ML19343D248
| ML19343D248 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 10/24/1980 |
| From: | Noell P, Stilwell T FRANKLIN INSTITUTE |
| To: | |
| Shared Package | |
| ML19343D244 | List: |
| References | |
| CON-NRC-03-79-118, CON-NRC-3-79-118 TER-C5257-252, TER-C5257-252-R01, TER-C5257-252-R1, NUDOCS 8105040041 | |
| Download: ML19343D248 (10) | |
Text
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1 THIS REPORT SUPERSEDES ISSUE OF JULY 2L 1980 O
TECHNICAL EVALUATION REPORT PRIMARY COOLANT SYSTEM PRESSURE ISOLATION VALVES i
l JERSEY CENTRAL POWER AND LIGHT COMPANY OYSTER CREEK UNIT 1 NRC DOCKET NO.
50-219 NRC TAC NO.
12919 FRC PROJECT CS257 NRC CONTR ACT NO. NRC-03-79-118 FRC TASK 252 4
Prepared by Franklin Research Center Author:
P. N. Noell The Parkway at Twentieth Street T. C. Stilwell Philadelphia, PA 19103 FRC Group leader: P. N. Nciell Prepared for Nuclear Regulatory Commission Washington, D.C. 20555 Lead NRC Engineer:
P. J. Polk March 20, 1980 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 age.cy 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, apparatus, product or process disclosed in this report, or represents that its use by such third party would not infringe privately owned rights.
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Ok b Franklin Research Center 810504 0 Mk A Division of The Franklin Institute The Ben.a n:n Frankjen Pa kway. Phila. Pa 19103 (215!448 1000
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TER-C5257-252 (Rev. 1)
1.0 INTRODUCTION
The NRC has determined that certain isolation valve configurations in systems connecting the high-pressure Primary Coolant System (PCS) to lower-pressure systems extending outside containment are potentially significant contributors to an intersystem loss-of-coolant accident (LOCA).
Such configu-rations have been found to represent a significant f actor in the risk computed for core melt accidents.
The sequence of events leading to the core melt is initiated by the con-current failure of two in-series check valves to function as a pressure isola-tion barrier between the high-pressure PCS and a lower-pressure system extend-ing beyond containment. This failure can cause an overpressurization and rup-ture'of the low-pressure system, resulting in a LOCA that bypasses containment.
The NRC has determined that the probability of failure of these check valves as a pressure isolation barrier car. be significantly reduced if the pressure at each valve is continuous,1y' monitored, or if each valve is periodi-cally inspected by leakage testing, ultrasonic examination, or radiographic inspection.
The NRC has established a program to provide increased assurance that such multiple isolation barriers are in place in all operating Light Water Reactor plants designated by DOR Generic Implementation Activity B-45.
In a generic letter of February 23, 1980, the NRC requested all licensees to identify the following valve configurations which may exist in any of their plant systems communicating with the PCS: 1) two check valves in series or 2) two check valves in series with a motor-operated valve (MOV).
For plants in which valve configurations of concern are found to exist, licensees were further requested to indicate: 1) whether, to ensure integrity of the various pressure isclation check valves, continuous surveillance or periodic testing was currently being conducted 2) whether 'any check valves of concern were known to lack integrity, ano 3) whether plant procedures should be revised or plant modifications be made to increase reliability.
Franklin Research Center (FRC) was requested by the NRC to provide tech-r.ical assistance to NRC's E-45 activity by reviewing each licensee's submittal
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4 TER-CS 257 -252 (Rev. 1) against criteria prov'ided by the NRC and by verifying the licensee's reported '.
findings from plant system drawings.
This report documents FRC's technical review.
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TER-C5257-252 (Rev. 1) 2.0 CRITERIA 2.1 Identification Criteria For a piping system to have a valve configuration of concern, the follow-ing five items must be fulfilled:
- 1) The high-pressure system must be connected to the Primary Coolant System;
- 2) there must be a high-pressure / low-pressure interface present in the line;
- 3) this san.e piping must eventually lead outside centainment;
- 4) the line must have one of the valve configurations shown in Figure 1; and
- 5) the pipe line must have a diametet greater than 1 inch.
