Radiological consequence assessments using time-varying source terms in ONERS- decision support system for nuclear emergency response

Nuclear off-site emergency response for nuclear power plants in Guangdong province is a complicated process, which is finished by many emergency response organizations. In a nuclear emergency, the source, format, content, take-over means and processing means of the information passed among these organizations are different. The aim of nuclear emergency response is to protect public and environment by taking some proper urgent protective action. The essential information from the original information is necessary for decision-making in the processing of nuclear response emergency, thus the key of emergency response is incepting and analyzing the information. An effective method of processing information is using a computer-based information system to aid the traditional handwork means. Nuclear Emergency management Information System in Guangdong Province is such systems, which covers preparedness, response and recover phase. At first, this paper analyzed the system functions according to the responsibilities of the emergency organizations in Guangdong province. Then the system frame is decided, which is composed of operation, information management, file processing, consequence assessment, operational intervention level (OIL) computing subsystem, geographic information system and a system database. A useful method for decision is applying the OILs in consequence assessment, and default OILs need be revised in a real nuclear emergency. Developing OIL computing subsystem is helpful to make decision with measurement result directly.

A meshless BEM for solving transient non-homogeneous convection-diffusion problem with variable velocity and source term

A new method for solving the fission gas diffusion equations with time-varying diffusion coefficient and source term considering recrystallization of fuel grains

In this paper, we study an inverse problem of identifying a time-dependent term of an unknown source for a time fractional diffusion equation using nonlocal measurement data. Firstly, we establish the conditional stability for this inverse problem. Then two regularization methods are proposed to for reconstructing the time-dependent source term from noisy measurements. The first method is an integral equation method which formulates the inverse source problem into an integral equation of the second kind; and a prior convergence rate of regularized solutions is derived with a suitable choice strategy of regularization parameters. The second method is a standard Tikhonov regularization method and formulates the inverse source problem as a minimizing problem of the Tikhonov functional. Based on the superposition principle and the technique of finite-element interpolation, a numerical scheme is proposed to implement the second regularization method. One- and two-dimensional examples are carried out to verify efficiency and stability of the second regularization method.

A time domain method building on the concept of wave splitting is used to study direct wave propagation phenomena in weakly nonlinear media. The starting point is the linear wave equation with time-dependent coefficients. This means that the studied nonlinear medium in some sense has to be approximated with a nonstationary medium which changes while the wave passes through. For the nonstationary equation homogeneous as well as particular solutions can be obtained. Two different iterative procedures to find the nonlinear solutions are discussed. They are illustrated by two problems fetched from different research fields of current interest. In the first case, the nonlinear term is linearized using the Fréchet derivative. This leads into a truly nonstationary, mixed initial boundary value problem with a linear equation characterized by both time-dependent coefficients and source terms. In this example a semiconductor device used for switching in high-frequency applications is considered. It can be described as a coplanar waveguide loaded with distributed resonant tunnel diodes. In the other example, wave propagation in Kerr media is considered. Then Taylor expansion transforms the nonlinear equation into a linear one with nonstationary source terms. In this case the nonlinearity does not lead to time-depending coefficients in the equation. The way to obtain the solution is a nonlinear variant of the Born approximation.

Potential impacts to operating nuclear power plants due to application of revised source term

The aim of this scoping review was to provide an overview and classification of existing studies on strategies and measures to reduce the workload of nuclear industry main control room operators and emergency response organization personnel to support their wellbeing and functional capacity during crises. The Preferred Reporting Items for Systematic Reviews and Meta-Analysis extension for Scoping Reviews (PRISMA-ScR) statement guidelines were followed. All the 49 studies included involved main control room operators. No studies were found on emergency response organizations. Forty studies addressed technical systems, interfaces and/or algorithms, 11 addressed guides, procedures and protocols, and three addressed training as workload management measures. Yet, only 11 studies evaluated the workload empirically. In conclusion, a large number of studies on technically oriented support measures, protocols and procedures was found. The empirical evidence on the effects of workload management measures was scarce. Further research is needed to truly evaluate the effects of these workload management strategies and measures on employees' workload, wellbeing, and functional capacity. Also, more research is needed on other measures such as management models, working hour arrangements, and social and psychological support measures. Further, the workload management of emergency response organization personnel should also be studied.

