[en] There exists more than 250,000 tonnes of irradiated nuclear graphite in the world, primarily as a result of the development of graphite-moderated power-reactor systems, (Figure 1). Only a very small number of such plants have been dismantled and, for most cases, the final destiny of the irradiated graphite (“i-graphite”) remains unresolved. Future high-temperature reactor programmes, such as the Chinese HTR-PM development, will produce more graphite and carbonaceous wastes from both structural components and the fuel pebbles (which are approximately 96% carbonaceous). The problem of dismantling irradiated graphite reactor stacks, possibly distorted through neutron damage and in some cases degraded further by radiation-chemical attack by gaseous coolants, and then finding the appropriate treatments and final destiny of the material, has exercised both the International Atomic Energy Agency and the European Union for more than 25 years, seeking to address the different issues and available disposal solutions in different IAEA Member States. This paper reviews the current ‘state of play’.

No abstract available

[en] TRISO particles are the specific features of HTR-10 and generally HTGR reactors. Their heterogeneity and random arrangement in graphite matrix of these reactors create a significant modeling challenge. In the simulation of spherical fuel elements using MCNPX are usually created repetitive structures using uniform distribution models. The use of these repetitive structures introduces two major approaches: the non-randomness of the TRISO particles inside the pebbles and the intersection of the pebble surface with the TRISO particles. These approaches could affect significantly the multiplicative properties of the core. In order to study the influence of these approaches in the multiplicative properties was estimated the K_inf value in one pebble with white boundary conditions using 4 different configurations regarding the distribution of the TRISO particles inside the pebble: uniform hexagonal model, cubic uniform model, cubic uniform without the effect of cutting and a random distribution model. It was studied the impact these models on core scale solving the problem B1, from the Benchmark Problems presented in a Coordinated Research Program of the IAEA. (Author)

[en] An atomic driven motor is proposed for land vehicles of all kinds and amphibian vehicles. The motor consists of a nuclear reactor and a steam turbine. Both components can be stopped when required indepently of one another. (HR/LH)

No abstract available

[en] This invention relates to a control and shim rod arrangement for a nuclear reactor. A second shield of concrete completely encloses a biological shield. Moveable plugs are mounted in the shield

[en] This book focuses on the broader ramifications of the Chernobyl disaster,such as the impact upon the environment, agriculture, health, the media and the arts. The author feels that there is much information not yet available about the accident, and he says the Soviet Government has essentially developed an official line that is patently untrue. Many of the key mistakes and short comings that figured prominently in the accident and that the Soviets have been reluctant to publicize are highlighted. The part that what might be termed the Soviet system played in the accident and events following the accident is explored. This is not limited just to the incompetence of the plant operators when the accident occurred but is extended to the system that placed unqualified operators on the staff of a nuclear power plant, produced the defective reactor design, was responsible for the poor quality of the initial construction, etc. The author contends that the International Atomic Energy Agency (IAEA) did not really press the Soviets for complete truthful reports because it was not expedient to do so as the Chernobyl accident threatened the global nuclear industry of which IAEA is a part

[en] A neutronic reactor is described comprising a moderator including horizontal layers formed of horizontal rows of graphite blocks, alternate layers of blocks having the rows extending in one direction, the remaining alternate layers having the rows extending transversely to the said one direction, alternate rows of blocks in one set of alternate layers having longitudinal ducts, the moderator further including slotted graphite tubes positioned in the ducts, the reactor further comprising an aluminum coolant tube positioned within the slotted tube in spaced relation thereto, bodies of thermal-neutron-fissionable material, and jackets enclosing the bodies and being formed of a corrosion-resistant material having a low neutron-capture cross section, the bodies and jackets being positioned within the coolant tube so that the jackets are spaced from the coolant tube. 2 claims, 9 figures

[en] The essential message in this book is that the true impact of the accident at Chernobyl is far greater than the Soviet government is willing to admit. The author says that he remains skeptical of the official version of the accident. The many key mistakes or shortcomings that figured prominently in the accident and that the Soviets have been reluctant to publicize are highlighted in this book. Problems with initial construction, the lack of instruments in the first hours and days after the accident to adequately measure the radiation level, the deliberate initial under-reaction to the accident, the evaluation fiasco, the mistakes made in taming the reactor fire, and the botched cleanup are all traced back to certain longstanding features of the Soviet system. The International Atomic Energy Agency (IAEA) is faulted for helping the Soviets coverup the accident effects at the August 1986 IAEA International meeting by not questioning deeply enough the Soviet reports concerning the accident

No abstract available