ML19322D173
| ML19322D173 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 05/29/1979 |
| From: | Ornstein H NRC - NRC THREE MILE ISLAND TASK FORCE |
| To: | Budnitz R NRC - NRC THREE MILE ISLAND TASK FORCE |
| References | |
| TASK-TF, TASK-TMR NUDOCS 8002100012 | |
| Download: ML19322D173 (11) | |
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?MFI Robert Bueriitz 2 79 PROJECT tiO. 2 - DESCRIPTION OF THE ACCIDEliT Major Objectives of project Purpose of the Objective 1.
Provide description of events as 1.
a.
Provide information for they occurred (the facility, the evaluation of adequacy of facility operating crew on duty and their design, construction, and operation advisors, the man / machine inter-b.
Provide information for face) evaluation of general adequacy of regulatory approach (mostly fiRR, a.
information directly known (data, etc.)
c.
Provide information for b.
indirect information, evaluation of effectiveness of the obtained after analysis research, standards dev., inspection of the direct information and license review processes (in detail, as contrasted with (b), which is more general) 2.
Provide description of infor-2.
a.
Provide information for evaluating mation available to the operator, the response of the operating crew, to flRC, to others at various times; utility management NRC staff, etc.
and (where possible) of infor-b.
Provide information for evalu-mation that should have been ating adequacy of the facility's available if plans or designed information gathering capability and equipment had functioned properly.
presentation of information to the Failures could be hardware or operating crew.
This includes evaluation administrative in nature.
Of methods for recording and processing facility data during an accident.
3.
Provide description of the 3.
Provide information for evaluating operating crew's use of pro +
the operating crew's utilization of cedures during their response their procedures, and the adequacy of to the accident, and of the i
the Frocedures.
procedural response for those likely, alternate scenarios developed in number (5) below.
4.
Provide description of those 4.
Provide information for evaluating facility components and systems adequacy of design, regulatory require-that did not function as ments, inspection, testing, and planned or designed.
maintenance.
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Major Objectives of Project Purpose of the Objective 5.
Provide description and 5.
a.
Provide information needed analysis of important scenarios, to evaluate operator and NRC decision-different from the one that making and accident-response capa-actually occurred, if the bilities, and analytical capabilities.
scenarios fit one of the b.
Provide information needed to following criteria:
evaluate the " remaining margin of safety" at THI, which margin separated
- a. the scenario might have what actually cccurredfrom other occurred, with reasonable scenarios involving much greater probability (in a stochastic consequences,
sense), including equipment Assist in ungey,s}an(1ng c.
that operated beyond its implications fo.r other rea,ctor ded,ign,s.
nominal design specifi -
cations.
- b. in. retrospect, the scenario probably (or surely) could not have occurred, or was of very low probability, but was considered likely or significant during the course of the acci-dent.
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'Ihis project is subdivided into seven tasks, as follows:
Task 1 Provide a Chronology of Plant Events Task 2 Use of Procedures by Operators Task 3 Key Equipment and Systems Task 4 Impact on Radiological Releases Task 5 Significant Alternative Courses of Events Task 6 Impact of Communications on the Event Task 7 Evaluation of Adequacy of Plant Design, Operation, and Emergency Response e
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Task 1 Provide a Chronology of Plant Events Objective Determine the chronology of events that occurred during the D1I-2 accident, beginning with the status of the facility just prior to the initial feed-water transient and continuing in depth until 3 to 5 days afterward; the later period, until the switchover to natural circulation cooling on April 13, will be covered in less detail.
Approach.
De draft chronology of events generated by the IE staff will be used as a starting point, supplemented by chronologies put together by Metropolitan
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Edison and by EPRI. However, these will be considered as points-of-departure, and will be subjected to initial analysis as a key part of this task.
For each item within the chronology, the following will be determined if considered relevant:
1.
H e information available to the operating crew.
2.
The reasons for a crew-initiated action.
3.
For crew-initiated actions, the availability of procedures and their use.
4 The status of hardware and sensors.
5.
The reason for a hardware failure, revival, actuation.
6.
The occurrence of a radiologically significant release, or of an event Icading directly to a later release.
7.
The environmental conditions and perfomance of hardware, emphasizing hardware experiencing conditions beyond its design envelope.
Also, at certain key points in the sequence of events, a key branch point may have occurred where alternative scenarios might have branched from the events that did occur. These will be indicated.
This task will require some interviewing of persons involved, but no good estimate is availabic now as to the extent of interviews needed.
Resources H e manpower required to complete this task is at least 50 man-weeks, but could be substantially more. A better estimate will be made after a week or more of actual effort. NRC staff will be supplemented, as needed, with contractor support.
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H0rnstein 5/25/79 Y'A b W - Use of Procedures by Operators Objective Determine the extent to which operators utilized procedures during the accident.
This information is necessary for assessing the adequacy of plant operational procedures, operator training, plant administrative controls, and NRC involvement in plant operations.
This task will also treat the adequacy /or inadequacy of information available to the operator during the accident.
Approach and Resources This task will require examination of the plant log, process computer output, I&E findings, plant operational procedures and the FSAR.
Interviews with plant operating staff, NRC I&E operator licensing staff, and possibly B&W staff will be required.
The estimated manpower required to complete this task is 2-4 man-weeks.
