[en] The aim of this paper is to present calorimetric assay measurements that were performed on a set of high burnup plutonium samples using the Mound No. 150 twin resistance bridge calorimeter. The samples and the calorimeter are described in the first part of the paper and the experimental results are discussed in a second part. The isotopic composition, obtained by destructive analysis, was combined with the measured power values for the Pu-assay

[en] Methods for plutonium isotopic measurements have been evaluated for nuclear safeguards inventory verification. A mobile, real-time, nondestructive assay, gamma-ray spectrometric measurement system has been assembled, moved and operated at several nuclear storage facilities to perform rapid, real-time plutonium isotopic measurements on Pu metal, Pu nitrate and Pu oxide

[en] The electronic and magnetic properties of Pu mono-pnictides and mono-chalcogenides, PuX (X= N, P, As, Sb, Bi, O, S, Se, Te, Po), are studied using the ab initio self-interaction-corrected local spin-density approximation. This approach allows for an integer number of f-states to be localized, while the remaining f(electron degrees of freedom are available for band formation. By varying the relative proportions of localized and delocalized f-states, the energetically most favourable (ground state) configuration can be established. We show that the experimental data can be interpreted in terms of the coexistence of both localized and delocalized f-states. (authors)

[en] Method of precision spectrophotometry with internal standardization (SPIS), developed at the V.G. Khlopin Radium Institute (KRI), was applied at manufacturing plutonium containing reference materials for their certification on a mass fraction of plutonium in such materials as solutions of ²³⁹Pu/²⁴⁰Pu - OSO 95.836-2002, ²⁴²Pu - GSO 8568-2004, metal plutonium - GSO 8567-2004, and also solutions of isotope spikes ²⁴⁴Pu, ²⁴⁰Pu and ²⁴²Pu, prepared for IAEA Network of Analytical laboratories for the Safeguards purposes. By the same method verification analysis of the first Russian Plutonium Dioxide 1-st Class Certified Reference Material - GSO 8781-2006 was performed. The relative total uncertainty achieved by the method was in the range (0.06-0.1) % at confidential level P = 0.95. The SPIS method, developed at RI is comparable in precision with such methods as gravimetry, potentiometry, and coulometry

[en] PuO₂ samples with expected amount of Pu as 87% are received for analysis of different elements. The results of the analysis from different analysts group are received to feed in the database and to perform statistical investigations as required. These samples seem to come from three streams. Theoretical linear relationships between the values of %Pu and its isotopic compositions using the observed data of these samples and using generalized least squares technique have been established for each of the three streams. χ² - Tests have been carried out to test the goodness of fit of the data to the proposed linear relationships. Predicted values of %Pu are found to lie within the 95% confidence limits of the corresponding observed values. (author)

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[en] This report presents a review of the methods and capabilities of nondestructive measurements of the isotopic composition of plutonium using gamma-ray spectroscopy

[en] Satisfactory reduction of molten plutonium trichloride (pure and in combination with 20 wt % sodium chloride) by calcium, lanthanum, and cerium has been demonstrated on the 10-g scale. The yields were satisfactory for this scale of operation, and it is indicated that these reductions may be useful for large-scale operations. Significant separations of plutonium from rare earth impurities was demonstrated for lanthanum and cerium reductions. Preparation of plutonium-cerium and plutonium-cerium-cobalt alloys during reduction was also demonstrated