[en] This paper gives briefly the characteristics of the RBMK reactors and describes the possible history of the accident of the reactor Tchernobyl-4

[en] Five years on, and there are still significant gaps in our understanding of the Chernobyl accident sequence. But recently there has been a distinct reapportioning of the blame. The role of the power plant operators (who were depicted as the chief culprits in early official Soviet accounts of the accident) is being downplayed, while greater emphasis is now placed on design deficiencies. A new judicial investigation into the accident is understood to be underway in the USSR. (author)

[en] Rafael Caro, president of the ENS, gives a comment on the Chernobyl reactor accident

[en] The author summarily evaluates the cause and sequence of the Chernobyl reactor accident. A table supplies data on major fission products released on explosion, and maximum air-borne activities. (DG)

[en] A historical overview of RBMK-1000 development is given, technical data of this reactor are presented and safety systems discussed

[en] On Friday, 26 April 1986, it was planned to shut down the fourth unit of the Chernobyl Atomic Power Station, U.S.S.R., for periodic maintenance. The procedure supplied the opportunity to perform a further experiment; operation of the turbine in free rotation regime, which occurs when the steam is cut down while the turbine is still running. It so happened that carrying out this experiment turned out to be the worst accident in the history of nuclear power industry. The first part of the article proceeds to a second by second detailed analysis of the causes of the catastrophe. The analysis uses official data and reports. The author covers the sequence of events, which led up to two explosions in the second hour of that tragic morning. In the second part of the article, the author provides hints and suggestions, so that 'the tragedy of Chernobyl does not become a useless lesson'. With regard to what, so far, has been published, the novelty of the article may be a diagram showing the excessive changes that affected the main parameters (power, water flow through circulating pumps, steam pressure in separators, and length of the immersed part of control rods) in the fourth unit during the last seconds before the explosion. If may be noteworthy to mention that the curves supplied here are based on data stored in the computer 'SCALA'. 2 figs

[en] In conjunction with the authorities in Kiev GRS is presently conducting studies for further protective measures for block 4 of the Chernobyl nuclear power station within a support programme promoted by the Federal Ministry for Environmental Protection which aims at establishing independent licensing and supervisory authorities and their technical-scientific organisation in the CIS countries. These studies are based on a stocktaking of the present radiological situation and the state of the buildings necessary for the assessment of the planned long-term safe encapsulation (sarcophagus 2). The latest findings are contained in this report. (orig./HP)

[en] The accident developed in the course of a test to find out whether the plant internal power supply works if feed-in from the national network fails. Major effects of the test on reactor behaviour were not expected. The chronology of events is described on the basis of the operational journal and computer protocol print-out. The most important safety-related deficits of the reactor type are summarized. (DG)

[en] This report contains a description and an evaluation of the course of the Tschernobyl accident up to the excursion. It is based on information obtained during the IAEA conference in Vienna in August 1986 and includes a first qualitative evaluation of the course of the accident as well as results of analyses carried out at GRS. This work was done with the aim to better understand the particular phases of the accident and to demonstrate the typical dynamic behaviour of the RBMK-1000 type reactor with a positive void coefficient in contrast to the behaviour of german BWRs with negativ void coefficients. The calculations also contribute to the evaluation of the consequences of the violations and errors executed by the operating team and the consequences of design weaknesses of the plant. (orig.)

[en] Short communication