The implementation of a human factors engineering checklist for human–system interfaces upgrade in nuclear power plants

The primary purpose of this paper is to provide a human factors engineering (HFE) checklist for human–system interfaces (HSIs) upgrades in nuclear power plants (NPPs). The HFE checklist is used to review the HSIs design submittals prepared by licensees or applicants for a license or design certification of a HSI upgrade. NUREG-series regulation documents are used to develop the main frame of the initial HFE checklist. The contents of the HFE checklist are constructed by the theories and principles governing human factors. Then, verification and validation (V&V) of the HFE checklist is accomplished by validity and reliability evaluation. The results show that the HFE checklist has sufficient validity and reliability for the review of HSI upgrades in NPPs.     

Ethylene Dosages in Denver and Marketability of Cut-Flower Carnations

Ethylene dosages required to reduce keeping life of the cut-flower, Dianthus caryophyllus L. cv “White Sim,” were compared with dosages estimated from air samples obtained in selected locations of the Denver Metropolitan region. Ethylene concentrations sufficiently high and prolonged to reduce significantly flower longevity prior to final sale are seldom attained. If flowers are harvested in an immature stage and immediately refrigerated, there should not be any economic loss. But, damage is likely after the flower is purchased and displayed at room temperature. Regardless of quality maintained in the marketing processes by the greenhouse industry, severe consumer dissatisfaction may result when ethylene sensitive plant material is purchased. The results emphasize means of avoiding pollution damage from ethylene.     

Carbon bed mercury emissions control for mixed waste treatment

Mercury has various uses in nuclear fuel reprocessing and other nuclear processes, and so it is often present in radioactive and mixed (radioactive and hazardous) wastes. Compliance with air emission regulations such as the Hazardous Waste Combustor (HWC) Maximum Achievable Control Technology (MACT) standards can require off-gas mercury removal efficiencies up to 99.999% for thermally treating some mixed waste streams. Test programs have demonstrated this level of off-gas mercury control using fixed beds of granular sulfur-impregnated activated carbon. Other results of these tests include (1) the depth of the mercury control mass transfer zone was less than 15-30 cm for the operating conditions of these tests; (2) MERSORB carbon can sorb mercury up to 19 wt % of the carbon mass; and (3) the spent carbon retained almost all (98.3-99.99%) of the mercury during Toxicity Characteristic Leachability Procedure (TCLP) tests, but when even a small fraction of the total mercury dissolves, the spent carbon can fail the TCLP test when the spent carbon contains high mercury concentrations.     

Recreation demand analysis under truncation, overdispersion, and endogenous stratification: an application to Gros Morne National Park

Using on-site survey data from Gros Morne National Park in Newfoundland, this paper estimates and compares several truncated count data models of recreation demand. The selected model accounts not only for the truncated and overdispersed nature of the data but also for endogenous stratification due to the oversampling of avid users. Moreover, the model that allows for a flexible specification of the overdispersion parameter dominates on the basis of goodness of fit. The results are used to estimate the users' value of access to the park.     

Automation design in advanced control rooms of the modernized nuclear power plants

This study evaluated the effects of levels of automation (LOAs) decisions in advanced control rooms of the modernized nuclear power plants. Following advancements in design of digitalized human–system interfaces (HSIs), the roles of human operators have changed significantly. Negative performance and safety consequences may occur as a result of these changes. These problems are viewed as the out-of-the-loop (OOTL) performance problems. This study conducted an experiment to compare the effects of different LOAs under different operating procedures on operating performance. Experimental results indicated that blended decision-making (level 6 LOA) generates the lowest mental workload. Furthermore, the pattern of SA observed in this study is found better SA at intermediate LOA and poorer SA at low level of automation and full automation. Subjective rating results suggest that LOAs distribute the roles of option generation, and selection between human and/or computer servers which significantly impacts automated system performance. This study provides a direction for the HSI designers in nuclear power plants (NPPs). Additionally, based on results obtained by this study, the user interfaces of PCTRAN system and the alarm reset system should be improved to ensure safe operation of NPPs.     

An Aquifer Vulnerability Assessment of the Paluxy Aquifer, Central Texas, USA, Using GIS and a Modified DRASTIC Approach

D epth to water, net Recharge, Aquifer media, Soil media, Topography, Impact of the vadose zone, and Conductivity of the aquifer). Using such an approach allows one to investigate the potential for groundwater contamination on a regional, rather than site-specific, scale. Based upon data from variables such as soil permeability, depth to water, aquifer hydraulic conductivity, and topography, subjective numerical weightings have been assigned according to the variable's relative importance in regional groundwater quality. The weights for each variable comprise a GIS map layer. These map layers are combined to formulate the final groundwater pollution potential map. Using this method of investigation, the pollution potential map for the study area classifies 47% of the area as having low pollution potential, 26% as having moderate pollution potential, 22% as having high pollution potential, and 5% as having very high pollution potential.     

Movement of diuron and hexazinone in clay soil and infiltrated pond water

Pre-emergence herbicide residues were detected in domestic wells sampled near Tracy, CA. This study sought to determine the source of contamination by comparing soil distribution of diuron [N'-(3,4-dichlorophenyl)-N,N-dimethylurea] and hexazinone [3-cyclohexyl-6-(dimethylamino)-1-methyl-1,3,5-triazine-2,4(1H,3H)-dione] in an agricultural field where the soil was a cracking clay to infiltration of residues in water captured by an adjacent holding pond. Diuron and hexazinone were applied in December to a 3-yr-old alfalfa (Medicago sativa L.) crop. Water content of soil taken after major rainfall but before irrigation at 106 d after application was elevated at the lowest depth sampled centered at 953 mm, indicating water was available for percolation. Herbicide residues (reporting limit 8 microg kg(-1)) were confined above the 152 mm soil depth, even after subsequent application of two border-check surface irrigations. The pattern of distribution and concentration of residues in the soil were similar to results obtained from the LEACHM model, suggesting that macropore flow was limited to a shallow depth of soil. Herbicide residues were measured in runoff water at the first irrigation at 20 microg L(-1) for diuron and 1 microg L(-1) for hexazinone. Runoff water captured in the pond rapidly infiltrated into the subsurface soil, causing a concomitant rise in ground water elevation near the pond. Herbicide residues were also detected in the sampled ground water. We concluded that the pond was the predominant source for movement to ground water. Since addition of a surfactant to the spray mixture did not reduce concentrations in runoff water, mitigation methods will focus on minimizing infiltration of water from the pond.     

The research on extracting the information of human errors in the main control room of nuclear power plants by using Performance Evaluation Matrix

Digitalized nuclear instruments and control systems have been the main stream design for the main control room (MCR) of advanced nuclear power plants (NPPs) nowadays. Digitalization of human–system interface (HSI) could improve human performance and, on the other hand, could reduce operators’ situation awareness as well. It might cause that humans make wrong decision during an emergency unintentionally. Besides, digital HSI relies on computers to integrate system information automatically instead of human operation. It has changed the operator’s role from mainly relating operational activity to mainly relating monitoring. However, if the operators omit or misjudge the information on the video display units and wide display panel, the error of omission and error of commission may occur. This study applies Content Category Analysis (CCA) and Performance Evaluation Matrix (PEM) methods to explore the potential problems in the MCR of advanced NPPs which are caused by human errors. The results show that the potential problems that would probably contribute to the human performance of MCR in the advanced NPPs are multiple accidents, pressure level, number of operators, and other factors such as working environmental. The conclusions of this research may be considered to avoid and prevent human errors in the human factor related researches especially in the nuclear safety field.