Electrorefining of uranium and plutonium - A literature review

In this study, a certified plutonium metal reference material (CRM 126) with a known production history is examined using analytical methods that are commonly employed in nuclear forensics for provenancing and attribution. The measured plutonium isotopic composition and actinide assay are consistent with values reported on the reference material certificate. Model ages from U/Pu and Am/Pu chronometers agree with the documented production timeline. The results confirm the utility of these analytical methods and highlight the importance of a holistic approach for forensic study of unknown materials.

Forensic investigation of plutonium metal: a case study of CRM 126

UNLABELLED The metabolism of 239Pu and 241Am in 3 site-specific industrial dusts has been studied after their deposition in the rat lung. A comparative experiment has also been carried out with a mixture of these actinides inhaled as their nitrates. The aim of this study was to provide an experimental basis for assessing limits on intake and to establish whether the 239Pu content in the lungs could be interpolated from measurements of 241Am. THE RESULTS 1 demonstrate the wide differences in the lung retention kinetics of the actinides and in the absolute and relative amounts translocated to the blood that can occur for industrially produced materials; 2 show that the annual limits on intake (ALIs) for the different materials vary between those postulated for class W and Y compounds by the International Commission on Radiological Protection; 3 indicate that acute intakes of 239Pu equivalent to the ALI can, depending on the nature of the dust, be estimated from 241Am chest monitoring data at times from a few days up to about 3 years after exposure.

Studies on the metabolic behaviour of industrial actinide-bearing aerosols after deposition in the rat lung: an experimental basis for interpreting chest monitoring data and assessing limits on intake for workers.

Pyrophoric potential of plutonium-containing salt residues

Radiochronometry analyses of two Pu metals were performed using the 237Np–241Am–241Pu, 234U–238Pu, 235U–239Pu, and 236U–240Pu decay series. For one sample, all radiochronometers yield concordant model dates in 1959–1960, indicating that the aqueous processing method used to purify Pu effectively removed U, Am and Np decay products from the bulk Pu. The second sample yields discordant model dates that are also older than the known production date in 1982. The excess U, Am and Np present in the sample indicate that the sample was purified during at least two different episodes, using a combination of aqueous methods and molten salt extraction.

A case study in plutonium radiochronometry using multiple isotope systems

The past 20 years have seen significant growth in the development and application of pyrochemical technology for the processing of plutonium. Non-aqueous high temperature processes offer key advantages over conventional hydrometallurgical systems for particular feed stocks and specific applications. Major processes in use today include 1. (1) direct oxide reduction for the conversion of PuO2 to metal 2. (2) molten salt extraction for americium removal from plutonium metal 3. (3) molten salt electrorefining for plutonium metal purification 4. (4) hydriding to remove plutonium from host substrates. Current major pyrochemical processes ranging from the classical calcination-fluorination-“bomb reduction” sequence to new techniques under development are reviewed. Each process is presented and brief descriptions of the production equipment are given.

W.Scott Moser

Papers

Review of major plutonium pyrochemical technology