ML20076E386
| ML20076E386 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 05/18/1983 |
| From: | Van Brunt E ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR |
| To: | Sternberg D NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| Shared Package | |
| ML20076E390 | List: |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, DER-82-61, NUDOCS 8306010072 | |
| Download: ML20076E386 (4) | |
Text
F RECBVED H30 Arizona Public Service ComigDY 26
- 20 PO BOX 21666. PHOENIX, ARIZONA 85036 May18,198}
ANPP-23798-B N'i U. S. Nuclear Regulatory Commission g 5*
Region V (7
Creekside Oaks Office Park 1450 Maria Lane - Suite 210 Walnut Creek, California 94596-5368 Attention: Mr. D. M. Sternberg, Chief Reactor Projects Branch 1
Subject:
Interim Report, Revision 1 - DER 82-61 A 50.55(e) Potentially. Reportable Deficiency Relating To Reactor Coolant Pump Diffusor - Ring Cap Screws May Fail And Damage Pump File:
83-019-026; D.4.33.2
Reference:
A) Telephone Conversation between J. Eckhardt and G. Duckworth on October 21, 1982 B) ANPP-22368, dated November 22, 1982 (Interim Report)
C) ANPP-23026, dated February 16, 1983 (Time Extension)
D) ANPP-23278, dated March 17, 1983 (Time Extension)
Dear Sir:
The NRC was notified of a potentially reportable deficiency in Reference A, an Interim Report was transmitted by Reference B, and Time Extensions were requested in References (C) and (D). At that time, it was estimated that a Final Report would be available by May 18, 1983.
Due to the extensive investigation and evaluation required, a revised Interim Report is attached.
It is now expected tha this information will be finalized by July 25, 1983, at which time a complete report will be submitted.
i Very truly ours,
j
(
),
C cLLU mte p E. E. Van Brunt, Jr.
APS Vice President, Nuclear Projects ANPP Project Director EEVB/RQT:db Enclosure cc:
See Page 2 l
8306010072 830518 i
PDR ADOCK 05000528 S
o' Mr. D. M. Sternberg ANPP-23798-RQT/BSK May 18, 1983 Page 2 cc:
Richard DeYoung, Director Office of Inspection and Enforcement U. S. Nuclear Regulatory Commission Washington, D. C. 20555 T. G. Woods, Jr.
G. C. Andognini J. A. Roedel D. B. Fasnacht A. C. Rogers B. S. Kaplan W. E. Ide J. Vorees J. R. Bynum P. P. Klute/D. D. Green A. C. Gehr W. J. Stubblefield W. G. Bingham R. L. Patterson R. W. Welcher R. M. Grant D. R. Hawkinson L. E. Vorderbrueggen G. A. Fiore11i Records Center Institute of Nuclear Power Operations 1100 Circle 75 Parkway - Suite 1500 Atlanta, Georgia-30339 i
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i INTERIM REPORT - REVISION 1 - DER 82-61 f
POTENTIAL REPORTABLE DEFICIENCY ARIZONA PUBLIC SERVICE COMPANY (APS)
PVNGS UNITS 1, 2 & 3 I..
PDTENTIAL PROBLEM Diffusor retaining cap screws for System 80 Reactor Coolant Pumps supplied by Combustion Engineering,(CE) as part of the NSSS failed i
in the CE-KSB test loop. These cap screws support the dif fuser-suction ring assembly of an idle pump. With the pump running, hydraulic forces unload the sixteen (16) cap screws in i
L question. Two (2) cap screws secure-each retaining ring segment and locking devices retain the cap screws. The screws failed either under the head, in the shank or at the first thread. CE has determined that the failure was caused by hydrogen induced stress p
I corrosion cracking as aLresult of the heat treatment condition of I
the screw material (Type 410 martensitic stainless steel). The s
hydrogen induced stress corrosion cracking was accelerated by high stress levels caused by positioning the diffuser halves in a non preferred orientation in the pump casing.
II.
APPROACH TO AND STATUS OF PROPOSED RESOLUTION CE has reviewed the potential failure mechanisms and their consequences, including a locked rotor, degraded pump coast down and core flow blockage and has determined that:
1)
During full power operation hydraulic ~ forces alone can i
i maintain the diffuser in place. Only during startup or coast down is there any potential for axial movement of the I
diffuser.. The design is such that the diffuser-suction pipe l
assembly is captured radially throughout any axial moveaent.
The diffu.er cannot rotate because it is restrained by two i
keys which engage the mating pump casing ledge. With these design features the potential for impeller binding is remote during startup and coast down.
2)'
The assessment of the effects on the coast down show the RCP maintains sufficient flow to' satisfy the criteria of the safety analysis.-
3)
The potential for core flow blockage has been examined and it has been concluded that the gap between the impeller and the diffuser is small enough to prevent the escape of particles 4
.that are large enoug5 to cause local core flow blockage.
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Page 2 CE and CE-KSB have completed a metallurgical and design investigation to determine the causes of the failures. provides a summary of the design investigation and details of the metallurgical investigation.
III.
PROJECTED COMPLETION OF CORRECTIVE ACTION AND SUBMITTAL OF THE FINAL REPORT Evaluation of this condition and submittal of the Final Report is forecast to be completed by July 25, 1983.
_