Depleted Zinc Isotopes

Depleted Zinc Isotopes Usage

Zinc, depleted in the isotope ⁶⁴Zn, is presently used as an additive in the cooling water systems of BWR nuclear reactors worldwide. The majority of U.S. reactors now utilize depleted zinc oxide (DZO) injections while PWR operators have started to evaluate the technology. Preliminary results indicate that depleted zinc acetate may be more advantageous for use in PWRs.

The addition of ⁶⁴Zn greatly reduces corrosion processes, including stress corrosion cracking. Furthermore, the added zinc reduces the amount of radioactive 60Cobalt formed because of the irradiation of natural cobalt in the construction materials of the reactor. 60Co is a major contributor to radiation build-up in the cooling systems and therefore causes elevated dose rates of maintenance personnel.

Production of Depleted Zinc Products¹

Diethyl zinc gas is depleted in custom-made facilities, which use advanced gas centrifuges. The use of centrifuges for isotope separation is a process that takes advantage of the difference in molecular weight between the various isotopes. A cascade of centrifuges is required to achieve significant changes in the enrichment. A single pass through the cascade can provide enough depletion such that ⁶⁴Zn (natural abundance of 48%) is reduced to less than 1%.

The ultracentrifuge consists of a vacuum recipient with a fast spinning rotor inside. The diethyl zinc gas is fed into the rotor, where it is accelerated until it has nearly the same rotational frequency as the rotor itself. The gas molecules are then subjected to centrifugal forces induced by the centripetal acceleration. Heavy molecules are subjected to larger forces than light molecules and will therefore migrate towards the rotor wall. The gas is extracted from the centrifuge by a set of gas extraction scoops; the heavy fraction scoop is located near the rotor wall, whereas the light scoop is more to the centre of the rotor.

Product Specification

⁶⁴Zn Content < 1%
Chemical Purity > 99.8%

The diethyl zinc produced during the depletion process is converted by a wet chemical process to the desired chemical form, such as the oxide, acetate, or any other zinc compound. The conversion to a powder occurs under strict supervision of process parameters giving accurate control of particle size and moisture content. If required, the zinc powder can be pressed into forms and sintered to high-density pellets.

Please visit the following links for complete chemical and physical specifications:

Depleted Zinc Oxide Specifications
Depleted Zinc Acetate Dihydrate Specifications
Depleted Zinc Oxide Powder Regular Grade
Depleted Zinc Oxide Powder Fine Grade
Depleted Zinc Oxide Powder Extra Fine Grade
Depleted Zinc Oxide Pellets
Depleted Zinc Acetate Dehydrate

Note: 1. H. Rakhorst in “Production of DZO at Urenco” presented at the 15th BWR Chemistry and materials Workshop, GE Nuclear San Jose Offices, US June 3-4, 2002.