[en] Short communication. 5 refs., 1 tab

[en] The so-called non-statistical Gamma.radiation emitted in the asymmetric fission of ²⁵²Cf can be interpreted as echoing the repercussions, in the doubly magic core ¹³²Sn, of the cataclysmic transfer of all, or almost all, of its 76 valence nucleons in rearrangement reactions of the diclusteric molecules involved in the process of asymmetric fission

[en] This document has to purpose the bibliographic study of conversion coefficients between the fluence of a neutron source (californium 252) and the dose equivalents in different configurations. The first chapter is devoted to generalities about the neutron dosimetry, then, the different methods used to evaluate the fluence rates and the dose equivalent rates are shown. The second chapter studies the dose coefficients. It presents the conversion coefficients between the neutron fluence and the dose equivalent for a ²⁵² californium source in several configurations. The dose equivalent are studied in the case of 252 cf source moderated by heavy water spheres in different sizes. (N.C.)

[en] In early 1995, the receipt of four sealed californium-252 sources from Oak Ridge National Lab was successfully accomplished by a team comprised of Radiological Engineering, Radiological Operations and Health Physics Instrumentation personnel. A procedure was developed and walked-down by the participants during a Dry Run Evolution. Several special tools were developed during the pre-planning phases of the project which reduced individual and job dose to minimal levels. These included a mobile lifting device for attachment of a transfer ball valve assembly to the undercarriage of the Cannonball Carrier, a transfer tube elbow to ensure proper angle of the source transfer tube, and several tools used during emergency response for remote retrieval and handling of an unshielded source. Lessons were learned in the areas of contamination control, emergency preparedness, and benefits of thorough pre-planning, effectiveness of locally creating and designing special tools to reduce worker dose, and methods of successfully accomplishing source receipt evolutions during extreme or inclement weather

[en] This report presents basic outcomes of development of methods and means of materials composition monitoring, using radioactive isotopes.Informative and measuring systems to analyze moisture of loose materials in technological circulation, using neutron sources, were considered. Method of moisture content measuring of loose materials with variable density, based on individual registration of thermal and above-thermal neutrons decelerated in a substance, was validated. Radioisotope method of solid fuel ash content determination in the conveyor belt, based on application of radioisotope Am-241 source, was considered.Basic errors of radioisotope methods of moisture and ash content measuring of heterogeneous substances with variable density and without sampling from technological circulation and preparation for the measuring, were studied and demonstrated.Examples of methodical, algorithmic, technical and constructive provision of radioisotope devices introduction, fabrication and designing were given.Technical and economical outcomes of large-scale industrial application of the developed devices and systems are presented. The issues to increase efficiency of activity on radioisotope apparatus designing were discussed

[en] The proton-neutron symplectic model with $Sp(12,R)$ dynamical algebra is applied for the simultaneous description of the microscopic structure of the low-lying positive-parity states of the lowest ground, β and γ bands in ${}_{238}U$. For this purpose, the model Hamiltonian is diagonalized in a $U(6)$-coupled basis, restricted to the state space spanned by the fully symmetric $U(6)$ irreps. A good description of the energy levels of the three bands under consideration, as well as the enhanced intraband $B(E2)$ transition strengths between the states of the ground band is obtained without the use of an effective charge. The results obtained show small admixtures from the higher major shells and a highly coherent mixing of different $U(6)$ irreps which is manifested by the presence of a good $U(6)$ quasi-dynamical symmetry in the microscopic structure of the collective states under consideration.

[en] Caliban is a benchmarked, bare metallic reactor, operated by the Criticality, Neutron Science and Measurement Department. A joint neutron noise measurement week was organized with a team from the LANL in June 2013. Its aim was to perform multiplication measurements from different subcritical configurations, to build an analysis of the uncertainties of this kind of experiments. The first results of this week are presented here. (authors)

[en] ²⁴¹Am and ^238,239(240)Pu concentrations have been determined in soil samples from the Atolls of Mururoa and Fagataufa as well as from Palomares for comparison. Mean activity ratios of ²⁴¹Am/^239(240)Pu for Mururoa, Fangataufa and Palomares with 0.017 ± 0.005, 0.050 ± 0.012 and 0.25 ± 0.07 respectively, show, that also in the most unfavorable case the ²⁴¹Am contamination remains less than about one third of the ^239(240)Pu level. The estimated isotopic composition of the different types of weapons-grade Pu based on these data suggests generally a much lower ²⁴¹Pu/^239(240)Pu ratio for Pu used in the first fission bombs than for the material taken later on for construction of thermonuclear devices. ²⁴¹Pu/^239(240)Pu activity ratios of 0.9 ± 0.2 have been found at the safety shot area of the Colette motu and 8.4 ± 0.8 at Palomares, with some hints to a lower one, viz. 5.7 ± 1.5 for at least one of the accidentally involved bombs. (author)

[en] Since 1977, seven national metrology institutes (N.M.I.s.) have submitted eleven samples of known activity of ²⁴¹Am to the International Reference System (S.I.R.) for activity comparison at the Bureau International des Poids et Mesures (B.I.P.M.). The activities ranged from about 1.9 MBq to 17 MBq. The results of the C.C.R.I.(II)-K2.Am-241 comparison held in 2003 with twenty-one participants have been linked to the B.I.P.M..R.I.(II)-K1.Am-241 results using the submission to the S.I.R. by the N.P.L. of two ampoules of the mother solution of the C.C.R.I.(II) comparison. This has enabled four N.M.I.s. to update their earlier S.I.R. results and fifteen N.M.I.s., the I.R.M.M. and the B.I.P.M. to have their result published, the previous international comparison of ²⁴¹Am having been held over 40 years ago. The results of a C.O.O.M.E.T..R.I.(II)-K2.Am-241 comparison held in 2006 have also been linked to the S.I.R. results. This is possible through the submission to the S.I.R. of an ampoule of the comparison by the pilot laboratory, the V.N.I.I.M.. This has enabled two further N.M.I.s. to have degrees of equivalence for activity measurements for this radionuclide. The key comparison reference value (K.C.R.V.) has been updated to include the recent N.P.L. and V.N.I.I.M. results. The degree of equivalence between each equivalent activity measured in the S.I.R., or linked to the S.I.R., and the K.C.R.V. has been calculated and the results are given in the form of a matrix. A graphical presentation is also given. Degrees of equivalence between pairs of participants are similarly given as a matrix. (authors)

[en] Super heavy nuclei may decay through the different decay modes such as spontaneous fission, ternary fission, cluster and alpha decay. There is a need to study the different decay modes such as spontaneous fission, ternary fission cluster decay and alpha decay of super heavy nuclei. The competition between different decay modes such as binary, ternary, cluster radioactivity and alpha decay finds important role in identifying the formation of heavy nuclei. The nuclei ²⁸¹Ds is stable isotope of Ds. We have studied the different decay modes such as binary, ternary, cluster and alpha decay in superheavy nuclei ²⁸¹Ds. The comparison of alpha decay half lives with other three decay half lives shows that alpha decay half lives are having smaller value compared to others. It is observed from calculation that alpha decay half-life is 1.022s and spontaneous fission half-life is 1.865s. That is half-lives of alpha decay and spontaneous fission are close (difference H”0.843s). The detail study of different decay modes reveals that the alpha decay leads spontaneous fission process by 0.843s. We studied driving potential, relative yield and half lives of ²⁸¹Ds. We also identified the most prominent decay mode of ²⁸¹Ds using branching ratios. (author)