Holtec’s HI-STORM FW Dry Cask Storage System Exceeds Expectations at TVA’s Sequoyah

This issue is adapted from a TVA news bulletin and a subsequent piece published by Nuclear News, on April 21, 2016.

Holtec and Sequoyah’s dry cask team safely and successfully loaded five HI-STORM FW dry cask storage systems on schedule, while remaining below dose goals, with no human performance events, no injuries, and no personnel contaminations. This is the first time that Sequoyah has used Holtec’s HI-STORM FW dry-storage cask system. The dry cask team prepared for several weeks leading up to the fuel loading campaign by performing dry rehearsals, to ensure the equipment worked properly and the procedures were correct.

The previous cask system that Sequoyah used was Holtec’s HI-STORM 100 system. The equipment and processes were very similar. The primary advantages of the FW system are higher capacity (37 spent fuel assemblies versus 32 for the 100 system) and higher decay heat handling capability (up to 46 kW versus 37 kW for the 100 system).

The Holtec and Sequoyah teams were able to keep dose low by strategic placement of fuel assemblies in the casks, improved HI-TRAC processing, cask shielding, and, most importantly, engaged safety-conscious workers. This brings the total number of dry storage casks on the independent spent fuel storage installation (ISFSI) to 49. The ISFSI has the capacity to store 90 containers.

Senior Manager of Radiation Protection, Mike Halter said, “We saw continuous improvement in both schedule and dose performance, thanks to the focus of the team.”

The cask dose performance including the original and revised estimates is shown in the table below.