ML20098B381
| ML20098B381 | |
| Person / Time | |
|---|---|
| Site: | Fort Saint Vrain  |
| Issue date: | 09/07/1984 |
| From: | Gahm J PUBLIC SERVICE CO. OF COLORADO |
| To: | Jay Collins, Johnson E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| References | |
| P-84341, NUDOCS 8409260060 | |
| Download: ML20098B381 (2) | |
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Unit #1 SEPI4B8g P-84341 l
M Mr. John T. Collins Regional Administrator U. S. Nuclear Regulatory Commission 611 Ryan Plaza Drive Suite 1000 Arlington, TX 76011
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ATTN: Eric Johnson
SUBJECT:
Existing Condition on the Fort St. Vrain Refueling Floor
Dear Mr. Johnson:
This letter is to provide you with a description of a situation at Fort St.
Vrain that has temporarily delayed control rod drive refurbishing efforts.
This situation was discussed with you and Phil Wagner during a telecon on September 4, 1984.
While removing a control rod drive and orifice assembly (CRDOA) from Region 7 for maintenance, a motor over-current condition on the auxiliary transfer _ cask (ATC) shutters occurred, preventing their full closure. Work was discontinued, and an investigation of the possible causes began.
The ATC shutters were opened, and an attempt to lower and reinstall the CRD0A into the core was made.
The mechanism could not be completely seated in the penetration, so the CRDOA was again withdrawn from the core into the ATC. Once this was completed, a radiation survey was performed around the ATC.
This indicated an abnormal radiation profile for a fully retracted control rod pair in the ATC, introducing the possibility that the control rod (s) were not fully retracted. The ATC shutter drive shafts were removed, and a borescope was inserted for visual examination. These examinations revealed that one of the two control rod strings was not fully retracted.
8409260060 840907 PDR ADOCK 05000267
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. 'Af special-test
.was-conducted on September 5,
1984, with Messrs. 'Chaney and Plumlee of the NRC on site and cognizant.
This test'. involved lifting the_ ATC approximately 4 inches to verify t
.borescope observations ~and.to obtain radiation level data.
Video tape taken during the test revealed that indeed only one control rod string was not fully' retracted.
Radiation levels at the circumference - of the ATC were on the -order of 5 R/hr.
This corresponds.to approximately 80 R/hr at one foot from the control rod
-string.
A11'CRD0A work has been discontinued until it is established that the CRD0A can be removed from the reactor in accordance with Fort St.
Vrain licensing requirements and without causing unnecessary health hazards to plant personnel.
As :always, Public Service Company will keep the Nuclear Regulatory Commission abreast of the existing conditions.
If you have any questions please contact Mr. Chuck Fuller, of my staff, at (303).785-2224, extension 202.
Sincerely,
/J. W. Gahm Manager, Nuclear Production JWG/dkh-
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