Man-Sung Yim

An Investigation into the Feasibility of Monitoring a Worker’s Psychological Distress

The objective of this study is to investigate the feasibility of developing a worker psychological distress monitoring system using Electroencephalogram (EEG). Psychological impairment has emerged as a key security (insider threat) and safety (human error) issue at Nuclear Power Plants (NPPs) as well as other industries. Although the U.S. Nuclear Regulatory Commission (NRC) highlighted the importance of NPP workers’ Fitness-For-Duty (FFD) to ensure personnel reliability, current FFD programs only consider drug and alcohol testing and fatigue management. However, today’s bio-signals technology makes it possible to monitor the physical and mental state of workers. Thus, this study examines the feasibility of using EEG indicators to identify potentially-at-risk workers, especially those with acute psychological distress. We reviewed historical cases of insider threat and human error at nuclear facilities, and analyzed these cases from the perspective of a suspect’s mental health. Based on bio-signal literature, a variety of EEG indicators identified at risk workers with a psychological impairment. As such, we selected the following: (1) Frontal EEG asymmetry; (2) EEG coherence; and (3) the variations of frequency domain EEG indicators (Theta, Alpha, Beta and Gamma) at certain brain area. To verify the appropriateness of these EEG indicators in realistic situations, this study performed a pilot experiment. The resting states of EEG (Eye Closed and Eye Open) were recorded on 56 student subjects (36 healthy and 20 with a high score for depression and anxiety symptoms). The resting states of EEG results showed a statistically significant difference between at-risk students and healthy students. This means specific EEG indicators can be used to classify the mental status of workers. These results can be applied directly to the mental health monitoring system of nuclear power plants as well as the industries requiring high reliability (aerospace, military and transportation).

The Effect of Alcohol-Use and Sleep Deprivation on Quantitative Changes in EEG for Normal Young Adults During Multitasking Evaluation

The Fitness-For-Duty (FFD) of a worker in high-reliability systems such as Nuclear Power Plants (NPPs) and the civilian aircraft industry has been largely recognized as a key indicator when identifying the causes for human-error related accidents/incidents. Specifically, an alcohol drinker and a sleep-deprived worker has been identified as fatal to nuclear safety. In NPPs, a reactor operator must be capable of multitasking to detect a system failure. Thus, the objective of this study is to understand the EEG variations underpinning the reactions of drinkers and drowsy persons during multitasking cognitive performance. An experimental task was performed which included multitasking, working memory and real time EEG signals recorded. Quantitative EEG (absolute and relative powers of the seven bands) was analyzed for 10 college students (five subjects with 0.05% Blood Alcohol Concentration (BAC) and five with less than one hour of sleep). The same experiment was performed again when each of the subjects had a normal health status (0% BAC and their typical sleep duration). The results indicated a statistical difference in cognitive performance depending on their physical status. These results can be used to investigate the feasibility of determining alcohol-use and sleep quality measurements using EEG indicators, as well as determining a worker’s FFD related to cognitive performance.

An Investigation of Human Error Identification Based on Bio-monitoring System (EEG and ECG Analysis)

Human error has been a critical issue at Nuclear Power Plants (NPP) as it accounts for a significant proportion of safety-related incidents. The objective of this research is to investigate the feasibility of using a bio-monitoring system (EEG and ECG) to predict and thereby minimize the risk of human error at NPPs. Ten subjects (8 male 2 female) with a mean age of 25 years participated in the experiment. Specifically, the Stroop test was used to measure each participant’s accuracy in judgement and reaction time, in answering congruent and incongruent questions. Using these data, both heart rate and brain waves were recorded and analyzed via a power spectrum analysis, EEG and ECG indicators were investigated to determine their potential for identifying human error.

Building trust in nonproliferation: transparency in nuclear-power development

ABSTRACT Nuclear transparency is beneficial to nonproliferation. It helps non-nuclear-weapon states demonstrate their commitment to the nonproliferation regime and nuclear-weapon states account for their stockpiles. It also buttresses the safeguards process of the International Atomic Energy Agency (IAEA). This article discusses the need for better transparency in nonproliferation efforts and offers a new tripartite model of nuclear transparency which emphasizes not only the states that want to prove their nonproliferation compliance through transparency, but also the audience for such transparency, and how transparency information is transferred from providers to recipients. The article discusses a range of issues concerning how such information is generated, appraised, and presented, taking into account the effect of cultural influences on different states’ transparency practices. To better synthesize various pieces of information intended to demonstrate nuclear transparency, we propose a nuclear-transparency dataset that includes nuclear-related factors as well as socio-political variables. Regression results using the dataset and responses from an expert survey show that the proposed transparency indicators provided a relatively similar assessment to the IAEA’s level of confidence about a state’s safeguards record, as stated in its 2013 safeguards report. Finally, the article proposes a direction for the development of this transparency index, as well as means by which states can improve their nuclear transparency.

Developing a Conceptual Design of Suction-Based Ex-containment Radioactive Release Barrier System and Defining its Design Limits

In a typical nuclear power plant, physical barriers and engineered safety systems are designed to protect the workers and the public in case of a severe accident from the in-containment radiological inventory, called the source term. If the barriers fail and the radioactivity leaks out to the environment, however, there is no engineered system to prevent the dispersion of the radioactive releases. Such radioactive release occurred in Fukushima, and as a result, the public’s fear of the nuclear energy increased. Now, the public may not accept the assurance that the likelihood of another such accident is very low. Therefore, it may be essential for the nuclear industry to gain the public trust by developing comprehensively engineered safety systems that can prevent or reduce the consequences of such accident. One such safety system currently being researched is called the Integrated Portable Suction-Centrifugal Filtration System (IPS-CFS), a suction-based ex-containment radioactive release barrier system. To design such safety system, the radioactive source term at the release to the environment must be well characterized. The purpose of this paper was to present a conceptual design of the IPS-CFS and to develop its design requirements. An extended station blackout accident sequence with no recovery of auxiliary feedwater to the steam generators was chosen to simulate one of the worst-case scenarios that can cause significant radioactive releases to the environment. Based on the MAAP4-simulated source term data and with conservative assumptions, physical properties of interest such as the temperature of the radioactive release and the release speed of the radioactive materials were estimated. In addition, possible radiation doses to the exposed workers in the vicinity of the IPS-CFS were estimated conservatively to define the required decontamination factor of the system to keep the workers’ doses below the regulatory limit set by the Nuclear Regulatory Commission (NRC). However, due to the number of conservative assumptions taken in this primary analysis, more detailed and realistic source term analysis for the required worst-case scenario must be performed in the future to refine the design requirements.