SSINS No.: 6835
Accession No.:
UNITED STATES 8008220180
NUCLEAR REGULATORY COMMISSION
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

« radiographic examioation 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 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 che 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 natu.e 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 cavicated
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 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.

8608320 186



IN-80-38
October 30, 1980
Page 2 of 2

A corrosion evaluation provided CECo by Westinghouse indicates the corrosion
rate of carbon steel subject to environmental conditions typical of the instal
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 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 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 contract the
director of the appropriate NRC Regional Office.

Enclosure:
Figure 1



SUCTION
"D0 PLATE

VGLO,

CINCUINEL)

SUCTION END. PLATE
(ASIE GR GU)

CLADDING
a (TIPE 308 st ST)
a |

Zove or Ceeea ag

LY = De rari a

CASING BARE
— (A266 GLI)

POOR ORIGINAL