ML22024A033

Breakout Questions - Trp 45 - Masonry Walls

ML22024A033
Person / Time
Site:	Oconee
Issue date:	01/20/2022
From:	Angela Wu NRC/NRR/DNRL/NLRP
To:
Wu A, 301-415-2995
Shared Package
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References
Download: ML22024A033 (2)

Text

ONS SLRA: Breakout Questions SLRA Section B2.1.32, Masonry Walls TRP: 045 Question Number SLRA Section SLRA Page Background / Issue (As applicable/needed)

Discussion Question / Request 1

Table 3.5.1 3-1343 Table Item 3.5.1-071 claims that ONS has no masonry walls in an outdoor environment in the scope of SLR.

However, it was noted in the on-site audit that there are many perimeter masonry walls covered by metal siding. The metal siding can protect the masonry walls from rain, but these external masonry walls are exposed to the wind even though they are not visible from the external inspection.

The outdoor environment consists of moist, possibly salt-laden air and spray, cooling tower plumes (which might contain chemical additives), industrial pollutants (e.g., fly ash, soot), ambient temperatures and humidity, and exposure to weather events, including precipitation and wind.

1. Please clarify if there are any masonry walls exposed to outdoor environment, and/or confirm if the claim in item 3.5.1-071 is in current license.

2. Please discuss whether an air-outdoor environment should be applicable to these masonry walls covered by metal siding, and potential aging effects caused by air-outdoor environments should be managed.

3. Please discuss how an evaluation of the acceptability of the inaccessible areas for masonry walls covered by metal siding should be conducted whenever conditions are detected in accessible areas that could indicate the presence of, or result in, degradation to such inaccessible areas.

2 B2.1.32 B-218 SLRA provides an enhancement for Element 3 to modify the parameters monitored to identify potential shrinkage and/or separation of masonry walls and include loss of material in addition to the currently managed cracking at joints.

Based on the proposed enhancement to Element 3, please discuss whether Element 6 "Acceptance Criteria" needs to be enhanced accordingly to be consistent

Acceptance Criteria of GALL-SLR XI.S5 recommends that observed degradation (e.g., shrinkage and/or separation, cracking of masonry walls, cracking or loss of material at the mortar joints and gaps between the supports and masonry walls) are assessed against the evaluation basis to confirm that the degradation has not invalidated the original evaluation assumptions or impacted the capability to perform the intended functions.

with the GALL-SRL report recommendations.

3 B2.1.32 N/A It is noted that the installation of fiber-reinforced polymer (FRP) to reinforce masonry walls was approved by NRC through a license amendment in 2011.

The graded inspection intervals were authorized by NRC. Based on continued no observed FRP degradation, the inspection interval may be increased to a nominal 6 years (every third unit refueling outage) thereafter through the end of the operating license in July 2034.

1. Discuss whether 6-year inspection frequency is considered a deviation or exception to GALL-SLR XI.S5 Masonry Walls AMP during the SPEO.

2. Discuss how the integrated function of masonry walls reinforced with FRP will be maintained and aging effects for both masonry wall and FRP will be properly managed during the SPEO.