Kinectrics' Novel SCEPTER™ Technology: Extracting Carbon-14 from Spent Ion Exchange Resins

Abstract

The Ion Exchange (IX) resins used to purify the water used in CANDU reactor systems contain high levels of Carbon-14 (¹⁴C). Because of the long half-life of this radioisotope, 5730 years, waste IX resins are classified as Intermediate Level Wastes (ILW), which cost much more to dispose of than Low-Level Wastes (LLW).

Promising technologies to meet the IX waste management challenges include (1) thermal processes, (2) acid stripping, (3) supercritical fluid extraction, and (4) non-selective ion exchange (salt regeneration). The main disadvantages of the four technologies are that they are complicated (sometimes involving high temperatures and pressures), that they have not been industrialized, and are not selective for ¹⁴C removal.

A novel technology has been invented and developed by Kinectrics. It is a proprietary, selective ion exchange process called SCEPTER™ (Selective Carbon Extraction Process Through Exchange Reaction). It operates at ambient temperature and pressure, uses a unique chemical that is regenerated (for re-use) by the process itself, and that it generates extremely small volumes of secondary waste (ILW).

The process can achieve > 99% extraction of ¹⁴C with minimal extraction of other radionuclides. Volume reductions of the LLW waste to one-third of the original have been achieved, with a reduction of the ILW component to 3% of the original waste volume. The chemicals used are low toxicity, recycled, and are never released into the environment. The process produces no gaseous emissions of tritium, ¹⁴C, sulfur, or nitrogen oxides.

The ¹⁴C that is extracted from the waste resin is exclusively contained in the ILW secondary waste, comprising 3% of the original waste volume. This byproduct is a stable, solid, water- insoluble form that can be safely stored. However, if needed, the ¹⁴C can be easily extracted from this material, isotopically enriched, and made available for use in various industries.