"No used fuel will go outside of the plant's security fence until it is removed to the permanent federal facility," said Herbert Woodeshick, special assistant to the president for Susquehanna. He also stressed that the dry-storage facility will have no radiological effect on the surrounding area.
The dry-storage facility uses natural air circulation to remove heat produced by the used fuel. The fuel is isolated inside 15' long, airtight, sealed stainless steel canisters. The canisters, weighing approximately 85 tons each, are placed inside 30" thick concrete modules. According to Woodeshick, the horizontal modules are built to withstand earthquakes, floods, tornadoes and temperature extremes.
Prior to the actual transfers, the plant's dry-fuel storage team successfully completed a dry run of the used fuel transfer process. As part of the training exercise, the team handled dummy fuel rod bundles without the actual fuel inside.
The entire dry-storage system process at the Susquehanna plant is monitored by three permanent, on-site inspectors from the Nuclear Regulatory Commission and one engineer from the Pennsylvania Department of Environmental Protection's Bureau of Radiation Protection.
PP&L Inc. chose dry-storage technology to provide temporary storage for the used fuel until the federal government opens a permanent central-storage facility early in 2000 or beyond.
A Look at the Used Fuel Transfer ProcessThe process utilized to transfer used nuclear reactor fuel at PP&L involves the following steps:
- A stainless steel canister is placed into a special transfer cask and lowered into the cask pit between the plant's two spent fuel pools, located next to the reactors. Each reactor uses 764 fuel assemblies, and each pool is designed to hold 2,840 used fuel assemblies.
- The canister is loaded with 52 used fuel assemblies from the pool. Each of the 14' long fuel assemblies consists of more than 80 separate fuel rods holding used uranium fuel pellets.
- The canister is sealed, drained of water and filled with helium gas to act as a heat transfer medium.
- The outside of the transfer cask is decontaminated, and the transfer cask, which contains the stainless steel canister and weighs approximately 100 tons, is loaded on a transfer trailer. The trailer has 32 independently steered wheels to navigate the 0.25 mile trip to the dry storage pad.
- Once at the storage pad, a special hydraulic plunger pushes the stainless steel canister from the transfer cask and into position inside the horizontal storage module.
- The lid of the horizontal storage module is welded closed.
- On an ongoing basis, the temperature of each horizontal storage module is monitored continuously.
Pennsylvania Power & Light's storage pad can accommodate as many as 105 horizontal storage modules.