ML19308B718
| ML19308B718 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 04/12/1974 |
| From: | US ATOMIC ENERGY COMMISSION (AEC) |
| To: | |
| Shared Package | |
| ML19308B699 | List: |
| References | |
| TASK-TF, TASK-TMR REGGD-01.XXX, REGGD-1.XXX, NUDOCS 8001160786 | |
| Download: ML19308B718 (13) | |
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'4/12/74 AU REGULATORY GUIDE 1.XX INSTRUMENTATION FOR LIGHT-WATER-COOLED NUCLEAR POWER PL*CCS TO ASSESS CONDITIONS
.DURING AND FOLLOWING A' ACCIDE'E A.
INTRODUCTION
.s Criterion 13, " Instrumentation and Control" of Appendix A " General Design Criteria for Nuclear Power Plants," to 10 CFR Part 50, " Licensing of Production and Utilization Facilities," includes a=ong its require-ments that instru=entatio'n be provided to conitor variables and systems for accid'ent conditions as appropriate to assure adequate" safety This-guide describes a =ethod acceptable to the Regulatory staff for cocplying with the Co==ission's requirements to provide instrumentation to monitor b!
plant variables and systems dtiring and following an accident in a light-water-cooled nuclear power plant.
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B.
DISCUSSION Monitored variables and systems are to be used by the operator in accident' surveillance (1) to help determine, the nature of an accident, (2) to help predict the course an accident will take, (3) to assure that the reactor trip and engineered safety feature systers are functioning proparly, (4) to determine if the plant is responding properly to the safety ceasures in operation, (5) to allow for early initiation of protective Chapter 15, " Accident Analysis," of Re:;ulatory Guide 1.70, " Standard Format and Centent of Safety Analysis Reports for Nuclear Pouer Plants" provides representative types of events which should be considered.
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action for public safety (if necessary), and (6) to furnish data needed to take manual action in the event that (a) an engineered safety feature malfunctions, (b) unanticipated conditions require operator intervention, or (c) the plant equipment i's not responding effectively to the safety r
systems in operation.
At the start of an accident, the operator cannot always immediately determine what accident has or is occurring and therefore cannot determine the appropriate response.
yer this reason, the reactor trip and certain engineered safety features e.g., emergency core cooling (ECC) actuation, ECC injection valve opening, containment isolation, automatic depressuri-zation, are performed automatically during the initial stages of an accident.
After the initial period, however, positive actions by the operator may be required to assist in placing and maintaining the plant in a stabiliced condition.
The quantity and quality of the information provided establish the operator's ability to interpret the accident, to determine the status of safety systems, and to evaluate the manner in which the plant is responding to safety measures.
Insufficient information-would limit his ability to evaluate the status of the systems and might lead him to the wrong conclusion, causing him to take action that would not improve the situation or preventing him from taking action that would improve the situation.
The selection of instrumentation to monitor l
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. variables and systems for accident conditions should be predicated on the type and sequences of accidents that are postulated to occur during the lifetime of a plant.
s.
To. identify which monitoring instrumentation should be installed, a study was made of a range of postulated accidents to determine the important variables and systems whose values or status should be displayed to the operator.
The study concluded that several vital conditions are principally important to.he integrity of the power plant:
the operating status of the reactor (e.g., at power or shutdown), the operating status of core cooling systems, the operating status of contain=ent cooling systems, containment conditions, the status of containment isolation, primary pressure system conditions, and the status of heat transfer paths from the core to a heat sink.
The containing of radioactive fuel element materia'. relies heavily on ability to maintain core geometry and fuel cladding integrity.
Instru=entation to detect fuel element melting or cladding failure would be a pri=ary concern in establishing plant variables to monitor.
The principal considerations in determining which variables a.td systems to monitor should be that:,
The display of variables and systems status provides sufficient s.
i information to indicate, una=biguously, the status of fuel element i
2/
- Battelle-Columbus Laboratories report " Monitoring Postaccident Conditions in Power Reactors," EMI-X-647 dated April 9,1973.
