United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No. 84-41: IGSCC in BWR Plants

                                                            SSINS No.:  6835
                                                            IN 84-41 

                                UNITED STATES
                        NUCLEAR REGULATORY COMMISSION
                    OFFICE OF INSPECTION AND ENFORCEMENT
                            WASHINGTON D.C. 20555

                                June 1, 1984

Information Notice No. 84-41:  IGSCC IN BWR PLANTS 

Addresses: 

All boiling water power reactor facilities holding an operating license (OL)
or construction permit (CP). 

Purpose: 

This notice is being issued to provide information on further significant 
IGSCC indications found in piping systems of boiling water reactors as a 
result of expanded inspection efforts not included within the scope of curr-
ent augmented inservice inspection requirements. The inspections cited in 
this notice do not constitute new NRC requirements. The Nuclear Regulatory 
Commission (NRC) staff is reviewing this information and its safety signifi-
cance. If the evaluation so indicates, the NRC may require further licensee 
action. In the interim, recipients are expected to review their facility's 
status and consider nondestructive examination (NDE), as appropriate, to 
assess potential degradation of such piping welds during their ISI 
activities or planned piping replacement programs. No specific action or 
written response is required at this time. 

Description of Circumstances: 

Pilgrim Station is presently shutdown for replacement of primary recircula-
tion piping systems and further ISI activities. Following piping removal, a 
dye penetrant test (PT) conducted on the exposed ID surfaces of the reactor 
vessel nozzle welds disclosed a number of axially oriented crack indications
in the Inconel 182 weld butter which joins the 28-inch diameter piping safe 
end to reactor vessel nozzle in the "B" loop (Ref. figure 1). No evidence of
cracking was observed in the "A" loop nozzle weld. Metallurgical evaluation 
of boat samples and surface replicas of the cracks is being conducted by 
General Electric for the licensee to determine the nature of the 
indications. Preliminary metallography results confirm the cracking to be 
IGSCC. Axial cracking of a similar,nature was also found in three of the 10 
Inconel 182 weld butters joining the 12 inch diameter jet pump inlet riser 
safe ends to the reactor vessel nozzles. 

The Monticello plant has been shut down since February 3, 1984 for refueling
and replacement of recirculation system piping due to IGSCC. During a 
routine inservice inspection on February 18, 1984, ultrasonic examination 
identified several cracks in a 4 x 8 inch reducer weld on the 'A' Loop jet 
pump instrument seal line at the reactor vessel nozzle. The cracks were 
located in the 8-inch 

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                                                            IN 84-41 
                                                            June 1, 1984 
                                                            Page 2 of 2 

diameter weld HAZ, were axially oriented, and appeared to be about 40 per-
cent through wall. The reducer is reportedly made of high carbon stainless 
steel. This is the first cracking incident found in this particular line 
which if non-isolable (PNO-III-84-17). The licensee is planning to replace 
the reducer assemblies on the jet pump instrument seal lines of both A & B 
Loops (PNO-III-84-17A). 

Browns Ferry Unit 3 has been shutdown since September, 1983 for refueling, 
torus modifications, and inservice inspection. A visual examination of the 
two 4-inch diameter jet pump instrument line nozzle welds disclosed two pin-
hole leaks at the safe end to reducer weld (Ref. figure 2). Ultrasonic exam-
ination (UT) further revealed extensive axial cracks in the stainless steel 
safe end side of this weld on both instrument lines. The cracks were found 
distributed 3600 around the safe ends. Based on UT measurements, the cracks 
were estimated to range upward to 2 inches in length and having depth, in 
some cases, of .280 inches of the full .340 inch wall thickness. 

No written response to this information notice is required. If there are any
questions regarding this matter, please contact the Regional Administrator 
of the appropriate NRC regional office or this office. 



                                   Edward L. Jordan, Director 
                                   Division of Emergency Preparedness 
                                     and Engineering Response 
                                   Office of Inspection and Enforcement 

Technical Contact:  W. J. Collins, IE 
                    (301) 492-9630 

Attachments: 
1.   Figures 1 and 2 
2.   Recently Issued IE Information Notices 
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