ML20070R637
| ML20070R637 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 02/02/1983 |
| From: | NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES |
| To: | |
| Shared Package | |
| ML20070R630 | List: |
| References | |
| RTR-REGGD-01.097, RTR-REGGD-1.097 NUDOCS 8302030230 | |
| Download: ML20070R637 (46) | |
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mlLL/TODE AUCLEAR POWER /TATIOn l
UnlT 5 i
o de/ign bo/i/
re/ponte to l
regulotory guide 1.97, revi/ ion 2 l
0302030230 e3o2o2 l
DR ADOCK 05o00
O Millstone 3 Design Basis to Respond to Regulatory Guide 1.97 Rev. 2 Instrumentation for Lignt-Water-Cooled Nuclear Power Plants to Assess Plant and Environs Conditions During and Following an Accioent O
This document presents Northeast Utilities' interpretation of wnat is required to meet the intent of Regulatory Guioe 1.97 Revision 2 for the Millstone 3 plant.
It should not be construed as tiie definition of the minimum set of instruments needed to safely operate tills plant.
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TABLE OF CONTENTS Page 1.0 Discussion 1_1
- 2. 0 Definition of Variable Types 2-1 2.1 Definitions 2-1
- 2. 2 Variable Functions 2-3 3.0 Criteria 3-1 3.1 General Requirements 3-1 3.2 Equipment Design and Qualification Criteria 3-1 3.2.1 Design and Qualification Criteria - Category 1 3-1 O
3.2.2 Design and Qualification Criteria - Category 2 3-6 3.2.3 Design and Qualification Criteria - Category 3 3-9 3.3 Extended Range Instrumentation Qualification Criteria 3-11 4.0 Type A Variables 4-1 1
4.1 Introduction 4-1 5.0 Type B Variables 5-1 5.1 Introduction 5-1 O
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TABLE OF CONTENTS (Continued) l 119_8 i
6.0 Type C Variables 6-1 6.1 Introduction 6-1 i
7.0 Type D Variables 7-1 7.1 Introduction 7-1 8.0 Type E Variables 8-1 8.1 Introduction 8-1 r
9.0 Summary of Variables and Categories 9-1 i
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LIST OF TABLES Table 3-1 Sumary of Selection Criteria Table 3-2 Sumary of Design, Qualification, and Interface Requirements Table 4-1 Sumary of Type A Variables i
Table 5-1 Sumary of Type B Varibles 1
Table 6-1 Sumary of Type C Variables
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Table 7-1 Sumary of Type D Category 2 Variables Table 8-1 Sumary of Type E Variables l
Table 9-1 Yariable Sumary - Cross Reference Listing of Variables by Type A,B,C,D,E with Category 1,2,3 O
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AFW Auxiliary Feedwater CCW Component Cooling Water CFR Code of Federal Regulations CST Condensate Storage Tank E0P Emergency Operating Procedure ECCS Emergency Core Cooling System HHSI High Head Safety Injection ICC Inadequate Core Cooling Low Head Safety Injection LHSI LOCA Loss of Coolant Accident MSIV Main Steamline Isolation Valve NDT Nil-ductility Transition NPSH Net Positive Suction Head PAMS Post Accident Monitoring System RCS Reactor Coolant System RWST Refueling Water Storage Tank RHRS Residual Heat Removal System SW Service Water Safety Injection SI SGTR Steam Generator Tube Rupture S/G Steam Generator Wide Range Hot Leg Reactor Coolant Temperature T
Hot T
Wide Range Cold Leg Reactor Coolant Temperature Cold O
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1.0 DISCUSSION An analysis was conducted to develop a response to the intent of Regulatory Guide 1.97, Rev. 2.
This analysis identified the appropriate variables and established appropriate design bases and qualification criteria for instrumentation employed by the control room operator during and following an accident.
This design basis establishes the key and preferred backup variables to be monitored by the control room operating staff of the Millstone 3 Nuclear Plant following the initiation of an accident. The design basis recognizes the variables essential to the control room staff up to the time other Emergency Operating Facilities are manned as well as the information essential to the control room staff in subsequently control-ling the plant and proceeding to safe shutdown conditions. Also included are criteria for determining the requirements for the instru-ments used to monitor these variables.
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The design bases for the processing and display of information (Safety Parameter Display System (SPDS) and Control Room Design Review) are not presented here, and will be sent at a later date.
The detailed method-ology for the handling of display will be discussed in conjunction with programs to address NUREG-0696 and NUREG-0700.
Section 3 describes interface criteria which must be satisfied for the display methodology to meet the intent of Regulatory Guide 1.97 Revision 2 and this design basis.
1.1 Planned Versus Unplanned Operator Actions The plant safety analyses and evaluations define the design basis acci-dent event scenarios for which pre-planned operator actions are required. Accident monitoring instrumentation is necessary to permit the operator to take required actions to address these analyzed situa-tions. However, instrumentation is also necessary for unplanned situa-tions (i.e., to ensure that, should plant conditions evolve differently
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than predicted by the safety analyses, the operator has sufficient 1-1
information to monitor the course of the event). Aduitional instrumen-tation is also needed to indicate to tue operator whether tne integrity
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of the in-core fuel clad, the reactor coolant system pressure boundary, or the primary reactor containment has degraded beyond tne prescribea V
limits defineo as a result of the plant safety analyses and other evaluations.
Such additional requirements are considered by this design ba si s.
1.2 Variable Types Five classifications of variables have been identified. Operator manual actions identified in the operating procedures, associatea witn design basis acciaent events, are pre-planned.