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integrity and other power plant vital conditions and to be used by the operator to obtain infor=ation needed for performing a required action.
C b.
The display of variables and systems status provides early recognition of abnormal conditir.ns and enhance differentiation of typss of accidents or transients.
The display of variab;.es and system status signals when an accident c.
condition has departed from expected sequences, providing a warning that extraordinary actions are needed.
The instrumentation used to assess accident conditions should be highly reliable.
The range, response, and accuracy provided by these instruments must be adequate to encompass the entire duration of an event, including when conditions may be extreme.
For example, pressure transducers ranging from subatmospheric to some margin over the vessel design pressure and with response times of 'the order of one second should be provided for pressure vessel measurement.
In order to provide adequate sensitivity in measuring a parameter it may be necessary to provide two or more instru=ents with overlapping ranges.
Since a degree of uncertainty is associated with a variable, the highest and lowest valuc51n the instrumentation range should bound predicted parameter values.
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'Each vital parameter should be recorded.
The operator =ay require trend infor=ation in the form of analce strip charts to i= prove his ability to ascertain plant conditions and to help determine required s -
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operator response.
Additionallf, the analog record form provides a
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diagnostic tool'for post accident. analysis.
It may also be necessary to use high-speed recording equipment that is capable of continuously tracking essential plant, variables during the course of a severe system transient to aid the operators understanding of plant conditions.
The method of display and the location of indicators have a major effect on the nu=ber of variables that can be successfully =onitored by an operator.
Two logical locations for the indicators of the principal plant variables are considered.
One option would be to place the indicators with the indicators of related systers.
For example, if a principal variable is emergency core cooling (ECC) flow, the indicator would be placed on the engineered safety features panel for ECC.
If an anomaly were observed in ECC flow, the operator would turn his attention to the other instrumentation on this panel.
l Another option would be to group together the indicators of the i
I principal plant variables.
This grouping would make it easy for the l
. operator to monitor all principal variables and would tend to focus his l
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attention en'these i=portant parameters.
This instrumentation could bc duplicated in the two locations, as is presently done uith soce indicators in the control room.
O'ther options may be considered, but all displays should be organised so as to si=plify the operator's surveillance, interpretation, and his response determination following an accident signal.
An indicator =onitored. during an acciden't should.tne the same one used in normal operation of the plant, since the operator vould be more familiar with it.
C.
REGUI.ATORY POSITION 1.
Instrumentation used to monitor accidents should be physically located tb give the operator the information necessary to determine the type of accident, to help predict the course an accident vill take, to
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determine the status of safety systems, to evaluate the manner in Ohich the plant is responding to safety measures, to provide the
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information required for possible operator action, and to track an accident until the plant has been brought to a stabilized safe condition and can be maintained in that ecadition.
During and following an accident, conitoring instrunantation should provide surveillance concerning the status of the plant uith respect to reactor power level and reactor shutdown, fuel ele =ent integrity, ccre ecoling, cen'tain=ent cooling, centainment isolation, beat transfer paths frem the core to a heat sink, pricary pressu e system integrity, and containment integrity.
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Tha applicant should deter =ine tha paramaters to be measured and tha instru=entation range, responsa, and accuracy required for post accident monitoring by perfor=ing detailed safcty analyses using guidelines set-forth in References 1 and 2.
Consideration should be given to the following paraceters:
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i A.
Operating Status of the Reactor
- a. Reactor pcver level
- b. Positions of control rods
,c.
Positions of i=pertant valves, i.e., valves. in piping containing high energy fluid B.
Status of Fuel Element Inte5rity Radiation level in vicinity of coolant recirculatica syste:
a.
b.
Radiation level in =ain steam lines (BWR)
Radiation level at c:ndenser air ejector exhaust c.
d.
Radiation level in contain=ent at=csphere (ga==a and neutron-)
C.
Status of Prir.ary Pressure Syste=
Pressure of reactor coolant system a.
b.
Pressure in stea= c_nerator (secondary) (P".iR)
Te=;erature of reac'.cr coolant c.
