Application and Development of Noncontact Detection Method of α-Particles Based on Radioluminescence

The detection of α particles is of great significance in military and civil nuclear facility management. At present, the contact method is mainly used to detect α particles, but its shortcomings limit the broad application of this method. In recent years, preliminary research on noncontact α-particle detection methods has been carried out. In this paper, the theory of noncontact α-particles detection methods is introduced and studied. We also review the direct detection and imaging methods of α particles based on the different wavelengths of fluorescence photons, and analyze the application and development of this method, providing an important reference for researchers to carry out related work.

Design of Intelligent Security Management and Control System for a Large Nuclear Facility

There are many kinds of safety control sub-systems of a large nuclear facility, and their information is isolated from each other, so the overall safety control efficiency is low. To solve this problem, based on the original security control sub-system, an intelligent security management and control system is designed by using the technology of system integration and multi-sensor cooperative scheduling. Firstly, the web service interfaces of each security control sub-system are developed, and the interconnection and information sharing of each security control sub-system are realized through these interfaces. Then, based on the multi-sensor system cooperative optimization scheduling technology and the improved ant colony algorithm, the information synthesis and security cooperative optimization scheduling of heterogeneous multi-sensor messages are realized. The highly integrated intelligent security management and control system reduces the alarm omission rate and false alarm rate of the safety control and improves the efficiency of the security control.

Decontamination of a Contaminated RCP Shaft Using the SP-HyBRID Process

It is very important to minimize the waste generation for decontamination of the reactor coolant system in a nuclear facility. As an alternative to commercial decontamination technologies, an inorganic acid chemical decontamination (SP-HyBRID) process can be effectively applied to the decontamination because it can significantly reduce the waste generation. In this study, the decontamination of a contaminated reactor coolant pump shaft from a nuclear facility was conducted using the SP-HyBRID process. First, equipment for a mock-up test of the decontamination was prepared. Detailed experimental conditions for the decontamination were determined through the mock-up test. Under the detailed conditions, the contaminated shaft was successfully decontaminated. The dose rate on the shaft surface was greatly reduced from 1400 to 0.9 μSv/h, and the decontamination factor showed a very high value (>1500).

A Model Based System Commissioning Approach for Nuclear Facilities

Commissioning is considered as a critical phase in the delivery of a Nuclear Facility (NF) as it is the first stage in the authorization of the NF to be exploited. Most of the nuclear projects start to overrun costs during commissioning mainly since this phase is not addressed properly and is affected by many issues from previous phases (Design, Procurement, and Construction). This article proposes a general methodology to prepare and realize the commissioning activities. Using models to do so improves communication and removes ambiguities between stakeholders. It also formalizes and clarifies the commissioning organization and activities prior to any implementation. It also allows for capitalizing and sharing the experience from previous projects, by drawing references models and good practices patterns. The so-called Model Based commissioning method is elaborated around concepts, languages, processes, tools, and patterns inspired from Model Based System Engineering (MBSE) principles and practices. The theoretical foundations will be supported by results from nuclear facilities demonstrating the added value.

Low Dose Assessment Uncertainty Analysis for Landauer® nanoDot™ OSLDs

This study aims to low-level background range measurements of commercial OSLDs. This work is the initial step to put a framework to detect any illicit nuclear activities in any nuclear facility at any time. The idea in this framework is to utilize already placed OSLDs in the facility which are normally read-out periodically. The results of these measurements could be distinguishable from the background radiation since this paper shows how the background dose with its statistical fluctuation provide detection limits in these applications. To do this, we measured dosimeters in two ways; without removal or replacement and full removal for each measurement. As a result of measurements, the initial dose, bleaching constant, and background dose was evaluated for different measurements. ANOVA was applied to all measurements and all measurements considered a measurement data set to analyze results. Consequently, we observed no statistically significant difference in these different kinds of measurement approaches relative to the total propagated uncertainty in any given dose estimate. This shows a passive detection can be verified with iterative measurements to improve statistics without compromising data quality when coupled with dose levels of potential interest serves to advance this potential nonproliferation application.

Knowledge base about risk and safety of nuclear facilities to support analysts and decision-makers

Epistemic uncertainty (related to lack of knowledge), often found in the documentation of nuclear facility engineering projects, can affect the decision-making process of managers and analysts on safety and risk issues. This article conceptualizes the nature of the major uncertainties involved in engineering projects and describes a knowledge base developed to gather data and information related to the project of an Open-Pool Light-water Research Reactor (OPLRR) and whose purpose is to assist professionals who work in the areas of nuclear facilities. To reduce the epistemic uncertainties that may arise in the project, the OPLRR knowledge base is designed with a set of information that allows identifying and facilitating the forwarding of solutions to address inconsistencies, and /or pending issues that may exist in the project. In this sense, the information and the documents related to the project are organized in a graphical and hierarchical architecture, allowing the knowledge base users to quickly and easily obtain information regarding the systems, processes, equipment, and components of the project. Besides that, a set of documents containing descriptions, reliability data, and some other information about the systems and components are specially created to the knowledge base and it is crucial to reduce epistemic uncertainties, once it raises the issues and the inconsistencies of the project, as well as it clarifies the interrelations between the systems, the functioning of the equipment, their failures modes and the consequences of their failures, and some other data, which are not originally contained in the documents of the project.

Overview of the seismic probabilistic safety assessment applied to a nuclear installation located in a low seismicity zone

Deterministic and probabilistic nuclear safety analysis methodologies have been developed and updated based on operational experience, investigation of past incidents or accidents, and analysis of postulated initiating events in order to maintain the protection of workers, the public and the environment. The evaluation of accident sequences and the total radiological risk resulting from off-site releases are general objectives addressed by these methodologies. There are hazards that continually challenge the safety of a nuclear facility or its nearby area. In particular, seismic events represent a major contributor to the risk of a nuclear facility. Different levels of ground motion induced by earthquakes may be experienced by the structures, systems and components (SSCs) of the installation. In this context, a seismic hazard analysis, seismic demand analysis and seismic fragility analysis must be carried out in order to characterize the local seismic hazard and what are the seismic demands on SSCs, allowing an adequate seismic classification of SSCs, even in installations located in sites with low seismicity. In this article, a general description of the Seismic Probabilistic Safety Assessment (Seismic PSA) methodology is presented, with emphasis on their support studies, aiming at applying the methodology described in this article to an experimental nuclear installation containing a PWR reactor designed for naval propulsion to be installed in a low seismicity zone in Brazil.