ML19340C758
| ML19340C758 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 10/30/1980 |
| From: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | William Jones OMAHA PUBLIC POWER DISTRICT |
| References | |
| NUDOCS 8012170365 | |
| Download: ML19340C758 (1) | |
Text
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CENTRAL FILES
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UNITED STATES PDR:HQ r -
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NUCLEAR REGULATORY COMMISSION LPDR is,]_f,j.
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%,,,,[ f 611 RYAN Pt AZA ORIVE. SUITE 1000 ARUNGTON. TEXAS 76011 STATE October 30, 1980 Oceket No.
50-235 0=aha Public Power District AI'"N:
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C. Jones, Division Manager -
Production Operations 1623 Earney Street Ocaha, Nebraska 68102 Gentle =en:
This IE Infor=ation Notice is forwarded to provide a cotification of a potential source of degradation that night occur in a safety-related component over long-term operation.
No specific action or written response to this
!afor=ation Notice is required at this time.
If you have any questions related to this =atter, please contact this office.
Sincerely, 7
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i Karl V. Seyfrit '//
Director
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Enclosures:
1.
II Infor=ation Notice No. 30-38 2.
List of Recently Issued II Infor=ation Notices S. C. Stevens, Manager Fort Calhoun Station Post Office Sox 98 Fort Calhoun, Nebraska 68102 8 01217 0 3 6T
SSINS No.:
6835 Accession No.:
UNITED STATES 8008220180 NUCLEAR REGULATORY COMMISSION I
OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 IE Information Notice No. 80-38 Date:
October 30, 1980 Page 1 of 2 CRACKING IN CHARGING PUMP CASING CLADDING Description of Circumstances:
In Janurry 1980 Commonwealth Edison Company (CECO) reported to the NRC that a radiopraphic examination had revealed crack indications in the cladding on the suction end plate of the 1A charging pump at Zion Unit 1.
This cen-trifugal charging pump 1A is one of two pumps installed in Zion Unit i for high taad safety injection of borated water to the reactor loops.
These pumps are additionally utilized as charging pumps during normal operation. ASME Section XI in-service inspection rules referenced in the plant-technical specification requires pump examination only once during the 10 year service interval and this pump had been in service about 7 years.
The pumps are 2-1/2 inch, 11 stage, Type IJ manufactured by the Pacific Pumps Division of Dresser Industries.
The pump casing end assembly in the area of interest, Figure 1, consists of a suction end plate of ASIS grade 60 carbon steel plate welded to the casing barrel forging of A266 class I carbon steel.
using an Inconel weldment. The entire inner surface is clad with type 308 stainless-steel applied by submerged are welding.
An in-situ ultrasonic examination conducted in late April coafirmed clad cracking indications at the barrel case to end plate inner radius for approximately 330 degrees around the circumference and that the cracking possibly extended into the pump base. material in the bottom 180. degrees of the assembly.
A review of the original radiographs revealed crack like indications in the clad overlay,.
however, not to the extent observed during this examination.
Subsequently, the entire suction end of the pump was removed and cross sections metallographically examined to.further evaluate the nature and extent of the cracking.
It was determined that initiation and propagation of the clad cracks probably resulted from' stress concentration and dilution effects in the initial corner bead pass due to the difficult access and bead sequencing required by the fairly sharp corner geometry.
Extension of the cracks at the base metal-clad interface ranged to a depth of 1/16 inch maximum in the 1-1/2 inch thick base material.
These crack tip areas were well blunted and slightly cavitated from corrosion effects due to lengthy exposure to the localized boric acid attack.
Examination of the crack morphology revealed that the clad cracking essentially arrested at the base metal-clad interface and that base metal corrosion progressed at a relatively slow rate.
IE Information Notice October ';0,1980 No. 80-38 Page 2 of 2 The 1A charging punp was replaced aith a new pump provided with a casing con-structed entirely if stainless steel. The licensee is currently developing improved NDE procec'tres for examination of the three remaining pumps at the next refueling outage.
Further, the licensee and pump manufacturer are developing repair procedures in the event cracks are discovered in the remaining pumps.
A corrosion evaluacion provided CECO by Westinghouse indicates the corrosion rate of carbon steel subject to environmental conditions typical of the installed pumps is on the order of 2-1/2 to 4 mils per month.
Additionally, a stress analysis of the pump casing by the manufacturer using ASME Section III, Sub-section NC rules, iudicates that at design conditions a flaw with depth of 0.763 inches could be tolerated.
Based on the available information no immediate safety concern is indicated.
However, the observed conditions reveal a potential source of pump degradation over long-term operations. Therefore, to assure maximum availability, it appears prudent to perform a nondestructive examination of this pump type at the earliest practical time during the first code required in-service inspection interval and if cracking is' confirmed, take appropriate corrective actions per the rules of AEME Section XI BP&V Code.
This IE Information Notice is provided as a notificaton of a potential source of degradation of a safety-related component that is still un/sr review by the NRC staff.
It is expected that recipients will review the information for possible applicability to their facility.
No specific action or response is requested at this time.
If you have any questions regarding this matter, please contact the director of the appropriate NRC Regional Offita.
Enclosure:
Figure 1
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m SUCTION END PLATE b
( ASIS GP. 60 )
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SUCTION CLAODING END PLATE
( TY D E 308 ST ':T )
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(INCONEL) ce a casup I
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CASING BARREL
( A 266 CL.11 b
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IE Information No. 80-38 October 30, 1980 LISTING OF RECENTLY ISSUED IE INFORMATION NOTICES Information Subject Date Issued To Notice No.
Issued 80-31 Maloperation of L..d-8/27/80 All light water reactor Brown Boveri Type 480 facilities holding volt type K-600S and Operating Licenses or and K-DON 600S circuit Construction Permits breakers (cps) l 80-32 Clarification of certain 8/12/80 All NRC and agreement l
requirements for Exclu-state licensees sive-use shipments of radioactive materials 80-33 Determination of Tele-9/15/80 All teletherapy therapy Timer Accuracy (G3) licensees 80-34 Baron Dilution of Reactor 9/26/80 All Pressurized Coolant During Steam Water Reactor Generator Decontamination Facilities holding power reactor Operating Licenses (OLs) 80-35 Leaking and Dislodged 10/10/80 All categories G and Iodine-124 Implant Seeds G1 medical licensees 80-36 Failure of Steam 10/10/80 All nuclear power Generator Support Bolting reactor facilities holding Operating Licensees (OLs) or Construction Permits (cps) 80-37 Containment Cooler Leaks 10/24/80 All nuclear power and Reactor Cavity facilities holding Flooding at Indian Point power reactor Operating j
Unit 2 Licenses (OLs) or Construction Permits (cps)
Enclosure
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