Early construction and operation of the highly contaminated water treatment system in Fukushima Daiichi Nuclear Power Station (IV) - Assessment of hydrogen behavior in stored Cs adsorption vessel

Abstract

Hydrogen diffusion behavior in a cesium adsorption vessel is assessed. The vessel is used to remove radioactive substance from contaminated water, which is proceeded from Fukushima accident. Experiment and numerical calculation are conducted to clarify the characteristics of natural circulation in the vessel. The natural circulation arising from the temperature difference between inside and outside the vessel is confirmed. We develop an evaluation model to predict the natural circulation and its prediction agrees well with the results obtained by the experiment and the calculation. Using the model, we predict steady and transient behavior of hydrogen concentration. Results indicate that hydrogen concentration is kept lower than the flammability limit when the short vent pipe is open.

Hydrogen Production by γ-Ray Irradiation from Different Types of Zeolites in Aqueous Solution

“…Zeolites are crystalline aluminosilicates that have nanometer-scale porous frameworks and exchangeable cations in extraframework positions. The radiolysis of zeolite/water systems also has a specific importance in the application of zeolites as ion-exchange adsorbents in treating radioactively contaminated water. − During the treatment and storage of spent zeolite adsorbents, it has been found that after the treatment water radiolysis produces H 2 . Appropriate estimation and control of H 2 are indispensable for the safe operation of the treatment process.…”