Development of Remote Sensing Assisted Water Quality Nowcasting and Forecasting Models for Coastal Beaches

A remote sensing assisted water quality modeling framework is developed in this dissertation for nowcasting and forecasting recreational water quality of Holly Beach in Louisiana, USA. The modeling framework is composed of four models/systems: (1) an Artificial Neural Network (ANN) model (Model 1) and an US EPA Virtual Beach (VB) Program-based model for predicting early morning enterococci (ENT) levels in beach waters; (2) an ANN model (Model 2) and an VB model for predicting early morning Fecal Coliform (FC) levels in beach waters; (3) a remote sensing assisted modeling system (Model 3) for predicting near real time ENT levels during daytime; and (4) a hybrid probabilistic/deterministic modeling approach (Model 4) for predicting the probability of beach water quality violation. New findings from Model 1 include (1) the identification of 7 explanatory variables and various combinations of the 7 variables responsible for the ENT level in coastal beach waters; and (2) Model 1 with Linear Correlation Coefficient (LCC) of 0.857 performs consistently better than the VB model with LCC of 0.320. A major finding from Model 2 is that a total of 6 independent environmental variables along with 8 different combinations are capable of explaining about 76% of variation in FC levels for model training data and 44% for independent data. Major new contributions made in Model 3 include (1) development of remote sensing algorithms for turbidity using Terra and Aqua satellite data; (2) development of an enhanced ANN model for predicting ENT levels at sunrise time by taking into account the cumulative effect of solar radiation on ENT inactivation; (3) development of a real-time model for predicting ENT level during the daytime by considering the turbidity effect on ENT inactivation. A novel feature of Model 4 (hybrid model) is the combination of advantages of a deterministic ANN model and a probabilistic Bayesian model. The hybrid model is capable of reproducing 86.25% of historical beach water quality advisories with 6.39% of false positive predictions and 7.36% of false negative predictions over the past 7-years. Applications of the models will improve the management of recreational beaches and the protection of public health

The compartment bag test (CBT) for enumerating fecal indicator bacteria: Basis for design and interpretation of results

For the past several years, the compartment bag test (CBT) has been employed in water quality monitoring and public health protection around the world. To date, however, the statistical basis for the design and recommended procedures for enumerating fecal indicator bacteria (FIB) concentrations from CBT results have not been formally documented. Here, we provide that documentation following protocols for communicating the evolution of similar water quality testing procedures. We begin with an overview of the statistical theory behind the CBT, followed by a description of how that theory was applied to determine an optimal CBT design. We then provide recommendations for interpreting CBT results, including procedures for estimating quantiles of the FIB concentration probability distribution, and the confidence of compliance with recognized water quality guidelines. We synthesize these values in custom user-oriented 'look-up' tables similar to those developed for other FIB water quality testing methods. Modified versions of our tables are currently distributed commercially as part of the CBT testing kit

Historical review of fire safety at NPP and application of fire PSA to Westinghouse PWR NPP in the frame of risk-informed decision making by

