ML17309A150
| ML17309A150 | |
| Person / Time | |
|---|---|
| Site: | Ginna  |
| Issue date: | 10/24/1980 |
| From: | Noell P, Stilwell T FRANKLIN INSTITUTE |
| To: | Polk P Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML17258A998 | List: |
| References | |
| CON-NRC-03-79-118, CON-NRC-3-79-118 TER-C5257-248, NUDOCS 8105040102 | |
| Download: ML17309A150 (13) | |
Text
Attachment 2
(TECHNlCAL EVALUATtONREPORT(
PRIMARY COOLANTSYSTEM PRESSURE ISOLATIONVALVES ROCHESTER GAS 8 ELECTRIC CORPORATION ROBERT E, GINNA UNIT 1 NRC DOCKET NO.
50-244 NRC TAC NO.
12915 NRC CONTRACT NO. NRC43-79-118 FRC PROJECT C5257 FRCTASK 248 Prepared by Franklin Research Center The Parkway at Twentieth Street Philadelphia, PA 19103 Author: P.
N. Noell T. C. Stilwell FRCGroupLeader:
P.
N. Noell Prepared for Nuclear Regulatory Commission Washington, D.C. 20555 Lead NRC Engineer:
P. J. Polk October 24, 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 agency thereof, or any of their employees, makes any warranty, expressed or implied. or assumes any legal liabilityor responsibility for any third party's use, or the results of such
- use, of any information, apparatus, product or process disclosed ln this report, or represents that!ts use by such third party would not infringe privately owned rights.
( ll Franklin Research Center iA Division of The Franklin Institute The Benjemin Franklin Parkway, Phile..'e. 19110 (215) 448-1000
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1 o 0 INTRODUCTlON The NRC has determined that certain isolation valve configurations in systems connecting the high-pressure Primary Coolant System (PCS) to lo~er-pressure systems extending outside containment are potentially significant contributors to an intersystem loss-of-coolant accident (LOCA) ~
Such configu-xations have been found to represent a significant factor in the xisk computed fox'ore 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-pxessure PCS and a lower-pressure system extend-ing beyond containment.
This failure can cause an overpressuriration 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
px essure 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 pxogram to pxovide increased assurance that such multiple isolation barriers axe in place in all operating Light Water Reactor plants designated by DOR Generic Implementation Activity B-45 ~
Zn a generic letter of February 23,
- 19SO, 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 motormperated valve'MOV).
For plants in which valve configurations of concexn are found to exist, licensees were further requested to indicate:
- 1) whether, to ensure integrity of the vaxious pressure isolation check valves, continuous surveillance or periodic testing was currently being conducted,
- 2) whether any check valves of concern wex'e known to lack integrity, and 3) whether plant procedures should be revised oz plant modifications be made to increase xeliability.
Franklin Research Center (FRC) was requested by the NRC to provide tech-nical assistance to NRC's B&5 activity by reviewing each licensee's submittal
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against criteria provided by the NRC and by verifying the licensee's reported findings from plant system drawings.
This report documents PRC's technical review.
2.0 CRITERIA 2.1 Identification Criteria Por 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 must have one of the valve configurations shown in Pigure 1'nd
- 5) the pipe line must have a diameter greater than 1 inch.
Valve Configurations Designated by the NRC To Be Included in This Technical Evaluation
2.2,peziodic Testing Critezia For licensees whose plants have valve configuzaeions of concezn aad choose to instieute periodic valve leakage
- testing, the NRC has established criteria for frequency of testiag, test conditions, and acceptable
'leakage tates.
These crieeria may be summarized as follovs:
2.2. 1 Frequency of Tes ting Periodic hydzoseatic leakage teseing* on each check valve shall be accom-plished every time the plant is placed in the cold shutdown condition foz zefueling, each time the plant is placed in a cold shutdown condition foz 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> if testing has aot been accomplished in the preceding 9 months, each time any check valve may have moved from the Eully closed position (i.e.,
any time the diffezen-tial pressure across the valve is less than 100 psig),
and prior to zeeurning the valve to service after maintenance,
- zepaiz, or replacemeae work is performed.
2.2.2 ',Hydrostatic Pressure Criteria/
Leakage tests involving pressuze differentials lower than funceion pres-sure differentials aze pezmieted in those eypes of valves in which service pressure vill tend to diminish the ovezaL1 leakage channel
- opening, as by pressing the disk ineo or onto the seat with greater force.
Gate valves, check valves, and globe-type valves, having function pressure diffezential applied over the seae, are examples of valve applications satisfying this requiremene.
f'When'eakage tests are made in such cases using pressures
~Lower than function maximum pressuze diffezeneial',
the observed leakage
'shill be adjusted to Euaction maximum pressure differential value.
This adjustment shall be made by calculation. appropriate to the test media and,.
the ratio between test and function pressure diEferential, assuming leak- (
age to be~ d'irectly proportional to the pressure diEfezeneial to the one-->
half power.'.2.3 Acceptable Leakage Rates:
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Leakage zaees Less than or equal to 1.0 gpm are considered acceoe-able.