Those variables that provice infomation needed by the operator to perform these manual actions are designated Type A.
The basis for selecting Type A variables is given in Section 2.2.1.
Those variables needed to assess that the plant critical safety functions are being accomplished or maintained, as identified in the q
plant safety analysis and otner evaluations, are designated Type B.
'V Variables used to monitor for the gross creach or the potential gross breach of the in-core fuel clad, the reactor coolant system pressure boundary, or the primary reactor containment, are designated Type C.
Type C variables used to monitor tne potential breach of containment have an extended range. The extended range shall be chosen to minimize the probability of instrument saturation even if conditions exceed those predicted by the safety analysis. The response cnaracteristics of Type l
C information display channels shall allow tne control room operator to l
detect conditions indicative of gross failure of any of the three l
fission product barriers or the potential for gross failure of these barriers.
Although variables selected to fulfill Type.. functions may rapidly approacn the values that indicate an actual gross failure, it is the final steady-state value reached that is important. Therefore, a high degree of accuracy and a rapid response time are not necessary for Type C information display channels, h
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Those variables needeo to assess the operation of individual safety systems and other systems important to safety are oesignated Type D.
q The variables that are required for use in determining the magnitude of the release and in continually assessing any releases of radioactive materials are designated Type E.
The five classifications are not mutually exclusive; that is, a given variable (or instrument) may be included in one or more types. This differentiation by variable type is intended only to guide the designer-in his selection of accident monitoring variables and applicable crite-ri a.
The cross referencing of Variable to Types is given in Section 9.
1.3 Design and Qualification Criteria Three categories of design and qualification criteria are identified.
The differentiation is made in order that an importance of information hierarchy can be recognized in specifying post-accident monitoring instrumentation. Category 1 instrumentation has the highest pedigree and should be utilized for information which cannot be lost under any r"]
circumstances. Category 2 and 3 instruments are of lesser importance in determining the state of the plant and do not require the same level of operational assurance.
The primary differences between category requirements are in qualifica-tion, application of single failure criterion, power supply, and display requirements.
Category I requires seismic and environmental qualifica-tion, the application of a single failure criterion, utilization of emergency standby power, and an immediately accessible display.
Cate-gory 2 requires qualification commensurate with the required function but does not require tne single failure criterion, emergency standby power, or an immeciately accessible display. Category 2 requires, in effect, a rigorous performance verification for a single instrument channel.
Category 3 does not require qualification, single failure criterion, emergency standby power, or an immediately accessible display.
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2.0 DEFINITION OF VARIABLE TYPES O
2.1 Definitions 2.1.1 Design Basis Accident Events Those events, any one of which may occur during the lifetime of a particular plant, and those events not expected tc cc::ur but postulated because their consequences would include the potential for release of significant amounts of radioactive gaseous, liquid, or particulate material to the environment. Excluded are those events (defined as "nonnal" and " anticipated operational occurrences" in 10 CFR 50) expected to occur more frequently than once during the lifetime of a particular plant.
The limiting accidents that were used to determine instrument functions are:
Steam Generator Tube Rupture.
2.1.2 Hot Standby The state of the plant in which the reactor is subcritical such that K is less than or equal to 0.99 and the reactor coolant eff system temperature is greater than or equal to 350 F.
2.1.3 Safe Shutdown (Cold Shutdown)
The state of the plant in which the reactor is subcritical such that K is less than or equal to 0.99, the reactor coolant eff system temperature is less than 200 F, and the reactor coolant system pressure is less than or equal to 10 CFR 50 Appendix G limits.
l 2.1.4 Controlled Condition The state of the plant that is achieved when the " subsequent action" portion of the plant emergency procedures is implemented 2-1 l
and the critical safety functions are being accomplished or main-tained by tne control room operator.
2.1.5 Critical Safety Functions Those safety functions that are essential to prevent a direct and immediate threat to the health and safety of tne public. These are the accomplishing or maintaining of:
1) reactivity control 2) reactor coolant systeni pressure control 3) reactor coolant inventory control 4) reactor core cooling 5) heat sink maintenance 6) primary reactor containment integrity.
2.1. 6 Immediately Accessible Information Information that is visually available to the control room opera-tor immediately (i.e., within human response time requirements),
N after he has made the decision that the information is needed.
2.1.7 Primary Information Information that is essential for the direct accomplishmant of the pre-planned manual actions specified in the E0P's; it does not include those variables that are associated with contingency actions.
l 2.1.8 Contingency Actions Those manual actions specified in the E0P's that address conditions beyond the Design Basis Accident Events.
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2.1. 9 Key Variables Those variables which provide the most direct measure of the infomation required.
2.1.10 Backup Infomation That information, made up of additional variables beyond those classified as key, that provides supplemental and/or confimatory infomation to the operator.
Backup variables do not provide an indication which is as reliable or complete as that provided by primary variables, and they should not be relied upon as the sole source of infomation.
2.2 Variable Functions The accident monitoring variables and infomation display channels are those that are required to enable the Control Room Operating Staff to perform the functions defined by Types A, B, C, D, and E below.
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2.2.1. For Type A (Note 1):
Those variables that provide the primary information required to permit the Control Room Operating Staff to:
Take the specified pre-planned manually controlled actions, for which no automatic control is provided, that are required for safety systems to accomplish their safety function in order to recover from the Design Basis Accident Event (Note 2), and Reach and maintain a cold shutdown condition.
