[en] In this paper the forbidden transitions in actinides were studied. The N-forbiddeness is seen to cause large hindrance. Detailed results of these investigations is reported

[en] The electron capture decay scheme of ²³⁷Am (73 min) has been investigated by measuring the γ-ray and conversion-electron spectra of mass-separated ²³⁷Am samples. The γ-ray spectra were measured with a Ge(Li) spectrometer and the conversion-electron spectra were measured with a cooled Si(Li) detector and a magnetic β-ray spectrometer. Thirty-five γ rays were identified and the multipolarities of most of the transitions were deduced. The half-life of ²³⁷Am was determined by following the decay of the 280.2 keV photopeak and was found to be 73.0 plus-or-minus 1.0 min. The α-particle energy and α branching were measured to be 6.042 plus-or-minus 0.005 MeV and (2.5 plus-or-minus 0.3) times 10^-2%, respectively. On the basis of the present investigation the following single-particle states have been identified in ²³⁷Pu: 7/2^-743, 0; 1/2⁺631, 145.5; 5/2⁺622, 280.2; 3/2⁺631, 370.4; 5/2⁺633, 407.8; 7/2⁺624, 473.5; 5/2^-752, 655.3; and 7/2⁺613, 908.8 keV. The ground state of ²³⁷Am has been deduced to be the 5/2^-523 Nilsson orbital. The logft values for electron capture transitions to the observed states were derived. The α-particle spectrum of a mass-separated ²⁴¹Cm sample was measured with the Argonne double focusing magnetic spectrometer. Eleven α groups identified in this spectrum populate the members of the ground state, 1/2⁺631, and 3/2⁺631 bands. The α-decay hindrance factors are consistent with the Nilsson-state assignments deduced from ²³⁷Am electron capture decay

[en] The available nuclear structure information for all nuclei with mass number A=237 is presented. Various decay and reaction data are evaluated and compared. Adopted data, levels, spin, parity and configuration assignments are given

[en] The purpose of paper is the search of a technique for hardening the fast reactor neutron spectrum and by this way, increasing the burning of Np-237, Am-243, and other minor actinides (MA) fissionable preferentially under hard neutron spectrum. The main concern is for using lead isotope, Pb-208, as a reactor coolant instead of natural lead, Pb-nat, which is the mixture of isotopes. Pb-208 has the high inelastic scattering threshold of 2.61 MeV. So, it slowly moderates the fission spectrum. The contribution of liquid metal coolants: sodium, Pb-nat, and Pb-208, minor actinides: Np-237, Am- 241, and Am-243, elements of structural materials: Fe, Cr, Ni, etc, to the fast-reactor neutron spectrum for a blanket is analyzed. For this calculation using Monte-Carlo Code 'MMKFK' is conducted. As a result, it is shown that the incineration of MA in the blanket is increased from 18 to 26 percent when one uses Pb-208 as a coolant instead of the usual natural lead. (author)

[en] Evaluated spectroscopic data and level schemes from radioactive decay and nuclear reaction studies are presented for all nuclei with mass number A = 237. This evaluation for A = 237 supersedes the earlier one by Y.A. Akovali (1995Ak01), published in Nuclear Data Sheets 74, 461 (1995)

[en] Recently an error has been identified in the beta decay energies in the library of the actinide inventory code HYACINTH which is also a module of the more comprehensive code RICE. This note details the revised beta energies and also includes a listing of the recently updated standard actinide cross-sections for use with RICE. (author)

[en] The purpose of paper is the search of a technique for hardening the fast reactor neutron spectrum and by this way, increasing the burning of Np-237, Am-243, and other minor actinides (MA) fissionable preferentially under hard neutron spectrum. The main concern is for using lead isotope, Pb-208, as a reactor coolant instead of natural lead, Pb-nat, which is the mixture of isotopes. Pb-208 has the high inelastic scattering threshold of 2. 61 Me V. So, it slowly moderates the fission spectrum. The contribution of liquid metal coolants: sodium, Pb-nat, and Pb-208, minor actinides: Np-237, Am-241, and Am-243, elements of structural materials: Fe, Cr, Ni, etc, to the fast reactor neutron spectrum for a blanket is analyzed. For this calculation using Monte-Carlo Code 'MMKFK' is conducted. As a result, it is shown that the incineration of MA in the blanket is increased from 18 to 26 percent when one uses Pb-208 as a coolant instead of the usual natural lead

No abstract available

[en] Weapons-grade substance is a material with level of enrichment or with characteristic suitable for nuclear bombs production. The most commonly used weapon-grade isotopes in different experiments are uranium-235 and plutonium- 239. It is known that isotopes like uranium-233, neptunium-237 and some isotopes of americium have also been used for the purposes of experimental researches, but by now there is no information they have been used for a real nuclear weàpons production. The goal of the present analysis is to be examined if the spent nuclear fuel of the most common nuclear reactors for electricity production, viz. pressurized water reactors, can be classified as practically unusable or not for nuclear explosive made-up. The possibilities for nuclear materials production are analyzed and the concentration levels of the main isotopes (plutonium-239, neptunium-237, americium-241, americium-242m and americium-243) are examined and estimated. The significant quantities necessary for nuclear bombs production according to International Atomic Energy Agency are also estimated by comparing them with the obtained results. The results of this analysis may be useful in specifying the technical and organization actions which can increase the proliferation resistance of the fissile materials. Keywords: explosive device, nuclear bomb, significant quantity, weapons-grade material

[en] The available nuclear structure information for all nuclei with mass number A=237 is presented. Various decay and reaction data are evaluated and compared. Adopted data, levels, spin parity, and configuration assignments are given