- d..Te=peratures of area at= sphere in the vicinity of vital equip-
=ent (e.g., =ain stes= lines, auxiliary fe'edvater pumps) e.
Rese cr pover level f.
Flov rate of react:r c:olant g.
Flev rate in main s ea=line b.
Level of coolant in resctor vessel (BUR)
L.
Pressurizer vater level (77 4) m l
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Water level in stet.m generator (53) k.
Positions of i=portant-valves (as,a mini =um, valves in piping.
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containing high energy f_.uid, pri=ary relier/ safety valves, 53 secondary system valves (isolation _and vent), and valves in lines of the ultimate heat sink) g' 1.
Pump operation, speed shere applicable,. (as a minimum, reactor
. coolant pu=rs, inter =ediate heat re= oval system pumps)
Boron concentration in primary coolant (&3) m.
n.
Radiation level in vicinity of coolant recirculation system o.
Radiation level at condenser air ejector exhaust p.
Radiation level in main steam lines (B'4R) q.
Status of =ain and auxiliary power supplies (a.c. and d.c.)
r.
Status of attto=atic actuation devices - initiated or uninitiated D.
Operating Status of Core Cooling System a.
Pressure of reactor coclant system b.
Pressure in contain=ent (53)
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c.
Pressure.in dryvell'and vetvell (53) d.
Pressure in accumulator or safety injection tank (M3) e.
Pressure in steam generator (secondary) (&*R) f.
Sump flow conditicns, i.e., pressure differential at intake (&S) g.
Temperature of reactor coolant l
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Temperature in containment (&B)
- i.. Temperature in dryvell and etvell (53)
J.
Temperature of coolant in containment su=p or suppression pool k.
Te=peratur.es of area st=:schere ir. the vicinity of vital equip-ment (e.g., rain stea= lines, auxiliary feedvater pu=ps)
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Plow in all ECC injection lines and auxiliary feedvater lines Level of coolant-in reactor vessel- (53) m.
Invel in accu =ulater or safety injection tank (33) n.
o.
Level of coolant in contain=ent su=p or suppression pool p.
Level in ehergency cooling vater storage tank s
q.
Pressuricer water level (&3) r.
Positions of i=portant valves (as a =inimu=, valves in piping containing high energy fluid, valves in ECCS suction lines, PWR seconda:y syste=
(isolation and vent), prirary relief / safety valves, and valves in lines of the ulti=2te heat sink) s.
Pu=p operation, speed where applicable (as a mini =um, reactor coolant pu=ps, ECCS and auxiliary feedvater pu=ps, intermediate heatre=ovalsyste=pu=ps) t.
Operating stctus of contain=ent heat ra= oval system (e.g., air cooler operation, flow rate, in/out te=perature, fan operation; spray pu=p operation, flow rate)
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Status of contain= erit vent syste=
v.
Status of autc=atic actuation aevices - initiated or uninitiated v.
Status of =ain and auxiliary power supplies (a. c. and d. c. ).
x.
Status of heat tra2sfer pat'n frc= core to ultimate heat sink E.
Status of Contain=ent Isolation and Centain=ent Conditions a.
Pressure in centain=ent (%'R) b.
Pressure in dryvell and vetvell (53) c.
Te=perature in centain=ent (53) d.
Te=perature in dryvell and. etvell (53)
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Tanperatura of crea atmoshperc in tha vicinity of vital equip-ment (e.g., =ain steam lines, auxiliary feedvater pumps) f.
Flow in all ECC injection lines, contain=ent cooling loops and auxiliary feedvater lines g.
Positions of'important valves (as a minimum, valves in piping con-taining high energy fluid, contain=ent isolation valves, vacuum
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s breakers, valves in ECCS suction lines, containment cooling system and injection lines valves, primary relief / safety valves, PWR sec-ondary system (isolation and vent), and valves in ulti= ate heat sink lines) h.
Pump operation, speed vhere applicable (as a minimum, reactor coolant l
pumps, ECCS and auxiliary feedvater pu=ps, containment cooling system i
j pumps, intermediate heat removal system pu=ps) 1.