Note 1: Consistent with the definition of Type A in Regulatory Guide 1.97 Revision 2, the verification of the actuation of safety systems has been excluded from the definition of Type A.
The variables which provide this verification are included in the O)
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definition of Type D.
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Note 2: Variables in Type A are restricted to pre-planned actions for Design Batis Accident Events.
Contingency actions AQ and additional variables which might be utilized in these proce-dures will be in Types B, C, D, and E.
2.2.2 For Type B:
Those variables that provide to the Control Room Operating Staff infomation to assess the process of accomplishing or maintaining critical safety functions, i.e., reactivity control, reactor coolant system pressure control, reactor coolant inventory control, reactor core cooling, heat sink maintenance, and primary reactor containment integrity.
2.2.3 For Type C (Note 3):
Those variables that provide to the Control Room Operating Staff infomation to monitor (1) the extent to which variables, which indicate the potential for causing a gross breach of a fission i
product barrier, have exceeded the design basis values and (2) that the in-core fuel clad, the reactor coolant system pressure boundary or the primary reactor containment may have been subject to gross breach.
These variables include those required to l
initiate the early phases of the emergency plan. Excluded are those associated with monitoring of radiological release from the plant which are included in Type E.
Note 3: Type C variables used to monitor the potential for breach of a fission product barrier have an extended range.
The extended range is chosen to minimize the probability of instru-ment saturation even if conditions exceed those predicted by the safety analyses.
2.2.4 For Type D:
Those variables that provide to the Control Room Operating Staff sufficient infomation (Note 4) to monitor the performance of:
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1) plant safety systems employed for mitigating the conse-quences of an accicent ano subsequent plant recovery to attain a cold shutdown conaition. These include verifica-tior: of the automatic actuation of safety systems, and 2) other systems normally employed for attaining a cola shut-down condition.
Note 4: To the extent feasible, this should be a direct measure-ment.
2.2.5 For Type E:
Those variables that provide the Control Room Operating Staff with information to:
1)
Estimate the magnitude of release of radioactive materials through identified pathways.
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3.0 CRITERIA 3.1 General Requirements The following design and qualification criteria are applied to instrumentation for Type A, B, C, D and E variables.
These are summarized in TaDies 3-1 ano 3-2.
3.2 Equipment Design and Qualification Criteria The qualification requirements of the Type A, B, C, D, and E accident monitoring instrumentation are subdivided into three categories (1, 2, 3). Descriptions of the three categories are given below.
Table 3-2 briefly summarizes the design and qualification requirements of the three designated categories.
3.2.1 Design and Qualification Criteria - Category 1 3.2.1.1 Selection Criteria - Category 1 The selection criteria for Category 1 variables have been subdivided according to the variable type.
For Type A, tnose key variables used for diagnosis or providing information for necessary operator action are designated Category 1.
(This does not include all Type A variables).
For Type B, those key variables which are useo for moni-toring the process of accomplishing or uaintaining critical safety functions are designated Category 1.
For Type C, those key variables whicn are used for monitoring the potential for breach of a fis-sion product barrier are designated Category 1.
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- 3. 2.1. 2 Qualification Criteria - Category 1
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The instrumentation is environmentally qualified in i
accordance with the Commissioners Memorancus ana Order (CLI-80-21).
The seismic portion of qualification is in accordance with Regulatory Guide 1.100.
Instrumentation shall continue to read within the requirea accuracy following but not necessarily during a seismic event. At least one instrumentation channel is qualified from sensor to di spl ay.
For the balance of instrumentation channels, qualification applies up to and includes the channel isolation device.
(Refer to section 3.3 in regard to extended range instrumentation quali fication).
3.2.1.3 Design Criteria - Category 1 (1)
No single failure within either the accident-monitoring instrumentation, its auxiliary support-ing features, or its power sources, concurrent with the failures that are a condition of or result from a specific accident, prevents the operator from being presented the required information.
Where failure of one accident-monitoring channel results in information ambiguity (e.g., the reaunaant dis-plays disagree), additional information is proviaed to allow the operator to deduce the actual condi-tions in the plant (Note 1).
This is accomplished by providing additional independent channels of infomation of the same variable (addition of an Note 1:
If amoiguity does not result from failure of the channel, then a third redundant or diverse channel is not required.
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identical channel), or by proviuing independent channels which monitor different variables wnich O
bear known relationships to the multiple channels V
(addition of a diverse channel (s)) (Note 2).
Redundant or diverse cnannels are electrically independent and physically separated from eacn other, to the extent practicaole witn two train separation, and from equipment not classified important to safety in accordance with Regulatory Guide 1.75, " Physical Independence of Electric Systems. "
Note 2: For situations such as isolation valves in series, the intent is generally to verify tne isolation function.
In such a situation a single indication on each valve is sufficient to satisfy the single failure criterion if those inaications are from different trains (i.e. unambiguous indica-tion of isolation).
(2)
The instrumentation is energized from station emergency standby power sources, battery backed where momentary interruption is not tolerable, as provided in Regulatory Guide 1.32, " Criteria for Safety-Related Electric Power Systems for Nuclear Power Plants."
(3)
The out-of-service interval is based on normal Technical Specification requirements on out-of-service for the system it serves where applicable or where specified by other requirements.
(4)
Servicing, testing, and calibration programs are specified to maintain the capability of tne monitoring instrumentation.
For those instruments where the required interval between testing is less O
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than the nomal time interval between gener; ting station shutdowns, a capability for testing during p
power operation is provided.
o (5)
Whenever means for removing channels from service 1
are included in the design, the design facilitates 1
administrative control of the access to such removal means.
