ML19256G194
| ML19256G194 | |
| Person / Time | |
|---|---|
| Site: | Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png |
| Issue date: | 12/18/1979 |
| From: | Counsil W CONNECTICUT YANKEE ATOMIC POWER CO. |
| To: | Ziemann D Office of Nuclear Reactor Regulation |
| References | |
| TASK-03-08.C, TASK-3-8.C, TASK-RR NUDOCS 7912270589 | |
| Download: ML19256G194 (2) | |
Text
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CONNECTICUT YANKEE AT O M IC POWER COMPANY Dec ember 18, 1979 Docket No. 50-213 Director of Nuclear Reactor Regulation Attn:
Mr. D. L. Ziemann, Chief Operating Reactors Branch #2 U. S. Nuclear Regulatory Commission Washington, D. C.
20555
Reference:
(1)
D. L. Ziemann letter to W. G. Counsil dated November 13, 1979.
Gentlemen:
Haddaa Neck Plant SEP Topic III-8.C Irradiation Damage, Use of Sensitized Steel and Fatigue Resistance In Reference (1), the NRC Staff transmitted the draf t evaluation of SEP Topic III-8.C, and requested review of this material. CYAPCO's review has determined that the following portion of the evaluation, concerning brazes on the control rod " spider", requires revision to maintain factual correctness:
"The breakage of the control rod cluster assembliea was traced to a manufacturing defect.
In each case, the break occurred in a brazed joint which connectc a vane, from which control rods are suspended, to a central hub called a spider. The brazed joint in one assembly was examined in detail in a hot cell and found to have no braze material inside the joint, probably due to improper cleaning of the joint prior to brazing.
The second failed joint had a similar appearance.
It is not feasible to inspect these joints on all control rod assemblies for brazing deficiencies but all joints were visually inspected to verify the integrity of the assemblies before the reactor was re-started.
Only two such joints have failed in all the operating reactors and there is no evidence that this condition is nrevalent in these assemblies."
The last sentence in this paragraph should be deleted, and revised as follows:
In November,1977, a third vane to hub failure was discovered on a RCCA. The mode of failure was concluded to be a poor braze bond between the vane and hub an experienced in earlier failures.
1642 041 7912270 N
Cubsequent to these failures and similar failures experienced by other operating reactors, the manufacturer has revised its manufacturing and testing processes to assure that a quality braze is obtained at each vane to hub joint.
There is no evidence that this condition is prevalent in these assemblics."
All other information is correct as, ritten.
We trust you find the above information responsive to your request.
Very truly yours, CONNECTICUT YANKEE ATOMIC POWER COMPANY Il181A~
W. G. Counsil Vice President i642 042