ML24347A205
| ML24347A205 | |
| Person / Time | |
|---|---|
| Site: | Nuclear Energy Institute |
| Issue date: | 12/02/2024 |
| From: | Richter M Nuclear Energy Institute |
| To: | Advisory Committee on Reactor Safeguards |
| Shared Package | |
| ML24347A204 | List: |
| References | |
| RG 3.78 | |
| Download: ML24347A205 (1) | |
Text
©2024 Nuclear Energy Institute 1 ASME Code Case N-860 and Reg Guide 3.78 NEI/Industry Perspective ACRS Fuels, Materials, and Structures Subcommittee Meeting Mark Richter Technical Advisor Nuclear Energy Institute December 19, 2024
©2024 Nuclear Energy Institute 2 Approaching 40 years of safe operation AMP inspections of inservice storage canisters to date have revealed no indications of corrosion indicative of confinement degradation Minor evidence of oxidation associated with ambient moisture noted The Code Case and endorsing Regulatory Guide align with the concept of learning aging management in NEI 14-03, as endorsed by the NRC in Regulatory Guide 3.76 Licensees could benefit from the flexibility offered by the CC and draft Regulatory Guide 3.78 while maintaining safe, risk-informed ISFSI operations Status of Spent Fuel Dry Storage
©2024 Nuclear Energy Institute 3 12 Part 72 specific ISFSI licenses renewed, one being finalized 10 Dry Storage System CoCs Renewed for Part 72 general licenses Most renewed licenses/CoCs include austenitic stainless steel canisters comprising 90+% of in-service DSSs About 3,800 such canisters in service, some for 30+ years Five more DSS CoCs to be renewed beginning in 2027 through 2037 Status of ISFSI Licenses & Technology
©2024 Nuclear Energy Institute 4 Canister AMPs for CISCC developed and approved uniquely for each license/CoC renewal Refer to Code where appropriate (e.g., visual NDE inspection technique)
No NRC or Code requirements existed for choosing which canister(s) to inspect, what to inspect, or how often Needed differentiators for different site service environments Needed actions to be taken if indications are found Need guidance for using inspection results to appropriately modify AMPs Dry Storage Canister AMPs
©2024 Nuclear Energy Institute 5 EPRI developed processes for relative site CISCC susceptibility and how to choose which canister(s) to inspect Renewed licenses and CoCs established the requirements for canister inspections - technique, frequency, acceptance criteria, corrective actions, etc.
In 2015, NRC requested ASME to develop a standard for canister inspections during the period of extended operations ASME, ISFSI owners, national laboratories, vendors, and NRC developed Code Case N-860, approved by ASME in 2020 Dry Storage Canister AMPs
©2024 Nuclear Energy Institute 6 The approved Code Case had no effect on renewed licenses and CoCs Licensees are bound to the AMPs in the renewed licenses and CoCs NRC developed draft Regulatory Guide 3.78 proposing a method for licensees and CoC to voluntarily adopt CC N-860 Licensees (in collaboration with CoC holders) need to evaluate the potential benefits of updating their canister AMPs to adopt the CC and RG Requires canister AMP revision via 10 CFR 72.48, program and procedure changes Future CoC renewals should seriously consider adopting the CC to enable a more efficient renewal review process Dry Storage Canister AMPs
©2024 Nuclear Energy Institute 7 Draft RG 3.78 is succinct and well-written Adopts the CC with no exceptions or clarifications Offers one additional alternative to extend canister inspection interval for sites with low CISCC relative susceptibility ranking This is important for establishing site-specific risk-informed inspection programs Storage service conditions are a key element of the aging management review process for license and CoC renewal Industry supports the RG as the final piece of the framework to allow the consensus standard CC to be used under ISFSI licenses Regulatory Guide 3.78
©2024 Nuclear Energy Institute 8 NEI commends the NRC staff for:
Using ISFSI service environment and material performance data in the development of DG-3058, including enabling modification of inspection intervals based on susceptibility criteria Recommending the use of 72.48 to adopt the Code Case without an amendment Recognizing the transformation of non-chloride salts into sodium sulfate and nitrite which act as CICSS inhibitors Recognizing testing results that demonstrate that CISCC of austenitic stainless steel welds at low-susceptibility sites is very unlikely NEI agrees with the staff decision rationale and implementation conclusion reflected in the associated draft regulatory analysis:
This guidance will result in total quantified benefits that exceed the relatively small costs of implementation. DG-3058 is a noteworthy example of applying risk insights to improve the regulatory framework Concluding Remarks
©2024 Nuclear Energy Institute 9 Questions?
mar@nei.org