Review Article: The Effects of Radiation Chemistry on Solvent Extraction: 2. A Review of Fission‐Product Extraction

Abstract

The partitioning of the long‐lived α‐emitters and the high‐yield fission products from dissolved nuclear fuel is a key component of processes envisioned for the safe recycling of nuclear fuel and the disposition of high‐level waste. These future processes will likely be based on aqueous solvent‐extraction technologies for light‐water reactor fuel and consist of four main components for the separation of uranium, fission products, and group trivalent actinides and lanthanides and separation of trivalent actinides from lanthanides. Since the solvent systems will be in contact with highly radioactive solutions, they must be robust toward radiolytic degradation in an irradiated, mixed organic and aqueous acidic environment. Therefore, an understanding of their radiation chemistry is important to the design of a practical system. In a previous paper, we reviewed the radiation chemistry of irradiated aqueous nitric acid and the tributyl phosphate ligand used for uranium extraction in the first step of the series of four extractions. In this paper, we review the radiation chemistry of the ligands proposed for use in the second extraction of cesium and strontium fission products. This includes not only the crown ethers and calixarenes but also cobalt dicarbollide and polyethylene glycol. Since many disparate units have been applied for measuring absorbed radiation dose in the literature, we also present a discussion of that topic and provide conversion factors.