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Valve Configurations Designated by the NRC To Be Included in This Technical Evaluation 1
TER-C5257-252 (Rev. 1) 2.2 Periodic Testing Criteria For licensees whose plants have valve configurations of concern and choose to institute periodic valve leakage testing, the NRC has established criteria for frequency of testing, test conditions, and acceptable leakage rates.
These criteria may be summarized as follows:
2.2.1 Frequency of Testing Perlocic hydrostatic leakage testing * (ultrasonic te: ting or radiographic testing) on each check valve shall be accomplished every time the plant is placeo in the cold shutdown condition for refueling, each time the plant is placed in a cold r5utdown condition for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> if testing has not been accomplished in the preceding 9 months, each time any check valve may have moved from the fully closed position (i.e., any time the differen-tial pressure across the valve is less than 100 psig), and prior to returning the valve to service after maintenance, repair, or replacement work is performea.
U 2.2.2 Hydrostatic Pressure Criteria Leakage tests involving pressure differentials lower than function pres-sure differentials are permitted in those types of valves in which service pressure will tenc to diminish the overall leakage channel opening, as by pressing the disk into or onto the seat with greater force.
Gate valves, check valves, and globe-type valves, having function pressure differential applied over the seat, are examples of valve applications satisfying this requirement. When leakage tests are made in such cases using pressures lower than function maximum pressure differential, the observeJ leakage shall be adjusted to function maximum pressure differential value. This adjustment shall be made by calculation appropriate to the test media and the ratio between test and function pressure differential, assuming leak-age to be directly proportional to the pressure differential to the one-half power.
2.2.3 Acceptable Leakage Rates:
Leakage rates less than or equal to 1.0 gpm are considered accept-i e
able.
Leakage rates greater than 1.0 gpm bLt less than or equal to 5.0 e
gpm are considered acceptable if the latest measured rate has not exceeded the rate determined by the previous test by an amcunt
- 5c. ratisfy ALARA (ar icw ce re asonably achievabic-) requir(n cnts, pre trur e it62catctr may te urea ir. accordance with erf roveo prc ec cur (s as decun.cnted ty calculation to detern. int-the need for hyorottatic testing.
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TER-C5257-252 (Rev. 1) that reduces the margin between the measured leakage rate and the maximum permissible rate of 5.0 gpm by 50% or greater.
Leakage rates greater than 1.0 gpm but less than or equal to 5.0 e
gpm are considered unacceptable if the latest measured rate ex-ceeded the rate determined by the previous test by an amount that reduces the margin between measured leakage rate and the maximum permissible rate of 5.0 gpm by 50% or greater.
- o. Leakage rates greater than 5.0 gpm are considered unacceptable.
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TER-C5257-252 (Rev. 1)
3.0 TECHNICAL EVALUATION
3.1 Licensee's Response to the Generic Letter In response to the NRC's generic letter [Ref. 1], the Jersey Central Power and Light Company (JCP) stated [Ref. 2] that, " Based on the review of the systems at' Oyster Creek, it has been concluded that the valve configurations at Oyster Creeks are not as described in your letter."
The licensee did, however, include a description of the valve configurations of concern existing in the Core Spray System at Oyster Creek Unit 1.
It is FRC's understanding that, with JCP's concurrence, the NRC will direct JCP to change its Plant Technical Specifications as necessary to ensure that periodic leakage tetting (or equivalent testing) is conducted in accor-dance with the criteria of Section 2.2.
3.2 FRC Review of Licensee's Response FRC has reviewed the licensee's response against the plant-specific Piping and Instrumentation Diagrams (P& ids) [Ref. 3) that might have the valve con-figurations of ecncern.
FRC has also reviewed the efficacy of instituting periodic testing for the check valvec involved in this particular application with respect to the re-duction of the probability of an intersystem LOCA in Core Spray System pipe lines.
