Plutonium processing Sampling

For an experienced analyst who knows the techniques involved, the laboratory time to complete this experiment (excluding time for preparation) is 6-8 hours it will take longer for those new to the procedure. The experiment can be interrupted conveniently before the ion-exchange process (Step 10), after the plutonium is stripped from the column (Step 12), and at the conclusion of the preparation for electrodepositon (Step 14). An alternative procedure is given for a 25-mL sample that skips the concentration Steps 3-8. 

The sampling of nuclear materials and the packaging of samples are very critical steps in the measurement process. Differing conditions at nuclear plants dictate the need for a variety of sample-taking and handling procedures before samples are sent for analysis. SAL has developed a set of procedures that take account of local conditions, and has been instrumental in improving the overall quality of the verification of uranium and plutonium samples. 

Further information about this event has been obtained by studying tracks which nuclear decay processes leave in certain minerals ( 8.1.2). Fission tracks can only persist in minerals that have not been heated because heating above 600°C erases the tracks. The fact that Pu fission tracks have been found in iron meteorites and in lunar samples shows that 244pu existed when the planetary system formed. Because of the short half-life of Pu (8 X10 y) it can be concluded that such mineral samples must have formed within a few hundred million years after the nuclide Pu itself was formed. This is probably also the time for planetary formation. The existence of primordial plutonium indicates that an r-process preceeded the formation of the planets. 

Alpha-particle counting is the most commonly used method for determining plutonium concentrations at low levels in biological samples, as well as in process waste streams, and in soil, water, and air filter samples (Brouns 1980). This method does not distinguish between the different alpha-particle emitters of plutonium (plutonium-236, plutonium-238, plutonium-239, plutonium-240, plutonium- 242), nor does it detect plutonium-241, a beta-particle emitter. 

An EPA-approved procedure for the analysis of plutonium in water is listed in Table 6-2. In addition, the following ASTM standard methods relate to the measurement of plutonium in water D 3648, D 3084, D 3972, and D 1943 (ASTM 1981, 1982a, 1982b, 1987). Recent work has focused on more rapid analytical methods in order to determine monitor plutonium levels in waste process streams at nuclear facilities. For example, Edelson et al. (1986) have investigated the applications of inductively-coupled plasma-atomic emission spectrometry (ICP-EAS) to routinely analyze water samples. 

Extant and planned collaborative research, related to nuclear materials safety and between the universities of the consortium operating the Amarillo National Resource Center for Plutonium and various Russian institutions of higher education, is outlined. The research includes activities in the following fields sampling of airborne radionuclides, transportation of hazardous materials, safe removal and processing of nuclear materials, quality assurance practices, and disposition of weapons-grade plutonium in reactors. 

Using lanthanum fluoride as a carrier, Seaborg isolated a weighable sample of plutonium in August 1942. At the same time, Isadore Perlman and William J. Knox explored the peroxide method of separation John E. Willard studied various materials to determine which best adsorbed plutonium Theodore T. Magel and Daniel K. Koshland, Jr., researched solvent-extraction processes and Harrison S. Brown and Orville F. Hill performed experiments into volatility reactions. 

The waste drum assay system (WDAS) measures the residual small plutonium amounts of in-process wastes in 200 liter drums. The system uses a modified neutron coincidence counter with a counter comprising 60 He tubes ( 20% efficiency) with low background. WDAS applies the add-a-source correction technique that corrects for the effects of the waste matrix on neutrons (Menlove et al. 1993, Menlove 1995). A small Cf source is placed in various positions near the external surface of the sample drum. The changes in the Cf coincidence counting rate provide a matrix correction for the plutonium inside the drum. 

---