INVESTIGATION OF RADIOACTIVE CONTAMINATION OF GRAPHITE SAMPLES FROM THE AM REACTOR

摘要

The world's first nuclear power plant operated for almost 48 years. Over this period of time, the neutron fluence on the graphite masonry reached ～10~(22) cm~(-2), which resulted in activation of the impurities present in the graphite. During operation, incidents occurred with loss of seal and sometimes loss of integrity of the fuel-element claddings in some cells and particles of the fuel and steam-water mixture entered the graphite masonry. This resulted in radiation contamination with a complex radionuclide composition. Experimental information about the content and distribution of radionuclides in the spent nuclear graphite is needed in order to plan methods and periods of time for disassembly and salvaging of the graphite masonry of the stopped reactor taking account of the dose loads on the workers and the ecological safety norms. The problems which can be solved on the basis of the present work included the determination of the ~(14)C and ~3H contents by liquid-scintillation β spectrometry, analysis of the actinide content by direct γ spectrometry, and neutron-activation analysis followed by γ spectmmetry. These invstigation yielded new data on the content of fission products and activation impurities in graphite.