[en] The uncertainties on the calculation of the temperature coefficient in thermal reactors are estimated. A table gives some numerical examples of these uncertainties for ²³⁵U, ²³⁸U, ²³⁹Pu, ²⁴⁰Pu and ²⁴¹Pu

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[en] Task of optimal control of thermal reactors is considered. Solution of optimal reactor control task including process equation solvability, optimal control existence and derivation of necessary conditions of maximum principle is given. Nonlinear integral functional is selected as an optimum criterion

[en] A panel which the IAEA had invited to attend in the Nuclear Research Centre Karlsruhe, dealt with the worldwide situation of plutonium recycling in thermal reactors. The results of the reports from the various countries concerning programmes, tendencies, questions of technology and economy are the background of the surveys and statements in this article. (orig./LN)

[en] Nuclear activation analysis of animal materials was performed as early as 1946. The materials studied were generally related in some way to human life (e.g. meat, blood, excreta) and were frequently of experimental origin (e.g. mouse, rat, rabbit or chicken). Major constituents as well as trace elements were studied, usually after activation with thermal (reactor) neutrons. Before 1962 only incidental work for biological research was performed. From then onwards a substantial increase can be noted in zoological research. The applications of nuclear activation are found in: 1. Descriptive studies: distribution of elements. 2. Experimental studies: (a) Dynamics and interaction of major and minor constituents; (b) Mineral metabolic cycle studies; (c) Radioecological studies; (d) Toxicological studies. Illustrative results in each of these sections are described. A few specific technical problems such as sampling, standardization and analysis are discussed briefly, and some of the possibilities for future research are outlined. (author)

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[en] Thermal recycle provides several potential benefits when used as stop-gap, mixed, or backup recycling to recycling in fast reactors. These three roles involve a mixture of thermal and fast recycling; fast reactors are required to some degree at some time. Stop-gap uses thermal reactors only until fast reactors are adequately deployed and until any thermal-recycle-only facilities have met their economic lifetime. Mixed uses thermal and fast reactors symbiotically for an extended period of time. Backup uses thermal reactors only if problems later develop in the fast reactor portion of a recycling system. Thermal recycle can also provide benefits when used as pure thermal recycling, with no intention to use fast reactors. However, long term, the pure thermal recycling approach is inadequate to meet several objectives. (authors)

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[en] The system of neutron calculation for fast reactors is given. This system was used for estimation of physical parameters of fast thermal reactors investigated. The results obtained and different specific problems of the reactors of this type are described. (author)

No abstract available