ML20003G334
| ML20003G334 | |
| Person / Time | |
|---|---|
| Site: | Salem  |
| Issue date: | 10/24/1980 |
| From: | Noell P, Stilwell T FRANKLIN INSTITUTE |
| To: | Polk P Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20003G328 | List: |
| References | |
| CON-NRC-03-79-118, CON-NRC-3-79-118 TER-C5257-266, TER-C5257-266-R01, TER-C5257-266-R1, NUDOCS 8104290057 | |
| Download: ML20003G334 (12) | |
Text
ATTACHMENT 2 THIS REPORT SUPERSEDES ISSUE OF AUGUST 22, 1980 0
TECHNICAL EVALUATION REPORT PRIMARY COOLANT SYSTEM PRESSU RE ISOLATION VALVES PUBLIC SERVICE ELECTRIC & GAS COMPANY SALEM UNIT 1 i
N RC 00CKET NO.
50-272 N RC TAC NO.
12935 FRC PROJECT C5257 N RC CONTRACT NO. NRC-03-79-118 FRC TASK 266 l
Prepared by i
Franklin Research Center Author:
P. N. Noell
(
The Parkway at Twentieth Street T. C. Stilwell l
Philadelphia, PA 19103 FRC Group Leader:
P. N. Neell Prepared for Nuclear Regulatory Cornmission Washington, D.C. 20555 Lead NRC Engineer:
P. J. Folk October 24, 1980 This report was prepared as an account of work sponsored by an l
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, apparatus, product or process disclosed in this report, or represents that its use by such third party would not infringe privately owned rights.
A
. Franklin Research Center A Division cf The Franklin Institute 810.4290 C, The Ben,amm Frarwin Parxway. FMa.. Pa 19103 (21*) 4 8 1000
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 factor 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 containme.nt. 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 can be significantly reduced if the pressure at each valve is continuously 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 "a'acer Reactor plants designated by DOR Generic implementation Activity 3-45.
In a generic lette' of Feb ruary 23, 1980, the NRC requestad all licensees to identify the following valve configurations which may exist in any of their plant systems co=sunicating 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, t
licensces were further requested to indicate: 1) whether, to ensure integrity of the various pressure isolation check valves, continuous surveillance or periodic testing was currently being conducted, 2) whether any check valves of concern were known to lack integrity, and 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-nical assistance to NRC's 3-45 activity by reviewing each licensee's submittal l
1.-
... ~ -.. -
against criteria provided by the NRC and by verifying the licensee's reported findings from plant system drawings. This report documents FRC's technical review.
2.0 CRITIRIA 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 same piping must eventually lead outside containment;
- 4) the line =ust have one of the valve configurations shown in Figure 1; and
- 5) the pipe line must have a diameter greater than l' inch.
wu PCS-
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Ev1 I
'A W
=
I k
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'M i
l
'/
c i
luowl
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l kcv i A
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HP=
= LP Figure 1.
Valve Configurations Designated by the NRC To 3e Included in This Technical I, valuation.,..
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 summarited as follows:
2.2.1 Frequency of Testing Periodic hydrostatic leakage testing
- on each check valve shall be accom-plished every time the plant is placed in the cold shutdown condition for refueling, each time the plant is placed in a cold shutdown 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 movec from the fully closed positio'n (i.e., any time the differen-tial pressure across the alve is less than 100 psig), and prior to returning the valve to service after maintenance, repair, or replacement work is performed.
2.2.2 Hydrostatic Pressure Criteria Leakage tests involving pressure differentials inwer than function pres-sure differentials are per=itted in those types of valves in which service pressure will tend to diminish the overall leakage channel opening, as by pressing the disk into or onto the seat with greater force. Cate valves, check valves, and globe-type valves, having function pressure differential applied over the seat, are examp'les of valve applications satis fying this requirement. When leakage tests are made in such cases using pressures lower than function =aximum pressure differential, the observed leakage shall be adjusted to function maximum pressure differential value. This adjust =ent 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 proportienal to the pressure differential to the one-half power.
