ML20079F292
ML20079F292 | |
Person / Time | |
---|---|
Site: | Robinson ![]() |
Issue date: | 03/31/1982 |
From: | Kaucher J, Stone J FRANKLIN INSTITUTE |
To: | Calvo J NRC |
Shared Package | |
ML14184A527 | List: |
References | |
CON-NRC-03-79-118, CON-NRC-3-79-118 TER-C-5257-184, TER-C5257-184, NUDOCS 8204020263 | |
Download: ML20079F292 (16) | |
Text
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ENCLOSURE 4 t
4
[ TECHNICAL EVALUATION REPORT
[ :
l OVERRIDE AND RESET OF CONTROL CIRCUlTRY IN THE VENTILATION / PURGE l ISOLATION AND OTHER ENGINEERED SAFETY FEATURE SYSTEMS d CAROLINA POWER AND LIGHT COMPANY
@ H. B, ROBINSON UNIT 2
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g; y) NRC DOCKETNO. 50-261 FRC PROJECT C5257
'.," NRC TAC NO. 08994 FRC ASSIGNMENT 7 4e NRC CONTRACT NO. NRC-03-79-118
~ FRC TASK 134
&K-x Preparedby
- D 1 Frankliri Research Center Author: J. E. Kaucher ij 20th and Race Street
- Philadelphia, PA 19103 FRC Group Leader: J. Stone h Prepared for c) Nuclear Regulatory Commission Washington, D.C. 20555 Lead NRC Engineer: J. calvo a
March 31, 1982 W 'This report was prepared as an account of worx sponsored by an agency of the United States Government. Neither'the United States
( Government nor any agency thereof, or any of their employees, 2d makes any warranty, expressed or implied, or assumes any legal
} liability or responsibility for any third party's use, or the results of I},t
- such use, of any information, apparatus, product or process id disclosed in this report, or represents that its use by such third
}l} party would not infringe privately owned rights.
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>p This report documents the technical evaluation of the design of electri-cal, instrumentation, and control systems provided in H. B. Robinson, Unit 2
$ to initiate automatic closure of valves to isolate the containment. The ft
% cvaluation was conducted in accordance with NRC criteria, based on IEEE Std A
279-1971, for a'ssuring that containment isolation and other engineered safety
@4 features will not be compromised by manual overriding and resetting of the r .' cafety actuation signals. It was concluded that the electrical, instru-W N
w mentation, and control systems in H. B. Robinson, Unit 2 partially conform If with the NRC criteria. .
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FORENORD
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y76 This Technical Evalua' tion Repor . was prepared by Franklin Research Center tyg under a contract with the U.S. Nuclear Regulatory Commission (Office of 3.,y Nuclear Reactor Regulation, Division of Operating Reactors) for technical f,%
t assistance in support of NRC operating reactor licensing actions. The e~5 7,
b technical evaluation was conducted in accordance with criteria established by
.% the NRC.
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. .q 42 9 Mr. J. E. Kaucher contributed to the technical preparation of this report e/4 through a subcontract with WEST".C Services, Inc.
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fv CONTENTS
'If Section Title Page a
's 1 INTRODUCTION . . . . . . . . . . . . 1 g
(% 2 REVIEW CRITERIA. . . . . . . . . . . . 2 E
] 3 TECHNICAL EVALUATION . . . . . . . . . . 4 r.3 M 3.1 Description of Containment Ventilation System Design . 4 p 3.1.1 Generalized System Design . . . . . . 4 g 3.1.2 Logic Circuits for Reset, Seal-in, and Trip. . 4 M:$s I
3.1.3 Individual valve Control Circuits . . . . 5 3 3.2 Evaluation of Containment Ventilation System Design . 5 Jr
.' 1 3.3 Other Engineered Safety Feature System Circuits . 6 f
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- p 3.3.1 Description of Containment Spray System
- l.y Design . . . . . . . . . . . 6 2 3.3.2 Evaluation of Other ESF Systems Design . . . 6 9
3.3.2.1 Containment Spray Sys. tem . . . . 6 m
,;] 3.3.2.2 Other ESF Systems . . . . . . 7 4 CONCLUSIONS . .
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. . . . . . . . . . 8 ig 5 RErEREuCES . . . . . . . . . . . . . 9 y .
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.'O-LIST OF FIGURES i v
g No. Title Page N
'M 1 Containment Ventilation Isolation Control Scheme . . . 10 hu 2 Containment Spray System Control Logic . . . . . . 11
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- 1. INTRODUCTION '
- f g Several instances have been c'eported at nucicar power plants where h automatic closure of de containment ventilation / purge valves would not have h, occurred because the. safety actuation signals were either overridden or blocked during normal plant operations. These events resulted from procedural inadequacies, design deficiencies, and lack of proper management controls.
