ML19224A868
| ML19224A868 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 06/01/1979 |
| From: | Mattson R Office of Nuclear Reactor Regulation |
| To: | Cornell K NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO) |
| References | |
| NUDOCS 7906070126 | |
| Download: ML19224A868 (2) | |
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JUN 1 1979 m.
MEMORANDUM FOR:
Kevin Cornell, Deputy Executive Director for Operations FROM:
Roger J. Mattson, Director Division of Systems Safety
SUBJECT:
ENGINEERING EVALUATIONS OF THE TMI-2 ACCIDENT Although the observed responses of the systems at the Three Mile Island Unit 2 plant during the accident are now generally understood, quantitative engineering evaluations are still necessary to confirm this qualitative understanding and investigate some aspects of the accident that are not completely understood. These engineering evaluations include the usual areas of nuclear engineering; thermal and hydraulic analysis of the reactor system, core physics, fuel performance, containment response, radioactive source tenns and dose detemination. Attached, as an example of the type of evaluations that are needed, is a detailed description of the thermal-hydraulic analyses of the reactor coolant system that are needed. The specific analyses that may be required in the other areas are being developed. Many of these evaluations are beyond the detailed calculational capabilities of the NRC and would have to be done by the national laboratories or other contractors.
- Further, the resource limitations in NRC at this time argue in the direction of using contractors. The Division of Reactor Safety Research would be the likely candidate for administering such contracts.
Since your investigation and our Lessons Learned Task Force need these evaluations, some coordination is required. Therefore I request that representatives from both our groups meet to identify the evaluations that are needed, assign some priority to each, and initiate requests for the perfonr.ance of these evaluations.
Roger t on, Di DivisionofSystemsS(ector hfe ty Attachment cc:
R. Minogue, SD V. Stello, NRR E. Case, NRR J. Davis, IE H. Denton, NRR S. Levine, RES R. Boyd, NRR R.
.R F. Schroeder, NRR 790ce70 % 169 061
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ENGINEERING EVALUATIONS OF THE TMI 2 ACCIDENT REACTOR SYSTEMS s
Using a systems computer code, such as TELAP, model the TMI-2 accident to provide a simulation of observed parameters. This Benchmark model can the:i be used to investigate or confirm the following aspects of the accident which are listed in order of priority.
1.
Determine the mass inventory and distribution within the reactor coolant system for the full course of the accident, if possible, but at least until the time of core heat-up. This analysis should also provide a plausible answer to the question of what was the rate and source of fluid loss (e.g., the PORV and letdown flow) and gain (e.g., the HPI).
2.
Determine the limiting conditions (primarily system void fraction) at which reactor coolant pump operation would provide adequate core cooling.
3.
Determine the source of the underestimate of coolant temperature during the first one tp two minutes as shown by early predictions.
4.
Provide estimates of coolant density distribution throughout the reactor system for use in other analyses of neutron flux readings during the accident and for future use in evaluation of methods for measuring reactor vessel water level.
5.
Determine the likely hydraulic conditions in the core for use in evaluations of fuel damage and metal-water reactions.
6.
Determine the effectiveness of the steam-generators during the various phases of the accident, including confirmation that the observed water level and inferred main and auxiliary feedwater flow and steam flows are consistent with the observed response.
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