(6)
The design facilitates administrative control of the access to all setpoint adjustments, module cali bration adj ustments, and test points.
(7)
The monitoring instrumentation design minimizes the development of conditions that would cause meters, annunciators, recorders, alams, etc., to give anomalous indications potentially confusing to the operator.
(8)
The instrunentation is designed to facilitate the recognition, location, replacement, repair, or l
adjustment of malfunctioning components or modules.
(9)
To the extent practicable, monitoring instrumenta-tion inputs are from sensors that directly measure the desired variables. An indirect measurement is made only when it can be shown Dy analysis to l
provide unambiguous infomation.
(11)
Periodic checking, testing, calibration, and calibration verification is in acconiance with the applicable portions of Regulatory Guide 1.118,
" Periodic Testing of Electric Power and Protection Sy stens. "
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i (11)
The range selected for the instrumentation encompasses the expected operating range of the variable being monitored to the extent that saturation does not negate the required action of the instrument in accordance with the applicable portions of Regulatory Guide 1.105, " Instrument Setpoi nts. "
3.2.1.4 Infomation Processing and Display Interface Criteria - Category 1 The interface criteria specified here provide requirements to be implemented in the establishment of the design basis for processing and displaying of the infomation. The design basis for infoma-tion processing and displaying is the subject of a separate document.
(1)
The operator has immediate access to the infoma-tion from redundant or diverse channels in units familiar to the operator (i.e., for a temperature reading degrees not volts). Where two or more l
instruments are needed to cover a particular range, overlapping of instrument spans is provided.
(2)
Where trend or transient information is needed, a historical record of a minimum of one instrumen-tation channel for each process variable is main-tai ned.
A recorded pre-event history for these channels is required for a minimum of one hour and continuous recording of these channels is required following an accident until such time as continuous recording of such infomation is no longer deemed necessary.
This recording is available when f
required, but need not be immediately accessible.
One hour was selected based on a representative O
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slow transient which is bounded by this time requi rement.
A one-half inch LOCA was selected bl v
since trip occurs at approximately fifty minutes after initiation. Where direct and immediate trend or transient infomation is essential for operator infomation or action, the recording is immediately accessible.
3.2.2 Design and Qualificatior Cr'.teria - Category 2 3.2.2.1 Selection Criteria - Category 2 The selection criteria for Category 2 variables are subdivided according to the variable type. For Types A, B, and C, those variables which provide preferred backup infomation and are subject to a HELB environment when required to perfom their functions, are designated Category 2.
For Type D, those key variables that are used for monitoring the perfomance of safety systems, are designated Category 2.
For Type E, those key variables to be monitored for use in detemining the magnitude of the release of radioactive materials and for con-tinuously assessing such releases, are designated Category 2.
3.2.2.2 Qualification Criteria - Category 2 Category 2 instrumentation are qualified in accordance with the Commissioners Memorandum and Order (CLI-80-21) for at least the environment (seismic and/or environmental) in which it must operate to serve its intended function.
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3.2.2.3 Design Criteria - Category 2 (1)
The instrumentation is energized from a highly
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reliable on-site power source, not necessarily the emergency standby power, which i s battery backed where momentary interruption is not tolerable.
(2)
The out-of-service interval is based on nonnal Technical Specification requirements on out-of-service for the system it serves where applicable or where specified by other requirements.
(3)
Servicing, testing, and calibration programs is specified to maintain the capability of the monitoring instrumentation. For those instruments where the required interval between testing is less than the normal time interval between generating station shutdowns, a capability for testing during power operation is provided.
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(4)
Whenever means for removing channels from service are included in the design, the design facilitates administrative control of the access to such removal means.
(5)
The design facilitates administrative control of the access to all setpoint adjustments, module cali bration adj ustments, and test points.
4 (6)
The monitoring instrumentation design minimizes the development of conditions that would cause meters, annunciators, recorders, alanns, etc., to give anomalous indications potentially confusing to the operator.
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(7)
The' instrumentation is designed to facilitate tne recognition, location, replacement, repair, or adjustment of malfunctioning components or modules.
(8)
To the extent practicaole, monitoring instrumenta-tion inputs are from sensors that directly measure the desired variables. An indirect measurement is made only when it can be shown by analysis to provide unambig;ous information.
(9)
Periodic checking, testing, calibration, and cali-bration verification is in accordance with the applicable portions of Regulatory Guide 1.118,
" Periodic Testing of Electric Power and Protection Systems. "
(10)
The range selected for the instrumentation encompasses the expected operating range of tne variable being monitored to the extent that saturation does not negate the required action of V
the instrument in accordance with the applicable portions of Regulatory Guide 1.105, " Instrument Setpoints."
3.2.2.4 Information Proceesing and Display, Interface Criteria - Category 2 The interface criteria specified here provide requirements to be considered in the establishment of the oesign basis for processing and displaying of the information. The design basis for infonna-tion processing and displaying is the subject of a separate document.
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The instrumentation signal is, as a minimum, processed for display on demand.
Recording requirements are variable specific and are
'ietermined on a case-by-case basis.
3.2.3 Design and Qualification Criteria - Category 3 3.2.3.1 Selection Criteria - Category 3 The selection criteria for Category 3 variables are subdivided according to tne variable type. For Types A, B, and C, those variables which provide preferred backup information and are not subject to a HELB environment when required to perform their functions are designated Category 3.
For Types D and E, those variables whicii provide preferred backup information are designated Category 3.
