[en] The purpose of this workshop was to assess the present status of measurements of cross sections and other nuclear data for the isotopes of Pu and Am relevant to reactor applications, and to assess the present and future needs for those measurements. The contents of the papers presented at the meeting are briefly summarized in this concluding talk. Seven specific recommendations and nine general recommendations are given. 1 table

[en] Procedures for determination of plutonium and americium isotopes in the three main sea components: water, bottom sediments and biota are described. In general, the methods consists of four stages: pre-treatment, chemical separation, source preparation and alpha-particle measurements. Depending on material which is analyzed, the pre-treatment is performed by use of coprecipitation, dry ashing, wet mineralization and acid leaching. For americium and plutonium separation from other anions and cations, ion-exchange chromatography, liquid-liquid extraction and coprecipitation are applied. The measurement samples are prepared by electrolytic deposition of separated elements or by transferring americium and plutonium previously coprecipitated with neodymium fluoride, onto membrane filters. Alpha-particles measurements are performed by α-spectrometry method with application of barrier surface silica (Si/Au) detectors or passivated implanted surface silica (PIPS) detectors. The choice of the needed procedure depends on the analyzed samples. In above described methods the lower detection limits for plutonium and americium are from 0.02 to 0.4 mBq/sample at measurement time in the range of 1400 to 10000 min. The final recovery ranged from 30 to 100%. The radiochemical separations followed by a spectrometry measurements are the only possibility for determination of plutonium and americium in the marine low activity environment samples. (author). 23 refs, 4 tabs

[en] This study presents a rapid and simple α source preparation method for a radioactive waste sample. The recovery of ²³⁹Pu, ²³²U and ²⁴³Am using a micro-coprecipitation method was over 95%. The α-peak resolution of Pu and Am isotopes through the micro-coprecipitation method is enough to discriminate the Pu and Am isotopes from other Pu and Am isotopes. The determination of the Pu and Am isotopes using the micro-coprecipitation method was applied to the radioactive waste sample, so that the activity concentrations of the Pu and Am isotopes using the micro-coprecipitation method in the radioactive waste sample were similar to those using the electrodeposition method

[en] A new neutron-deficient isotope ²³⁵Am was produced via ²³⁸Pu(p, 4n)²³⁵Am reaction. The products were identified by means of the transporting of He-jet system, separating of rapid radiochemical method and measuring of γ and X rays as well as X-γ coincidence. The measured half-life of ²³⁵Am is 15 +- 5 min

[en] Studies have been carried out on the migration of plutonium and americium in solutions flowing through porous and crushed rock and through fissures. The migration process can be described in terms of the surface absorption of these elements. In addition, chemical effects on the absorption have been observed. One of these effects is possibly due to the presence of a plutonium polymer that migrates at a more rapid rate than normal plutonium

No abstract available

[en] Radiochemical separation of Pu, Am and U was tested from synthetic solutions and evaporator concentrate samples from nuclear power plants for isolation of each of them for alpha-spectrometry analysis. The separation was performed by anion-exchange chromatography, extraction chromatography, using TRU resin, and precipitation techniques. The aim of the study was to develop a sensitive analytical procedure for the sequential determination of ²⁴²Pu, ²³⁸Pu, ^239+240Pu, ²⁴¹Am and ^235,238U in radioactive wastes. ²³⁸Pu, ²⁴²Pu, ²⁴³Am and ²³²U were used as tracers. The measurements of α emitting radionuclides were performed by semiconductor detector that is used especially when spectrometric information is needed. For synthetic solutions the chemical recovery was based on associated iron concentration and was about 93%. (author)

[en] The origins of different artificial radionuclides found in soils from Northern and Southern Bulgaria was determined by measurements of their actual concentrations and respective ratios. On the basis of the measured mobility and concentrations of the investigated radionuclides in soils, it was estimated that after the Chernobyl accident the mean depositions of fresh ¹³⁷Cs were 3.0 ± 2.5 kBq/m² for Northern Bulgaria and 15 ± 7 kBq/m² for Southern Bulgaria. As a result of global fallout following atmospheric nuclear weapon tests in the 1950s, mean depositions (corrected to 1965) were calculated for Northern and Southern Bulgaria as follows: for ⁹⁰Sr-1.0 ± 0.5 and 2.3 ± 1.3 kBq/m², ²³⁸Pu-1.3 ± 0.8 and 2.8 ± 1.6 Bq/m², ^239+240Pu-15 ± 14 and 47 ± 38 Bq/m^, and ²⁴¹Pu-520 ± 200 and 760 ± 260 Bq/m². (author)

[en] It had previously been shown that 2,6-di(5,6-dialkyl-1,2,4-triazine-3-yl)pyridines extract Am(III) selectively over Eu(III), giving a separation factor of 100-120. In this work a more detailed study of the distribution equilibria was made. If not given otherwise, 2,6-di(5,6-di-propyl-1,2,4-triazine-3-yl)pyridine (=B) was taken as a representative of the title extractant class and a mixture of branched alkanes (TPH) modified with 2-ethyl-1-hexanol was taken as a diluent. Since Am(III) and Eu(III) (=M) are extracted as complexes of the type M(NO₃)₃3B, their distribution ratios increase strongly with the activity of nitrate ions in the aqueous phase and the concentration of the extractant in the organic phase. The distribution ratios of the metals are suppressed in the presence of macro amounts of Eu(III), due to lowering the free extractant concentration as the solvent loading is not negligible, but the Am(III)/Eu(III) separation factor remains unchanged. The extraction of Am(III) and Eu(III) is little changed if 1-octanol is taken as a TPH modifier instead of 2-ethyl-1-hexanol, and the highest distribution ratios are attained at 10-20 vol% alcohol. The optimum concentration of the alcohol is 20 vol%, giving appropriate solubilization of the extractant in the mixed diluent. Higher distribution ratios are obtained in the presence of 1-butanol which, however, solubilizes the extractant less effectively than the octanols. Both the extraction efficiency and the Am(III)/Eu(III) separation factor decrease in the following order of diluents (each modified by 20 vol% 2-ethyl-1-hexanol): TPH > cyclohexane > 2-methyl-4-pentanone > 2-ethylhexyl acetate > chloro-benzene > benzene > xylene. (author)

[en] The results of irradiation experiments of the transmutation of technetium and americium, performed by the EFTTRA group, are described. First the results of the recent tests, T1 and T2, for technetium in the HFR are discussed. In two subsequent experiments targets of metallic technetium were transmuted to an extent of about 6% and 16%. Post-irradiation examination of the targets revealed an excellent in-pile behaviour. Secondly, the results of the T4 test, the transmutation of americium in a spinel-based fuel (micro-dispersed), are presented. It is shown that extensive swelling of the fuel took place, probably due to the damage of the matrix by fission product and/or accumulation of helium as a result of alpha decay. A more promising concept for an inert matrix fuel for transmutation of americium, based on a macro-dispersion of a host phase in the inert matrix is discussed. (author)