ML25104A305
| ML25104A305 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 04/14/2025 |
| From: | Mark Yoo Office of Nuclear Reactor Regulation |
| To: | Wilson C Constellation Energy Generation |
| Shared Package | |
| ML25104A303 | List: |
| References | |
| Download: ML25104A305 (1) | |
Text
1 REQUEST FOR CONFIRMATION OF INFORMATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION DRESDEN, UNITS 2 AND 3, SUBSEQUENT LICENSE RENEWAL REVIEW - SAFETY CONSTELLATION ENERGY GENERATION, LLC DRESDEN, UNITS 2, 3 DOCKET NO. 05000237, 05000249 ISSUE DATE: 4/14/2025 Set #3 RCI B.2.1.33-1 Operating experience in SLRA Section B.2.1.33 describes effectiveness of the AMP in managing aging effects of Units 2 and 3 Reactor Building roof. The Reactor Building roof was replaced in 2019.
During the NRC onsite audit from 12/10/2024 to 12/12/2024, the staff observed significant damage and vegetation growth at some areas of Units 2 and 3 Turbine Building roof, which could eventually lead to roof leakage. The staff reviewed WO 1508043 and finds that the Turbine Building roof will be replaced once the contract is awarded.
Confirm that building roofs with significant degradation that resulted in a potential loss of intended function for components and protected by the roofs will eventually be replaced.
When necessary, temporary measures are implemented to ensure that roof leakage does not impair the operability of underlying equipment.
Confirm that the Turbine Building roof will be replaced prior to entering the SPEO.
RCI 3.5.2.2.2.1-1 SLRA Section 3.5.2.2.2.1, Item 4, as modified by SLRA Supplement 2 (ML25072A153), states, Operating experience at DNPS, which inspects for concrete deterioration due to any aging effect and mechanism, has identified increases in porosity and permeability and loss of strength due to the effects of carbonation. Concrete degradation that would indicate a reduction in its structural integrity has not been identified. The inconsequential increase in porosity and permeability, and loss of strength due to leaching of calcium hydroxide and carbonation does not impact the intended functions of concrete structures.
SLRA Section 3.5.2.2.2.3, Item 3 states, Some minor leaching of calcium hydroxide has been observed on DNPS Group 6 concrete structures; however, it did not result in a loss of intended function.
SRP-SLR Report states that a plant-specific program is not required for the reinforced concrete exposed to flowing water if evaluation determined that the observed leaching of calcium hydroxide and carbonation in accessible areas has no impact on the intended function of the concrete structure.
In addition, SLRA Section 3.5.2.2.2.1, Item 1, as modified by SLRA Supplement 2 (ML25072A153), states, The inconsequential loss of material (spalling, scaling) and cracking due to freeze-thaw does not impact the intended functions of concrete structures.
2 SLRA Section 3.5.2.2.2.3, Item 1, as modified by SLRA Supplement 2 (ML25072A153), states, The inconsequential loss of material (spalling, scaling) and cracking due to freeze-thaw does not impact the intended functions of concrete structures.
SRP-SLR Report states that a plant-specific program is not required if documented evidence confirms that the existing concrete had air content of 3 percent to 8 percent and subsequent inspection did not exhibit degradation related to freeze-thaw.
Confirm that evaluations exist and demonstrate that the observed leaching of calcium hydroxide and carbonation has no impact of the intended functions of the concrete structure, which was described in SLRA Sections 3.5.2.2.2.1, Item 4 and 3.5.2.2.2.3, Item 3.
Confirm that evaluations exist and demonstrate that the observed loss of material (spalling, scaling) and cacking due to freeze-thaw has no impact of the intended functions of the concrete structure, which was described in SLRA Sections 3.5.2.2.2.1, Item 1 and 3.5.2.2.2.3, Item 1.