ML19322C238
| ML19322C238 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 03/28/1979 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19322C232 | List: |
| References | |
| REF-GTECI-A-34, REF-GTECI-IP, RTR-REGGD-01.097, RTR-REGGD-1.097, TASK-A-34, TASK-OR, TASK-TF, TASK-TMR NUDOCS 8001160664 | |
| Download: ML19322C238 (9) | |
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Draft Report of Completion of Generic Activity A-34:
" Instruments for Monitoring Radiation and Process Variables During Accifents" e
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Division of Site Safety and
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Environmental Analysis Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D. C. 20555
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.1. 0. INTRODUCTION In Decerter, ;975 the Staff issued for comment Regulatory Guide 1.97;
" Instrumentation for Light-Water-Cooled Nuclear Power Plants to Assess Plant Conditions During and Following an Accident." After reviewing the coments received the staff issued Revision 1 to this Regulatory Guide z
in August 1977.
(A copy of Regulatory Guide 1.97, Revision 1 is provided in Appendix A).
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The objective of Regulatory Guide 1.97 is to insure tpat during and following an accident, appropriate parameters and system functions are monitored in order that plantpersonnel will have sufficient information to take appropriate actions to restrict the co'urses' and. consequences of an h
accident. At the start of an accident, the operator cannot always determine
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what accident has occurred and therefore cannot always de'termine the appropriate response.
For this reason, the reactor trip and certiin safety actions
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(e.g. emergency core cooling actuation) are designed to be performed automatically during the initial stages of an accident. However, instru-mentation is also necessary to provide infomation about plant parameters and system functioning that alerts the operator to conditions beyond those
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Er expected so that appropriate operator actions may be taken.
The operator must have suf'ficient information available to: (1) detemine the course of an accident; (2) make intelligent decisions about taking manual action; and (3) assist in determining what actions, if any, are needed to execute i.s:
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l the plant emergency plan.
It should be goted that it is not the intent of Regulatory Guide 1.97 that operators be encouraged to circumvent 7Jtomatic features prematurely, but rather that they be adequately informed in order that they can take necessary planned and unplanned actions.
In August 1977, the staff issued Task Action Plan A-34, " Instruments for Monitoring Radiation and Process Variables During an Accident" (a copy of the most recent revision of the Task Action Plan is contained in Appendix B).
The purpose of the Task Action Plan is to develop guidance for applicants, licensees and staff reviewers concerning imple-mentation of Revision 4 of Regulatory Guide 1.97.
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In the course of implementing the initial phase of the Task Action Plan, it became obvious that Regulatory Guide 1.97 included a few provisions which industry claimed to be impractical at the present time, and other provisions for which more definitive guidance was needed to define acceptable means of compliance. The primary issues in controversy are Positions C.1 and.C.3 of the Regulatory Guide.
l Position C.1 is intended to insure that the station design includes sur'ficient instrumentation to meet the objectives described in Position C.1 for each of the Design Basis Accidents normally analyzed by an applicant in Chapter 15 of a Safety Analysis Report.
t Position C.3 describes specific instrumentation to be used if accident conditions degrade beyond those assumed in the FSAR. Various industry representatives expressed concern about the ranges of the instruments
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described in Position C.3 and the implication of monitoring for Class 9
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accidents.
This Position is not explicitly intended to monitor Class 9 accidents.
Position C.3 is intended to provide assurance that even under conditions that degrade far beyond'those that are assumed in the accident analyses, the coe rator will have usable instrumentation that will provide a basis for decision making. The operator must not be
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placed in a position where all his relevant instrumentation is off-scale.
The ranges of the instruments described in Position C.3 are not based
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directly on accident scenarios but are based on engineering judgment:5 of the admittedly extreme points beyond which the high probability of
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failure of important fission product barriers (e.g., reactor pressure vessel or containment structure) would make the need for instru-mentation a moot point.
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The remaining Positions in the Regulatory Guide describe the details of the design and qualification of the accident monitoring instrumentation and therefore do not pose the same type of implementation problems.
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2.0 IMPLEMENTATION j
During the months since issuance of Regulatory Guide 1.97 and Task Action Plan A-34, the staff and representatives of the nuclear industry have attempted to clarify the intent of the Regulatory Guide. Based on this work the staff has reached the following conclusions concern-
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ing implementation of Regulatory Guide'l.97 Revision 1.
