SEPARATE EFFECT TESTS ON THE REVAPORISATION BEHAVIOR OF FISSION PRODUCT DEPOSITS FROM THE PHÉBUS FPT3 PROJECT

In nuclear safety the main goal is to ensure the safe enclosure of radioactive material inside the containment barriers of a nuclear facility. In consequence of their chemical and thermodynamic properties, the volatile and semi-volatile fission products (e.g. iodine, cesium) are of major importance in nuclear safety research. In case of a hypothetical severe accident and following damage to the core a substantial amount of the volatile and semi-volatile fission products (FP) will be released from the fuel and deposited inside the primary circuit. In case of a primary circuit rupture, deposition inside the containment has also to be taken into account. To study the phenomena related to fission product transport and deposition the Phébus FP project was launched and the first experiment (FPT0) conducted in 1993 [1]. These FP which deposit inside the primary circuit and/or containment have (as long as they stay immobile) no or only negligible influence on the release source term. However, especially in the late phase of a severe accident there is a high possibility that a considerable amount of FP revalorizes. This can be triggered through steam surges (reflooding), temperature increase (decay heat) or chemical reactions. The revaporisation device at ITU was built to investigate this phenomenon and produce experimental data for state of the art severe accident codes (e.g. ASTEC). Within the SARNET programme a series of experiments focusing on Cs-137 has been conducted to examine this phenomenon, but as it is stated in [2]: “The work under SARNET has shown improved understanding of the revaporisation phenomenon, but a full predictive capability has yet to be established.”

KNEBEL Kevin;  BOTTOMLEY Paul;  RONDINELLA Vincenzo;  AUVINEN A.;  JOKINIEMI J.; 

2014-01-31

Deutsche Atomforum e.V. & Kerntechnische Gesellschaft e.V.

JRC77114

http://www.kernenergie.de/kernenergie/service/veranstaltungen/tagungen/2013-05-14_jahrestagung.php,    https://publications.jrc.ec.europa.eu/repository/handle/JRC77114,