ML20246E553
| ML20246E553 | |
| Person / Time | |
|---|---|
| Site: | Fort Saint Vrain  |
| Issue date: | 08/24/1989 |
| From: | Brey H PUBLIC SERVICE CO. OF COLORADO |
| To: | Weiss S NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), Office of Nuclear Reactor Regulation |
| References | |
| P-89329, NUDOCS 8908290186 | |
| Download: ML20246E553 (2) | |
Text
,,
.s; w
.p;.
hPublicl Service-2420'W.'26th Avenue, Suite-100D, Denver, Co. 80211 August 24, 1989
' Fort St. Vrain:
Unit No. 1 P-89329 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk l
Washington, D, C. 20555 ATTN: Mr. Seymour H. ~ Weiss, Director
- Non-Power-Reactor, Decommissioning and Environmental-Project Directorate Docket No. 50-267
SUBJECT:
Review of Commitment to Install Clevis Pins in CRD0As
REFERENCES:
- 1) PSC Letter, Gahm to Johnson, Dated February)3,1985 (P-85046 j
- 2) PSC Letter, Lee to L
Johnson, Dated March 1, 1985 t
(P-85061)
- 3) PSC Phone Call, Holmes to Heitner Dated August 23, 1989
Dear Mr. Weiss:
in early 1985, as a response to the failure to scram of six control rod drives in June of 1984, PSC transmitted a Control Rod Drive and Orifice Assembly (CRD0A) refurbishment plan (Reference 1). The plan had several objectives established as a result of finding chloride j
i stress corrosion cracking on the CRD0A cables and no definitive cause for the failure to scram of the six control rods.
One of those objectives was to replace miscellaneous CRD0A components with like components made from materials not as susceptible to chloride stress
. corrosion cracking.
One of the components chosen for replacement was the clevis pins attaching the control rod to the cable. PSC elected to replace the A286 high strength steel clevis pins with Inconel pins even though no gol chloride stress corrosion cracking was found on the clevis pins.
r 1
8906290186 890824 S
DR ADOCK'05000267 PDC
I
. +
1 P-89329 August 24, 1989 Ir the process of refurbishing the CRDOAs it was determined that the Inconel clevis pins were difficult items to obtain.
As a result, letter P-85061 (Reference 2) was issued seeking permission to replace some of the clevis pins with new A286 steel clevis pins.
Accordingly, a commitment was made to replace the new A286 steel clevis pins with Inconel clevis pins as the CRDOAs were replaced in the core. The schedule for this eventual replacement extends to the ninth refueling of Fort St. Vrain.
The control rod in region 19 has become immoveable and it his been determined that a CRD0A unit, CRD0A #26, is needed for placement into the core for the final 10 months of operation. CRD0A #26 has the A286 steel clevis pins. The tools for replacement of the clevis pins are not in the hot service facility as this area is being made ready for defueling. As described in Reference 2, PSC has determined that the A286 steel clevis pins are acceptable for interim use in the core until the ninth refueling. A chloride stress corrosion cracking failure is not considered feasible on the clevis pins, and new A286 clevis pins were installed in 1985.
In addition, new sources of chlorides will he minimal during the remaining plant operational lifetime.
Therefore, PSC will continue to use the existing A286 steel clevis pins in CRDOA #26 from the end of August 1989 to the end.of operation which is to be no later than June 30, 1990. This changed commitment was discussed with Mr. K. L. Heitner, of the NRC, on August 23, 1989 (Reference 3).
If you have any questions about this matter, please call Mr. M. H.
Holmes at (303) 480-6960.
Very truly yours, G-P H. L. Brey, Manager Nuclear Licensing and Resource Management HLB /JMW/km cc: Regional Administrator, Region IV ATTN: Mr. T. F. Westerman, Chief Projects Section B Mr. Robert Farrell Senior Resident Inspector Fort St. Vrain
_