Dynamic analysis of Chernobyl accident with one-dimensional program TRAB

Riitta Kyrki-Rajamäki, Markku Rajamäki

Research output: Contribution to journalArticle in a proceedings journalScientificpeer-review


The accident in the Chernobyl nuclear power plant in April 1986 was a reactivity-initiated accident. The catastrophic nature of the accident was due to the large positive void coefficient of reactivity. In order to study the effects of the positive feedback coefficient of voidage and the other axial phenomena in this transient, illustrative calculations were made with the one-dimensional Finnish computer program TRAB. The space-time neutronics models are needed instead of the point kinetic models when the power distribution changes considerably during the transient. The positive reactivity effect of the voidage makes the RBMK power distribution particularly sensitive to the spatial alteration of the steam content. It is important to have the axial phenomena included in the calculations because the reactivity effect caused by local voidage can be 40% greater than the effect of only average voidage. The initial shape of the axial power distribution also has outstanding influence. The integrated energy of the power peak was threefold in the case in which the initial power distribution was double-humped compared to the case in which the initial power distribution peak was down-skewed
Original languageEnglish
Pages (from-to)222-223
JournalTransactions of the American Nuclear Society
Publication statusPublished - 1987
MoE publication typeA4 Article in a conference publication


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