Analysis and assessment of the risk of accidents of a structure as a system by the method of "Fault Tree Analysis" on the example of a nuclear power facility under seismic impact

The article discusses a method for analyzing the risk assessment of failures of the structure as a system by developing a "Fault Tree Analysis". Formulas were proposed for the numerical estimation of the probability of system failure, taking into account the stochastic dependence of the failures of its elements. On the example of a nuclear power facility, a "wet" stand-alone storage facility for spent nuclear fuel, an analysis of possible scenarios of a facility failure was carried out, a "Fault Tree Analysis" was developed and calculated under seismic impact. It has been determined that the risk of structure as a system under seismic impact is determined by the risk of falling process equipment and building structures on the overlap of storage compartments or stored nuclear fuel. To increase the safety of building structures under seismic impact, it is necessary to pay special attention to the design features of the frame part and the interface between the monolithic storage compartment and the frame part, as the most vulnerable link.

Fessenheim—Nuclear Power Plant for Peace

This paper explores the construction of a nuclear power facility at Fessenheim, Alsace, and its role in the remaking of French-German post-war relations and the consolidation of the post-war peacebuilding process. The siting and materiality of nuclear energy technology, I argue, was a key component of the top-down peace-building strategy that guided reconciliation processes at the national and regional levels. This study analyses archival documents, newspapers articles, interviews with Alsatian antinuclear activists and amateur films in order to reconstruct how the site for a joint nuclear power plant at Fessenheim was chosen and how it affected cross-border interactions. Although the planning of a French-German nuclear facility at Fessenheim embodied the appeasement that characterised post-war relations at a governmental level between the two nations, its construction had limited impact on the regional reconciliation processes. However, the site of the nuclear plant became central for reconciliation in ways that industry planners did not foresee: opposition to the nuclearization of the Upper Rhine Valley became the driving force for the cross-border reconciliation process. This grassroots mobilisation against the presence of nuclear technology formed the nexus for transcending the legacy of World War II through cooperation toward a common, anti-nuclear future.

A Study and Optimization of Nuclear Power Facility Control Systems with the Use of Simulation Models

Matters concerned with development of a fully variable nonlinear simulation model of a double-loop system for automatically controlling the steam pressure in the main steam header (MSH) of a VVER type reactor based NPP power unit’s secondary circuit are considered. A two-stage procedure for optimizing the control system dynamic tuning is described, which uses the linear system frequency analysis method at the first stage and a numerical simulation and optimization method at the second stage, which takes into account the nonlinearities of the control equipment and control object. An evolutionary algorithm of multiparametric optimization with respect to a complex optimality indicator than takes into account the specific requirements for the system is used. The system performance efficiency in a wide range of the power unit outputs has been studied.

Power density dynamics in a nuclear reactor with an extended in-core pulse-periodic neutron source based on a magnetic trap

The article examines the features of the spatial kinetics of an innovative hybrid nuclear power facility with an extended neutron source based on a magnetic trap. The fusion-fission facility under study includes a reactor plant, the core of which consists of an assembly of thorium-plutonium fuel blocks of the HGTRU reactor of a unified design and a long magnetic trap that penetrates the near-axial region of the core. The engineering solution for the neutron plasma generator is based on an operating gas-dynamic trap based on a fusion neutron source (GDT-FNS) developed at the Novosibirsk G.I. Budker Nuclear Physics Institute of the Siberian Branch of the Russian Academy of Sciences. The GDT-FNS high-temperature plasma pinch is formed in pulse-periodic mode in the investigated hybrid facility configuration, and, at a certain pulse rate, one should expect the formation of a fission wave that diverges from the axial part of the system and propagates throughout the fuel block assembly in a time correlation with the fast D-D neutron pulse source. In these conditions, it is essential to study the fission wave propagation process and, accordingly, the power density distribution formation within the facility blanket. The paper presents the results of a study on the steady-state and space-time performances of neutron fluxes and the power density dynamics in the facility under investigation. The steady-state neutronic performance and the space-time fission wave propagation were simulated using the PRIZMA software package developed at FSUE RFNC-VNIITF.

