ML19340C756
| ML19340C756 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 10/30/1980 |
| From: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | Gary R TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| References | |
| NUDOCS 8012170360 | |
| Download: ML19340C756 (1) | |
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UNITED STATES
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NUCLEAR REGULATORY COMMISSICN
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= $,A, #r 611 RYAN PLAZA DRIVE. SUITE 1000
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In Reply Refer To:
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Docket Nos.
50-445/IE Information Notice No. 80-38
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Texas Utilities Generating Company m
ATTN:
Mr. R. J. Gary, Executive Vice President and General Manager 2001 Bryan Tower Dallas, Texas 75201 Gentlemen:
This IE Information Notice is forwarded to provide a notification of a i
potential source of degradation that might occur in a safety-related component over long-ters operation.
No specific action or written response to this Information Notice is required at this time.
If you have any questions related to this matter, please contact this office.
Sincerely, d'??fac &d a
Karl V. Seyfrit Director
Enclosures:
1.
IE Information Notice No. 80-38 2.
List of Recently Issued IE Information Notices 8032170 300 A
SSINS No.:
6835 Accession No.:
UNITED STATES 8008220180 NUCLEAR REGULATORY COMMISSION N'\\
OFFICE OF INSPECTION AND ENFORCEMENT g
WASHINGTON, D.C.
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IE Information Notice No. 80-38 Date:
October 30, 1980 Page 1 of 2 CRACKING IN CHARGING PUMP CASING CLADDING Description of Circumstances:
In January 1980 Commonwealth Edison Company (Ceco) reported to the NRC that a radiographic 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 1 for high head 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 Dresse? 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 arc welding.
An in-situ ultrasonic examination conducted'in late April confirmed 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.
Extencion 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 langthy 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.
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IE Information Notice October 30, 1980 No. 80-38 Page 2 of 2 The 1A charging pump was replaced with a new pump provided with a casing con-structed entirelv of stainless steel. The licensee is currently developing improved NDE procedures 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 evaluation 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, indicates 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 ASME Section XI BP&V Code.
This IE Information Notice is provided as a notificaton of a potential source cf degradation of a safety-related component that is still under 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 thin time.
If you have any questions regarding this matter, please contact tha director of the appropriate NRC Regional Office.
Enclosure:
Figure 1
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SUCTION CLADDING END PLATE (TYoE 308 ST ST)
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CASING BARREE.
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IE Information No. 80-38 October 30, 1980 LISTING OF RECENTLY ISSUED TE INFORMATION NOTICES Infor=ation Subject Date Issued To Notice No.
Issued 80-31 Maloperation of Gould-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) 80-32 Clarification of certain 8/12/80 All NRC and agreement 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 Boron 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 C 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 Unit 2 Licences (OLs) or Construction Permits (cps)
Enclosure