ML20137F455
| ML20137F455 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 08/13/1985 |
| From: | Van Brunt E ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR |
| To: | Kirsch D NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| References | |
| REF-PT21-85, REF-PT21-85-378-000 ANPP-33204-TDS, DER-85-16, PT21-85-378, PT21-85-378-000, NUDOCS 8508260222 | |
| Download: ML20137F455 (6) | |
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P.O. BOX 52034 e PHOENIX. ARIZONA 85072-2034 August 13, 1985 ANPP-33204-TDS/TPS U. S. Nuclear Regulatory Camission Region V 1450 Maria Lane - Suite 210 Walnut Creek, California 94596-5368 Attention: 'Mr. D. F. Kirsch, Acting Director Division of Reactor Safety & Projects
Subject:
Final Report - DER 85-16 A 53.55(e) Reportable Condition Relating To Cracked.
Spoke on AHU File: 85-019-026; D.4.33.2
Reference:
A) Telephone Conversation between C. Sorenson and P. Coffin on May 7, 1985 B) ANPP-32787, dated June 6, 1985 (Interim Report)
C) ANPP-33012, dated July 15, 1985 (Time Extension)
Dear Sir:
Attached is our final written report of the Reportable deficiency under 10CFR50.55(e), referenced above. The 10CFR21 evaluation is also included in this report.
Very truly yours, l
CLL mu N E. E. Van Brunt, Jr.
Executive Vice President Project Director EEVB/TPS/nj Attachment cc: See Page Two
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August' 13,.1985 ANPP-33204-TDS/TPS Mr. D. F. Kirsch' DER 85-16 Page Two l
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Richard DeYotng, Director Office of Inspection and Enforcement U. S. Nuclear Regulatory Commission Washington, D. C.
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D. B. Karner W. E. Ide D. B. Fasnacht L'. A. Souza A. C. Rogers D. E. Fowler T. D. Shriver C. N. Russo B. S. Kaplan J. R. Bynun J. M. Allen l
D. Canady A. C. Gehr W. J. Stubblefield W. G. Binghan R. L. Patterson R. W. Welcher H. D. Foster D. R. Hawkinson R. P. Zimnerman M. L. Clyde B. T. Parker T. J. Bloan D. N. Stover J. D. Houchen J. E. Kirby Records Center Institute of Nuclear Power Operations' 1100 Circle 75 Parkway, Suite 1500 Atlanta, GA 30339 i
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FINAL REPORT - DER 85-16 DEFICIENCY EVALUATION 50.55(e)
ARIZONA NUCLEAR POWER PROJECT (ANPP)
PVNGS UNITS 1, 2, 3 1.
Description of Deficiency While investigating the cause of vibration on Air Handling Unit (AHU) 1M-HJB-Z04 (Reference 1), it was discovered that two of the three spokes on the hub of the fan wheel were cracked. The Air Handling Unit had been in operation in Unit 1 for approximately two years. Further investigation has also revealed that the problem existed on a similar Air Handling Unit in Unit 3, tag no. 3M-HJB-Z04, which had never been placed in operation.
This condition was documented in Engineering Evaluation Report (EER)
Numbers 85-HJ-051 and 85-1U-054.
These units are located in the Control Building and provide conditioned air to cool the safety-related equipment inside Train "B", Essential Safety Feature Switchgear Room and D. C. Equipment Rooms.
The Air Handling Units were manufactured by American Air Filter Conpany, Inc. (AAF) and purchased under Bechtel Specification 13-MM-721A.
Evaluation Based on an engineering evaluation of the cracked fan wheel hubs, it was detennined that new hubs should be fabricated of a stronger material to replace the ones supplied with the units by American Air Filter Co., Inc.
The new hubs are made of 1018 carbon steel material as shown Drawing Number FGD-5042-P, Revision 0 (EER No. 85-HJ-054) in lieu of cast gray iron which was used in the original hubs.
The modified hub design was seismically analyzed, calculation 13-CC-ZQ-M01, by Bechtel Engineering and the results were found to be acceptable.
For a definitive identification of the failure mechanism, the two cracked fan wheel hubs were shipped to AAF for laboratory studies and root cause analysis (Reference 2). Reference 3 presents the results of the examinations and test perfonned by " Materials Development Incorporated,"
the metallurgical consultant of AAF. Based on laboratory examination and measuranents made of the fractured hub, it was concluded that pocr quality castings is the root cause of the problem. The vertical mismatch of the two spoke fractures and existence of rust and peening of the fractured faces is considered strong evidence that cracks existed before i
the fan hub was put in service. It is also postulated that fracture to final failure propagated rapidly when the fan was put into operation.
