.1 0.0 0.0 1980 223.5 l' (0.9% ) (0.9%)

1-573.9 0.0 0.0 0.0 5.5 0.0 5.5 0.0 0.0 Tbtal 1 (1.0%) (1.0%)

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a. Commerical operation began 11/20/77.

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TE3H:5506-273 3.3 REVIEN OF PROPOSED CHANGES TO IMPMOVE THE AVAILABILITY OF ECC EQUIPDG24T In References 4 and 5, TE did not include any recommendations to improve the availability of ECC systems and components.

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4. CONCLUSIONS l

l Toledo Edison Company (TE) has submitted two reports for Davis-Besse Nuclear Power Station Unit 1 which reference (1) outage dates and duration estimates, (2) causes of the outages, (3) ECC systems or components involved in the outages, and (4) corrective actions taken. It is concluded that TE has fulfilled the requirements of NUREG-0737, Iten II.K.3.17, and that changes to improve the availability of ECC systems are not required.

In addition, the historical unavailability of the core flood tank, high pressure injaction (HPI), low pressure injection (LPI), and borated water l' storage tank (BWST) systems has been consistent with the performance of those systems throughout the industry. The observed unavailability was less than the industrial 1eean for the core flood tank and BKST and less than about one standard deviation above the mean for the HPI and LPI systems. The outages were also consistent with existing technical specifications.

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5. REFERENCES l.

1. NUREG-0626

" Generic Evaluation of Feedwater Transients and Small Break l ,

Iosse f-03olant Accidents in GE-Designed Operating Plants and Near-Tern Operating License Applications" NBC, January 1980

2. NUREG-0660 l "NBC Action Plan Developed as a T.uult of the MI-2 Accident" NRC, March 1980

3. NUREG-0737

" Clarification of MI Action Plan Requirements"

- NRC, October 1980

4. R. P. Crouse (TE)

J.a ttar ..to Director of.mnalmar anactor .Rea"1 =*iaa: 1. W. Reid (M E)

Subject:

3esponse to NUREG-0737 February 24, 1981

5. R. P. Crouse (TE)

Letter to Division of Operating Reactors, J. F. Stolz (NBC)

Subject:

Additional Information in Response to NUREG-0737

, July 30,1982

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

Letter to Dr. S. P. Carfagno (FE)

Subject Contract No. NRC-03-81-130, hntative Assignment F July 21, 1981 i

7. NRC l Neeting between NRC and FRC

! Subject C5506 Tentative Work Assignment F, Operating Reactor PORY

( and ECCS Outage Reports August 12, 1981

. 8. NRC l Meeting between NBC and FRC l

Subject:

Resolution of Review Criteria and Scope of Work July 26,1982 9 NASE-1400

" Reactor Safety Study" NBC, October 1975

10. NUREG-0366 "Maclear Power Plant Operating Experience 1976" NBC, December 1977 nklin Research Center A Dhimon af The Frenaden buenme Fg"NW uw Y-+7-'k 9+= -

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11. NUREG-0483 "Raclear Power Plant Operating Experience 1977" NBC, Pobruary 1979

12. NUREG-0618 "Maclear Power Plant Operating Experience 1978"

• NBC, December 1979

13. NUREG/CR-1496 "leaclear Power Plant Operating Experience 1979" '

NBC, May 1981

14. NUREG-0020

" Licensed Operating Reactors Status Sunumary Report" volume 4, Nos.1 through 12, and vblume 5, No.1 NBC, December 1980 through January 1981 4"

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