ML19289D740
| ML19289D740 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 03/06/1979 |
| From: | Reed C COMMONWEALTH EDISON CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 7903140309 | |
| Download: ML19289D740 (3) | |
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Commonwealth Edison One First National Plaza. Chicago, litanois Address Reply to: Post Office Box 767 Chicago, Illinois 60690 March 6, 1979 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C.
20555
Subject:
Zion Station Unit 2, Cycle 4 Reload NRC Docket No. 50-304
Dear Mr. Denton:
Zion Unit 2 is currently in its third cycle of operation with a refueling outage scheduled to commence on March 10, 1979.
Cycle 3 operation will be terminated within a cycle burnup range of 9800 to 10,800 MWD /MTU.
Startup for Cycle 4 is expected to occur in late April 1979.
This letter is to advise you of Commonwealth Edison Company's review of and plans regarding the Zion Unit 2, Cycle 4 reload core.
The Zion Unit 2, Cycle 4 reload core was designed to perform under current nominal design parameters, Technical Specifications and related bases, and current setpoints such that:
1.
Core characteristics will be less limiting than those previously reviewed and accepted; or 2.
For those postulated incidents analyzed and reported in the Zion Final Safety Analysis Report (FSAR) which could potentially be affected by fuel reload, reanalysis has demonstrated that the results of the postulated events are within allowable limits.
Commonwealth Edison Company per-formed a detailed review at Westinghouse on the bases, including all the postulated incidents considered in the FSAR, of the Westinghouse Reload Safety Evaluation Report (RSER).
Based on this review and the Westinghouse RSER, safety evaluations were performed by Commonwealth Edison On-Site and k
Off-Site Review pursuant to the requirements of 10 CFR 50.59(a) and 10 CFR 50.59(b).
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Commonwealth Edison NRC Docket No. 50-304 Mr. Harold R. Denton: March 6, 1979 The reload fuel mechanical and thermal-hydraulic design for the Cycle 4 reload core is unchanged from that of the previously reviewed and accepted reload designs.
The currentFfH limit of less than 1.55 and penalties for rod bow insure that the DNB ratio remains above 1.30.
In addition, based on the Westinghouse " Eighteen Case" analyses, a total nuclear peaking factor (F ) of 2.17 could occur for the full 9
range of power distributions, including load follow maneuvers, allowable under Constant Axial Offset Control (CAOC).
Therefore, in order to accommodate the current Zion Station FQ peaking factor limit of 1.86 axial power distribution monitoring type surveillance will be utilized for power levels above 85.7% of rated power.
As in the past, the reload safety evaluation relied on previously reviewed and accepted analyses reported in the FSAR, fuel densification reports and previous reload safety evaluation reports.
A detailed review of the core characteristics was performed to determine those parameters affecting the postulated accident analyses reported in the Zion FSAR.
For those incidents whose consequences could potentially be affected by the reload core characteristics, the incidents were re-analyzed.
Commonwealth Edison verified that the reanalyses were performed in accordance with the Westinghouse reload safety evaluation methodology as outlined in the March 1978 Westinghouse topical report entitled " Westinghouse Reload Safety Evaluation Methodology" (WCAP-9272).
Commonwealth Edison also verified that the results of these reanalyses were within previously reviewed and accepted limits.
The relcad safety evaluation demonstrated that Technical Specification changes are not required for operation of Zion Unit 2 during Cycle 4.
Commonwealth Edison On-Site and Off-Site Review concluded that no unreviewed safety questions as defined by 10 CFR 50.59 are involved with this reload.
More specifically with this reload:
1.
There is no increase in the probability of occurrence or the consequences of an incident or malfunction of equipment important to safety previously evaluated in the safety analysis report; 2.
No additional accident or malfunction of a different type than any evaluated previously in the safety analysis reported has been created; and
Commonwealth Edison NRC Docket No. 50-304 Mr. Ilarold R.
Denton: March 6, 1979 3.
There has been no reduction in the margin of safety as defined in the basis for any Zion Unit 2 technical specification.
Therefore, based on this review application for mmendment to the Zion Unit 2 operating license is not required.
Finally, verification of the reload core design will be performed per the standard startup physics tests normally performed at the start of each Zion reload cycle.
These tests will include, but not be limited to:
1.
Control rod drive tests rnd drop time; 2.
Critical boron concentration measurements; 3.
Control rod bank worth measurements; 4
Moderator temperature coefficient measurement; 5.
Power coefficient measurement; and 6.
Startup power distribution measurements using the incore flux mapping system.
Very truly yours,
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Cordell Reed Assistant Vice-President