2.2.3 Acceptable Leakage Rates:
Leakage rates less than or equal to 1.0 gpo are considered accept-able.
Leakage rates greater than 1.0 gpm but less *han or equal to 5 0 e
l gpm are considered acceptable if the la*es t =easured rate has not
~
exceeded the rate deter =ined by the previous test by an a=ount i
- To satis fy ALARA requirements, leakage may be =easured indirectly (as from the performance of pressure indicators) if accomplished in accordance with approved procedures and supported by co=putations showing that the =ethod is capable of de=enstrating valve compliance with the leakage criteria.
.., -. + -,.
that reduces the margin between measured leakage rate and the maximum permissible rate of 5.0 gym by 50% or greater.
e Leakage rates greater than 1.0 spa but less than or equal to 5.0 gym are considered unacceptable if the latest measured rats ex-ceeded the rate determined by the previous test by an amount that reduces the margin between measured leakage rate and the uaximum permissible rate of 5.0 gpm by 50% or greater.
Leakage rates greater than 5.0 gpa are considered unacceptable.
e
3.0 TECHNICAL EVALUATION
l 3.1 Licensee's Response to the Generic Letter In response to the NRC's generic letter [Ref. l}, the Public Service Electric & Gas Company (PEG) stated [Ref. 2] that, "There are five (5) basic configurations with twenty (20) paths from the High Pressure Reactor Coolant System (PCS) to the Low Pressure Injection System (LPIS) piping."
The Licensee further stated " Currently, there is no specific surveillance program to insure these valves are not leaking. All The valves are periodi-cally exercised in accordance with the IST program to insure operability.
Leakage through the pressure isolation. paths would be indicated by an increase in RCS make-up."
It is FRC's understanding that, with PEG's concurrence, the NRC will direct PEG to change its Plant Technical Specifications as necessary to ensure that periodic leakage testing (or equivalent testing) is conducted in accor-dance with the criteria of Section 2.2.
3.2 F1C 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 migat have the valve con-(
- rguracious of concern.
l FRC has also reviewed the efficacy of in. ~. *ag periodic testing for the check valves involved in this particular application with respect to the re -
duction of the probability of an intersystem LOCA in the Low-Pressure (600 i
psig) and Intermediate-Pressure (1750 psig) Safety Injection System piping lines.
_4_
In its review of the P& ids [Ref. 3] for the Salem Unit 1, FRC found the following two piping systems to be af concern:
Ihe Low-Pressure Safety Injection System (' PSIS) is connected to the L
cold-leg side of each of the fcur primary coolant loops as well as to the hot-leg side of PCS loops 13 and 14.
Each cold or hot leg of the LPSIS has two check valves and a motor-operated valve (MOV) in one of the series configurations of concern.
The Intarmediate-Pressure Safety Injection System is joined co both the cold and hot leg sides of all four primary coolant loops. As in the LPSIS case the same double check valve in series with a MOV configuration was found.
In each of these two systems the high-pressure / low-pressure inter-face is on the upstream side of the single motor-operated valve (MOV). The valve arrangements of concern existing in each of these two systems for Salem Unit 1 are listed below.
Low-Pressure Safety Injection System Loop 11
)
Cold Leg Hot Leg high-pressure check valve,11SJ56 high-pressure check valve,11SJ43 N/A high-pressure MOV,11SJ49, locked closed (1.c.)
Loop 12 high-pressure check valve, 12SJ56 high-pressure check valve, 12SJ43 N/A high-pressure check MOV, 12SJ49, 1.c Loop 13 high-pressure check valve, 13SJ56 high-pressure check valve, 13SJ156 high-pressure check valve, 13SJ43 high-pressure check valve, 13RH127 high-pressure MOV, 11SJ49, 1.c high-pre s sure MOV, 1RH26, 1.c.
Loop 14 I
high-pressure check valve, 14SJ56 high-pressure check valve,14SJ156
_3_
l l
I 1
high-pressure check valve, 14SJ43 high-pressure check valve, 14RH127 high-pressure MOV, 12SJ49, 1.c.
high-pressure MOV,1RH26,1.c.
