Information Notice 1980-38, Cracking in Charging Pump Casing Cladding

Cracking in Charging Pump Casing Cladding

ML031180437
Person / Time
Site:	05000000
Issue date:	10/30/1980
From:	NRC/OI
To:
References
IN-80-038, NUDOCS 8008220180
Download: ML031180437 (4)

SSINS No.: 6835 Accession No.:

UNITED STATES 8008220180

NUCLEAR REGULATORY COMMISSION IN-80-38 OFFICE OF INSPECTION AND ENFORCEMENT

WASHINGTON, D.C. 20555 October 30, 1980

IE Information Notice No. 80-38: 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 charaing pump 1A is one of two pumns installed in Zion Unit 1 for

high head safety injection of borated water to the reactor loops. These pumps

are additionally utilized as charging Dumps durina normal operation. ASME

Section 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, Figure 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 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 130 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 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 pumn was replaced with a new pump provided with a casing con- structed entirely 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.

IM-80-33 October 30, 1980 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 numo casing by the manufacturer iisinn ASME Section III, Subsec- tion NC rules, indicates that at desion 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 durino the first code required in-service inspection

interval and if cracking is confirmed, take appropriate corrective actions per

the-rules of ASilE 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 tnat recioients 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 approoriate iiRC Regional Office.

Enclosure:

Figure 1

4 FlJIGJF< /

I/ SUCTION END PLATE

.- (A55lb

r GR.60)

SUCTI')N CLADDING

.;!.D Pi ATE P(T(E 306 ST ST)

M; i i .,-

( l X) t \lL)

A ,- -

p.. , 0 Coo

.a Co - .

CASItN(i BARPEL

(A266 CL. I)

.- a

4:

IN 20-38 October 30, 1980

RECNITLY ISSUED

IE IMIFORMATION NOTICES

Information Mate of

Notice No. Subject Issue Issued to

80-37 Containment cooler leaks 10/24/80 All nuclear power

and reactor cavitv facilities holdina

floodina at Indian Point power reactor OLs

Unit 2 or CPs

80-36 Failure of Steam 10/10/80 All nuclear power

Generator SuDoort Boltinr reactor facilities

holdina Power reactor

OLs or CPs

80-35 Leakinc and dislodged 10/10/80 All categories G and

Iodine-124 imDlant seeds G1 medical licensees

80-34 Boron dilution of reactor 9/26/80 All pressurized water

coolant during steam reactor facilities

Generator decontamination holding power reactor OLs

80-33 Determination of teletherapy 9/15/80 All teletherapy

-ier accuracy (G3) licensees

80-32 Clarification of certain 8/12/80 All N'RC and agreement

recuir2Henns 7or Exclu- state licensees

si'e-use sipipments of0

radioactive materials

80-31 i'alooeration of Gould- 3/27/80 All light water reactor

Brotin Boveri Type 480 facilities holding OLs

volt tope K-600S and or CPs

K- O001! 5oscircuit

breakers

80-30 Potential for unaccept- 8/19/80 All boiling water reactor

able interaction between facilities holding power

the control rod drive scram reactor OLs or CPs.

function and non-essential

control air at certain GE BWR

facilities

30-29 Broken studs on Terry 8/7/80 All light water reactor

turbine steam inlet facilities holding

flange power reactor OLs or CPs*

• Operating Licenses or Construction Permits