Hydrogen concentration at top of contain=ent J.
Radiation level in containment atmosphere (ga==a and neutron) k.
Radiation levels in area of the reactor, turbine, and auxiliary buildings 1.
Radiation ~ levels offsite m.
Status of centain=ent vent system l
n.
Operating status of contain=ent heat removal system (e.g., air cooler
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pump operation,' fl
- rate, in/out temperature, fan operation; l
spray pu=p operation, flow rate) o.
Status of hydrogen reconbiner system (e.g., gas flev, coil temperature) (PWR)
- p. ~ Status of che=ical addition to spray vater for iodine removal,(PER) q.
Status of =ain and auxiliary power supplies (a.c. and d.c. )
r.
Status of auto =atic actuation devices - initiated or uninitiated s.
Status of heat transfer path frc= core to ulti= ate heat sink e
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F.
Operating Status of Contai=ent Cooling System a.
Pressune in centain=ent (53) b.
Pressure in dryvell and vetvell (53) c.
Te=perature in contain=ent (33) d.
Te=perature of coolant in contai=ent su. p or suppression pool e.
Te=perature in dryvell.and vetvell (Ek'R) f.
Te=peratures of area atmosphere in the vicinity of vital equip-ment (e.g., =ain stea= lines, auxiliary feedvater pu=ps) g.
Flow in all contain=ent cooling leops and auxiliary feedvater lines
- h. ' Level of coolant in contain=ent su=p or suppression pool 1.
Invel in e=ergency cooling vater storage tank J.
Positions of i=portant valves (as a =ini=u=, contain=ent isolation valves, vacuum breakers, contain=ent cooling syste= and injection lines valves, valves in lines of the ultimate heat sink)
Pu=p operation, speeds where applicable (as a =ini=u=, contain=ent cooling syste= pu=ps) 1.
Opereting status of contain=ent heat re= oval syste=
(e.g., air cooler operation ~, flow rate, in/out te=perature, fan operation; spray pt p operation, flow rate) m.
Status of contain=ent vent syste=
n.
Status of che=ical addition to spray water for iodine removal (Pk3) o.
Status of =nin and auxiliary power supplies (a.c. and d.c.)
p.
Status of autc=2 tic actuation devices - initiated or uninitiated q.
Status of heat transfer path from core to uli.imate heat sink G.
Status of Heat Transfer Paths to Ulti= ate Heat Sink a.
Positions of i=;ortant valves in lines of the ultimate heat sink l
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b.
Radiaticn icvals offsit2 (racoiving water bodies) c.
Status of main and auxiliary power supplies (a. c. and d. c. )
d.
Status of eutematic actuation devices - initiated or uninitiated i
e 3.
The accident monitoring system should be designed with redundant channels such that the loss of a single monitoring channel should not prevent the operator from determining the nature of an accident, the functioning of the engineered safety features, or the need for operator action and,the response of the plant to, the safety measures in operation.
In lieu of redundancy, diverse channels (e. g., saturated pressure, saturated temperature) or several channels measuring the spatial distribution of a parameter (e.g., containment tecperature distribution) cay be utilized where the loss of one channel will not mean the loss of all parameter information.
Where redundancy is used, one channel of each redundant set of channels shall be recorded and powered from the station d.c. system.
Ehere other' arrangements are,
used in lieu of redundancy, each channel shall be recorded and energized from the station d.c. system.
4.
To the extent practical, the same indicators should be used for the monitoring system as are used in the nor=al operation of the plant.
-5.
The monitoring instrumentation should have 'a range, response, and accuracy adequate to encompass the entire duration of an event.
Direct measuremant techniques should be used uherever possible.-
6.
The instrumentation components (sensor, associated equip =ent and j
indicator) cf the designs used in post accident conitoring, including i
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those ' serving a dual function of nor=al operations, should be qualified to verity that they function during and following all conditions imposed by design basis events.
7.
The accident _ monitoring instrunentation should be designed to permit periodic online t'esting that er.tends to, and includes sti=ulus to sensors wherever practical.
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