Intermediate-Pressure Safety Injection S. Jtem Loop 11 Cold Leg Hot Leg high-pressure check valve,11SJ56 high-pressure check valve, llSJ156 high-pressure check valve, 11SJ144 high-pressure check valve, llSJ139 high-pressure throttled valve llSJ143 high-pressure throttled valve,llSJ138 high-pressure MOV, ISJ135, l.o.
high-pressure MOV,12SJ40,1.c.
Loop 12 high-pressure check valve 12SJ56 high-pressure check valve,12SJ156 high-pressure check valve 12SJ144 high-pressure : heck valve,12SJ139 high-pressure throttled valve, 12SJ143 high-pre s sure throttled valve,12SJ138 high-pressure MOV, ISJ135, l.o.
higb-pressure NOV,12SJ40,1.c.
. Loop 13 high-pressure check valve,13SJ56 high-pressure check valu,13SJ156 high pressure check valve,13SJ144 high-pressure check valve, 13SJ139 high-pressure throttled vavle, 13SJ143 high-pressure throttled valve, 13SJ138 high-pressure MOV, ISJ135, l.o.
high-pressure MOV, llSJ40, 1.c.
Loop l'4 high-pressure check valve,14SJ56 high-pressure check valve, 14SJ156 high-pressure check valve, 14SJ144 high-pressure check valve,14SJ139 high-pressure throttled valve, 14SJ143 high-pressure throttled valve, 14SJ138 high-pressure MOV, ISJ135, l.o.
high-pressure MOV, llSJ40,1.c.
In accordance with the criteria of Section 2.0, FRC has found no other valve configurations of concern existing in this plant. These findings con-firm the licensee's response [Re f. 2]. -_
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 vill 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 functions. It is also a step toward achieving a corresponding reduction in the plant probability of an intersystem LOCA in the Salem Unit.1.
4.0 CONCLUSION
The Salem Unit I has been decernined to have valves in one of the configu-rations of concern in the Low and Intermediate-Pressure Safety Injection
- Systems, If PEG modifies the Plant Technical Specification for Salem Unit 1 to incorporate periodic testing (as delineated in Section 2 2) for the check valves itemized in Table 1.0, theh FRC considers this an acceptable means of achieving plant compliance with the NRC staff objectives of Retirence 1.
Table 1.0 Primary Coolant Syctem Pressure Isolation Valves System Check Valve No.
Allowable Leakage
- Low Pressure Safety Injection Loop 11, cold leg 11SJ56 11SJ43 Loop 12, cold leg 12SJ56 12SJ43 l
Loop 13, cold leg 13SJ56 13SJ43 Loop 13, hot leg 13SJ156 13RH127 Loop 14, cold leg 14SJ56 14SJ43
_7_
s Loop 14, hot leg 14SJ156 14RH127 Intermediate Pressure Safety Injection Loop 11, cold leg 11SJ144 Loop 11, hot leg 11SJ156 11SJ139 Loop 12, cold leg 12SJ144 Loop 12, hot leg 12SJ156 12SJ139 Loop 13, cold leg 13SJ144 Loop 13, hot leg 13SJ156 13SJ139 Loop 14, cold leg 14SJ144 i
Loop 14, hot leg 15SJ156 14SJ139 s
5.0 REFERENCES
I (1}. Generic NRC letter, dated 2/23/80, from Mr. D. G. Eisenhut, Department of Operating Reactors (DOR), to Mr. F. P. Librizzi, Public Service Electric & Cas Cc=pany (PEG).
[2]. Public Service Electric & Gas Company's response to NRC's letter, dated 3/14/80, from Mr. F. P. Lib rizzi (PEG) to Mr. D. G. Eisenhut (DOR).
[3]. List of. examined P& ids:
Public Service Electric & Gas Company Drawings:
205201 A 8760-9 205228 A 8761-8 205229 A 8761-7 205230 A 8761-7 205232 A 8761-6 205234 A 8761-10 l
205244 A 8761-5 I