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The large amount of experience accumulated to date permits identification of those parameters that should'be monitored t
to satisfy Position C.1.
The list of parameters is provided as Appendix C.
The staff will require that these parameters be monitored on all plants for which a construction permit application was docketed after September 30, 1977 (as per section D of Regulatory Guide 1.97 Revision 1). The accident monitoring instrumentation of plants for which a construction permit application was docketed prior to September 30, 1977 has been reviewed as part of the licensing process. Although the parameters monitored at specific plants may be different than those specified in Appendix C,
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the staff still believes that with the addition of the g described in Position C.3, existing accident monitor-i ing equipment is acceptable. Therefore, the staff has concluded that the resources that would be required to backfit the instruments required to monitor the parameters listed in Aapendir r_would l
not be justified based on the benefits derived from having a l
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standard set of accident monitoring instruments on all plants.
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The staff concludes that technology currently exists to permit implementation of the instrumentat' ion described in Positions C.3.a through C.3.c.
Prior to issuance of Regulatory Guide 1.97 Revision 1 the staff did not require that accident :nonitoring instrumentation be provided with ranges extending beyond the conditions expected to result from Design Basis Accidents. For the reasons discussed in Section 1.0, the staff now believes that such instrumentation should be required on all plants. Therefore, th'e staff,reguir2s
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that the instrumentation ductibed_in Position C.3.a throuch C.3.c be implemented for rea.ctor olant license app]ic.ations and all plants licensed for construction or operation.
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With respect to Position C.3.d. the staff is not certain that' existing release rate monitoring technology is sufficient to permit adequate monitoring of the ranges of radioactivity release rates that might be encountered if, as assumed in Position C.3, conditions degrade beyond those expected to result from the Design Basis Accidents. Therefore, the staff will delay requiring implementation of Position C'.3.d until studios of the capabilities of existing re-
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lease rate monitoring technology can be undertaken.
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It has been pointed out that it may not be feasible to qualify instrumentation to extreme conditions consistent with the instru-menc ranges described in Position C.3, particularly radiation levels inside containment of up to 1[ rads / hour (Position C.3.b).
The staff agrees that qualification of instrumentation located
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.However, the staff believes that all of the instrumentation de-j scribed in Position C.3 can either be shielded or located outside the containment, where a less hostile environment would exist, and appropri.cely calibrated.
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Position C.6 states that accident monitoring instrumentation should j
i be designed so that a single failure does not prevent the operator from accomplishing the objectives of Position C.l.
However, it is the staff's position that redundant instrume,ntation is not re-quired on each train of a system that has a redundant counterpart.
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The staff worked closely with several applicants for construction permits and operating licenses, and with the Atomic Industrial 1
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Forum Ad Hoc Committee on Post Accident Monitoring Instrumentation.
All of the concerns raised by the involved industry representatives have not been resolved to the satisfaction of all parties. However, the staff believes that sufficient guidan:2 has been developed so that Task A-34 can be classified as comp' te. The staff will continue to work with the industry representatives in au1 attempt to resolve any
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minor. issues that remain unresolved.
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INSTRUMENTATION TO FOLLOW THE COURSE OF AN ACCIDENT JtoC.Hu Parameter Containment pressure Hot leg flow (PWR)
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Cold leg flow (PWR)
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Level in steam generator.
Main steamline flow rate y
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s Pressure of reactor coolant Pressurizer level (PWR)
Radiation level in condenser air ejector Steam-generator pressure (PWR)
Temperature of reactor coolant Position of Valves in Vital Systems Component cooling water system Flow Containment cooling fan flow Containment spray flow Containment sump and suppression pool level Control rod position" indicators Emergency cooling water storage tank level Emergency filter train operation Emergency ventilation system (s) damper positions 7
Injection flow Power (Neutron flux)
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Appendix C Ak:.
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parameter Safety infection.ficw Status of power supplies Ultimate heat sink temperature and level Area radiation levels in auxiliary buildings Boron concentration and/or flow (PWR)
Containment temperature Hydrogen concentration in containment hdiation level in containment
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Reactor vessel coolant level-Temperature af space in vicinity of vital t/
equipment Activity levels in surface and ground water Activity release rate from principle pla.it vents and discharge points Wind direction, speed and vertical temperature difference Environmental Radiation ~ Levels l
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