[en] The first available results are related to tests in which the release of the main components of the core melt, namely the steel, zircaloy and uranium components was determined using ThO₂ crucibles. The release products are dispersed onto the pipe walls of the transport system and the measuring filters which were installed at about 1 m distance from the melt crucibles. Of these, only the precipitates on the filters have been analyzed so far. In the tests under air, the release was clearly dependent on the maximum temperature reached for the 10 most important elements of corium. The release values for Mo and Mn were the highest with 5-10%; uranium with 0.1% on the other hand, was the lowest. In a steam atmosphere over the melt, the analysis of the filter precipitates for all elements gave considerably lower values than with the tests in air. (orig./LH)

[en] A researcher at MIT, while doing work for his Ph.D. thesis, has discovered that the radioactivity release at Chernobyl was greater than claimed by Soviet officials. He estimates that the release was >185 million curies, with more than 65% and 85% of the cesium and iodine being released from the core, respectively

[en] Leaky seal in the condensate collection tank with steam release in the turbine house. (HP)

[en] Discussion of fundamental issues of implementation of fission gas release models in the AMP code.

[en] The role of the containment for the retention of radioactive fission products after a hypothetical loss of coolant accident will be analysed. The reduction of the airborne activity due to radioactive decay and due to natural removal mechanisms inside the containment and the resulting release of activity to the atmosphere as a function of time are discussed in detail. (orig.)

[en] A fission gas release model is presented, which solves the atomic diffusion problem with xenon and krypton elements tramps produced by uranium fission during UO₂ nuclear fuel irradiation. The model considers intra and intergranular precipitation bubbles, its re dissolution owing to highly energetic fission products impact, interconnection of intergranular bubbles and gas sweeping by grain border in movement because of grain growth. In the model, the existence of a thermal gradient in the fuel pellet is considered, as well as temporal variations of fission rate owing to changes in the operation lineal power. The diffusion equation is solved by the finite element method and results of gas release and swelling calculation owing to gas fission are compared with experimental data. (author)

[en] In this article experimental investigation is described into the spread of fission products within a nuclear power plant, which after an accident involving melting of the nucleus, will be possible in spite of prohibiting constructions for the case of severe unbalancing of generated and carried-off energy. 6 refs.; 4 figs

[en] The Melt-Dilute process consolidates aluminum-clad spent nuclear fuel by melting the fuel assemblies and diluting the 235U content with depleted uranium to lower the enrichment. During the process, radioactive fission products whose boiling points are near the proposed 850 degrees C melting temperature can be released. This paper presents a review of fission product release data from uranium-aluminum alloy fuel developed from Severe Accident studies. In addition, scoping calculations using the ORIGEN-S computer code were made to estimate the radioactive inventories in typical research reactor fuel as a function of burnup, initial enrichment, and reactor operating history and shutdown time.Ten elements were identified from the inventory with boiling points below or near the 850 degrees C reference melting temperature. The isotopes 137Cs and 85Kr were considered most important. This review serves as basic data to the design and development of a furnace off-gas system for containment of the volatile species

[en] An accident scenario in which the end-fitting of one channel of the Pickering B. Canadian Pressurized Heavy Water Reactor (CANDU) is assumed to fail completely is considered. All of the 12 bundles of the channel are assumed to be discharged to the fuelling- machine vault and onto the floor. Three cases are analysed; the case of intact bundle, bundle broken into separate intact fuel pins and broken bundle with broken pins. Release of (131)I and Xe+Kr to the atmosphere are estimated for both cases of intact and impaired containment using AECL computer codes HOTSPOT, CURIES, FIREBIRD and PRESCON. For conservatism, the channel with the maximum power was used in the analysis. The activity released to the environment in both events of intact containment (single failure) and impaired containment (dual failure) was estimated to be below the permissible regulatory limits. However, the activity released in the dual failure case is much higher than that for the single failure. (Author). 23 refs

[en] Conclusions: Two complementary approach: • Reference set of codes: – Progressive extension of the application domain; – Performance improvement Simplified code for PRA. Code assessment: • Existing experimental data base; • EAGLE 1&2; • SAIGA; • FOURNAISE