ML20205P465
| ML20205P465 | |
| Person / Time | |
|---|---|
| Site: | Harris  |
| Issue date: | 04/29/1986 |
| From: | Watson R CAROLINA POWER & LIGHT CO. |
| To: | Grace J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| CON-NRC-442, REF-PT21-86-158-000 227, HO-860287-(O), PT21-86-158-000, NUDOCS 8605210420 | |
| Download: ML20205P465 (4) | |
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. 40 CP&L Carolina Power & Light Company SHEARON HARRIS NUCLEAR PROJECT P. O. Box 165 New Hill, North Carolina 27652 APR 2 9 gggg File Number SHF/10-13510 Letter Number: HO-860287(0)
NRC-442 Dr. J. Nelson Grace United States Nuclear Regulatory Commission Region II 1
101 Marietta Street, Northwest (Suite 2900)
Atlanta, Georgia 30323 CAROLINA POWER & LIGHT COMPANY SHEARON HARRIS NUCLEAR POWER PLANT 1986 - 900,000 KW - Unit 1 MAIN FEEDWATER ISOLATION VALVES, ITEM 227
Dear Dr. Grace:
Attached is our second interim report on the subject item, which was deemed reportable per the provisions of 10CFR50.55(e) and 10CFR, Part 21 on March 20, 1986. CP&L is pursuing this matter, and it is currently projected that corrective action and submission of the final report will be accomplished by May 22, 1986.
Thank you for your consideration in this matter.
Yours very truly,
. A. Watson
'Vice President Harris Nuclear Project RAW /bwh Attachment cc: Messrs. C. Maxwell (NRC-SHNPP)
J. M. Taylor (NRC) 8605210420 860429 PDR ADOCK 05000400 S
l CAROLINA POWER & LIGHT COMPANY SHEAROM HARRIS NUCLEAR POWER PLANT UNIT 1 INTERIM REPORT MAIN FEEDWATER ISOLATION VALVES ITEM 227 APRIL 25, 1986 REPORTABLE UNDER 10CFR50.55(E) & 10CFR21 NBI-MS-863517/2-0S5
SUBJECT:
10CFR50.55(e) and 10CFR21 reportable item Shearon Harris Nuclear Power Plant Unit 1 main feedwater isolation valve operator piston rod failures.
ITEN:
Main feedwater isolation valves 2FW-V28SAB-1 and 2FW-V27SAB-1 SUPPLIED BY:
Borg-Warner Fluid Controls NATURE OF DEFICIENCY:
During stroke testing of the above referenced feedwater valves the operator piston rods failed (snapped in two).
DATE PROBLEMS IDENTIFIED:
2FW-V28SAB-1 August 8, 1985 2FW-V27SAB-1 March 17, 1986 DATE PROBLEM REPORTED:
On March 20, 1986, CP&L (Mr. K. V. Hate') notified the NRC (Mr. P. Fredrickson) that this was reportable per the provisions of 10CFR50.55(e) and 10CFR21.
SOURCE OF PROBLEN:
Examination of the piston rod and hub on valve 2FW-V28SAB-1 indicated several areas of concern a s' outlined in the previous April 11, 1986, Interim Report:
1.
Ultimate Tensile Strength 2.
Radius at Stem-to-Hub Junction 3.
Hub Thickness 4.
Crack Indication on the Piston Head 5.
Coupling Deformation SAFETY IMPLICATIONS:
Failure of these piston rods would result in loss of control of the main feedwater isolation valves.
REASON DEFICIENCY IS REPORTABLE:
This condition would eliminate the ability to isolate the feedwater pipelines entering containment.
CORRECTIVE ACTION:
Borg-Warner has redesigned manufactured and supplied replacement piston rods and couplings.
The replacement piaton rod material is ASTM A304 Cr. 4340H, heat treated to a tensile strength of 180-200 ksi.
In addition the radii of the piston rod groove has been increased to 0.090 - 0.095 inches.
The groove diameter has been increased from NBI-MS-863517/3-0S5
CORRECTIVE ACTION: (Cont'd) 3.000/3.04r inches to 3.250 inches and the groove width has been enlarged to 0.640 - 0.650 inches.
The rod hub thickness is now 0.840 - 0.850.
The groove and hub surfaces are shot peened to an intensity of 0.012 - 0.016.
Analysis of the modified piston rod end has shown that the resultant stresses are within allowable limits.
Borg-Warner is confident that this new design has eliminated the repeat of the type of failure noted above.
Replacement with these new piston rods and couplings is currently underway for the two subject valves and valve 2FW-V26SAB-1 (which has yet to fail).
Completion is estimated by May 22, 1986.
1 NBI-MS-863517/4-055