S. G. KALI AKIN, Yu. P. DZHUSOV,

R. V. SHUMSKY, Yu. STEIN Institute of Physics and Power Engineering,

Obninsk, Kuluga Region,

Russian Federation

Abstract

The results of the investigation of siectm-zirconinm reaction kinetics at the HPE simulator surface are presented in the paper. The dynamic characteristics of the hydrogen production resultedfrom the healed surface dry out are determined.

INTRODUCTION

The necessity of the knowledge of the laws of hydrogen generation during the interaction between the HPE shells made of the zirconium alloy and water coolant is highly increased when the problem of severe out-of-project accident was initiated, so their evolution is determined by the hidrogen discharge.

In [1] on the base of publications available the analisis was made of the hidrogen generation processes under severe accidents resulted from the circulation break off. From the estimations presented there regarding the amount of generated hydrogen during some first hours after the accident, it follows that the general source of the hydrogen is the reaction of zirconium with steam-water mixture. For example, the velocity of hydrogen generation may reach the value of 726 kg/h for the ordinery commercial APP USA.

Among the latter publications dealing with this problem the paper of the Japan authors 12] is remarcable. In this paper the results of the in-pile experiments are presented devoted to the study of hydrogen generation during the steam-zirconium reaction when the accidant situation was initiated by reactivity. The HPE was cooled by subsaturated water in the film boiling regime. The amount of the hydrogen generated was determined by the void fraction gauge at the channel exit and from the metallografic examinations also. In spite of the significant discrepancy between the results obtained by these two methods, the data allow to make conclusions about the strong temperature influence upon the hydrogen production.

Investigation.

1 — Heating Element (HPE Simulator); 2 — Transparent Body; 3 — Bars; 4 — Фланец; 5 — Thermocouples; 6 — Refrigerator; 7-Hydrogen Accumulator; 8 — Level Gauge SAPPHIRE-22DD Type; 9 — Replacing Tank; JO — Water Feed Tank.

The aims of the present paper are as follows: experimental study of the hydrogen generation process as a result of the HPE zirconium shell oxigation in steam-water atmosphere under conditions of assembly dryout due to the circulation failure; using of the data obtained when developing the corresponding codes.

Presented in the paper are the results of first experiments having, in general, methodological purposes. At the one-rod assembly model the peculiarities of the hydrodynamic processes of its drv-out was visualised and the reliable method of hydrogen production measurement was veryfied.