The psychological impact of a low probability or rare event is typically large relative to that of the event's actuarial likelihood. This overweighting follows a two‐stage process. First, rare events tend to be overestimated because of the availability heuristic, anchoring on the “ignorance prior,” and coarse chance categories. Second, when making decisions, low probability events are overweighted because of the “possibility effect”—decision makers are more sensitive to probability changes close to 0 than to probability changes away from 0.

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A Severe Accident Test Station (SATS) capable of examining the oxidation kinetics and accident response of irradiated fuel and cladding materials for design basis accident (DBA) and beyond design basis accident (BDBA) scenarios has been successfully installed and demonstrated in the Irradiated Fuels Examination Laboratory, a hot cell facility at Oak Ridge National Laboratory. Two test station modules provide various temperature profiles, steam, and the thermal shock conditions necessary for integral lossof-coolant accident (LOCA) testing, defueled oxidation quench testing, and high-temperature BDBA testing. Installation of the SATS system restores the domestic capability to examine postulated and extended LOCA conditions on spent fuel and cladding and provides a platform for evaluating advanced fuel and accident-tolerant fuel cladding concepts.This document reports on the successful in-cell demonstration testing of unirradiated Zircaloy-4. It also describes the integral test facility's capabilities, installation activities, and out-of-cell verification testing to calibrate and optimize the system.

The world of medicinal therapies has been historically, and remains to be, dominated by the use of elegant organic molecular structures. Now, a novel medical treatment is emerging based on CeO2 nano-crystals that are discrete clusters of a few hundred atoms. This development is generating a great deal of exciting and promising research activity, as evidenced by this Special Issue of Biomolecules. In this paper, we provide both a steady-state and time-dependent mathematical description of a sequence of reactions: superoxide generation, superoxide dismutase, and hydrogen peroxide catalase and ceria regeneration. This sequence describes the reactive oxygen species (ROS); superoxide, O2–, molecular oxygen, O2, hydroxide ion OH– and hydrogen peroxide, H2O2, interacting with the Ce3+, and Ce4+ surface cations of nanoparticle ceria, CeO2. Particular emphasis is placed on the predicted time-dependent role of the Ce3+/Ce4+ ratio within the crystal. The net reaction is succinctly described as: H2O2 + 2O2– + 2H+ → 2H2O + 2O2. The chemical equations and mathematical treatment appears to align well with several critical in vivo observations such as; direct and specific superoxide dismutase (SOD), ROS control, catalytic regeneration, ceria self-regulation and self-limiting behavior. However, in contrast to experimental observations, the model predicts that the 4+ ceric ion state is the key SOD agent. Future work is suggested based on these calculations.