ML20062K073
| ML20062K073 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 07/31/1982 |
| From: | Farmer F, Mays S EG&G, INC. |
| To: | Scholl R Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20062K072 | List: |
| References | |
| TASK-05-02, TASK-5-2, TASK-RR EGG-EA-5931, NUDOCS 8208170003 | |
| Download: ML20062K073 (10) | |
Text
LM@MMM EGG-EA-5931 July 1982 SYSTEMATIC EVALUATION PROGRAM, TOPIC V-II.A, ELECTRICAL, INSTRUMENTATION, AND CONTROL FEATURES FOR f
ISOLATION OF HIGH AND LOW PRESSURE SYSTEMS, BIG ROCK i
POINT NUCLEAR STATION S. E. Mays F. G. Farmer U.S. Department of Energy Idaho Operations Office
- Idaho National Engineering Laboratory y$ U h.ch ushA M W dl g g [__powwur. T- &
$5[
g a *- C l
4 "W
?
- R : -
h de __
ern a sumer mmmeri gAk/w.
MN p
N i
g EE - Z
<,, i T W M 7J E % y _. c c 9Im 7- % ~ T 9 W P " _.,
gA f
' [ [ % n s:m es b I
i
~ i~
l g.
._ m,._._..%
-~
o
\\
h C.
-Q_
f_- N M m l) 4+
dN MV.s ETM l
This is an informal report intended for use as a preliminary or working document 4
Prepared for the U.S. Nuclear Regulatory Comission i
under DOE Contract No. DE-AC07-761D01570 FIN No. A6425 E
Idaho 8208170003 820812 4
E G c G e.-
FORM EG4G 398 is.
ii si, INTERIM REPORT Accession No.
Report No.
EGG-EA-5931 Contract Program or Project
Title:
Electrical, Instrumentation, and Control Systems Support for the Systematic Evaluation Program (II)
Subject of this Documents Systematic Evaluation Program, Topic V-II.A, Electrical, Instrumentation, and Control Features for Isolation of High and Low Pressure Systems, Big Rock Point Nuclear Station Type of Document:
Informal Report Author (s):
S. E. Mays F. G. Farmer Date of Document:
July 1982 Responsible NRCIDOE Individual and NRCIDOE Office or Division:
R. F. Scholl, Jr., Division of Licensing This document was prepared primarily for preliminary orinternal use. it has not received full review and approval. Since there may be substantive changes,this document should not be considered final.
EG&G Idaho, Inc.
Idaho Falls, Idaho 83415 Prepared for the U.S. Nuclear Regulatory Commission Washington, D.C.
Under DOE Contract No. DE AC07 761D01570 NRC FIN No.
A6425 INTERIM REPORT
0138J SYSTEMATIC EVALUATION PROGRAM TOPIC V-II.A ELECTRICAL, INSTRIMENTATION, AND CONTROL FEATURES FOR ISOLATION OF HIGH AN9 LOW PRESSURE SYSTEMS BIG ROCK POINT NUCLEAR STATION Docket No. 50-155 July 1982 S. E. Mays F. G. Farmer EG&G Idaho, Inc.
7 82
ABSTRACT l
This SEP technical evaluation, for the Big Rock Point Nuclear Station, reviews the electrical, instrumentation and control features used to isolate low pressure systems from the reactor coolant primary system.
FOREWDRD This report is supplied as part of the " Electrical, Instrumentation, and Control Systems Support for the Systematic Evaluation Program (II)"
being conducted for the U.S. Nuclear Regulatory Commission, Dffice of Nuclear Reactor Regulation, Division of Licensing, by EG&G Idaho, Inc.,
Reliability & Statistics Branch.
The U.S. Nuclear Regulatory Commission funded the work under the authorization B&R 20-10-02-05, FIN A6425.
i o
I Electrical,-Instrumentation and Control Systems Support for the Systematic Evaluation Program (II)
NRC FIN No. A6425 ii
- - - - + -
CONTENTS 1
1.0 I N TR ODU CT I O N....................................................
I 2.0 CRITERIA........................................................
1 2.1 Res idual Hea t Remov al {R HR ) Sys tem........................
2 2.2 Emer gency Core C ool ing Sys tem.............................
2 2.3 O t h er Sy s te ms.............................................
2
- 3. 0 D IS CUSS ION AND E VALU AT IO N.......................................
2 3.1 Sh utdo wn C ool i n g Sys te m...................................
3 3.2 C or e S pr ay S ys t em.........................................
