Study of a hot particle with a matrix of U-bearing metallic Zr: Clue to supercriticality during the Chernobyl nuclear accident

JOURNAL OF NUCLEAR MATERIALS

卷:488

Article

Poeml, P.¹  Burakov, B.² 

[1] European Commiss, Joint Res Ctr, Directorate Nucl Safety & Secur G, POB 2340, D-76125 Karlsruhe, Germany

[2] VG Khlopin Radium Inst, 28,2-Nd Murinskiy Ave, St Petersburg 194021, Russia

关键词: Chernobyl;    Lava;    Nuclear accident;    Zirconium;   

DOI  :  10.1016/j.jnucmat.2017.01.041

来源: Elsevier

【 摘 要 】

This paper is dedicated to the 30th anniversary of the severe nuclear accident that occurred at the Chernobyl NPP on 26 April 1986. A detailed study on a Chernobyl hot particle collected from contaminated soil was performed. Optical and electron microscopy, as well as quantitative x-ray microbeam.analysis methods were used to determine the properties of the sample. The results show that the particle (approximate to 240 x 165 mu m) consists of a metallic Zr matrix containing 2-3 wt. % U and bearing veins of an U,Nb admixture. The metallic Zr matrix contains two phases with different amounts of 0 with the atomic proportions (U,Zr,Nb)(0.73)O-0.27 and (U,Zr,Nb)(0.61)O-0.39. The results confirm the interaction between UO2 fuel and zircaloy cladding in the reactor core. To explain the process of formation of the particle, its properties are compared to laboratory experiments. Because of the metallic nature of the particle it is concluded that it must have formed during a very high temperature (> 2400 degrees C) process that lasted for only a very short time (few microseconds or less); otherwise the particle should have been oxidised. Such a rapid very high temperature process indicates that at least part of the reactor core could have been supercritical prior to an explosion as it was previously suggested in the literature. (C) 2017 The Authors. Published by Elsevier B.V.

【 授权许可】

Free