ML25196A196
| ML25196A196 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 06/17/1977 |
| From: | Bender M Advisory Committee on Reactor Safeguards |
| To: | Rowden M NRC/Chairman |
| References | |
| Download: ML25196A196 (1) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION ADVISORY COMMITTEE ON REACTOR SAFEGUARDS WASHINGTON, D. C. 20555 Honorable Marcus A. Rowden Chairman U.S. Nuclear Regulatory Commission Washington, D.C.
20555 June 17, 1977
SUBJECT:
REPORT ON THE ZION STATION, UNITS 1 AND 2
Dear Mr. Rowden:
During its 206th meeting, June 9-10, 1977, the Advisory Committee on Reactor Safeguards continued its review of the operation of the Zion Station, Units 1 & 2.
The Committee had previously discussed operation of the Zion Station in its reports of August 17, 1972, May 17, 1973, December 9, 1974, and June 9, 1976.
A Subcommittee meeting was held in Kenosha, Wisconsin, on May 17, 1977, following a tour of the station by Committee members.
During its review, the Committee had the benefit of discussions with representatives of the Commonwealth Edison Company (Licensee), Westinghouse Electric Corporation, and the Nuclear Regula-tory Commission Staff.
The Committee also had the benefit of the docu-ments listed.
In its June 9, 1976 report, the Committee identified ten unresolved mat-ters that should be dealt with in a timely fashion if the Zion reactors are to continue to be operated at full power over the lifetime of the plant.
The ten matters identified are as follows:
(1) A review of the entire Station for systems interaction that might lead to significant degradation of safety.
(2) A review of the Station with regard to differences from current criteria, and judgments concerning possible back-fitting requirements.
(3) The implementation of instrumentation to provide early information concerning the course of a full range of postulated serious accidents, and procedures for inter-preting and relating this information to emergency plans.
(4) Installation of a loose-parts monitoring system as soon as practicable.
(5) Evaluation and prompt implementation of improvements in fire protection capability, as necessary.
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Honorable Marcus June 17, 1977 (6)
Timely implementation of modifications required in connec-tion with the resolution of ATWS.
(7)
Continued studies directed to enhancement of the capability and reliability of the Emergency Core Cooling Systems.
(8)
Demonstration of the reliability of the diesel generators to operate with load for extended periods of time.
(9)
Assessment of the safety significance of the large number of reportable events experienced at the station, and prompt implementation of significant improvements in operational quality assurance.
(10)
Prompt implementation of improvements in industrial security as appropriate.
The current status of these items was the principal matter of this latest review of the Zion Station.
The Committee believes that little progress has been made toward res-olution of item 1.
Discussion with the Licensee and the NRC Staff suggests that this has been the result, at least in part, of a lack of understanding by the Licensee and the NRC Staff of just what is meant by "systems interaction." In this respect the Committee calls attention to its letter of November 8, 1974, to L. Manning Muntzing, Director of Regulation.
The Committee recommends that, within nine months, the Licensee submit to the NRC Staff, as a minimum, the results of a study of systems interaction relating to the possibility that failure of safety and non-safety systems wi 11 interfere with the pl ant operators 1 ability to accomplish shutdown heat removal, together with a plan and schedule for studies of other system interactions of potential safety significance to the Zion Station.
With respect to item 2, for which little has been done, the Committee recommends that, during the next twelve months, the Licensee review the Zion Station for possibly significant differences from current criteria, and that the NRC Staff evaluate this review and report to the ACRS its conclusion concerning possible backfitting requirements.
The Committee wishes to review the status of items 1 and 2 within the next eighteen months.
Items 3, 5, 6, 7, and 10 are considered by both the ACRS and the NRC Staff to be unresolved matters generic to all operating light water 1882
Honorable Marcus June 17, 1977 reactors.
During the past twelve months, some progress has been made toward the resolution of these generic items and in the planning for the application of appropriate solutions to the Zion Units.
The Com-mittee recommends that the NRC Staff and Licensee urgently seek means to expedite solutions to outstanding generic items and the implementa-tion of solutions, when feasible, to the Zion Station.
The Licensee has made a commitment to install loose-parts monitoring systems on the two Zion Station reactors during the 1978 refueling out-ages.
The NRC Staff considers item 4 resolved.
The Committee concurs.
In response to item 8, one of the diesel generators was run continuously for seven days at a controlled power output equivalent to the ECCS load.
Where-a~ the unit ran satisfactorily during this period, the significance of the test results in confirming the capability of the emergency power system to perform its intended functions was obscured when, on the seventh day, an operator error led to a large surge in the load and the destruction of the generator by fire.
The generator failure was the result of an unanticipated interaction between the main electrical power generating system, the emergency power system, and the loads they were sharing.
This unexpected result increases the urgency for a review of the entire station for interactions between electrical generation, distribution, consumption, and control systems that might lead to signi-ficant degradation of safety.
The Committee recommends that this phase of the review (item 1) be given particular attention.
The Committee wishes to be kept informed.
The Licensee has, in response to concerns expressed by the NRC Staff, rewritten his operating procedures, expanded employee training programs, and organized as part of the Quality Assurance program, two independent audit groups:
one group to verify procedural compliance and to audit work in progress, and the other group to identify and resolve problems promptly.
The NRC Staff has also issued amendments to the Zion license which revise the entire administrative control section of the Technical Specifications.
The Committee concludes that these actions of the NRC Staff and Licensee are responsive to item 9 and encourages the Licensee to continue to seek further improvement in these areas.
The Advisory Committee on Reactor Safeguards believes that, if due regard is given to the items mentioned above, there is reasonable assurance that the Zion Station Units 1 and 2 can continue to operate at full power, 3250 MWt, without undue risk to the health and safety of the public.
Sincerely,
/s/ M. Bender M. Bender Chairman 1883
Honorable Marcus June 17, 1977 References
- 1.
Report to the ACRS by the Office of Nuclear Reactor Regulation, U. S. Nuclear Regulatory Commission in the Matter of Commonwealth Edison Company Zion Station, Units 1 and 2, dated April 22, 1977.
- 2.
Supplement to the Report by the Office of Nuclear Reactor Regulation, NRC, to the ACRS concerning Zion Station, Units 1 and 2, dated June 8, 1977.
- 3.
Letter from Commonwealth Edison Co. to the Office of Nuclear Reactor Regulation, NRC concerning installation of a loose parts monitoring system, dated January 1, 1977.
- 4.
Letter from Commonwealth Edison Co. to the Office of Nuclear Reactor Regulation, NRC, concerning information on gaseous releases from Zion Station, dated April 1, 1977.
- 5.
letter from Commonwealth Edison Co. to the Office of Nuclear Reactor Regulation, NRC, concerning a summary of the diesel generator test, dated April 6, 1977.
- 6.
letter from Commonwealth Edison Co. to the Office of Nuclear Reactor Regulation, NRC, concerning a report on fire protection, dated April 29, 1977.
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