The importance of fire as a potential initiator of multiple-system failures took on a new perspective after the cable-tray fire at Browns Ferry in 1975 The review have shown that the first generation Nuclear Power Plant (NPP) fire safety was not factored as high risk area that needed to be effectively assessed and quantified. This resulted in development of peculiar fire safety regulations, standards and expensive backfits. Lack of appropriate regulations and effective methods of fire risk assessment, prescriptive, difficult and expensive retrofit regulations were instituted in USA. The alternative risk-informed performance based regulation was established in USA to resolve the challenges of the prescriptive rules. The review have revealed that both the prescriptive and risk-informed performance based approaches will not represent adequate design basis for new Nuclear Power Plants. The Japanese were pulled in the path of renew fire safety regulations and risk quantification after the Fukushima accident. It has been recognized that effective fire safety assessment, and culture, in concert with countermeasures to prevent, detect, suppress, and mitigate the effect of fires if they occur, will minimized NPP fire risk. Among the numerous recommendation the fire safety at NPP must be planned and engineered before construction begin using the state-of-the-arts technology. Also, the methods of fire risk assessment must integrate the state-of-the-arts deterministic and probabilistic approaches. Two methods are presented which serve to incorporate the fire-related risk into the current practices in nuclear power plants with respect to the assessment of configurations. The first method is a fire protection systems and key safety functions Unavailability Matrix (UM) which is developed to identify structures, systems, and components significant for fire-related risk. The second method is a fire zones and key safety functions (KSFs) fire risk matrix which is useful to identify fire zones which are candidates for risk management actions. The UM is an innovative tool to communicate fire risk. The Monte Carlo method has been used to assess the uncertainty of the UM. The analysis shows that the uncertainty is sufficiently bounded. The significant fire-related risk is localized in six KSF representative components and one fire protection system which should be included in the maintenance rule. The unavailability of fire protection systems does not significantly affect the risk. The fire risk matrix identifies the fire zones that contribute the most to the fire-related risk. These zones belong to the control building and electric penetrations building. The aggregation of Internal Events PSA model and Fire PSA model have shown that the Fire PSA contributes 38.4% to the Risk increase. The feasibility of developing Fire-related Risk Monitor from the FIRE PSA for the Spanish NPP was carried out. One of the main challenges is that RiskSpectrum® fire PSA has 384 fire cases and 384 CDF but in Risk Monitor one CDF is required. However, CAFTA is unable to convert a Sequential Fault Tree structure of the internal Event tree in the Fire PSA. The conversion fails to implement neither all of the sequences leading to core damage nor the Fault Tree selection of the frequency of fire. The proposal is to suppress exchange events and introduce the alignment of the consequences so that a unique result of core damage can be quantified. The detection and fire suppression Event Trees in the reference model were replaced by detection and fire extinction Fault trees. The frequency of each Fire Case of the conversion model and the reference model are quantified and the frequencies compared. The results shows that 90% of the cases are valid, however, the rest have challenges with MCS. A unique CDF of 7.65x10-7 is quantified compared with 9.83×10-6 of the reference. The conversion of the new model in CAFTA was not successful due to software incompatibility.La importància del incendi com un potencial iniciador de sistema múltiples fallides van agafar una nova perspectiva després del incendi al cable-safata de Browns Ferry el 1975. La revisió ha mostrat que la primera generació de seguretat contra incendis de centrals d'Energia Nuclear (NPP) no va ser àrea de alt risc, àrea que necessitava ser efectivament avaluada i quantificada. Això va resultar en el desenvolupament de normes de seguretat de incendi peculiar, estàndards i cares revisions. La manca d'una reglamentació adequada i mètodes eficaços d'avaluació de risc d'incendi, va fer que als USA foren instituïts mètodes d'adaptació de normativa preceptius, difícils i costós. L'alternativa de regulació informada per el risc es va establir als USA per resoldre els reptes de la regulació preceptiva. La revisió ha mostrat que tant als enfocaments de normativa preceptiva i regulació informada per el risc no representen bases de disseny adequades per a noves NPP. Ha estat reconeguda que la efectiva avaluació de seguretat al incendi i la cultura en concert amb mesures per prevenir, detectar, suprimir i mitigar l'efecte d'incendis, si es produeixen, minimitzarà el risc d'incendi en una NPP. Entre les nombroses recomanacions la seguretat contra incendis a una NPP s'hauran previst i dissenyat abans de començar la construcció i utilitzant estat del art de la tecnologia. També, els mètodes d'avaluació del risc d'incendi tindran que integrar el estat del art en els enfocaments de determinista i probabilístics. Dos mètodes són presentats que serveixen per incorporar el risc relacionats amb el foc a les pràctiques actuals en centrals nuclears en respecte a l'avaluació de configuracions. El primer mètode és un sistema de protecció contra incendis i una matriu de indisponiblitats de les funcions clau de seguretat (MU) que es desenvolupa per a identificar estructures, sistemes i components significatius per riscos relacionats amb els incendis. El segon mètode és zones de focs i matriu de risc d'incendi i funcions (KSFs) clau de seguretat que és útil identificar les zones de foc que són candidats per a les accions de gestió de risc. La MU és una eina innovadora per comunicar el risc d'incendi. El risc significatiu relacionats amb el incendi està localitzat en sis components representatius KSF i un sistema de protecció de foc que cal que figuri en la regla de manteniment. La manca de sistemes de protecció contra incendis no afecta significativament al risc. La matriu de risc d'incendi identifica les zones de foc que mes contribueixen al risc relacionats amb el incendi. Aquestes zones pertanyen a l'edifici de control i edifici de penetracions elèctriques. L'agregació del model de PSA de esdeveniments interns i model de incendis PSA han demostrat que el PSA de incendis aporta 38.4% a l'augment de risc. S'ha desenvolupat la viabilitat del Monitor de risc de incendis a partir del PSA de incendis per a una central nuclear espanyola. Un dels reptes principals és que RiskSpectrum® incendis PSA te 384 casos de incendis i te 384 CDF però en risc Monitor és necessària una CDF. Tanmateix, el CAFTA és incapaç de convertir una estructura seqüencial de arbre de fallida de l'arbre esdeveniment interna en el PSA de incendis. La conversió fracassa al posar en pràctica totes les seqüències de danys al nucli i la selecció de l'arbre de fallida de la freqüència de incendi. La descoberta i supressió de arbres de l'esdeveniment de incendi en el model de referència es van substituir per detecció i els arbres de fallades d'extinció d'incendi. La freqüència de cada cas de incendi del model de conversió i el model de referència son quantificades i les freqüències son comparades. Els resultats demostra que el 90% dels casos són vàlid, no obstant això, la resta té reptes amb MCS. Un únic CDF de 7.65x10-7 s'ha quantificat en comparació amb 9.83 × 10-6 de la referència. La conversió del nou model a CAFTA no va tenir èxit a causa de la incompatibilitat del programari

