Leaching of radionuclides from products of underground nuclear explosions in granite: Experiments with radioactive samples of melted rock from explosion cavities on Semipalatinsk test site

Abstract

Leaching of ¹³⁷Cs, ⁹⁰Sr, and ^239+240Pu from products of underground nuclear explosions in tunnels 504R, 148/5, and 190 of the Semipalatinsk test site was studied. Samples were taken from central zones of the explosions. Sample characteristics are presented. Leaching experiments were performed in the batch and dynamic modes. The degrees and rates of ¹³⁷Cs, ⁹⁰Sr, and ^239+240Pu leaching with granite aqueous extract were determined. The leach rates determined in batch experiments are in the following ranges: ⁹⁰Sr 2.3 × 10⁻⁶−1.6 × 10⁻⁴, ¹³⁷Cs 5.0 × 10⁻⁶−2.5 × 10⁻⁴, and ^239+240Pu 5.6 × 10⁻⁷−2.1 × 10⁻⁴ g cm⁻² day⁻¹, and those determined in dynamic experiments are in the following ranges: ⁹⁰Sr 9.2 × 10⁻¹⁰−10⁻⁸, ¹³⁷Cs 1.0 × 10⁻⁹−1.6 × 10⁻⁷, and ^239+240Pu 1.3 × 10⁻¹¹−2.5 × 10⁻¹¹ g cm⁻² day⁻¹. The values obtained are close to those reported in the literature for vitrified radioactive wastes.