ML22010A100

Trp 033 Psl Selective Leaching Breakout Questions - Allik

ML22010A100
Person / Time
Site:	Saint Lucie
Issue date:	01/07/2022
From:	Florida Power & Light Co
To:	Office of Nuclear Reactor Regulation
Rodriguez-Luccioni H
References
EPID L-2021-SLR-0002
Download: ML22010A100 (3)

Text

St. Lucie SLRA: Breakout Questions SLRA Section AMP B.2.3.21: Selective Leaching TRP: 33 Note: Breakout Questions are provided to the applicant and will be incorporated into the publicly-available audit report.

Technical Reviewer Allik 1/5/2022 Technical Branch Chief Bloom Concurrence Date Breakout Session Date/Time To be filled in by PM Applicant Staff NRC staff To be filled out by PM during breakout Question SLRA SLRA Background / Issue Discussion Question / Request Outcome of Discussion Number Section Page (As applicable/needed) 1 B.2.3.21 B-180 SLRA Section B.2.3.21 states [t]his review The staff requests additional identified that a failure of fire protection piping discussion on the subject serving the north warehouse had occurred. operating experience (OE). For The failed piping was analyzed and wall loss example:

due to selective leaching was determined not to be a significant contributor to the pipe 1. Have any other failures of failure. The cause of the failure was fire protection piping determined to be mechanical stress. occurred?

2. Clarification on the source of mechanical stress.

2 B.2.3.21 B-177 SLRA Section B.2.3.21 states [e]ach of the Based on recent industry OE, the one-time and periodic inspections for the staff seeks clarification with various material and environment populations respect to using the reduced at each Unit comprises a 3 percent sample or sample size (i.e., 3 percent with a a maximum of 10 components. maximum of 10 components) for gray cast iron components NUREG-2222, Disposition of Public exposed to soil.

Comments on the Draft Subsequent License

Renewal Guidance Documents NUREG-2191 and NUREG-2192, provides the basis for reducing the extent of inspections for selective leaching during the subsequent period of extended operation (i.e., 3 percent with a maximum of 10 components per GALL-SLR Report guidance) when compared to the extent of inspections for selective leaching during the initial period of extended operation (i.e., 20 percent with a maximum of 25 components per GALL Report, Revision 2 guidance). Part of the basis for reducing the extent of inspections is that industry OE has not identified instances of loss of material due to selective leaching which had resulted in a loss of intended function for the component.

The NRC issued Information Notice (IN) 2020-04, Operating Experience Regarding Failure of Buried Fire Protection Main Yard Piping, to inform the industry of OE involving the loss of function of buried gray cast iron fire water main yard piping due to multiple factors, including graphitic corrosion (i.e., selective leaching), overpressuration, low-cycle fatigue, and surface loads. As noted in the IN, a contributing cause to the failures of buried gray cast iron piping at Surry Power Station (SPS) was the external reduction in wall thickness at several locations due to graphitic corrosion.

3 B.2.3.21 B-180 SLRA Section B.2.3.21 states [a] review of The staff request a discussion plant OE was performed, however, since the with respect to the OE search for PSL Selective Leaching AMP is a new the Selective Leaching program program for SLR, the amount of internal OE is (e.g., keywords used with respect not as extensive as other existing AMPs. to this degradation mechanism, discussion on the OE noted by the During its review related to a previous SLRA staff from a previous SLRA applicant, the staff reviewed a document applicant).

which noted the following: (a) multiple cast

iron breaks due to graphitic corrosion had occurred at St. Lucie; and (b) approximately 4,000 ft of cast iron piping was replaced at St. Lucie.

4 19.2.2.21 A1-27 UFSAR Section 19.2.2.21, Selective NEESL0008-REPT-079 (program A2-27 Leaching, states [w]here the sample size is basis document for the Selective not based on the percentage of the population Leaching program) addresses and the inspections will be conducted how aqueous environments (e.g.,

periodically (not one-time inspections), a raw water) are similar between reduction in the total number of inspections is both units, but does not address acceptable as follows. Eight visual and how the soil environment is mechanical inspections (reduced from 10 consistent between both units.

visual and mechanical inspections) and two The staff requests a clarifying destructive examinations will be conducted discussion on how the soil environment is consistent between both units.

5 N/A N/A NEESL0008-REPT-079 Section 4.1 (scope of The staff request a clarifying program program element) states discussion with respect to whether

[c]omponents that are internally coated may buried components are being be excluded from the scope of this program in excluded from the Selective each 10-year inspection interval. In addition, Leaching program based on the Section 4.4 of the subject document states condition of external coatings

[d]ependent on plant-specific OE and and/or cathodic protection implementation of preventive actions, the efficacy. Section 4.4 of exclusions for external surfaces coatings of NEESL0008-REPT-079 indicates buried components may no longer apply that this may be the case; however, Section 4.1 of NEESL0008-REPT-079 only address excluding components based on internal coatings.