THE STUDY ON THE MIGRATION OF RADIONUCLIDES IN THE SHALLOW LAND

ABSTRACT From 1995 through 2001 a cooperative study project on the migration of radionuclides in shallow land was carried out by CIRP and JAERI, which covers field test, laboratory simulation test , other laboratory studies and related model development. The radionuclides studied involve 90 Sr, 237 Np, 238 Pu. For comparison the nonradioactive elements Sr, Nd and Ce were also studied. The field test was performed both in aerated zone and aquifer zone of loess. In the aerated zone the nuclide migration in engineering materials were also studied. The study in the aerated zone was carried out in 9 pits with the size of 2m×2m under natural conditions or artificial sprinkling conditions. The study in Pu and Nd, Ce was not observable in both aerated zone and aquifer zone, the nuclide of 237 Np migrated a small distance, and the nuclide of 90 Sr had a relative large migration. The migration of the nuclides in engineering materials was not detected, which include cement, degraded cement, cement mortar, Chinese bentonite and Japanese bentonite. INTRODUCTION Wide varieties of nuclear applications have generated a wide range of radioactive wastes, 95% of which are, in terms of volume, classified to low-and intermediate-level radioactive wastes (LILWs). Shallow land disposal is an approach mainly for radioactive wastes bearing short-lived radionuclides, and also for the low level radioactive waste containing acceptable levels of long-lived nuclides