3.2.3.2 Qualification Criteria - Category 3 The instrumentation is high quality comercial grade which is not required to provide information when exposed to a post-accident adverse environ-ment.
Only normal and abnormal environments are applicable.
3.2.3.3 Design Criteria - Category 3 l
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Servicing, testing, and calibration programs are l
specified to maintain the capability of the monitoring instrumentation. For those instruments where the required interval between testing is less than tne normal time interval between generating station shutdowns, a capability for testing during l
power operation is provided.
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(2)
Wnenever means for removing channels from service are included in the design, the design facilitates O
administrative control of the access to such removal means.
(3)
The aesign facilitates administrative control of the access to all setpoint adjustments, module calibration adjustments, and test points.
(4)
The monitoring instrumentation cesign minimizes the development of conditions tnat would cause meters, annunciators, recorders, alarms, etc., to give anomalous indications potentially confusing to the operator.
(5)
The instrumentation is designed to facilitate the recognition, location, replacement, repair, or adjustment of malfunctioning components or modules.
(6)
To the extent practicable, monitoring instrumenta-tion inputs are from sensors that directly measure v
the desired variables.
An indirect measurement shall be made only wnen it is shown by analysis to provide unambiguous information.
3.2.3.4 Information Processing and Display, Interface Criteria - Category 3 The interface criteria specified here provide requirements to be considered in the establisnment of the design basis for processing and displaying of the information. The design basis for informa-tion processing and displaying is tne subject of a separate document.
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The instrumentation signal is, as a minimum, pro-cessed for display on demand.
Recording require-ments are variable specific and are determined on a
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case-by-case basi s.
3.3 Extended Range Instrunentation Qualification Criteria The qualification environment for extended range infonnation dis-play channel components is based on the design basis accident events, except the assumed maximum of the value of the monitored variable is the value equal to the specified maximum range for the vari abl e.
The monitored variable is assumed to approach this peak by extrapolating the most severe initial ramp associated with the Design Basis Accident Events.
The decay for this variable is considered proportional to the decay for this variable associated with the Design Basis Accident Events.
No additional qualifica-tion margin needs to be added to the extended range variable. All environmental envelopes except that pertaining to the variable measured by the infonnation display channel are those associated with the Design Basis Accident Events.
The environmental qualifi-O) cation requirement for extended range equipment does not account for steady-state elevated levels that may occur in other environ-mental parameters associated with the extended range variable.
For example, a sensor measuring containment pressure must be qualified for the measured process variable range (1.e., 3 times design pressure for concrete containments), but the corresponding ambient tenperature is not mechanistically linked to that pres-sure.
Rather, the ambient tenperature value is the bounding value for design basis accident events analyzed in Chapter 15 of the FSAR. The extended range requirement is to ensure that the equip-ment will continue to provide infonnation if conditions degrade beyond those postulated in the safety analysis.
Since extended variable ranges are nonmechanistically detennined, extension of associated parameter levels is not justifiable and is therefore not required, l
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O WESTINGHOUSE PROPRIETARY CLASS 2 i
Taole 3-1 i
Summary of Selection Criteria TYPE CATEGORY l CATEGORY 2 CATEGORY 3 A
KEY variables that are used Variables wnich provide Variables which provide for diagnosis or providing PREFERRED BACKUP information PREFERRED BACKUP information ana information for necessary and ARE subject to a HELB when ARE NOT subject to a HELB when operator action required to perform their required to perform their functions f unctions B
KEY variables that are used Variables which provide Variables which provide for monitoring the process of PREFERRED 8ACKUP information PREFERRED BACKUP information and accomplishing or maintaining and ARE subject to a HELB when ARE NOT subject to a HELB when critical safety functions required to perform their required to perform their functions functions C
KEY variables that are used Variables which provide Variables which provide for monitoring the potential PREFERRED INFORMATION and PREFERRED BACKUP information and for breach of a fission product ARE subject to a HELB when ARE NOT subject to a HELB when barrier required to perform their required to perform their functions functions D
KEY variables that are used KEY variables (which have not Variables which provide PREFERRED for monitoring the performance been included under Category 1)
BACKUP information which are used l
of safety systems, which are which are used for monitoring for monitoring the performance of essential to maintaining the performance of plant plant systems j
critical safety functions and systems which may lead the operator to take contingency actions that are not necessary and would be q
adverse to safety.
E None KEY variables to be monitored Variables to De monitored which for use in determining the provide PREFERRED BACKUP informa-1 magnitude of tne release of tion for use in determining the radioactive materials and magnitude of the release of radio-for continuously assessing active materials and for continu-such releases ously assessing such releases
l Table 3-2 Sumary of Design, Qualification, and Interface Requirements Quali fication Category 1 Category 2 Category 3 Environmental Yes As appropriate No Seismic Yes As appropriate No Design Single Failure Yes No No i
Power Supply Emergency On-Si te As Required Standby Channel out of Service Technical Technical No Speci fications Specifications Testability Yes Yes As Required Interface Mi nimum Immediately Demand Demand j
Indication Accessible Recording Yes As Required As Requirea
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SECTION 4.0 TYPE A VARIABLES 4.1 Introduction Type A Variables are oefined in Section 2.2.1.
They are tne variables which provide primary information required to permit tne Control Room Operating Staff to:
1.
Take specified pre-planned manually controlled actions, for whicn no automatic control is provided, that are required for safety systems to accomplish tneir safety function to recover from tne Design Basis Accident Event (Verification of actuation of safety systems is excluded from Type A and is included as Type D);
2.
