ML19340A929
| ML19340A929 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 04/28/1965 |
| From: | Boyd R US ATOMIC ENERGY COMMISSION (AEC) |
| To: | |
| Shared Package | |
| ML19340A928 | List: |
| References | |
| NUDOCS 8009080626 | |
| Download: ML19340A929 (2) | |
Text
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SAFETY EVALUATION BY THE RESEARCH AND POWER REACTOR SAFETY BRANCH DIVISION OF REACTOR LICENSING IN THE MATTER OF 0
COMMONWEALTH EDISON C04PANY d
DOCKET No. 50-10 PROPOSED CHANCE NO. 11 - TYPE PF-10 FUEL ELEMENT, MODIFIED Introduction By application dated April 14, 1965, Commonwealth Edison Company has requested that Appendix "A" of License DPR-2 be amer.ded to authorize operation of the Dresden reactor with a modified Type PF-10 fuel assembly. The proposed modifi-cation consists of removing a single fuel rod from the presently authorized PF-10 asse=bly for isotopic and metallographic examination.
Dis cus s ion The Type PF-10 fuel assembly is an experimental assembly consisting of an 8 x 8 rod configuration with 55 regular rods and 9 special corner rods.
The proposed change involves removing a rod from the central region of the bundle by cutting the 4 webs of the upper tie plate, thus permitting the selected rod and its associated section of the upper tie plate to be removed from the fuel bundle.
The effect of the absence of this rod on fuel performance has been estimated by Commonwealth Edison to be an increase in local power peaking of 10 percet.t in the rods adjacent to the removed rod.
However, even with this increased peaking, the flux peak at these rods does not exceed the peak in the corner rods of the assembly.
The renoval of one rod also causes some bypassing of the flow from the other rods in the assembly. The reduction in flow has been conservatively calculated by Commonwealth Edison to be approximately 10 to 15 percent, resulting in a change in burnout ratio from 3.1 to 2.85 at 125 i
percent of the rated power.
In our opinion, the results of these calculations appear to be a conservative estimate of the performance of the altered fuel bundle and we have concluded that the PF-10 performance will remain well within that specified in the License.
Other characteris tics of PF-10 do not significantly effect the nuclear or thereal perfornssce o f the reactor core and thus any minor alterations of the assembly have a negligible effect on reactor performance.
The only other item of concern in our evaluation of the proposed _ change was to assure that the mechanical integrity of the remainder of the bundle would not be adversely effected by cutting and removal of part cf the upper tie plate. Co=monwealth Edison will inspect the region of alteration, i.e. the upper tie plate, with an underwater borescope to verify its mechanical soundness.
This operation will be conductec in the spant fusi s torage pool where similar operations have been conducted.
We believe. that this inspection should serve to indicate the suitability of the fuel asse=bly for reinsertion in:o the core.
8009080 h g
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.l Technical Specifications To provide authorization of Proposed Change No. 11, the Technical Specifica-tions of License No. DPR-2 should be amended by addition of a paragraph to Section B.2 as follows:
"It shall be permissible to remove one of the fuel reds from fuel assembty PF-10 for the purpose of isotopic and metallegraphic examination. The assembly may then be operated with the remaining 63 fuel rods."
Conclusion Based upon our review of the information submitted, we have concluded that operation of the reactor in accordance with the proposed change does not involve significant hazards considerations not described or implicit in the hazards summary report and that there is reasonable assurance that the herith and safety of the public will not be endangered.
Accordingly, we believe that the Technical Specifications of License No.
DPR-2 should be revised as indicated above.
Odginal signed by-Roger S. Boyd Roger S. Boyd, Chief Research & Power Reactor Safety Branch Division of Reactor Licensing 28 E Date:
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