Hydrogeological Characterization of the Thyspunt Area, Eastern Cape Province, South Africa

This paper presents a comprehensive hydrogeological investigation that involves field work, aquifer test, hydrogeochemical analysis, environmental isotope analysis, and interpretations around a proposed nuclear power facility in South Africa. The study was undertaken to test the complementarity of the various methods in the coastal aquifer and to verify the hydrogeological conditions within and around the site. The study revealed the presence of two types of aquifers: an upper primary aquifer made up of the Cenozoic deposits of the Algoa Group, and a deeper fractured aquifer made of the Palaezoic Table Mountain Group (TMG) metasedimentary rocks. Owing to ductile deformation in the form of folding, the fractured quartzite and shale aquifers resulted in an artesian condition, often characterized by slightly acidic (pH ≤ 6) and iron-rich groundwater. The most important hydrogeochemical processes responsible for the observed changes in the hydrochemical composition and facies are mineral dissolution, ion exchange and mixing. The environmental isotope results suggest that all groundwater samples are characterized by a depleted δ18O and δ2H signal, indicating high latitude moisture source (southern polar region) and recharge from rainfall, with no or minimal evaporation before and during infiltration. Similarities in the stable isotope signatures between the deeper and shallow aquifer confirm the presence of a strong hydraulic link. The residence time of groundwater in the aquifers underlying the proposed nuclear power plant is estimated using tritium (3H) and 14C, and the results indicate that in the shallow aquifer it ranges from recent recharge to 50 years, and in the deeper aquifer, it ranges from 430 ± 5 years to 1000 ± 10 years, which exists in a quasi-pristine condition.

Fukushima: U.S. Response and the Short-Term Impact on U.S.-Japan Trade in Fish and Seafood

The U.S. regulatory response to the import of potentially contaminated food from Japan following the Fukushima Daiichi nuclear power facility meltdown has not been closely examined. The incident caused global concern about the safety of foods imported from Japan. U.S. scientists and policymakers conducted an initial evaluation of the potential health risks, analyzed information and data from foreign governments and international organizations, adopted an import alert, and conducted extensive monitoring. They did not detect radionuclides in, adopt a ban on, or advise consumers to alter their consumption of foods from Japan. Using a modified Global Simulation Model, National Marine Fisheries Service monthly seafood import data and United Nations trade data, we performed a comprehensive retrospective benefit-cost analysis of U.S. actions on U.S.-Japan trade in fish and seafood. We estimate that U.S. regulatory policy preserved approximately $150 million in annual consumer surplus from the continued import of Japanese fish and seafood (at a cost of less than $1 million for import sampling), while finding no additional exposure to harmful radionuclides. The lesson of our analysis is that investment in regulatory infrastructure has tangible economic benefits, and that retrospective benefit-cost analysis can be a useful framework for evaluating catastrophe risk-related policy strategies.

Sensing pipes of a nuclear power mechanism using low-cost snake robot

Snake robots have come to represent a new subfield of bionic robot research in recent years. A snake robot comprises many modules and performs various movements in arranged connections. The structure of a snake body enables it to move smoothly in narrow spaces or pipes with high stability and reliability. This article studies the application of a snake robot on a large-scale nuclear power facility to sense in pipe components. Therefore, a snake robot must move in pipes in which high radiation is present to explore the surrounding environment and take samples. A simple but effective method of locomotion is developed and executed to confirm feasibility of motion, especially in narrow space. A sampling mechanism with a storage box is designed at the tail of the snake to take and keep the samples well at designated locations. We built a pipe system which has two right-angled turns to simulate the pipes of a large-scale nuclear power facility. A user interface helps operators to manipulate the snake robot.