Power Plant Accident Research Articles

Identification of reactor vessel failures using spatiotemporal neural networks

Identification of vessel failures provides operators and technical support center personnel with important information to manage severe accidents in a nuclear power plant. It may be very difficult, however, for operators to identify a reactor vessel failure simply by watching temporal trends of some parameters because they have not experienced severe accidents. Therefore, we propose a methodology on the identification of pressurized water reactor (PWR) vessel failure for severe accident management using spatiotemporal neural network (STN). STN can deal directly with the spatial and temporal aspects of input signals and can well identify a time-varying problem. Target patterns of seven parameter signals were generated for training the network from the modular accident analysis program (MAAP) code, which simulates severe accidents in nuclear power plants. We integrated MAAP code with STN in on-line system to mimic real accident situation in nuclear power plants. Using new patterns of signals that had never been used for training, the identification capability of STN was tested in a real-time manner. At the tests, STN developed in this study demonstrated acceptable performance in identifying the occurrence of a vessel failure. It is found that STN techniques can be extended to the identification of other key events such as onset of core uncovery, coremelt initiation, containment failure, etc.

Nuclear anxiety and emotional distress: Reciprocal effects in prospective data

Abstract Although fears about nuclear war and power plant accidents have been linked to psychological distress, these associations have all been cross-sectional or anecdotal and thus no causal inferences can be drawn. To examine possible bi-directional influences, prospective data were obtained at two time points separated by two months from a group of 94 young adult university students. At both assessments, participants completed the Nuclear Attitudes Questionnaire (that assesses four related dimensions of Nuclear Anxiety) and the Symptom Checklist 53 (that captures nine types of psychopathology generally reflecting Emotional Distress). Cross-lagged latent variable structural equation models were used to analyze the data. Results indicated that latent constructs of Emotional Distress and Nuclear Anxiety were quite stable over time, were modestly related to each other at the first time period, and had no cross-lagged effects between each other (as latent constructs) over time. Specific across-time relationships were evaluated with nonstandard paths (that include measured variables) and revealed several significant effects. More paranoid ideation increased nuclear support and more Emotional Distress reduced nuclear denial. On the other hand, more nuclear support reduced anxiety, reduced somatization, and increased psychoticism, whereas nuclear concern increased Emotional Distress. Theoretical implications of these results are discussed.

Into the Abyss: International Regulation of Subseabed Nuclear Waste Disposal

The nuclear age has been marked by fantastic scientific advances without corresponding development in humankind's social, political, or legal capacity to deal with technological problems.2 The solution to threats such as nuclear war or power plant accidents has been sought through more and better technology. The nuclear nations have plunged into weapons manufacture and energy production, putting faith in technology to handle the most predictable consequence of such development: the production of vast quantities of high level nuclear waste (HLW).3 The result of this

The straightforward numerical treatment of the time dependent advection in air pollution problems and its verification

A very simple Lagrangian finite difference scheme has been developed to calculate the time dependent advection of air pollutants. It is mass conserving and avoids numerical pseudo-diffusion. No condition of numerical stability is required. The Eulerian grid used for the diffusion part of the pollutant transport equation remains unchanged. There are no restrictions on temporally and spatially variable emission rates, production and destruction processes, wind velocity, diffusion coefficients, roughness parameters or inversion heights. The only exception is that the wind field should not be too far from being homogeneous in the horizontal direction (test of D. W. Pepper and P. E. Long, 1978, J. appl. Met. 17, 228–233). Steady state solutions are nearly identical with corresponding analytical solutions. The propagation of a pollutant cloud is simulated more realistically as compared with the advection treatment of E. Runca and F. Sardei (1975) Atmospheric Environment 9,69–80) and M. Dunst (1980 Z. Met. 30, 47–59). The course of a diffusion experiment is modelled to demonstrate the efficiency of the proposed method. Because of its simplicity, the method is especially suited for use in license processes, for control and for calculating health risks in relation to industrial and power plant accidents with the goal of organizing efficient protection or evacuation.