CP-202500105, CP-ISI-2025-3 Full Description Detail
| ML25106A320 | |
| Person / Time | |
|---|---|
| Site: |  |
| Issue date: | 04/16/2025 |
| From: | Vistra Operations Company |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML25106A319 | List: |
| References | |
| CP-202500105, TXX-25018 | |
| Download: ML25106A320 (1) | |
Text
Comanche Peak ISI Alternative Application CP-ISI-2025-3 Full Description of the Proposed Alternative. Note: Consider adding information regarding material specifications, component Group or Class, and ASME Code Class.
The Unit 2 moisture barrier is shown on CPNPP drawing S2-0519 with sheets A though C [Unit 1 S1-0519]
delineating the following components: a sealer, bond breaker and elastic joint filler. In the Joint Fillers and Sealers Specification 2323-SS-13, the sealer is described as a two-component polysulfide system. The bond breaker on the drawing is described as a butyl or polyethylene backing joint placed over the elastic joint filler.
The elastic joint filler is a unicellular (closed cell) PVC foam. Section 3-3 from drawing S2-0519 [Unit 1 Section E-E drawing S1-0519] below shows the configuration.
Unit 2 Unit 1 The cap material covers the accessible moisture barrier. Detail C from S2-0519 [Unit 1 Detail C drawing S1-0519]
shows a stepped slice representation of the different layers. The cap material is shown but not labeled on the detail.
Unit 2 Unit 1 Page 1 of 2 Attachment to Comanche Peak ISI Alternative Application CP-ISI-2025-3
The BISCO penetration seal drawings for the 808 elevation depict the gap around the outside area of containment
[vendor drawing Unit 1 CB-808-154 sheets 40,42,44,46, & 47, Unit 2 M2-1900-RB-154C sh 6, -154A sh 6, -154B sh 7 and -154D sh 8]. These drawings point to the Unit 1 gap as Trace No. 5187 [Unit 2 Trace No. 5001] and reference detail 37. According to the Engineering Report on the Evaluation of Fire Rated Penetration Seal Details, penetration detail 37 has an elastomer cap which is included for housekeeping purposes and no credit is taken for the cap in the fire rating [ER-ME-038 Rev. 2]. Drawing M1-1901 sheet 3, (M2-1901 sheet 3, Unit 2), Penetration Seals Typical Details, depicts the cap material for detail 37 (shown below). This drawing shows the cap material, seal material (sealer) and the damming material (bond breaker). The cap material covering the moisture barrier is a 1/2 cap made from Promatec 45B (or equivalent), a silicon elastomer material that is adhered to the top of the moisture barrier. Additionally, DCN-11381, Rev 0, states that the 1/2 cap material for detail 37 is for housekeeping and traffic protection only and will not affect the performance of the seals.
The examination of the moisture barrier is limited by the presence of the cap material. Only the limited areas that are degraded can be inspected prior to being repaired.
Proposed Alternative:
1.
Visually inspect the cap material on a once per period basis and in areas where degradation has occurred inspect the accessible area of the moisture barrier.
2.
Implement work orders to repair degraded areas of the protective cover within one cycle of discovery.
Page 2 of 2 Attachment to Comanche Peak ISI Alternative Application CP-ISI-2025-3