Holtec’s Forced Helium Dehydrator (FHD) provides an alternative to the vacuum dryer. The FHD was certified by the NRC in 2001 and was extensively used to dehydrate Trojan’s fuel assemblies, a number of which had water-laden fuel rods. Since then, over 20 nuclear units utilize the FHD including Chernobyl in Ukraine and Sizewell B in the U.K.

Protecting the integrity of the used fuel while its physical environment is changed from aqueous (high heat transfer capability) to gaseous (low heat transfer capability) is an important consideration in its inertization process.

The Forced Helium Dehydrator provides certain benefits that are not available from the vacuum dryer. For example:

  • The drying process must not only be efficient, but (1) it must also prevent the generation of high thermal strains (which may damage the fuel cladding, and (2) ensure that any moisture entrapped inside a breached cladding is removed. Vacuum drying, the classical method of used fuel de-moisturization, has proved to be marginal or inadequate.
  • In addition to ensuring that NRC’s mandated level of dryness will be achieved regardless of the state of the fuel, the FHD minimizes the thermal strains on the fuel cladding during the drying process, thus minimizing the potential of crack initiation or propagation of any existing crack in the fuel cladding.


TitleYearPatent No.Status
System and Method for Preparing a Container Loaded with Wet Radioactive Elements for Dry Storage2023US 10,839,969 B2, US 8,561,318, US 9,165,690 B2, US 10,229,764 B2, EP 2 227 655 B1, EP 3 364 136 B1, US 11,742,102 B2Granted
Method for Preparing Spent Nuclear Fuel for Dry Storage2022US 11,217,353 B2, US 10,535,439 B2, US 9,761,338 B2, US 8,737,559 B2, US 8,266,823 B2, US 7,707,741 B2, EP 1 888 988 B1Granted
Forced Gas Flow Canister Dehydration2007US 7,210,247 B2, US 7,096,600 B2Granted