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HL0rnstein qg[,/ 7 5/29/79
- M r,ey Equipment and Systems Objective Provide information on key equipment and systems which failed at TMI or which operated beyond their design capabilities (including safety classification, environmental qualification; environmental and operational conditions encountered, pertinent design requirements, causes of failures 'ailure modes and times of failure - or if applicable, duration for which the systems or equipment worked successfully beyond their design envelopes).
Such information will be necessary for the assessment of the adequacy of plant design analyses (accidents and transients), as well as system and equipment design requirements.
Approach and Resources Utilize FSAR, plant maintenance records, plant technical specifications, equipment specification documents, equipment qualification testing data y
to determine the equipment and system design capabilities, and use the plant chronology, stripcharts, etc., to determine equipment and system operations and times of failure.
This task will require some inter-viewing with GPU/S&W and Burns & Roe.
The estimated manpower required to complete this task is 4-6 man-weeks.
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Shar-44 Impact on Radiological Releases
[dIObjective: Provide information about those specific events and actions, that had an effect upon radiological releases.
This information is necessary to enable one to completely understand many of the actions taken to bring the plant to a safe shutdown, and to minimize the' public's exposure.
Furthermore, th.is information is necessary for assessing the
- adequacy of the plant (design, construction, analysis, licensing, operating procedures, ope.rators, emergency response, etc.).
Aoproach and Resources Review the accident chronology, plant and offsite dosimetry data, plant operating data (logs, process computer output).
Interviews t
with plant operating staff and emergency response personnel from NRC, and B&W, and others will be necessary.
, Some analyses may be necessary to construct time-release and equipment histories.
(Infonnation from item II-3 (design parameters for key equipment and systems) will be required to accomplish this task.
The estimated manpower required to complete this task is 2-4 man-weeks, plus 2-4 contractor man-weeks.
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ikker te Significant alternative courses of action that the operators s
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could have taken and their projected outcomes.
e Objective provide delineation and provide analyses of the events that would have ensued if the operators had taken actions other than the ones they did.
Such analyses are necessary to make a determination of "how close TMI-2 was to a disaster," as well as "how much additional margin TMI 2 had." These determinations will be important in revealing weak and strong points in plant design and operation.
This information is required for identifying deficiencies in plant design, or plant design requirements, and is also necessary to satisfy questions raised by Congress and the public on "how close were we?",as well as "how much margin did we have?"
Aporoach and Resources This task will require careful examination of the chronology, plant logs, interviews with utility, B&W, Burns & Roe, NRC, and contractor personnel.
Some computer analysis might be necessary (cither by NRC or contractors).
Present plans are for examining the most important alternate scenarios - e.g., to go on RHR, keep the primary system pumps on early in the accident, isolate contain-ment, etc.). The number of such scenarios is presently estimated at about a dozen.
The estimated manpower to complete this task is 3-5 manweeks by the special incuiry staff and a comparable amour.t of contractor support.
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HL0rnstein 5/29/79 N - Alternative events
]([y[T Objective Provide delineation and provide analyses of the events that would have ensued if key equipment or systems that were available were lost (e.g., loss of offsite power during thunderstorm, loss of control room habitability, inability to isolate containment, etc.)
Such analyses are necessary to reveal the weak and strong points in plant design and also are important in determining the adequacy of NRC's licensing requirements.
Approach and Resources The task will require examination of the chronology and may require c
some computer analysfs (either by NRC or contractors).
The number of alternative events is presently estimated at about The. estimated manpower to complete this task is 3 to 5 (?) man-weeks by the special inquiry staff and man-weeks of contractor support.
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Task 6 Imoact of Communications on the Event Objective Detemine the impact on the chronology that occurred of communict.tions between the operating crew and others (utility management, NRC staff, B5W, and others). This will involve detemining what communications were received and sent by the operating crew, when, and with what result.
Approach and Resources This task will require examination of the plant log, of interviews with the operating crew, and of other relevant material. The aim will be to discover major decision points that were reached by the crew, and the role of comnunications influencing those decisions. Only the most important decisions will be studied in depth (perhaps a dozen in number).
It may be necessary to conduct interviews to accomplish this task's objective, but these interviews are probably only supplemental to interviews conducted for other purposes.
The estimated required manpower to complete this task is two to four man-weeks.
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Task 7 Evaluation of Adequacy of Plant Design, Operation, and Emergency Response Objective Based upon the facts gathered in the earlier tasks, this task will provide an evaluation of a number of items closely linked to those facts. Among these are:
1.
Design adequacy to respond to feedwater transients and related accidents.
2.
Instrumentation requirements.
3.
Operator training and procedures.
4.
Adequacy of NRC licensing and operational review.
5.
Comunication adequacy.
6.
Qualification requirements of equipment.
7.
Degree of-reliance on non-safety-grade or non-qualified equipment.
Approach and Resources This evaluation will rely in part on work now unde way by the NRC staff, by the utility, by EPRI, by B5W, and by the ACRS. This on-going work will be subjected to critical review and will be supplemented and compiled into a coherent set of adequacy evaluations.
It is estimated that the completion of this task will require at least 25 man-weeks of effort, mostly by the same staff that will have worked on the earlier tasks. The 25 man-week estimate might be an underestimate, but it is thought not by a factor of two.
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