The Use of Stochastic Safety Analysis Methods to Establish Control Strategies and Estimate Future Risk

2002 ◽  
Author(s):  
Grant W. Ryan ◽  
Jonathan Young ◽  
Mike Grisgby
Keyword(s):  
Waste Treatment ◽  
Control Strategies ◽  
Full Range ◽  
Treatment Plant ◽  
Safety Analysis ◽  
Hanford Site ◽  
Analysis Methods ◽  
The Future ◽  
Future Risk ◽  
Waste Transfer

Stochastic safety analysis methods have been used at the Hanford Site in Washington State to establish control strategies and to estimate the future risk of waste transfer leak accidents. The Hanford Site tank farms currently store approximately 208 ML (55 Mgal) of radioactive/hazardous waste in 177 underground storage tanks. To move this waste a complex network of transfer piping and equipment is used. Each waste transfer carries a potential risk that a waste leak may occur. Waste transfer leaks into waste transfer structures, the soil (above ground and below ground), and into actively ventilated facilities due to a variety of causes were analyzed. A number of parameters (e.g., leak size, radiological composition of the leaked waste, wind speed and atmospheric dispersion) were treated as probability density functions (pdfs) in the safety analysis to determine the full range of potential consequences of waste transfer leaks. Each pdf was sampled in a Monte Carlo simulation model to determine the distribution of potential consequences from the various leak events. The resulting consequence distributions were evaluated with respect to risk guidelines to determine the appropriate control sets for daily operations to ensure that the risk from waste leak events could be minimized. The results were also used in the development of a probabilistic risk assessment to estimate accident risks to the public and co-located workers for both the tank farms and the future Hanford Site Waste Treatment Plant.

Application of Optical and Imaging Techniques to Inspection of Off-Line Joule-Heated Melter at the West Valley Demonstration Project

2003 ◽  
Author(s):  
M. John Plodinec ◽  
Ping-Rey Jang ◽  
Zhiling Long ◽  
David L. Monts ◽  
Walter P. Okhuysen ◽  
...  
Keyword(s):  
Waste Treatment ◽  
Imaging Techniques ◽  
Treatment Plant ◽  
Quantitative Information ◽  
Demonstration Project ◽  
Hanford Site ◽  
The West ◽  
Refractory Wear ◽  
Waste Treatment Plant ◽  
Crucial Information

The West Valley melter has been taken out of service. Its design is the direct ancestor of the current melter design for the Hanford Waste Treatment Plant. Over its eight years of service, the West Valley melter has endured many of the same challenges that the Hanford melters will encounter with feeds that are similar to many of the Hanford double shell tank wastes. Thus, inspection of the West Valley melter prior to its disposal could provide valuable — even crucial — information to the designers of the melters to be used at the Hanford Site, particularly if quantitative information can be obtained. The objective of Mississippi State University’s Diagnostic Instrumentation and Analysis Laboratory’s (DIAL) efforts is to develop, fabricate, and deploy inspection tools for the West Valley melter that will (i.) be remotely operable in the West Valley process cell; (ii.) provide quantitative information on melter refractory wear and deposits on the refractory; and (iii.) indicate areas of heterogeneity of deposits, requiring more detailed characterization. A collaborative arrangement has been established with the West Valley Demonstration Project (WVDP) to inspect their melter.

scholarly journals Applying performance indices in plantwide modelling for a comparative study of wastewater treatment plant operational strategies

Water SA ◽  
2018 ◽  
Vol 44 (4 October) ◽  
Author(s):  
Justine De Ketele ◽  
Dries Davister ◽  
David S Ikumi
Keyword(s):  
Wastewater Treatment ◽  
Mathematical Models ◽  
Wastewater Treatment Plant ◽  
Waste Treatment ◽  
Control Strategies ◽  
Treatment Plant ◽  
Expert Advice ◽  
Energy Costs ◽  
Performance Indices ◽  
Effluent Quality

Achievement of good effluent quality is always the main goal for wastewater treatment plant (WWTP) systems. However, these WWTPs have developed further objectives that include efficient design and strategic control options, with the prospect of their conversion into waste resource recovery facilities (WRRFs) that operate on reduced energy costs. With all these aspects becoming an intrinsic part of waste treatment, mathematical models that simulate WWTP unit processes are becoming of increasing relevance for the achievement of WRRF goals (including good effluent quality, low energy costs and nutrient recovery). It is expected that these mathematical models will benefit potential future applications of automation process control, which have also been developing rapidly with the availability of more reliable and affordable sensors. However, simulated automation control strategies require a thorough evaluation protocol to ensure their viability prior to being adopted as efficient operation control measures. This study considers the comparison of different control strategies implemented on a standard WWTP layout, for plant optimization. The initial task was to define performance indices, effluent quality index (EQI) and operation cost index (OCI), based on a previous investigation by the International Water Association (IWA) benchmark simulation modelling (BSM) task group. These performance indices were then used to evaluate the following strategies: (i) adding a fermentation tank, (ii) dosing flocculant and (iii) implementing a balancing tank. A control strategy was only assumed to be effective with improvement or maintenance of effluent quality. Overall, the evaluation exercise proved to be useful for providing expert advice on efficiency of proposed waste treatment system layouts, towards determination of the best configuration of future WRRFs. For instance, it was notable that significant organic strength is needed for removal of nutrients recycled back from the anaerobic digestion (AD) system into the activated sludge (AS) – hence alternate methods to put the nutrient-rich outflow from the AD system to good use are required.