-3 4.0
SUMMARY
3 5.0 R EF ER EN C E S......................................................
i i
l iii l
l l
[
SYSTEMATIC EVALUATION PROGRAM ELECTRICAL, INSTRUMENTATION, AND CONTROL FEATURES FOR ISOLATION OF HIGH AND LOW PRESSURE SYSTEMS
^
BIG ROCK POINT NUCLEAR STATION 1.0 INTRODUCT ION
~
The purpose of this review is to determine if the electrical, instru-mentation, and control (El&C) features used to isolate systems with a lower pressure rating than the reactor coolant primary system are in compliance with current licensing requirements as outlined in SEP Topic V-11A. Current guidance for isolation of high and low pressure systems is contained in Branch Technical Position (BTP) EICSB-3, BTP RSB-5-1, and the Standard Review Plan (SRP), Section 6.3.
2.0 CRITER IA 2.1 Residual Heat Remraal (RHR) Systems.
Isolation requirements for RHR systems contained in BTP RSB-5-1 are:
1.
The suction side must be provided with the following isolation f ea tures:
Two power-operated valves in series with position indicated a.
in the control room.
b.
The valves nust have independent and diverse interlocks to prevent opening if the reactor coolant system (RCS) pressure is above the design pressure of the RIR system.
c.
The valves must have independent and diverse interlocks to ensure at least one valve closes upon an increase in RCS pressure above the design pressure of the RHR system.
2.
The discharge side nust be provided with one of the following features:
The valves, position indicators, and interlocks described in a.
(1)(a) through (1)(c) above.
b.
One or more check valves in series with a normally-closed power-operated valve which has its position indicated in the control room.
If this valve is used for an Emergency Core Cooling System (ECCS) function, the valve must open upon receipt of a safety injection signal (515) when RCS pressure has decreased below RHR system design pressure.
c.
Three check valves in series, d.
Two check valves in series, provided that both may be period-ically checked for leak tightness and are checked at least annually.
1
2.2 Emergency Core Cooling System.
Isolation requirements for ECCS are contained in SRP 6.3.
Isolation of ECCS to prevent overpressurization must meet one of the follwing features:
One or nore check valves in series with a normally-closed motor-1.
operated valve (MOV) which is to be opened upon receipt of a SIS when RCS pressure is less than the ECCS design pressure.
2.
Three check valves in series.'
Two check valves in series, provided that both may be periodically 3.
checked for leak tightness and are checked at least annually.
All other kow pressure systems interfacing with 2.3 Other Systems.
the RCS must meet the following isolation requirements from BTP EICSB-3:
At least two valves in series nust be provided to isolate the 1.
system when RCS pressure is above the system design pressure and valve position should be provided in the control room.
For systems with two M0Vs, each M0V should have independent and 2.
diverse interlocks to prevent opening until RCS pressure is below the system design pressure and should automatically close when RCS pressure increases above system design pressure.
For systems with one check valve and a MOV, the M0V should be 3.
interlocked to prevent opening if RCS pressure is above system design pressure and should automatically close whenever RCS pressure exceeds system design pressure.
3.0 DISCUSSION AND EVALUATION There are two systems at Big Rock Point, with direct interface to the RCS pressure boundary, which have a design pressure rating for all or part These systems of the system which is lower than the RCS design pressure.
are the Shutdown Cooling System (SOCS) and Core Spray (CS) system.
3.1 Shutdown Cooling System.
The SDCS system takes suction from the RCS, cools the water by circulation through the SOCS heat exchangers, and returns the water to the RCS via the recirc ling. The suction side of the Isolation on the dis-system has two motor-operated isolation valves.The MOVs cannot open if pressure in charge side is provided by two MOVs.
They will automatically the RCS is higher than the SDCS design pressure.
clos room.3 "However, the interlocks for these valves are not diverse, sincg only one interlock contact and one pressure measuring system are used.
Isolation provisions of the 50CS do not meet the current licensing criteria since the interlocks for the isolation valves are not diverse as required by BTP RSB-5-1.
2 i
i
the reactor vessel through two MOVs and a chec< valve per line.gs su 3.2 Core Spray System. The CS system colsists of two lin Each MOV has position indicated in the control room. Tae.MOVs will open upon a CS system initiation signal when RCS pressure has decreased below 200 psig; CS system design pressure is 150 psig. The MOVs will not automatically close upon clearing the initiation signal or on increasing RCS pressure above CS system design pressure. No interlocks exist to prevent opening of the CS system MOVs from the local control station when RCS pressure exceeds CS system design pressure.
The CS system does not meet the isolation criteria of current licensing requirements since no interlocks exist to prevent opening of isolation valves from the local cnntrol station when RCS pressure exceeds CS system design pressure.
4.0
SUMMARY
Big Rock Point has two systems with lower design pressure ratings than the RCS which are directly connected to the RCS. The SDCS and CS systems do not meet current licensing criteria contained in SRP 6.3 and BTP RSB-5-1 for isolation of high and low pressure systens as listed below.