In itc review of the P& ids [Ref. 3] for Oyster Creek Unit 1, FRC found the following piping system to be of concern:
The valve configuration of concern, existing in both the A and B loops e
of the Core Spray System, consists initially of two parallel air-operated check valves inside the Drywell, leading away from the Peactor vessel.
These two check valves join together in a common line leading to two parallel, normally closed, motor-operated valves (MOVs) outside the containment. These two MOVs then join in a common line to a single, locked open MOV.
The high-pressure / low-pressure interface was indicated by the Licensee to exist at the upttream side of this l
ringle, locked cpen, MOV.
The apprcpriate valves of the Core Spray Fystem are listed b,elow:
l TER-C5257-252 (Rev. 1)
Core Spray System Loop A high-pressure, air-operated, parallel check valve, NZO2A high-pressure, air-operated, parallel check valve, NZ02C high-pressure, pe allel MOV, V-20-15, normally closed (n.c.)
high-pressure, parallel MOV, V-20-40, n.c.
high-pressure, MOV, V-20-12, locked open (l.o.)
Loop B high-pressure, air-operated, parallel check valve, NZO2B high-pressure, air-operated, parallel check valve, NZO2D high-pressure, parallel MOV, V-20-21, n.c.
high-pressure, parallel MOV, V-20-41, n.c.
high-pressure, MOV, V-20-18, 1.o.
In accordance with the.cr'iteria of Setilon 2.0, FRC found ne other valve configurations of concern existing in this plant, FRC reviewed the effectiveness of instituting periodic leakage testing of the check valves in these lines as a means of reducing the probability of an intersystem LOCA occurring.
FRC found that introducing a program of check valve leakage testing in accordance with the criteria summarized in Section 2.0 will be an effective measure in substantially reducing the probability of an intersystem LOCA occurring in these lines, and a means of increasing the probability that these lines will be able to perform their safety-related i
functions.
It is also a step toward achieving a corresponding reduction in the plant probability of an intersystem LOCA in Oyster Creek Unit 1.
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TER-C5257-252 (Rev. 1)
4.0 CONCLUSION
Based on the previously docketed information and drawings made available for FRC review, FRC found that loops A and B of the Core /4 pray System in Oyster Creek Unit 1 contain a valve configuration of concern (identified in Figure 1).
Thus, if the licensee's review of the valving configuration contained in the loops A and B of the Core Spray System confirms FRC's finding,then the valve configurations of concern existing in Oyster Creek Unit 1 incorporate the valves listed in Table 1.0.
If JCP modifies the Plant Technical Specifications for Oyster Creek Unit 1 to incorporate periodic testing (as delineated in Section 2.2) for the check valves itemited in Table 1.0, then FRC considers this an acceptable means of achieving plant compliance with the NRC ' staff objectives of Reference 1.
able 1.0 Primary Ogcisp' System Pressure Isolation Valves Systeni Check Valve No.
Allowable Leakaot*
Core Spray Loop A NZO2A NZO2C Loop B NZO2B NZO2D
- 7c be provideo by the licensee at a future date in accordance with Section 2.2.3.
TER-C5257-252 (Rev. 1) 5.0 REFERENkES 2.
Generic NRC letter, dated 2/23/80, from Mr. D. G. Eisenhut, Department of Operating Reactors (DOR), to Mr. I. R. Finbrock, Jr., Jersey Central Power and Light Company (JCP).
2.
Jersey Central Power and Light Company's response to the generic NRC letter, dated 3/17/80, from Mr. I. R. Finbrock (JCP) to Mr. D. G. Eisenhut (DOR).
3.
List of examined P&lDs:
General Electric Drawings of Oyster Creek Unit 1:
148P711 (Rev. 7) 148F444 (Rev. 11) 148F723 (Rev. 5) 197E871 (Rev. 7) 237E487 (Rev. 15) 237E726 (Rev. 10) 237E798 (Rev. 10) 2406 (Bev. 8) 706E249 (Rev. 3) 885D781 (Rev. 11) 886D403 (Rev. 2) l l
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