scholarly journals Classification and Control of Key Factors Affecting the Failure of Aviation Piston Turbocharger Systems Using Model-Based System Safety Analysis

2021 ◽  
Vol 2021 ◽  
pp. 1-19
Author(s):  
Mengyao Bao ◽  
Shuiting Ding ◽  
Guo Li
Keyword(s):  
Failure Probability ◽  
Control Strategies ◽  
Safety Analysis ◽  
System Failure ◽  
Key Factors ◽  
System Safety ◽  
Safety Control ◽  
Factors Affecting ◽  
Model Based ◽  
Analysis Methods

Turbocharging is an effective way to address the problem of reduction in power and increase in fuel consumption of aviation piston engines during high-altitude flight. However, turbochargers have greatly increased the degree of complexity of power systems. The model-based system safety analysis methods for the safety analysis of turbocharging systems are introduced in this study to overcome the limitations of the traditional safety analysis methods regarding complex matching and coupled safety issues. On the basis of the established system models and the formed failure mode work boundaries and safety boundaries, the column profile coordinates F of correspondence analysis with the numerical deviation of the key factors are used to identify the key factors affecting failure, thereby proposing safety control strategies in a targeted manner. Then, the failure probability of the turbocharging system is assessed through the Monte Carlo method. System failure modes and probabilities before and after the execution of safety control strategies are compared to accurately determine the effectiveness of those strategies. The verification examples show that a safety control strategy that adjusts the diameter of the wastegate e 2 can reduce system failure probability and enhance safety level.

scholarly journals More Weight on the Job

2010 ◽  
Vol 132 (07) ◽  
pp. 36-38
Author(s):  
Harry Hutchinson
Keyword(s):  
Radioactive Waste ◽  
Treatment Plant ◽  
Chemical Waste ◽  
Hanford Site ◽  
Geological Repository ◽  
Processing Plants ◽  
Stable Glass ◽  
Waste Transfer ◽  
Under Construction ◽  
High Level

This article discusses that new methods and heavier equipment are expected to hasten the nuclear waste transfer at the Hanford Site’s tank farms. The site includes old processing plants, groundwater that exceeds safe levels of radioactivity, and high-level radioactive waste held in 149 aging tanks—some more than 60 years old—that lie underground just 10 miles from the Columbia River. The objective is to remove the highly radioactive waste from the old tanks, which have a single shell construction, and transfer it to 28 newer, more-secure double-shell tanks nearby, where the waste will safely reside until it can be treated in facilities now under construction. There are approximately 53,000,000 gallons of nuclear and chemical waste stored in the tanks at the Hanford Site. Bechtel National Inc., another of the prime contractors for Office of River Protection, is building a treatment plant that will process the wastes being stored in the underground tanks into a stable glass form for permanent disposal in a federal geological repository.

Evaluating Risk After a Hazardous Waste Treatment Plant Released Persistent Organic Pollutants: Part 3, Aboriginal Health Risk and Impact

2018 ◽  
Vol 2 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Tee L. Guidotti
Keyword(s):  
Health Risk ◽  
Organic Pollutants ◽  
Persistent Organic Pollutants ◽  
Waste Treatment ◽  
Treatment Plant ◽  
Aboriginal Health ◽  
Treatment Center ◽  
Hazardous Waste Treatment ◽  
Waste Treatment Plant ◽  
Health Canada

On 16 October 1996, a malfunction at the Swan Hills Special Waste Treatment Center (SHSWTC) in Alberta, Canada, released an undetermined quantity of persistent organic pollutants (POPs) into the atmosphere, including polychlorinated biphenyls, dioxins, and furans. The circumstances of exposure are detailed in Part 1, Background and Policy Issues. An ecologically based, staged health risk assessment was conducted in two parts with two levels of government as sponsors. The first, called the Swan Hills Study, is described in Part 2. A subsequent evaluation, described here in Part 3, was undertaken by Health Canada and focused exclusively on Aboriginal residents in three communities living near the lake, downwind, and downstream of the SHSWTC of the area. It was designed to isolate effects on members living a more traditional Aboriginal lifestyle. Aboriginal communities place great cultural emphasis on access to traditional lands and derive both cultural and health benefits from “country foods” such as venison (deer meat) and local fish. The suspicion of contamination of traditional lands and the food supply made risk management exceptionally difficult in this situation. The conclusion of both the Swan Hills and Lesser Slave Lake studies was that although POPs had entered the ecosystem, no effect could be demonstrated on human exposure or health outcome attributable to the incident. However, the value of this case study is in the detail of the process, not the ultimate dimensions of risk. The findings of the Lesser Slave Lake Study have not been published previously and are incomplete.

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