ML19309B571
| ML19309B571 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 03/28/1980 |
| From: | Counsil W NORTHEAST UTILITIES |
| To: | Ziemann D Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8004040306 | |
| Download: ML19309B571 (2) | |
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i March 28, 1980 Docket No. 50-2h 5 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:
D. L. Ziemann letter to W. G. Counsil dated January 11, 1980.
Gentlemen:
Millstone Nuclear Power Station, Unit No.1 Control Rod Insertions The referenced letter requested information on control rods failing to fully insert after a scram and a summary of other control rod drive malfunctions for the period January 1,1978 to December 31,1979 The following table provides the requested data for this period:
Date of Scram Control Rods Not Fully Inserted March 10,1978 None May 19, 1978 None May 29, 1978 None July 14, 1978 None December 12, 1978 06-31, 14-35, 14-39, 22-15, 22-19, 22-27, 26-31, 26-35.
Position 02 January 6, 1979 None January 17, 1979 06-31, 14-35, 14-39, 18-31, 22-19, 22-23, 22-27, 26-31 Position 02 January 25, 1979 None February 26, 1979 06-31,14-35,1h-39, 22-15, 22-19, 22-27, E6-31. Position 02 800404o 3 p q
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April 28, 1979 06-31, 22-15, 22-19, 22-27, 14-35, 14-39, 22-23, 26-43, 42-35 Position 02 December 19, 1979 26-03, Position 02 December 21, 1979 None At various times during 1978 and 1979, thirteen different control rods did not fully insert after a reactor scram. Twelve of these rods were overhauled during the May/ June, 1979 Refueling Outage. The thirteenth rod, Number 26-03, failed to fully insert after the 1979 refueling.
If this control rod continues to not fully insert after a reactor scram, it will be overhauled during the Fall,1980 refueling. The insertion to the "02" position can generally be attributed to leakage past the stop piston seals, which is corrected by the overhaul of the CRD during refueling outages.
A significant event occurred to one control rod drive, Number 22-07, when it was unable to insert or withdraw from Position h6. This event was reported as LER 79-04/3L on June 14, 1979 The control rod drive was overhauled during the 1979 refueling. It was discovered that the guide cap was jammed over the index tube at a position corresponding to the point at which the control rod had become inoperable. Further inspection revealed a metallic object, part of a broken source holder, vedged between the guide cap and the index tube.
Additional detail of this event can be obtained from LER 79-04/3L.
The plant staff vill continue to maintain records of any further events of this nature.
Very truly yours, NORTHEAST NUCL ENERGY COMPf.NY
/
W7 G. Counsil Vice President
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