6 w These events also brought into question the mechanical operability of the jQ~
containment isolation valves themselves. These events were determined by the
[j U.S. Nuclear Regulatory Commission (NRC) to be Abnormal Occurrences (#78-5) h y and were, accordingly, reported t.o the U.S. Congress.
As a followup to these Abnormal Occurrences, the NRC staff is reviewin'g h[$
q the electrical override aspects and the mechanical operability aspects of
- .4 h containment purging for all operating power reactors. On November 28, 1978, the NRC issued a letter entitled " Containment Purging During Normal Plant y Operation" [1]* to all boiling water reactor (BWR) and pressurized water
- h reactor (PWR) licensees. In a letter dated January 19, 1979 (2], the Carolina
-b et Power and Light Company (CPL), the Licensee for H. B. Robinson, Unit 2, replied h.e j to the generic letter. Additional information was provided by the Licensee in v.C d, a letter dated May 1, 1979 (3]. On March 21, 1980 [4], the NRC request;ed that v.y W
r/t the Licensee provide further information concerning electrical bypass and
$; reset of engineered safety feature - (ESF) signals for H. B. Robinson, Unit 2.
3; Subsequently, on October 7, 1980 [5], CPL submitted information in response to Reference 4. On April _16, 1981 (6], CPL provided clarification of several hh items involved with bypass and reset features of engineered safety feature systems. Finally, on February 8,1982 [7], CPL provided information on a cesign change which was implemented to meet the NRC staff criteria.
h, l This document addresses only the electrical, instrumentation, and' control h[
s design aspects of the containment ventilation isolation (CVI) and other '
d n engineered safety features.
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.g 2. REVIEW CRITERIA
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'Y The primary intent of this evaluation is to determine if the following k NRC staff criteria are met for the safety signals to all ESF equipment:
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jj o Criterion 1. In keeping with the requirements of General Design
$) Criteria (GDC) 55 and 56, the overriding
- of one type of safety 96 actuation signal (b.g. , radiation) should not cause the blocking of jZ any other type of safety actuation signal (e.g. , pressure) for those
._ y valves that have no function besides containment isolation.
o Criterion 2. Sufficient physical features (e.g., kay lock switches) r1 are to be provided to facilitate adequate administrative controls.
?f o Criterion 3. A system-level annunciation of the overridden status
.1[% should be provided for every safety system impacted when any override j) is active. (See NRC Regulatory Guide 1.47.)
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Incidental to this review, the following additional NRC staff design
[4 criteria were used in the evaluations e..
?A o Criterion 4. Diverse signals should be provided to, initiate isolation
_v of the containment ventilation system. Specifically, containment high j radiation, safety injection actuation, and containment high pressure '
dl (where containment high pressure is not a portion of safety injection 09
-m actuation) should automatically initiate CVI.
J o criterion 5. The instrumentation and control systems provided to V
initiate the ESF should be designed and qualified as safety-grade equipment.
6: o Criterien 6 J
The overriding or resetting + of the ESF actuation signal should not cause any valve or damper to change position.
g x In this review, Criterion 6 applies primarily to other related ESF h.i systems, because implementation of this criterion for containment isolation
- .3 has been reviewed by the Lessons Learned Task Force, based on the recommen-qq dations in NUREG-0578, Section 2.1.4. Automatic valve repositioning f.-
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, perform a function contrary to the signal.
o 9 +Rese t: the signal has come and gone, and the circuit is being cleared in
'. crder to return it to the normal condition.
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TER-C52 57-184 upon reset may be acceptable when containment isolation is not involved. The acceptaoility of repositioning upon reset will be determined on a case-by-case basis. Acceptability will be dependent upon system function, design intent, pg and suitable operating procedures.
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- 3. T"CHNICAL EVALUATION 1
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3.1 DESCRIPTION
OF CONTAINMENT VENTILATION SYSTEM DESIGN G
s ,g 3.1.1 Generalized System Design jlq The Licensee has indicated that the circuitry for H. B. Robinson, Unit 2 y was designed as engineered safety features equipment; however, informatior. on d
Q the design and qualification standards used was not available. A review of (p the initiation logic and wiring diagrams has confirmed that no credible single malfunction will prevent proper protective action at the system level when fy required.