ABSTRACTThis paper is devoted to solve an inverse time-dependent source problem for a time-fractional diffusion-wave equation. The source function in the time-fractional diffusion-wave equation is assumed as a multiplication of a temporal function and a spatial function. We try to identify the time-dependent source term according to an additional solute concentration distribution measured at a point on the boundary or an inner point in the solution domain. Firstly, we discuss the continuity of the weak solution for the direct problem. Then, we transform the inverse problem into a first kind of Volterra integral equation and show its ill-posedness. We use a generalized Tikhonov regularization to solve the Volterra integral equation. The generalized cross-validation choice rule is applied to find a suitable regularization parameter. Lastly, we test three examples for the inverse time-dependent source problem and show the effectiveness of the proposed regularization method.

In this study, a technical index system for nuclear accident emergency response measures was established and comprehensively evaluated by studying the impact of time, ventilation speed, and leakage speed on the radiation consequences after a loss of coolant accident (LOCA) in a marine reactor. The weight of each index was calculated by the analytic hierarchy process (AHP), and the weight of the radiation protection measure in the second-level index emergency measure was 0.625, accounting for the maximum proportion. The weights of improving radionuclide detection technology in chambers, improving detection capability, and improving the diagnosis efficiency of radiation damage in the three-level indicator emergency measures were 0.4442, 0.4384, and 0.4521, respectively, accounting for the maximum proportions. The fuzzy comprehensive evaluation method was used to quantify and comprehensively evaluate the index system of emergency measures. The quantitative evaluation result was 82.8 points, indicating that the evaluation result was adequate. Therefore, the nuclear emergency response measure based on the radiation consequences of a marine reactor LOCA is reasonable and feasible. It provides valuable measures and practical guidance for the emergency response of a marine reactor LOCA, and dramatically reduces the harm of radiation to staff and the environment.

Off-site nuclear emergency response in Germany is divided into disaster response under the responsibility of the Länder and measures for precautionary radiation protection pursuant to the Precautionary Radiation Protection Act under the lead of federal authorities. Early countermeasures at the regional level require a different management than long-term and comprehensive actions of precautionary radiation protection. As situations may arise in which measures of both approaches overlap with regard to place and time, it is essential to make thorough preparations in order to avoid problems with implementation.

Large-scale sampling and radioactivity analysis of agricultural soil and food during nuclear emergencies in Japan: Variations over time in foodstuffs inspection and sampling

A new analytical method for groundwater recharge and discharge estimation

Nonlinear Heat Conduction through an Externally Heated Radiant Plasma: Background Analysis for a Numerical Study

The analytic solutions of Boulton (1954) and Neuman (1972) for transient flow to a well in an unconfined aquifer are based on the assumption that the role of the unsaturated zone can be adequately accounted for by restricting attention to the release of water from the zone through which the water table moves. Both researchers mathematically treat this released water as a time-dependent source term. The differences between the models of Boulton and Neuman are that the former neglects vertical components of flow in the aquifer, but allows for an exponential process for the release of water as a function of time, whereas the latter assumes instantaneous release from storage, but accounts for vertical components of flow. Given this set of assumptions, we examine the applicability of these two methods using a general purpose numerical model through a process of verification extension and comparison. The issues addressed include: the role of well-bore storage in masking intermediate-time behavior, combined effects of exponential release as well as vertical flow, logic for vertical averaging of drawdowns, and the sensitivity of system response to the magnitude of specific yield. The issue of how good the assumptions of Boulton and Neuman are in the context of the general theory of unsaturated flow is addressed in part 2 of this two-part series of reports.

Indonesia has three nuclear research reactors, nemely: RSG-GAS in Serpong, TRIGA2000 reactor in Bandung, and Kartini reactor in Yogyakarta. Besides being useful, nuclear reactor has inharent risk due to its radiation hazard. The research reactor nuclear contingency plan was prepared for nuclear preparedness. The study aimed to analyze the implementation of the research reactors’ nuclear contingency plans. The study used an analytic descriptive qualitative methods. The results showed that the nuclear contingency plans of the three research reactors have different implementation range due to their different hazard risks. However, the nuclear emergency responses were the same, they were: sheltering, evacuation, provision of KI tablets, and prohibition of consumption of local food and contaminated river/ ground water. The research reactors’ nuclear contingency plans have not discussed criteria used for taking nuclear emergency responses. The results also showed that the nuclear contingency plan of RSG-GAS in Serpong and the Kartini reactor in Yogyakarta have been implemented partially. While for the TRIGA2000 reactor nuclear contingency plan in Bandung has not been implemented yet. A legal umbrella is needed to implement the research reactor nuclear contingency plan. Thus, coordination and active role from all stakeholders are needed to be enhanced in order to be able to resolve the existing obstacles and challenges.