ML16340B268
| ML16340B268 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 10/30/1980 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Crane P PACIFIC GAS & ELECTRIC CO. |
| References | |
| NUDOCS 8012170416 | |
| Download: ML16340B268 (10) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION REGION V 1990 N. CALIFORNIABOULEVARD SUITE 202, WALNUTCREEK PLAZA WALNUTCREEK, CALIFORNIA94598 October 30, 1980 Docket Nos. 50-275, 50-323 Pacific Gas and Electric Company 77 Beale Street San Francisco, California 94106 Attention:
Mr. Philip A. Crane, Jr.
Assistant General Counsel Gentlem>n:
This Information Notice is forwarded to provide a notification of a potential source of degradation that might occur in a safety related component over long term operation. 'o 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, R. H. Engelken Director Encl osures:
1.
IE Information Notice No. 80-38 2.
List of Recently Issued IE Information Notices cc w/enclosures:
J.
D. Shiffer, PGSE M. Raymond, PG&E E. B. Langley, Jr.,
PG8E 8 OX@X 'FO
'h i
I,
UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT LIASHIHGTON, D.C.
20555 SSINS No.:
6835 Accession Ho.:
8008220180 IH-80-38 October 30, 1980 IE Information Notice Ho. 80-38:
CRACKING IN CHARGING PUMP CASIflG CLADDING Descri tion of Circumstances:
In January 1980 Commonwealth Edison Company (CECo) reported to the HRC 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 charqing 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 Sec<ion XI inservice 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, Fiqure 1, consists of a suction end plate of A515 grade 60 carbon steel plate welded to the casing barrel forging of A266 class 1 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 cohducted in late April confirmed clad cracki'ng 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 ar eas were well blunted and slightly cavitated from corrosion effects due 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 progres-sed at a relatively slow rate.
The 1A charging pump was replaced with a new pump provided with a casing con-structed entirely of stainless steel.
The licensee is currently developing improved HDE 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.
i
IN-80-38 October 30, 1980 Page 2 of 2 A corrosion evaluation provided CECo by !lestinghouse 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, Subsec-tion 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 oerform a nondestructive examination of this pump type at the earliest practical time during the first code reauired in-service inspection interval and if cracking is confirmed, take approoriate corrective actions per the-rules of ASt'lE Section XI BP&V Code.
This Information Notice is provided as a notificaton of a potential source of 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 this time.
If you have any questions regarding this matter, please contact the Oirector of the approoriate NRC Regional Office.
Enclosure:
Figure 1
0 FIGURE t
SUCTION END PLATE (0 Bi~-
GR. 60)
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C LADDINC~
~ a
~'
on/c aF" C ZA'dwrMp CASII"JG. BAI"I.E,L
( AZ66 QL. I )
V Pp
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Ill 80-38 October 30, 1980 RECENTLY ISSUED IE INFORMATION NOTICES Informati on Notice Ho.
80-37 80-36 80-35 Subject Containment cooler leaks and reactor'avity flooding at Indian Point Unit 2 Failure of Steam Generator Supoort Bolting Leaking and dislodged Iodine-124 implant seeds Date of Issue 10/24/80 10/10/80 10/10/80 Issued to All nuclear power facilities holding power reactor OLs or CPs All nuclear power reactor facilities holding power reactor OLs or CPs C
All categories G and Gl medical licensees 80-34 80-33 80-32 Clarification of certain requirements for Exclu-sive-use shipments of radioactive materials 8/12/80 Boron dilution of reactor 9/26/80 coolant during steam generator decontamination Determination of tel etherapy 9/15/80 timer accuracy All pressurized water reactor facilities holding power reactor OLs All teletherapy (G3) licensees All NRC and agreement state licensees 80-31 80-30 Maloperation of Gould-Brown Boveri Type 480 volt type Y.-600S and Y,-DON 600S circuit breakers Potential for unaccept-able interaction between the control rod drive scram function and non-essential control air at certain GE BHR faci 1 ities 8/27/80 8/19/80 All light water reactor facilities holding OLs or CPs All boiling water reactor facilities holding power reactor OLs or CPs.
80-29 Broken studs on Terry turbine steam inlet flange 8/7/80 All light water reactor facilities holding power reactor OLs or CPs*
- Operating Licenses or Construction Permits
1