ML19345A399
| ML19345A399 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 09/29/1966 |
| From: | Boyd R US ATOMIC ENERGY COMMISSION (AEC) |
| To: | |
| Shared Package | |
| ML19345A396 | List: |
| References | |
| NUDOCS 8011210296 | |
| Download: ML19345A399 (2) | |
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SAFETY EVALUATION BY THE RESEARCH AND POWER REACTOR SAFETY BRANCH DIVISION OF REACTOR LICENSING IN THE MATTER OF YANKEE ATOMIC ELECTRIC CCMPANY PROPOSED CHANGE No. 73 DOCKET NO. 50-29 Introduction Pursuant to the provisions of Section 50.59 of the Commission's regulations,
Yankee Atomic Electric Company in Proposed Change No. 73, dated August 31, 1966, requested authorization of a change to the Technical Specifications attached as Appendix A to License No. DPR-3.
The proposed change would authorize the installation of twenty-four inconel-clad, silver-indium-cadmium (Ag-In-Cd) control rods with zircaloy follower sections that are welded to the control rods.
This change was requested to provide a control rod design that would preclude inadvertent disassembly of the follower section unde certain reactor shutdown conditions.
Discussion The Yankee control system contains 24 control rods that are cruciform in shape and contain zircaloy follower sections. The current compicment of control rods consists of 20 hafnium rods, two inconel-clad Ag-In-Cd rods, and two stainless steel clad Ag-In-Cd rods. Yankee has proposed to replace these rods with 24 new inconel-clad Ag-In-Cd control rods. The physical dimensions and reactivity worth of these control rods are essentially identical to those currently in Two inconel-clad Ag-In-Cd control rods have been in service during se rvice.
Cores III, IV, and V and inspections during refueling shutdowns have indicated no problems with respect to mechanical wear and corrosion.
The replacement control rods will have follower sections that are welded to the I
absorber sections. The current design contains a snap joint that connects the absorber to the follower section by rotation about the vertical axis. Yankee has reported that inspection of the two control rods removed during the 1965 This wear refueling indicated that some wear of the snap joint has occurred.
could allow the follower section to rotate and fall from the absorber during refueling operations when the upper core suppor t plate is removed. However, l
such separation could not occur during reactor operation since relative l
rotation suf ficient. to permit separation of the two sections is precluded by the The use of follower sections that are welded to the internal core structure.
l absorber sections will prevent inadvertent disassembly of the control rods even l
during the refueling operation.
In this respect we believe that the safety of i
reactor operations will be improved by the use of the proposed control rods.
80112102 9 6 I
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k 2-Conclusion We have concluded that the proposed change does not present significant hazards considerations not described or implicit in the hazards summary report, and that.there is reasonable assurance that the health and safety of the public will not be endangered.
Orignal Sig'ed by D. R. Mutter c" Roger S. Boyd, Chief Research & Power Reactor Safety Branch Division of Reactor Licensing Date:
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