W t e.1 Q 3.1.2 Logic Circuits for Reset, Seal-in, and Trip v
The CVI system consists of the containment ventilation purge valves as well as the containment ventilation pressure and vacuum relief val.ves. The 2 ~
isolation signals for each train are:
- 1. Automatic Isolation Signals w a. Safety Injection Actuation (1 of 1)
- b. Containment Radiation Monitoring System (1 of 2)
- 2. Manual Signals
, a. Containment Isolation Phase A
- b. Containment Isolation Phase B
- c. Containment Spray Actuation
- s y Trip relays associated with the various isolation signals operate con-q tacts (arranged in series-parallel configuration, Figure 1) to provide power
.. to one slave relay (Vl/V2) in each train. When the level of an isolation m
2] signal exceeds its setpoint, power is supplied to the slave relays via the 4 trip logic network. The slave relays are energized and mechanically latched
( in, opening contacts in the individual valve control t circuits and reposi-t tioning the valves. Slave relays can be deenergi' zed following a trip signal j only after all signals are cleared and the reset switch b manully positioned.
g During normal operation, the slave relays are deenergiz'ed (unlatched) , with i
their associated contacts closed, allowing the ,CVI valves'to be opened.
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... 3.1.3 Individual Valve Control Circuits
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TA The containment ventilation purge, vacuum relief, and pressure relief i
valve control circuits receive isolation signals from the output of the trip y logic network. Consequently, the pilot solenoids for these valves may be
[4 energized only when all trip signals are cleared (the same condition required
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$ The control circuit for each pressure and vacuum relief valve includes a
'T three-position (close-auto-open), epring-return-to-auto, control switch.
P y There are two sets of switch contacts (open and close) in each valve control u; gq circuit. The opening contacts are closed only when the switch is in the open W position and provide momentary power to a seal-in relay which in turn closes lVi ih contacts in series with the valve solenoid, causing the valve to open. The closing. contacts are in series with the valve solenoid and ,open when the switch is placed in the closed position, thus causing the valve solenoid and Ch seal-in relay to deenergize. y
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The control circuit for the purge valves are structured such that the
, purge valve pilot solenoids are in series with slave relay contacts from the 0[ trip logic network and permissive contacts from the purge fan control circuits.
u 3.2 EVALUATION OF CONTAINMENT VENTILATIC'I SYSTDi DESIGN The containment ventilation isolation (CVI) control system contains no isolation parameter bypasses or overrides; therefore, Criteria 1 2, and 3 do i not apply. ..1 The CVI system is initiated by safety injection actuation and containment w
!'N Al high radiation; therefore, the diversity requirement of Criterion 4 is Vf satisfied at H. B. Robinson, Unit 2.
b +; The Licensee has indicated that the CVI system was designed and procured as safety-grade, meeting the safety standards applicable at that timer
- 7 therefore, Criterion 5 is satisfied for the purpose of this review, with the
; exception of the radiation monitoring system. The radiation monitoring system ,] was not designed as part of the ESF system and is' not safety-grade. I L
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- b. The overriding or resetting of any actuation signal will not cause any 9 .
l'{ valve or damper to change position. This is accomplished by the use of seal-in
.{1 a relays and contacts at the equipment level. Therefore, it is concluded that NRC staff Criterion 6 is satisfied in the CVI system at H. B. Robinson, Unit 2. &q r:, @ 3.3 OTHER ENGINEERED SAFETY FEATURE SYSTDi CIRCUITS
.Y a Q;,e
'Ib provide a complete evaluation of the ESF system circuits, a general JR. review of all ESF system circuits and an in-depth review of the circuit for the containment spray (CS) system was conducted. .' 8 .
yp 3.3.1 Description of Containment Spray System Design
- .y Initiation signals, Phase A and Phase B, are provided for all containment spray ESF equipment on each of two separate electrical trains, A and B. Each
- ;c f" train consists of automatic and manual inputs processed through relay logic
- $' circuitry to actuate a relayed logic component actuation system. The initia-tion signals 'for each electrical train are arranged to provide automatic ini-tiation upon receipt of 2 of 3 (taken twice) containment high pressure signals.
. g., The containment high pressure signals activate slave relays (ASl/AS2), which e
in turn close contacts in the initiation logic circuit (Figure 2) . The logic y' section contains mechanisms for automatic and manual activation and reset of 3.' e slave relays (S1/S2) which operate contacts to energize the automatic spray initiation relays (S10X/S20X) (Figure 2) . A containment spray initiation , / signal is locked in by mechanically latching the Sl/S2 relays.
