Application of Nuclear Criticality Safety to Early Earth Age Uranium

摘要

There has only been one naturally occurring reactor region (Oklo) identified historically. There has to have been other factors that prevented uncontrolled nuclear criticality events. There are higher concentration uranium depositions in the earth's crust than the Oklo region, that did not go critical based on uranium enrichment. There are many papers on the Oklo phenomena which do not address why the uranium did not reach criticality prior to the historical point of 2 billion years ago, nor do they specifically address the lack of radiogenic lead in any of the uranium deposits. Consideration of the lack of lead as a potential indicator of the age of the earth as being a possible factor. Reports which address the leaching effect could consider the reactivity effect of moderation associated with higher enrichment uranium. The lack of radiogenic lead associated with the uranium may or may not be due to leaching. Also, the higher concentration uranium deposits (>15%) were discovered in the 1990s, and reevaluation of the overall effect on a natural reactor criticality were not considered. The high reactivity levels and the low quantity of radiogenic lead identified in uranium tailings, tends to favor a significantly shorter time period or a highly efficient naturally occurring leaching process. A shorter time period would reduce uranium mass and enrichment. Given even a small quantity of moderator would allow an uncontrolled nuclear criticality for high concentration uranium deposits for enrichment between 3 and 8 percent ~(235)U. The evaluation and analysis of the nuclear criticality safety factors should be evaluated further to document the actual uranium ore grade, and Pb constituents. Identification of the macro-scale quantity (PPM) of radiogenic lead coupled with the NCS factors could be a more useful tool for determining the age of the earth. Further calculations could be considered to determine the impact of different rock formations and materials where uranium is located, and evaluation of the natural leaching of uranium and its decay by-products to associate the effect of radiogenic lead or other materials.