ML20084D777
| ML20084D777 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 12/18/1970 |
| From: | Hoyt H COMMONWEALTH EDISON CO. |
| To: | Morris P US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 8304120334 | |
| Download: ML20084D777 (2) | |
Text
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Regulatory Filo Cy.
Commonwealth Edison Company ONE FIRST NATIONAL PLAZA
- C H I C A G O.
POST OFFICE SOX 747
- C H I C A G O, ILLINOl$ 40490 Dresden Necicar Power Station R.R.#1 Morris, Illinois 60450 December 18, 1970 Dr. Peter A. Morris Director of Division Reactor Licensing U.S. Atomic Energy Commission Washington, D.C.
20545
SUBJECT:
LICENSE DPR-19 DRESDEN NUCLEAR POWER STATION UNIT #2
Dear Dr. Morris:
h is is to report a condition relating to the operation of the station in which Control Rod Drive 26-15 (G-4) would not withdraw past the position 46.
Problem and Initial Action On November 17, 1970 CRD G-4 was re-installed in the reactor after overhaul.
In the sequence of testing that normally follow the re-installation of a CRD, it was discovered that the drive would not retract past position 46, although the travel from positions 00 to 46 was completely normal.
The estimated scram time for 907. insertion was 2.91 seconds.
Drive operation has been normal in all other respects and was therefore left in service.
Investightion and Corrective Action The possible causes of inability to withdraw beyond position 46 was reviewed with General Electric Co.
It was felt that a situation could exist within the c' rive which could result in damage to the drive if additional scrams occurred.
Therefore the drive was declared inoperable and valved out-of-service on December 17, 1970 following Station Review Board review.
The drive cannot be removed during the current otage because it cannot be withdrawn to the backseat position and therefore must be delayed until an outage requiring rc p
removal.
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O Dr. Peter Morris Page 2 December 18, 1970-It is intended to reactivate the drive for withdrawal to position 46 in its regular withdrawal sequence during the next startup and then valve the drive out-of-service so that it will not scram.
It will be considered as an inoperable drive as specified in section 3.3 of the Technical Specifications.
Sincerely,
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H.K. Hoyt
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Superintendent HKH:rh 9
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