Under the assumption that a nonmechanistic accident induces a condition such that it is not possible to cool the core of a high temperature gas cooled reactor, the temperature of the core will gradually rise due to decay heat. There are several barriers to the release of fission products t o t h e environment: the fuel particle coatings, the graphite moderator, the prestressed concrete reactor vessel and the containment. A code, EVAP, has been written to calculate one stage in the release, the migration of the fission products along the coolant channels. lations, using the code, are reported for 10 fission products, based on typical conditions which might occur in the course of the hypothetical accident. The calcu-The sensitivity of the results to several important parameters is examined.
The code SORS was written by General Atomic to calculate the release of fission products from the fuel into the primary coolant during a hypothetical uncontrolled transient temperature excursion. The code assumes that the graphite core remains structurally intact. The release from the fuel particles is calculated using a coarse time step for several sections of the core. For the non-volatile elements, the code calculates a diffusion rate and an evaporation rate in each section of the core. The expression used for the evaporation rate is found to be incompatible with the rest of the assumptions used in the calculation.
Understanding the factors controlling the relative abundance, distribution, and diversity of organisms is a fundamental challenge in ecology. For plants and animals, macroecological rules have been developed that describe these large-scale distributional patterns and attempt to explain the underlying physiological and ecological processes behind them. Similarly, microorganisms exhibit patterns in relative abundance, distribution, and diversity across space and time, yet it remains unclear the extent to which microorganisms follow macroecological rules initially developed for macroorganisms. With rapid advancements in sequencing technology, we have seen a recent increase in microbial studies that utilize macroecological frameworks. Here we review and synthesize these macroecological microbial studies with two main objectives: (1) to determine to what extent macroecological rules explain the distribution of host-associated and free-living microorganisms, and (2) to understand which environmental factors and stochastic processes may explain these patterns among microbial clades (archaea, bacteria, fungi, protists) and habitats (host-associated and free living; terrestrial and aquatic). Our review is the first, to our knowledge, that examines whether or not the same environmental drivers contribute to similar trends to macroecological studies when rules are upheld for microorganisms. Further, we outline several outstanding questions and recommendations for future studies in microbial ecology.
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