ML20080Q383

Ro:On 830308,radiographic Exams Conducted on 10 HPCI Turbine Reversing Chambers.Seven Chambers Did Not Meet Augmented Acceptance Criteria.Cracking Caused by Mfg Process & Pressure Pulsing Fatigue

ML20080Q383
Person / Time
Site:	Duane Arnold
Issue date:	08/23/1983
From:	Mineck D IES UTILITIES INC., (FORMERLY IOWA ELECTRIC LIGHT
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
DAEC-83-681, NUDOCS 8310120380
Download: ML20080Q383 (2)

Text

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.x lowa Electric Light and Ibwer Company August 23,1983 DAEC-83-681 Mr. James G. Keppler Regional Administrator Region III-U. S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, IL 60137

Subject:

Duane Arnold Energy Center Docket No. 50-331 Op. Lic. No. DPR-49 HPCI Reversing Chambers

References:

(1) Iowa Electric letter DAEC-79-269 of October 9, 1979 (2) Iowa Electric letter DAEC-80-230 of May 20, 1980 ..

(3) Iowa Electric letter DAEC-81-363 of June 30, 1981

Dear Mr. Keppler:

This report updates and supplements the information provided in the above references.

Problem On March 8, 1983, radiographic examinations were conducted on the HPCI turbine reversing chambers in stock and in service as part of our continuing l program to resolve HPCI reversing chamber prcblems. Ten in-stock chambers were examined and seven were found not to meet our augmented DAEC acceptance criteria. These seven chambers were rejected. The ten inservice chambers

! were also inspected and found to have indications of flaws and shrinkage.

Although the extent of these problems, in our engineering judgement, did not degrade HPCI operability, one chamber (#4) demonstrated cracking that has been a repetitive problem. All ten inservice chambers were replaced with new chambers which meet our acceptance criteria. As noted above, similar problems have occurred at DAEC and were reported on Unique Reports 78-1, i 80-1, and 81-3.

Cause The cause of this cracking problem is that (1) the manufacturing process produces flaws that have not been detected prior to installation (2) pressure pulsing fatique caused by the cyclic duty experienced by the HPCI turbine propagates flaws.

9310120380 830823 h

l PDR ADOCK 05000331 S PDR Duane Arnold Energy Center e P.O. boa 351 e CedarItapids, Iowa 52406

• 319'8517611 4

h1r. Jam:sG.Kcppler August 23,1983 Page 2 Corrective Action Corrective action has been initiated to augment the inspection of reversing chambers and to require our supplier to place increased emphasis on their inspection prior to shipping to Iowa Electric. During our recent refueling outage, all replacement reversing chambers were source inspected by DAEC Quality Control personnel. One chamber was rejected for problems similar to those described above. All chambers now inservice have been inspected and approved. Clearance tolerance on chamber #4 was modified to mitigate our repetitive problem. Terry Turbine is now inspecting their new replacement reversing chambers with radiography and liquid penetrant tests. Future DAEC purchase orders for replacement chambers will require radiography per ASTM E-192 Level 5 and liquid penetrant testing in accordance with ASTM E-165. DAEC will continue to inspect replacement chambers to ensure they meet the prescribed specifications until improved performance is assured.

We will continue to monitor our vendor's evaluation of this problem.

Inspection of the inservice HPCI reversing chambers will be conducted during our 1984 refueling outage to determine if the revised acceptance criteria, the revised manuf acturing process and our clearance modification on chamber

1. 4 has resolved these problams.

Very truly yours, p FM Daniel L. Mineck Plant Superintendent - Nuclear Duane Arnold Energy Center DLM/WJM/pf*

Docket No. 50-0331 cc: NRC Resident Inspector File A-118 s