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Individual pump and valve control circuits have both manual and automatic p control schemes for start-stop or open-close as well as an indication for run y status or position. Wd f;{ 3.3.2 Evaluation of Other ESP Systems Design W , 3.3.2.1 Containment Spray System 3, jj The containment spray system contains no isolation parameter. bypasses or n @ override; therefore, Criteria 1, 2, and 3 do not apply. A 6 k x M -g M 0 0 Franklin Research Center A omas.an or m n n.en monu
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A,i. Ik1 * (1:f ,w . k i, TER-C5257-184 34 . M tj Criterion 4 does not apply to ESF systems other than CVI. p lj{] The Licensee has indicated that the CVI system was designed and procured iM as safety-grade, meeting the safety standards applicable at that time; St L., therefore, Criterion 5 is satisfied for the purposes of the review. The overriding or resetting of any actuation signal will not cause any IM., valve or damper to change position. Therefore, NRC Criterion 6 is satisfied l [j in the CS system at H. B. Robinson, Unit 2. n W
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3.3.2.2 Other ESF Systems
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'm An audit of other ESF valve control circuits indicated that equipment M ] level. bypasses are provided for at least three valves (V-739, excess letdown heat exchanger outlet isolation valve; V-1786 and V-1721, waste disposal T
Q:s u system containment isolaton valves) which, if actuated following one safety ht actuation signal, will block a second safety actuation signal (or will block an w.
".f; initiating signal if actuated prior to receipt of the signal),. thus preventing . ;c?
m the equipment from performing its protective action." This equipment, however, n 3 serves functions other than containment isolation and is provided with valve H position indication. y
.~ ,'.; Although not a literal violation of Criterion 1, this situation has been
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?J & identified for NRC staff evaluation with respect to acceptability. At least d one valve (V-739) will change position upon resetting of an ESF actuation ;c $ signal and consequently does not ' satisfy Criterion 6.
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- 4. CONCLUSIONS Q
-1 The electrical, instrumentation, and control dasign aspects of ESF systems tur H. B. Robinson, Unit 2 were evaluated using staff design criteria. , .s . ji. It is concluded that the CVI circuit design satisfies the NRC staff m
34j
.T; criteria for containment ventilation and purging operation with the exception
[] of the radiation monitors,iwhich are not safety grade. Final determination on
.'..d p the acceptability of these detectors will be made by the NRC.
jf Other ESF System Circuits
.g 12
- 1. CS System r;.
; The CS system circuit design at H. B. Ibbinson, Unit 2 satisfies the NRC h staff criteria for containment ventilation and purging operation.
- 2. Other ESF Sysrems t.(
,y In the case of the valves identifed in Section 2.4.2.2, it is recommended .J-that:
- a. The Licensee conduct a complete review of ESF valve control circuits I
- s to identify all possible violations of Criteria 1, 2, and 3.
'M ? b. The Licensee conduct a complete review of ESF valve control circuits to determine their compliance with Criterion 6 and modify those circuits that do not comply with the criterion.
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.+ TER-C52 57-184 ,o ihl .3 5. REFERENCES M
h, 1. NRC, Letter to all BWR and PWR licensees. 4
Subject:
Containment Purging During Normal Plant Operation
.[, 28-Nov-78 .D g 2. E. E. Utley (CPL)
L1 Letter to A. Schwencer (NRC)
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Subject:
Containment Purging During Normal Plant Operations
'.1 .v:
Carolina Power and Light Company, 19-Jan-79 m
,j; 3. E. E. Utley (CPL) g Letter to A. Schwencer (NRC) f
Subject:
Containment Purging During Normal Plant Operations Ih'" n Carolina Power and Light Company, 01-May-79 M 4. , A. Schwencer (NRC) 14 h Letta: to E. E. Utley (CPL)
Subject:
Request for Additional Information -
/jdj Bypass and Reset of ESF Features fj,] NRC, 21-March ....
h;; 5. E. E. Utley (CPL)
}.? Letter to A. Schwencer (NRC) ~
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Subject:
Bypass and Reset of ESF Features i.C
.:. 9 Carolina Power and Light Company, 07-Oct-80 v
- 6. E. E. Utley (CPL)
Letter to S. A. Varga (NRC) J':,
Subject:
Additional Information for Bypass and Reset of ESF Features
.'$ Carolina Power and Light Company, 16-April-81 4.n a; 7. S. R. Zimmerman (CPL) .
7d Letter to S. A. Varga (NRC) - [-
Subject:
Engineered Safety Features Override f
& Carolina Power and Light Company, 8-Feb-82 y
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