Campaign underway to safely store GTCC waste

Though considered low-level radioactive waste, Greater-Than-Class-C, or GTCC waste, must be stored on site at nuclear plants across the country. Just as with spent nuclear fuel, there is currently no federal repository to ship it to.

The Nuclear Regulatory Commission has established various classifications of low-level radioactive waste: Class A, B, C and GTCC.

SONGS is using the TN-NUHOMS storage system to store an additional 12 canisters of the GTCC material from the Unit 2 and 3 spent fuel pools, as well as reactor components, such as the core barrel, which contained the fuel assemblies when the reactors were operating.

On Saturday (April 16), crews successfully transported and stored the first of the 12 new canisters. (See photos above).
GTCC Transfer Cask Dry Run_1 edit
During a practice dry run, the crew inserts a weighted GTCC canister into its storage module. Unused modules that had been in storage on site were added to the NUHOMS system to accommodate the additional canisters. The crews include experienced personnel who worked on previous NUHOMS loading campaigns at SONGS.

The system held one canister of GTCC waste from Unit 1, which was retired and partially decommissioned in 1992.

What is GTCC waste?

GTCC waste comprises certain materials that have been stored in the spent fuel pools in special containers, such as fuel-related components used for monitoring during operations, fuel assembly inserts and instrumentation wires. There will be one canister of material from each spent fuel pool.

The other material is activated metals that were positioned closest to the nuclear fuel during operation. One such piece is the core barrel, which is being segmented using an underwater cutting technique to be placed in stainless steel canisters.

09-20-2021 Unit 2 Reactor 4
The core barrel in the Unit 2 reactor cavity. The heavy metal component is being segmented for storage as GTCC waste.

On the move

On Saturday, the first stainless steel canister containing the material from the Unit 2 spent fuel pool was transferred to the dry fuel storage pad and loaded into the TN-NUHOMS storage system. Additional modules had previously been added to the system to accommodate the GTCC canisters.

04-16-2022 GTCC FIrst Canister Transport and Loading _MP11627
Making final preparations before inserting the canister into its storage module.

Safety will be the top priority as the team works through the process of storing all 12 canisters. Some of the team members have deep experience with the process of loading and storing the NUHOMS canisters, having worked on the initial spent fuel loading campaigns for the system.

The team is using lessons-learned from those previous campaigns as well as the Holtec campaign that was completed in August 2020.

"We have a strong level of experience with this crew and good supervisory oversight through every step of the process," said Jerry Stephenson, ISFSI (Independent Spent Fuel Storage Installation) engineering manager.

The GTCC campaign is expected to be completed in 2023.

(Posted April 20, 2022)