From: ML103630735 (Highlighted items done by me, not NRC).

We have been concerned about the problems with alloy 600 since 1999. PSEG fired their senior chemist back in 1997-1998 over his concerns about alloy 600.





SEPTEMBER 16, 2010

The U.S. Nuclear Regulatory Commission (NRC or the staff) and representatives of PSEG Nuclear, LLC held a telephone conference call on September 16, 2010, to discuss and clarify the NRC's request for additional information (RAI) related to potential primary water stress corrosion cracking in steam generator divider plates (RAI 3.1.1-02).

Discussion on Follow-up RAI 3.1.1-02


Draft RAI 3.1.1-02

Follow-up to RAI 3.1.1-01 on Salem Steam Generator PWSCC


Based on recent foreign operating experience, the staff's concern in RAI 3.1.1-01 was about the potential impact of primary water stress corrosion cracking (PWSCC) in steam generator (SG) divider plate assembly on adjacent components, which are part of the reactor coolant pressure boundary (channel head, tubesheet, tubesheet cladding ... ). In its response to RAI 3.1.1-01, dated July 08, 2010, the applicant describes the materials of its SGs divider plate assembly, which are Alloy 600 for the stub runner and the divider plate, and Alloy 82/182 for the welds that attach the divider plate and stub runner to each other, and to the channel head and to the tubesheet. The applicant also provides additional elements in order to justify why the potential for cracking of its SG divider plate propagating into adjoining components and resulting in loss of the integrity of the reactor coolant pressure boundary would not be expected to occur, and therefore the SGs divider plate does not require an aging management program consisting of inspections for crack propagation.


Although not considered to be an immediate safety issue, the likely presence of cracks in Alloy 600 steam generator divider plate assemblies constitutes a condition that is adverse to quality. In addition, this condition could lead to propagation of these cracks into surrounding pressure boundary areas, such as the tube-to-tubesheet welds and the channel head. Although the applicant has provided qualitative arguments for concluding that divider plate cracking is not a concern, the RAI response does not provide a reasonable and sufficient basis for justifying the applicant's conclusions. Further, the use of analytical tools to predict the behavior of serviceinduced cracking (in other components) has not always bounded actual service performance of these cracks.


The applicant is requested to provide an aging management program (AMP) that would demonstrate the condition of the steam generator divider plate assembly to support a conclusion that there will be no adverse consequences of divider plate assembly degradation during the renewed license period.