Memory Effect of Ionization Chamber for Tritium Vapor

Abstract

Tritium measurement system utilizing an ionization chamber is widely used but the memory effect often gives obstruction for accurate measurement.
We designed a method of tritium removal from electrode surface utilizing an isotope exchange reaction, namely, water vapor mixing to the process gas just before entering the ionization chamber, and good results were observed for an ionization chamber made of copper or stainless steel.
In case of the ionization chamber having stainless steel electrodes, smaller memory effect, though larger amount of tritium sorption, was observed than for the copper chamber, because of porous Fe₃O₄ film formed on stainless steel surface.