NUREG-0600, 11-14-79 NUREG-0600 Investigation Into the Three Mile Island Accident by Office of Inspection and Enforcement
| ML25195A208 | |
| Person / Time | |
|---|---|
| Issue date: | 11/14/1979 |
| From: | Carbon M Advisory Committee on Reactor Safeguards |
| To: | Hendrie J NRC/Chairman |
| References | |
| Download: ML25195A208 (1) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION ADVISORY COMMITTEE ON REACTOR SAFEGUARDS WASHINGTON, D. C. 20555 November 14, 1979 Honorable JoseP1 M. Hendrie Olairman
- u. s. Nuclear Regulatory Commission Washington, D.C. 20555
SUBJECT:
NUREXHl600 *INVESTIGATION INTO THE MARCH 28, 1979 THREE MILE ISIAND ACCIDENT BY OFFICE OF INSPECTIOO AND ENFORC.EMEN'r-
Dear Dr. Hendrie:
During its 235th meeting, November 8-10, 1979, in accordance with the Com-mission's request, the }..dvisory Committee on Reactor Safeguards canpleted its review of NUREG-0600.
The report was also discussed at a Subcommittee meeting in Washington, D. C. on October 30, 1979. During its review the Conmittee had the benefit of discussions with the Nuclear Regulatory Com-mission (NRC) Inspection and Enforcement (I&E) Staff, am of comments from the licensee.
The stated scope of NUREG-0600 is limited to investigation of the licensee's operational actions prior to am during the course of the accident, and his actions to control release of radioactive materials and to implement his emergency plan during the course of the accident. Consistent with this limi-tation, emphasis is placed on departure from Technical Specifications prior to the accident and departure from the licensee's procedures during the course of the accident, with little consideration of other factors.
Other investigations and other NRC task force studies have considered not only the actions taken by the licensee, but also other facets of the acci-dent, inclooing peculiarities of the nuclear steam supply system that tended to inhibit recovery or to confuse the operators by leading to pressure aoo level conditions not anticipated by the written procedures, and deficiencies of the control room and system design that degraded the quality of informa-tion available to the operator..Additional details not in NUREG-0600 can be fotmd, for example, in a report entitled "Analysis of Three Mile Island Unit 2 Accident* (NSAC-1, July 1979) prepared by the Electric Power Research In-stitute, Nuclear Safety Analysis Center.
NURPX;-0600 inclooes a factual chronology with event descriptions, and a fim-ing of operational and administrative shortcomings and errors. It concludes (Appendices IB aoo IIF) that a total of 36 items of potential operational or administrative noncompliance existed. The Office of Inspection and En-forcement subsequently, by letter of October 25, 1979 to Metropolitan Edison Company, imposed fines for seventeen violations, infractions and deficiencies, many of them multiple occurrences.
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Honorable Josep, M. Hendrie 2 -
November 14, 1979 Because the limited scope of the report tends to lead to a catalog of viola-tions with only limited recognition of other factors that contributed to er-rors by the operators, the Committee has some concern that it may be con-cluded from the charges of failure to follow accident procedures that such failure is automatically a violation.
Accident procedures are prepared by the licensee aoo are not approved by NRC, but the licensee is required to follow them. The Committee believes that an accident procedure cannot be sufficiently detailed to encompass every possible sequence of events, and that it must be based on the assump-tion that a particular set of conditions exists; a deviation from this set of conditions may make it necessary to depart from the procedure.
As an example, 'IMI-2 Emergency Procedure 2202-1.3 (Loss of Reactor Coolant/Reactor Coolant System Pressure) which is referred to in NUREX;-0600, is believed by the Committee to include confusing symptoms and instructions for the case of a loss of reactor coolant at the top of the pressurizer. Likewise 'IMI-2 E;mergency Procedure 2202-1.5 (Pressurizer System Failure) which calls for pressurizer level control is believed to be unacceptable for the 'IMI-2 ac-cident or for any other loss of reactor coolant at the top of the pressuri-zer. The question, therefore, arises whether an operator, using his best jmgment, is guilty of a violation if he consciously takes an action that is at variance with procedures which in themselves may contain confusing or in-correct guidance. The Committee believes that, if so, this is the wrong approach to protecting the health and safety of the public during an emer-gency and that the operator, guided by the written procedures, his training, and available technical advice, should be allowed to use his best judgment to deal with the problem. His judgment will obviously be subject to post-factun appraisal.
The Committee has found this report less than satisfactory, and its title misleading, chiefly because of limitations in its predefined scope.
For this reason, the Committee recommends the preparation and issuance of a sumnary report that consolidates and integrates the findings of the several NRC Task Forces that have investigated and reported on this accident.
Sincerely, 0:t~~
Olairman 1674