ML20036A819
| ML20036A819 | |
| Person / Time | |
|---|---|
| Site: | Fort Saint Vrain  |
| Issue date: | 05/07/1993 |
| From: | Crawford A PUBLIC SERVICE CO. OF COLORADO |
| To: | Joseph Austin NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| Shared Package | |
| ML20036A820 | List: |
| References | |
| P-93045, NUDOCS 9305170049 | |
| Download: ML20036A819 (3) | |
Text
c O Public Service' EOh.
P O BOX 840 DENVER CO 80201-0B40 May 7,1993 Fort St. Vrain A. Clegg Crawford Unit No. I Vee President Electric Producton P-93045 r
U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555 ATrN:
Mr. John H. Austin, Chief Decommissioning and Regulatory Issues Branch Docket No. 50-267
SUBJECT:
Proposed Amendment to Decommissioning Technical Specifications i
Dear Mr. Austin:
This letter submits Public Service Company of Colorado's (PSC's) proposed change to Design Feature 4.3 of the Fon St. Vrain (FSV) Decommissioning Technical Specifications (DTS), to facilitate removal of core outlet coolant thermocouple assemblies. Design Feature 4.3 currently requires that penetrations in Fort St. Vrain's Prestressed Concrete Reactor Vessel (PCRV) be sealed by welding or by installing blind flanges, to protect against leakage of shield water.
There are seven PCRV penetrations that provide access to core outlet coolant thermocouple assemblies.
PSC originally intended to remove the thermocouple assemblies through these penetrations and then install blind flanges, before shielding water was introduced into the PCRV. However, radiation levels from the thermocouple assemblies were too high for removal through the penetrations, and it was decided to remove them underv>ater.
The underwater uermocouple removal method chosen by PSC's decommissioning contractor is described and illustrated in the attached No Significant Hazards Consideration Evaluation (Attachment 3). In general, the thermocouple assemblies will be pushed into the PCRV cavity, by use of a push-rod assembly through the penetration.
Inside the PCRV cavity, the thermocouple assemblies can be handled underwater with long-handled tools. During use of the push-rod assembly, the penetration blind flanges d this requires a revision to Design Feature 4.3.
must be v
/F 9305170049 930507 DR ADOCK 05000267 l
~
P-93045 May 7,1993 Page 2
]
~
PSC proposes to revise the requirements of Design Feature 4.3 to allow the core outlet coolant thermocouple penetration blind flanges to be removed, one at a time, during l
underwater removal of the thermocouple assemblies. While blind flanges are removed, shield water leakage will be prevented by redundant shaft seals 'on the push-rod j
assemblies. Blind flanges will be installed before and after the thermocouple assembly l
removal process, which is expected to be completed within eight hours per penetration.
l PSC's proposed change to Design Feature 4.3 is described in the following attachments:
, - Summary of Proposed Change f
. - Proposed Change
- - No Significant Hazards Consideration Evaluation I
PSC has determined that the proposed change to Design Feature 4.3 involves No
[
Significant Hazards Consideration, as described in 10 CFR 50.92. Further, PSC i
considers that the consequences of postulated PCRV shield water leakage during use of push-rods are substantially less than the worker doses that would result from removal of the 200 R/hr thermocouples externally through the PCRV penetrations. Approval of this proposed DTS amendment is consistent with PSC's efforts to keep worker radiation exposures as low as is reasonably achievable.
t PSC requests NRC approval of the attached proposed Decommissiomng Technical Specification amendment as soon as is reasonably possible, to support thermocouple removal activities that are currently planned for the third quarter of 1993.
i If you have any questions concerning this submittal, please contact Mr. M. H. Holmes f
at (303) 620-1701.
j Very truly yours, l
A. Clegg Crawford
(
Vice President Electric Production i
i ACC/SWC
{
Attachments i
f J
a
1 i
P-93045 May 7,1993 Page 3 I
cc:
w/ attachment Regional Administrator, Region IV Mr. Ramon E. Hall, Director Uranium Recovery Field Office j
Mr. Roben M. Quillin, Director f
Radiation Control Division -
i Colorado Department of Health l
i i
f i
h i
t i
f I
f f
i 9
=
r
.,