Reach and maintain a cold shutdown condition Key Type A variables are designated Category 1.
These are the variables which provide the most direct measure of the infonnation required. The KEY Type A variables are 1.
RCS Pressure (Wide Range) 2.
Hot Leg Reactor Coolant Temperature (Wide Range Thot) 3.
Cold Leg Reactor Coolant Temperature (Wide Range Tcold) t 4.
Wide Range Steam Generator Level l
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Narrow Range Steam Generator Level 6.
Pressurizer Level O
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7.
Primary Reactor Containment Pressurr 8.
Steamline Pressure 9.
Refueling Water Storage Tank (RWST) Level
- 11. Containment High Range Internal Radiation Monitor
- 11. Core Exit Temperature
- 12. Auxiliary Feedwater Flow
- 13. Containment Water Level (Wide Range)
- 14. Fuel Drop Monitors (Containment Radiation)
- 15. RCS Pressure (Extended Range)
- 16. Containment Hydrogen Concentration Preferred backup Type A Variables are designated Category 2.
Only RCS Subcooling is designated as Type A, Category 2.
It i s recognized that the degree of subcooling can be obtained from System Pressure and Temperature using Type A Category I variables and a Steam Table.
However, it is also recognized that the operator will most likely use his subcooling monitor (required by the NRC's post-TMI Action Plan).
Therefore, RCS Subcooling is considered a backup Type A which in turn requires Category 2 qualification.
No Type A Variables have been designated Category 3.
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TABLE 4-1
SUMMARY
OF TYPE A VARIABLES RCS Pressure Al Wide Range T Al hot Wide Range T Al cold Wide Range S/G Level Al Narrow Range S/G Level Al Pressurizer Level Al Primary Reactor Containment Pressure Al Steamline Pressure Al Refueling Water Storage Tank (RWST) Level Al Containment High Range Internal Radiation Monitor Al Core Exit Temperature Al Auxiliary Feedwater Flow Al Containment Hydrogen Concentration Al RCS Subcooling A2 Containment Water Level (Wide Range)
Al Fuel Drop Monitors (Containment Radiation)
Al RCS Pressure (Extended Range)
Al i
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SECTION 5.0 TYPE B VARIABLES 5.1 Introduction Type B variables are defined in Section 2.2.2.
They are the variables that provide to the Control Room Operating Staff information to assess i
the process of accomplishing or maintaining critical safety functions, i.e.
1 1.
Reactivity Control 2.
Reactor Coolant System Pressure Control 3.
Reactor Coolant Inventory Control i
4.
Reactor Core Cooling 5.
Heat Sink Maintenance I
6.
Primary Reactor Containment Integrity Variables which provide the most direct indication (i.e. KEY variable) to assess each of the 6 critical safety functions' are designated Category 1.
Pra' erred b2.ckup variables have been designated Category 2 (if subject to high energy line break (HELB) environment wnen required) or Category 3 (if not subject to HELB when required). These are listea
)
in Table 5.1.
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TableSJ Surnary of Type B Variables O
Reactivity Control Key:
Neutron Flux B1 Preferred
- a. Wide Range T B2 Hot Backup:
- b. Wide Range TCcid 0
- c. Control Rod Position B3 Reactor Coolant System Key:
B1 Pressure Control Preferred
- a. Containment Pressure B2 Backup:
- b. Wide Range S/G Level B2 Reactor Coolant Key:
Pressurizer Level Bl Inventory Control Preferred
- a. Containment Water Level B2 Backup:
(Wide Range)
- b. Wide Range S/G Level B2 Reactor Core Cooling Key:
Core Exit Temperature B1
' Preferred
- a. Wide Range T B2 p/
Hot L
Backup:
- b. Wide Range T B2 Cold
B2
- d. RCS Subcooling B2 Heat Sink Maintenance Key:
- a. Narrow Range S/G Level B1
- b. Wide Range S/G Level Bl
- c. Steamline Pressure B1
- d. Core Exit Temperature B1 Preferred
- a. Main Steamline Isolation 82 Backup:
and Bypass Valve Status Primary Reactor Key:
- a. Containment Pressure B1
- b. Containment Hydrogen B1 Containment Integrity Preferred None Backup:
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SECTION 6 Type C Variables O
6.1 INTRODUCTION
Type C variables are cefined in Section 2.2.3.
Basically, they are the variables that provide to the Control Room Operating Staff information to monitor the potential for breach or actual gross breach of:
1.
In-core fuel clad; 2.
Reactor Coolant System Boundary; or 3.
Primary Reactor Containment Boundary.
(Variables associated with monitoring of radiological release from the plant are included in Type E).
Those Type C key variables which provide the most direct measure of the POTENTIAL for breach of one of the 3 fission product boundaries are designated Category 1.
Backup information indicating potential for breach is designated Category 2.
Variables which indicate actual Dreach have been designated as preferred backup information and have been designated to Category 2 or Category 3 depending on Qualification Requirements.
Tah'e 6-1 summarizes the selection of Type C variables.
