Analysis of Relation Between Lifetime Rates and Incorporation of Plutonium-239 in Atomic Production Workers Regarding Tumor and Non-Tumor Causes of Death

Purpose: The objective of the study was in quantitative assessment of the effect of internal exposure to lifetime in Mayak PA workers based on analyzing dependence of certain lifetime rates on incorporation of plutonium-239 regarding tumor and non-tumor causes of death. Material and methods: The cohort of deceased Mayak PA workers employed in1948–1958 with known Pu-239 body burden comprising 2343 individuals, of them 1739 males and 604 females, was investigated. Using regression analysis we have assessed dependence of general lifetime and lifetime after start of work as well as of proportion of individuals who did not survive until standard age in general and after start of work from incorporated Pu-239 separately for workers of different age regarding tumor and non-tumor causes of death. Statistical values were defined using Statistica software. Results: It was stated that in case of increase of plutonium-239 body burden in males and females reliably increased shortening of lifetime and lifetime after start of work was observed as well as increased proportion of individuals who did not survive until standard lifetime rate and until standard lifetime after start of work. Reliable regression equations for dependence of the studied lifetime values from radionuclide incorporation rate were obtained based on regression analysis. Generally, changes in the studied characteristics of lifetime after start of work were more evident than in general lifetime characteristics. Conclusion: Reliable dependence of shortening of lifetime and lifetime after start of work, of increased proportion of individuals who did not survive until standard lifetime and lifetime after start of work among Mayak PA workers of different gender from incorporation of plutonium-239 regarding tumor and non-tumor causes of death was stated. Dependence of lifetime after start of work on incorporated plutonium-239 was higher than of general lifetime that could be probably due to direct contact of workers with radionuclide after start of work. The results obtained indicate feasibility of using not only general lifetime but also lifetime after start of work in assessment of lifetime among workers who are in contact with production hazardous factors.

New route for synthesis of Synroc-like ceramic using non-selective sorbent LHT-9

ABSTRACT:Immobilization of bulk liquid high level radioactive waste (HLW) in Synroc ceramic is well-known reliable way for final isolation of dangerous long-lived radionuclides from biosphere. The alternative method of Synroc-like ceramic synthesis has been proposed. Radionuclide incorporation into crystalline titanate host-phases can be provided as a result of direct radionuclide sorption from liquid HLW using non-selective sorbent – layered hydrazinium titanate (LHT-9). Such an approach allows excluding expensive multi-stage procedure of precursor preparation. The precipitate obtained after sorption can be easily transformed into Synroc-like ceramic by cold pressing followed with sintering in air at 1000-1200°C. The highly radioactive samples of titanate ceramic loaded with real HLW have been synthesized and preliminary studied at KRI hot-cell facility. Chemical durability of this sample has been studied using static leach test in distilled water at 90°C and the leach rates for 154Eu, 241Am, 244Cm were (in g·m-2·day-1) from 2·10-4 to 5·10-3. Normalised 137Cs mass loss was 0.3 g·m-2 for 110 days at the same conditions.

Analysis of the antidote requirements and outcomes of different radionuclide decorporation strategies for a scenario of a “dirty bomb” attack

Objective: In radiological emergencies, there is a risk of radionuclide incorporation. The radiological doses absorbed can be reduced by decorporation treatment. Antidote requirements depend on the scenario and treatment strategy (“urgent approach”: immediate treatment of all patients with possible incorporation; “precautionary approach”: treatment only after confirmation of incorporation). We calculated the number of daily antidote doses for different scenarios and the differences in outcome for both treatment strategies.Design: The number of potentially contaminated victims was varied from 1,000 to 60,000 (a maximum that might seem plausible for “dirty bomb” scenarios in Germany), the proportion of patients actually needing decorporation treatment from 0.1 percent to 100 percent, the radioactive screening capacities from 250 to 2,500 people/day and treatment duration from 10 to 90 days. The outcomes were assessed as total statistical lifetime saved assuming an inhalation of 1 mCi cesium-137 and the achievable dose reductions by a Prussian Blue treatment.Results: Assuming 1 percent of the potentially contaminated people actually needing treatment, applying an “urgent approach” the requirements for 1,000 victims range from 1,100 to 3,400 and for 60,000 victims from 489,000 to 4,400,000 daily doses, depending on treatment duration and screening capacities. The “urgent approach” is associated with larger stockpile requirements than the “precautionary approach”, up to several hundred times in large-scale scenarios if the proportion of people actually needing treatment is low. The impact of the screening capacities is particularly important in large-scale scenarios, a low proportion of people needing treatment and extended treatment duration. The outcome is better for an “urgent approach” particularly in large-scale scenarios and low screening capacities.Conclusions: If only a small fraction of the victims actually needs treatment, their timely identification by enhancing screening capacities may be the most efficacious way to reduce antidote requirements. In large-scale scenarios, it might be necessary to abandon the medically preferable “urgent approach” for an antidote-sparing “precautionary approach”.

Radionuclide Incorporation in Secondary Crystalline Minerals from Chemical Weathering of Waste Glasses

ABSTRACTData from corrosion and radionuclide sequestration studies on two waste glasses indicated chemical weathering resulted in the formation of zeolite minerals such as herschelite and analcime. We also found that these minerals incorporated ∼8 – 22%, ∼1- 13% and ∼8 – 25% of spiked 125I, 99Tc, and 75Se respectively. Increasing concentrations of radionuclides in spike solution resulted in higher degree of sequestration as observed by significantly higher proportion of stable isotopes (∼70 – 95% I, ∼58 – 100% Re, and ∼100% Se) in secondary minerals. The radionuclide incorporation mechanisms for these minerals appear to be mainly isomorphic substitution of Se and Re in tetrahedral sites and iodide substitution for framework oxygen.