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Leakage rates, gzeaeer chan 1.0 gpm but less than or equal to 5.0 gpm are considered acceptable if the latest measured rate has not exceeded the rate deeermiaed by the previous test by an amount TPaLgsis4rv ouv ~is>i~q~
Tech Sped,
- To satisEy ALARA requiremenes, leakage may be measured indirectl (as from the performance of ressure indicators) if accomplished in accordance with approved procedures and supported by computations showing that the meehod is capable of demonstrating valve compLiance with the Leakage criteria.
that reduces the margin between the measured leakage rate and t'he maximum permissible rate of 5.0 gpm by 50X or greater.
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Leakage rates greater than 1.0 gpm but less than or equal to 5.0 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 50X or greater.
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Leakage rates greater than 5.0 gpm are considered unacceptable.
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3.0 TECHNICAL EVALUATION
3.1 Licensee's
Response
to the Generic Letter In response to the NRC's generic letter [Ref. 1], the Rochester Gas and Electric Corporation (RGE) indicated that the High-Head Safety Injection
- System, cold leg side, and the Low-head Safety Injection System are two suspect piping systems.
The licensee further stated "At the present time there is no continuous surveillance or periodic testing on these valves to ensure pressure integrity.
However, in ten years of operation there has been no indication of any gross leakage in any of these check valves."
It was discovered by FRC that the hot leg branches of the High-Head Safety Injection System also contain valve configurations of concern.
It is FRC's understanding that, with RGE's concurrence, the NRC will direct RGE 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 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 concern.
FRC has also reviewed the efficacy of instituting 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 cold and hot legs of
the High>>Head Safety Injection as well as in the Low-Head Safety Injection System piping.
In its review of the P&IDs [Ref. 3] for Robert E. Ginna Unit 1, FRC found the following two piping systems to be of concern:
The High-Head Safety Injection System is connected to the two Reactor Coolant System loops by two hot and cold leg branches.
Each branch contains two check valves and a motor-operated valve (MOV) in a series configuration of concern.
In all four branches, the high-pressure/low-pressure interface is on the upstream side of the MOVs.
0 The Low-Head Safety Injection System, connected by two branches di-rectly to the Reactor Vessel, contains a single check valve and MOV in a series configuration of concern.
Again, the high-pressure/low-pressure interface is located on the upstream side of the MOV.
All valves of concern are listed for both systems below:
High-Head Safety Injection System Loo A, cold le high-pressure check valve, 867B high-pressure check valve, 878J high-pressure MOV, 878D, normally open (n.o.)
Loo A, hot le high-pressure check valve, 877B high-pressure check valve, 878H high-pressure MOV, 878C, normally closed (n.c.)
Loo', cold le high-pressure check valve, 867A high-pressure check valve, 8 78G high-pressure MOV, 878B, n.o'.
Loo B, hot le high-pressure check valve, 877A high-pressure check valve, 878F high-pressure MOV, 878A, n.c.
Low-Head Safety Injection System Reactor Vessel Branch A
high-pressure check valve, 853A high-pressure MOV, 852A Branch B
high-pressure check valve, 853B high-pressure MOV, 852B In accordance with the criteria of Section 2.0, FRC found no 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 functions
~ It is also a step toward achieving a corresponding reduction in the plant probability of an intersystem LOCA in Robert E. Ginna Unit 1.
4.0 CONCLUSION
It has been determined that the High-Head Safety Injection system, cold-leg
- branches, and the Low-Head Safety Injection system in Ginna Unit 1, incorporate valving in two of the configurations (identified in Figure 1) designated by the NRC as valve configurations of concern.
- Moreover, based on the previously docketed information and drawings made available for FRC review, FRC found that the High-head Safety Injection system, hot-leg branches also incorporate a
valve configuration of concern.
Thus, if the licensee's review of the valve configurations contained in the hot-leg branches of the High-Head Safety Injection system confirms FRC s finding, then valve configurations of concern existing in Ginna Unit 1 incorporate the valves as listed in Table 1.0.
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If RGE modifies the Plant Technical Specifications for Robert E. Ginna Unit 1 to incorporate periodic testing (as delineated in Section 2.2) for the check valves itemized in Table 1.0, then FRC considers this an acceptable means of achieving plant compliance with the NRC staff objectives of Reference 1 ~
Table 1.0 Primary Coolant System Pressure Isolation Valves
~Ss tern High-Head Safety Injection Check Valve No.
Allowable Leaka e*
Loop A cold Leg hot leg 867B 878 J 877B 878H Loop B
cold Leg hot leg 867A 878G 877A 878F Low-Head Safety Injection Branch A Branch B
853A 853B Mo be provided by the licensee at a future date in accordance with Section 2.2.3.
- 5. 0 REFERENCES 1.
Generic NRC letter, dated 2/23/80, from Mr. D. G. Eisenhut, Department of Operating Reactors (DOR), to Mr. L. D. White Jr., Rochester Gas and Electric Corporation (RGE).
2.
Rochester Gas and Electric Corporation's response to the NRC's letter, dated 3/14/80, from Mr. L. D. White (RGE) to Mr. D. G. Eisenhut (DOR).
3.
List of examined PSIDs:
Rochester Gas and Electric Corporation dravings of Robert E. Ginna Unit 1:
33013-422-C 33013-424-B 33013-425-A 33013-426-D 33013-427-B 33013-432-A 33013-433-A 33013-434-0 33013-435-0 33013-436-0