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O TABLE 6 I - Type C POTENTIAL FOR BREACH ACTUAL BREACH IN-CORE Key: Core Exit Temperature Preferred Backup: RCS Sampling FUEL CLAD (C1)
(C3)
RCS BOUNDARY Key: RCS Pressure (Cl)
Preferred Backtp: RCS Pressure (Extended Range)
(Wide Range) (C2)
Containment Pressure (C2)
Containment Water Level Wide Range (C2) l Containment Structure Radiation Internal (C2)
Fuel Drop Radiation Monitors (Containment Radiation) (C2)
Hydrogen Recombiner Cubicle Ventilation (C2) Radiation CONTAINMENT Key: Containment Pressure Preferred Backup: Ventilation Vent BOUNDARY (Cl) (Extended Range)
(Extended Range) (C2)
Hydrogen Concentration Supplementary Leak Collection and Release (C1)
System (C2) 1 of 2
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TABLE 6 Type C (Continued)
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l POTENTIAL FOR BREACH ACTUAL BREACH Containment Hecircula-tion Cooler Service Water Outlet (C2)
Containeent Isolation Valwe Status (C2)
Containment Pressure (C2) f l
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SECTION 7.1 TYPE D VARIABLES O
7.1 INTRODUCTION
Type D variables are defined in Section 2.2.4.
Basically, they are those variables that provide sufficient information to the Control Room Operating Staff to monitor the performance of:
1.
Plant safety systems snployed for mitigating the consequences of an accident and subsequent plant recovery to attain a cold shutdown condition, including verification of the automatic actuation of safety systems; and 2.
Other systems normally snployed for attaining a cold shutdown condi-tion.
All Type D KEY variables are designated Category 2.
No Type D variables requiring Category 1 qualification were identified.
l Preferred backup information is designated Type D Category 3.
The following systems have been identified as requiring Type D informa-tion to be monitored:
1.
Pressurizer Level and Pressure Control (assess status of RCS following return to normal pressure and level control under certain post-accident conditions) 2.
Chemical and Volume Control System (CVCS) (employed for attaining a safe shutdown under certain post-accident conditions) 3.
Secondary Pressure and Level Control (employed for restoring / main-taining a secondary heat sink under post-accident conditions)
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4.
Emergency Core Cooling System (ECCS) 5.
Containment Systems 7.
Component Cooling Water 8.
Residual Heat Removal (employed for attaining a cold shutdown con-dition under certain post-accident conditions)
- 10. Heating, Ventilation, Air Conditioning
- 11. Electric power to vital safety systems
- 12. Verification of Automatic Actuation of Safety Systems Table 7-1 lists the key variables identified for each system listed above, and specifies the seismic and environmental qualification for each variable.
For purposes of specifying seismic qualification for Type D Category 2 variables, it is assumed that a seismic event and a break in Category I piping will not occur concurrently. As a result, the limiting event is an unisolated (single failure of a MSIV) break in ASME Class 2 main steam piping.
Instrumentation associated with the safety systems which are required to mitigate and monitor this event should be seismically qualified instrumentation.
Similarly, the environmental qualification for Type D Category 2 variables depends on whether the instrumentation is subject to a HELB when required to provide information.
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O TABLE 7-1 Type 0 Key Variables Systen Designation Key Variable Instrumentation Seismic Envi romental l
1.
Pressurizer Level and PORV Status Yes HELB Pressure Control Safety Valve Status Yes HELB Heater Breaker Position No Ambi ent Pressurizer Level Yes HELB RCS Pressure (WR)
Yes ELB j
2.
CVCS Charging Flow No Ambient j
Letdown Flow No Ambient VCT Level No Ambi ent Seal Injection Flow No Ambi ent Valve Status Yes (Isolation l
valves only)
Ambi ent 3.
Secondary Pressure and S/G PORY Status Yes HELB*
Level Control Main Steamline Isolation and Bypass Yes HELB*
Valve Status S/G Safety Valve Status Yes HELB*
Steamline Pressure Yes ELB
- MFW Control and Bypass Valve Status Yes HELB*
MFW Isolation Valve Status Yes HELB*
MFW Flow No Ambi ent Auxiliary Flow Yes HELS*
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S/G Level (WR) and (NR)
Yes HELB S/h Blowdown Isolation Valve Status Yes Ambi ent 1 of 3
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O TABLE 7-1 (Continued)
Type D Key Variables System Designation Key Variable Instrumentation Seismic En vironent al 4.
ECCS RWST Level Yes Ambient Total HHSI Flcw Yes HELB**
Total LHSI Flow No HELB**
Containment Water Level (Wide Range)
No HELB Valve Status Yes HELE**
Accunulator Tank Pressure Yes HELB Accumulator Isolation Valve Status Yes HELB Accunulator Nitrogen Vent Isolation Valve Status Yes HELB 5.
Auxiliary Feed Auxiliary Feedwater Flow Yes HELB*
Valve Status Yes HELB DWST Level Yes Ambient 6.
Containment Containment Temperature No HELB Containment Water Level (WR)
No HELB Spray System Valve Status No HELB**
Containment Pressure No HELB Containment Spray Flow No HE LB *
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CCW Header Temperature Yes Ambient Valve Status Yes Ambient Flow to ESF Conponents Yes HELB 2 of 3
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O TABLE 7-1 (Continued) i System Designation Key Variable Instrunentation Seismic En vironental 4
8.
Service Water Valve Status Yes HEL8 Flow to RSS Heat-exchanger Yet Ambient 9.
RHR Heat Exchanger Discharge Temperature No HELB**
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Flow Nc HELB**
Valve Status No HELB**
Yes HELB i
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- 11. Electric Power Emergency Bus (s) Voltage Yes Ambient j
- 12. Verification of Autanatic Reactor Trip Breaker Position Yes Ambient Actuation of Safety AFW Punp Status Yes Ambient Systems S1 Punp Status Yes Ambient Service Water Pump Status Yes Ambient CCW Pung Status Yes Ambient SI Valve Alignment Yes HE LB Containment Spray System Pump Status Yes HELB i
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- These systems must be qualified to the worst case environment in which they must function (including HELB's inside and outside containment).
