Session: OAC-03-02/07-01 Monitoring, Diagnostics & Inspection and Plant Life Extension: Aging & Life Management

Paper Number: 60688

Start Time: Thursday, July 15, 2021, 05:00 PM

60688 - Development and Implementation of an In-Situ Repair Method for ISFSI Canisters 

A remote, robotic method of mitigating damage to an ISFSI canister has been developed and tested. It is currently ready for implementation if required for a vertical canister system and will be ready for implementation in 2020 for a horizontal canister system. The development was in response to State of California directives to be ready and able to implement a canister repair technology if needed at San Onofre Nuclear Generating Station.

The method was developed by miniaturizing existing cold spray technology and combining it with robotics previously used on site. The Metallic Overlay method (also known as 'Cold Spray') has been tested and accepted for use at San Onofre.

The testing involved the miniaturization of the Metallic Overlay Equipment, testing of several metals which were considered for use, the decision process for the down-selecting of the chosen material, the combining of mitigation tooling and robotics, and the final testing and qualification of the process. It will also discuss the details needed to implement on site.

This paper will focus on the development, testing and implementation of the robotic overlay system. The background leading to the development of the process will be provided, and will note the tie to (in development) Code Case N-860[1], which would indicate the conditions that would occur to direct the site towards implementation of the Metallic Overlay process.

Mitigation methods have been initially researched by EPRI, and on-going projects funded by the NEUP Program are on-going. However, a fully developed mitigation method which would allow in-situ repair of a loaded fuel canister is not currently available. It is considered highly unlikely that significant degradation which would require mitigation would occur during the initial license period (approximately 20 years) of loaded spent fuel canister operation. A renewed license for spent fuel storage canister operation (after the initial 20-year period) requires the implementation of an Aging Management Program for the loaded fuel canisters, which includes periodic visual inspection requirements of selected canisters. There have been several ISFSI canister systems which have been granted renewed licenses. As part of the renewals, several canisters have been visually inspected across the United States, with all canisters in very good condition, with none requiring mitigation. The inspection results are consistent with the conclusions of NUREG-2214, ‘Managing Aging Processes In Storage (MAPS) Report’, published in 2019, which analyzed potential canister (and ISFSI System) degradation methods over 60 years of operation, and provides guidance for the future licensing, operation, and inspection of ISFSI systems long term.

The process has been developed in advance of being required. It is a proactive action intended to allow efficient response in the event mitigation is required at San Onofre.

Presenting Author: Allen Williams WDPMS

Authors:

Allen Williams WDPMS
Jamie Beard Robotic Technologies of Tennessee, LLC
Kyle Johnson VRC Metal Systems
Jerry Stephenson Southern California Edison
Stephen Canfield Robotic Technologies of Tennessee, LLC