Final Report DER 85-16 Page Two Chicago Blower Company, the supplier of the fans, agrees with this root cause assessment and, as indicated in Reference 5, has not used Gilt Edge Foundry, located in Cedar Grove, Wisconsin, which produced the original poor quality castings for the past year and a half.
In addition, to preclude recurrence, Chicago Blower has instituted a program to perform visual inspection on a statistical sample of eight of each 100 hubs received. If a single defect is found, the entire chipment is returned to the foundry. Similarly, AAF has instituted as a standard feature of their inspection process for cast hubs on all future nuclear orders, a requirement to perform radiographic examination of these hubs prior to installation.
This deficiency applies to all six AHUs supplied on Bechtel Purchase Order 10407-13-FM-721A. The tag numbers of these units are:
- 1) 1M-lUA-204
- 2) 2M-1UA-204
- 3) 3M-1UA-Z04 4) 1M-1UB-204 5) 2M-IUB-ZO4 6) 3M-lUB-Z04 II. Analysis of Safety Inplications If this deficiency were to ranain uncorrected, the air supply to cool various safety-related equipment inside the Essential Safety Feature Switchgear Roan and D. C. Equipment Rooms would be cutoff in the event of fan failure. This would result in room tanperatures exceeding the maxinun design value. The safety-related electronic devices inside these rooms would be exposed to temperatures higher than what they were designed for, hence malfunction of these devices might occur due to overheating. Additionally, the high temperatures would reduce the qualified life of the equipment.
Based on the above, this condition is evaluated as Reportable under the requirauents of 10CFR50.55(e) since, if this condition were to renain uncorrected, it would represent a significant safety condition.
The project also has evaluated this condition as Reportable under 10CFR21.
This report addresses all the reporting requiranents of 10CFR21.21(b)(3) with the exception of subpart (vi) regarding the number and location of such components supplied to other facilities.
Final Report DER 85-16 Page Three III. Corrective Action 1.
New hubs have been fabricated and installed on Air Handling Units 1M-1UB-Z04 and 3M-1UB-ZO4. The work was perfonned per Reference 1.
2.
However, AAF recmmends that all six hubs on the six Air Handling Units supplied under the IE-721A contract be replaced with new castings. The use of machined forgings for the two units mentioned in Item 1 above is not reemmended by AAF as a permanent solution because the units may not operate at the rated operating point for the fan.
To deteunine the acceptability of these two hubs, APS operations will conduct testing per Reference 6 to verify the performance, i.e., fan capacity (CFM), fan speed (RPM) and current drawn (AMPS).
The results of the test will be suhnitted to AAF for their concur-rence. This work will be performed by Septaber 1,1985. T mpera-tures within the areas supplied by the Unit 1 AHU have been within specified limits without additional cooling required.
3.
Upon notification of the initial failure, AAF had shipped three hubs produced at a different foundry (JBM Foundry of Cedar Grove, Wisconsin), as replacment for the two failed hubs plus one spare.
Since the site' implemented corrective action did not utilize these new hubs, they were stored in the warehouse. Per AAF's request, these hubs now have been returned to AAF to be inspected by radiograph techniques.
4.
One of the three hubs returned from AAF will be used to replace the' original hub installed on AHU 1M-lUA-Z04. This work will be perfonned in accordance with Reference 7.
5.
In addition to the three hubs that NT will radiograph and return to the site, they will provide three rmre hubs, with new castings which will be radiographically inspected to be used on the remaining units.
In sunmary, AAF will provide six new hubs, for of which Will be used to replace the hubs in Air Handling Units 1M-lUA-Z04, 2M-1UB-Z04, and 3M-lUA-ZO4. The other two will be used to replace the forged hubs on 1M-1UB-204 and 3M-1UB-Z04, if required.
The wrk for Unit 1 will be implemented per References 1 (completed 4/20/85) and 7.
Work for Reference 7 is to be performed pending results of Reference 6.
Work on Units 2 and 3 will be performed in accordance with NCRs SM-5880 and SM-5881, respectively, to be com-pleted prior to fuel load.
y Final Report DER 85-16 Page Four 6.
With the empletion of the corrective action outlined in References 1 and 7, the original design condition of Unit 1 AHUs will be restored.
IV. References.
1.
APS Work Order No. 81425 2.'
APS letter to American Air Filter Co., Inc., PVNGS-RKW-L85-1, dated May 15, 1985 3.
American Air Filter Co., Inc. letter to Bechtel, dated June 14, 1985 4.
American Air. Filter Co., Inc. letter to Bechtel, dated June 19, 1985 5.
American Air Filter Co., Inc. letter to Bechtel, dated June 26, 1985 6.
APS Work Request No. 073481 (Verification of Speed and CFM for the New Machined Hub) 7.
APS Work Request No. 073482 (Replace Cast Hub of IM-lUA-ZO4 with New Hub)
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