- These systems may see radiation from conponents in the recirculation path.
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l Section 8.0 Type E Variables 8.1 Introduction
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Type E variables are definea in Section 2.2.5.
They are those variables that provide the Control Room operating staff with infonnation to:
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1)
Estimate' the magnitude of release of radioactive materials through identified pathways.
Key Type E variables shall be qualified to Category 2 requirements.
)
Preferred backup Type E variables shall be qualified to Category 3 l
requirements.
Taole 8-1 summarizes tne selection of Type E variables.
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i TABLE 8.1
SUMMARY
OF TYPE E VARIABLES Containment Structure High Range Internal Radiation Monitor E2 Ventilation Vent (Extended Range) Monitor E2 Supplementary Leak Collection and Release System Extended E2 Range Monitor Hydrogen Recombiner Cubicle Ventilation Monitor E2 Condenser Air Ejector Monitor E3 Turbine-Driven Auxiliary Feedwater Pump Turbine Discharge E2 Monitor Main Steam Relief Line Monitor E2 O
Contairunent Recirculation Cooler Service Water Outlet E2 Monitor Flow Rate Out Ventilation Vent E2 Flow Rate to Unit 1 Stack E2 Site Environmental Radiation Level E3 Fuel Drop Monitors (Containment Radiation)
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SECTION 9.0 l
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SUMMARY
The variables in this document have been defined by Northeast Utilities as Types A, B, C, D, or E and Category 1, 2, or 3 in response to tne intent of Regulatory Guide 1.97 based upon the design oases and qualification criteria set forth in this document.
Table 9-1 sunnarizes the variables by type and category.
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O Table 9-1 Summary of Variables and Categories Variable Type and Category Type Type Type Type Type A
B C
D E
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l RCS Pressure (Wide Range) l 1,2 2
2 Wide Range T hot 1
2 Wide Range T cold 1
2 i
Wide Range S/G Level 1
1,2 1
j Narrow Range S/G Level 1
1 2
Pressurizer Level 1
1 2
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Containment Pressure 1
1,2 2
2 Steam..e Pressure 1
1 2
4 RWST Level 1
2 l
Containment Water Level (Wide Range) 1 2
2 2
l Auxiliary Feedwater Flow 1
2 Containment Structure High Range 1
2 2
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Internal Radiation Level 1
i Core Exit Temperature 1
1 1
Fuel Drop Monitors (Containment 1
2 2
Radiation) i RCS Subcooling 2
2 J
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Neutron Flux 1
Containment Isolation Valve Status 2
Control Rod Position Ind.
3 Containment Hydrogen Concentration 1
1 1
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l Table 9-1 (Continued)
Summary of Variables and Categories (Excluding Selection of D-3) i i
Variable Type and Category Type Type Type Type Type l
A B
C D
E i
Contaimnent Pressure (Extended Range) 1 RCS Pressure (Extended Range) 1 1
RCS Sampling 3
4 PORY Valve Status 2
Primary Safety Valve Status 2
Pressurizer Heater Breaker Position 2
Charging System Flow 2
Letdown Flow 2
VCT Level 2
CVCS Valve Status 2
RCP Seal Inj ection Flow 2
S/G Atmospheric PORY Status 2
Main Steam Line Isol/ Bypass Valve 2
2 S/G Safety Valve Status 2
Main Feedwater Control Valve 2
Main F/W Control Bypass Valve 2
liain F/W Isolation Valve 2
Hain Feedwater Flow 2
S/G Blowdown Isolation Valve Status 2
2 of 5
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l Table 9-1 (Continued) l l
Sunmary of Variables and Categories (Excluding Selection of D-3)
Variable Type and Category Type Type Type Type Type A
B C
D E
i Total HHSI Flow 2
Total LHSI Flow 2
ECCS Valve Status 2
Aux F/W Valve Status 2
PWST Level 2
Containment Spray System Valve Status 2
Containment Spray System Punp Status 2
j CCW Valve Status 2
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l Service Water System Valve Status 2
i Service Water Flow to RSS Heat-exchanger 2
RHR Heat-exchanger Discharge Temp 2
RHR Flow 2
RHR Valve Status 2
Reactor Trip Breaker Position 2
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O Table 9-1 (Continued)
Summary of Variables and Categories (Excluding Selection of D-3) i Variable Type and Category i
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Type Type Type Type Type I,
A B
C D
E l
Auxiliary F/W Pump Status 2
SI Pump Status 2
SI Valve Alignment 2
Service Water Pump Status 2
CCW Pump Status 2
f Accumulator Tank Pressure 2
l Accumulator Isolation Valve Status 2
Accumulator Nitrogen Vent Isolation 2
Valve Status Flow Out Ventilation Vent 2
Flow Rate to Unit 1 Stack 2
Supplementary Leak Collection 2
2
]
(Extended Range)
Containment Recirculation Cooler 2
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Ventilation Vent (Extended Range) 2 2
)
Turbine Driven Auxiliary Feedwater 2
i Pump Discharge i
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O Table 9-1 (Continued)
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Sununary of Variables and Categories (Excluding Selection of D-3) i j
Variabl e Type and Category i
Type Type Type Type Type A
B C
D E
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1 Main Steam Relief Line 2
l Condenser Air Ejector 3
t Hydrogen Recombiner Cubicle 2
2 Ventilation Site Environnental Radiation Level 3
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