Calculational and experimental investigations of tritium accumulation in heavy water reactors

A set of equations is derived which determines the tritium (T) buildup in heavy water moderated reactors. The process of T buil odup is assumed to be gverned mainly by the D + n → T and 3He + n → T + p reactions as well as by the β decay of T. A mass-spectrospic method of determining T concentraitons is described at length. The method is based on measuring isotopic composition of helium. For the ITEP reactor tritium concentration has been measured to equal 4.87 +- 0.11 Ci/l. The findings presented show that at neutron fluxes of about 1014 and 1015 neutron/cm2xs the heavy water activity due to T accumulation will amount to 50 and 500-1000 Ci/l respectively after 25-30 yrs. of reactor operation. In the case of fluxes phi > 1014 neutron/cm2xs, the contribution of the 3He(n,p)T reaction becomes substantial