1.
The SDCS isolation valves do not have diverse interlocks to prevent operation when RCS pressure exceeds SOCS design pressure.
2.
The CS system has no interlocks to prevent opening the isolation valves from the local control station when RCS pressure exceeds CS system design pressure.
5.0 REFERENCES
1.
NUREG-75/087, Branch Technical Positions EICSB-3, RSB-5-1; Standard Rev iew Pl an 6. 3.
2.
Big Rock Point Piping and Instrumentation Drawing M-107, Rev. Q.
3.
Big Rock Point Electrical Drawing E-112, Sheet 1, Rev. M.
4.
Letter, Consumers Power (Vincent) to NRR (Crutchfield), dated November 12, 1981.
5.
Big Rock Point Piping and Instrumentation Drawing M-123, Rev. AG.
3
'GCI OSRIEN SYSTEMATIC EVALUATION PROGRAM TOPICS V-ll.A AND V-ll.B BIG ROCK POINT TOPICS:
V-ll.A, REQUIREMENTS FOR ISOLATION OF HIGH AND LOW PRESSURE SYSTEMS V-ll.B, RHR INTERLOCK REQUIREMENTS 1.
INTRODUCTION Several systems that have a relatively low design pressure are connected to the reactor coolant pressure boundary.
The valves that form the interface between the high and low pressure systems must have sufficient redundancy and interlocks to assure that the low pressure systems are not subjected to coolant pr essures that exceed design limits.
The problem, is complicated since under certain operating modes (e.g., shutdown cooling and ECCS injection) these valves must open to assure adequate reactor safety.
II.
REVIEW CRITERIA The review criteria are presented in Section 2 of EG&G Report EGG-EA-5931,
" Electrical Instrumentation and Control Features for Isolation of High and Low Pressure Systems."
111. RELATED SAFETY TOPICS AND INTERFAC_E_S_S The scope of review for this topic was limited to avoid duplication of ef fort since some aspects of the review were perfomed under related topics.
The related topics and the subject matter are identified below.
Each of the related topic reports contain the criteria and review guidance for its subject matter.
V-10.B RHR Reliability VI-4 Containment Isolation Vill-1.A Degraded Grid Voltage IV.
REVIEW GUIDELINES The review guidelines are presented in Section 7.3 of the Standard Review Pl an.
l V.
EVALUATION As noted in EG&G Report EGG-EA-5931, Big Rock Point has two systems with lower design pressure ratings than the RCS which are directly connected to the RCS.
The SDCS* and Core Spray (CS) systems do not meet current r
/r f
~* The RHR f unction for the Big Rock Point Plant is accomplished by j
l the Shutdown Cooling System (SDCS).
~
1
o
, licensing criteria contained in SRP 6.3 and BTP RSB 5-1 for isolation of high and low pressure systems as listed below:
1.
The SDCS isolation valves do,not have diverse and independent interlocks to prevent operation when RCS pressure exceeds SDCS design pressure.
However, redundant pressure switches (two in series) and relays (two in parallel) are provided.
Relay contacts are segregated with one relay controlling the inboard valves and the other the outboard valves. Because the relays share a common power supply, they are not independent and could, theoretically, be damaged by an overvoltage or underfrequency transient.
SEP Topic VIII-1. A examined such transients and found that suitable protec-tion was provided at this plant. The system is designed to close the valves on high pressure (either switch opens) or loss of instrument power.
All four valves are powered from the same bus.
Power is locked out during power operations.
Should the valve power fail during SDCS operation the only source of pressure available is decay heat.
The pressure buildup could be controlled by the use of the pressure relief system and the core spray system if the valves could not be closed manually in sufficient
- time, Topics V-10-B, "RHR Reliability" and VII-3, " Systems Required for Safe Shutdown" also have examined the subject of RHR Interlocks and found them to be acceptable.
2.
The CS systen has no interlocks to prevent opening the isolation valves from the local control station when RCS pressure exceeds CS system design pressure.
A check valve is provided between the two motor operated valves in each train that is tested monthly.
One could argue that the failure of this check valve and the manipulation of the local control station constitute two independent single failures and as such find that the present design satisfies the single failure criterion. This, however, is not true under accident conditions when valve action is desired and there are no suitable provisions to augment administrative controls over the operator's actions.
In this event, a check valve failure alone may result in a loss of the low pressure system.
VI. CONCLUSIONS Because of the severe consequences of a LOCA outside of containment the staff proposes that control of the CS valves should be modified to satisfy the interlock provisions of SRP Section 6.3 and BTP RSB 5-1.
The staff does not recommend modification of the SDCS because the present design satisfies the single failure criterion and further modifications to provide diversity or redundancy will not provide a significant improve-ment in the protection of the public health and safety.