Uncertainty-based decision-making in fire safety: Analyzing the alternatives

Large accidents throughout the 20th century marked the development of safety fields in engineering, devoted to better identify hazards, understand risks and properly manage them. As these fields evolved rather quickly and moved from a compliance to a risk-based approach, a significant delay in this transition was experienced in fire safety engineering (FSE). Devastating fires well into the 21st century and the restrictive nature of prescriptive codes signaled the need to transition towards a performance-based one. A performance-based approach provides flexibility and capitalizes on learning from accidental events and engineering disciplines such as process safety and FSE. This work provides an overview of the main alternatives to account for uncertainty in safety studies within the context of FSE, including traditional probabilistic analyses and emerging approaches such as strength of knowledge. A simple example is used to illustrate the impact of the uncertainty analysis on the results of a simple fire safety assessment. A structured evaluation is performed on each alternative to assess its ease of implementation and communication. The outcome is a compendium of advantages and disadvantages of the alternatives that constitute a toolbox for fire safety engineers to configure and use within their fire risk assessments. Process safety engineers are expected to gain an understanding of the similar and important challenges of FSE, being it directly relevant for process risk management and fire risk management in administrative buildings

Misunderstanding Models in Environmental and Public Health Regulation

Computational models are fundamental to environmental regulation, yet their capabilities tend to be misunderstood by policymakers. Rather than rely on models to illuminate dynamic and uncertain relationships in natural settings, policymakers too often use models as “answer machines.” This fundamental misperception that models can generate decisive facts leads to a perverse negative feedback loop that begins with policymaking itself and radiates into the science of modeling and into regulatory deliberations where participants can exploit the misunderstanding in strategic ways. This paper documents the pervasive misperception of models as truth machines in U.S. regulation and the multi-layered problems that result from this misunderstanding. The paper concludes with a series of proposals for making better use of models in environmental policy analysis.The Kay Bailey Hutchison Center for Energy, Law, and Busines

Risk control in recycled water schemes

Recycled water is becoming one of the indispensable and reliable water resources at present. When it is introduced as an alternative source, risks on human health and the environment become major constraints driving the application and extension of recycled water. The authors examine the sources and associated risks of recycled water and introduce the practical risk control technologies on various end uses. They also review some existing risk assessment models by comparing their strengths and weaknesses toward the good approach of integrated modeling. Some critical suggestions on risk management and communication are made based on the given information. © 2013 Taylor and Francis Group, LLC

Historical review of fire safety at NPP and application of fire PSA to Westinghouse PWR NPP in the frame of risk-informed decision making by

The importance of fire as a potential initiator of multiple-system failures took on a new perspective after the cable-tray fire at Browns Ferry in 1975 The review have shown that the first generation Nuclear Power Plant (NPP) fire safety was not factored as high risk area that needed to be effectively assessed and quantified. This resulted in development of peculiar fire safety regulations, standards and expensive backfits. Lack of appropriate regulations and effective methods of fire risk assessment, prescriptive, difficult and expensive retrofit regulations were instituted in USA. The alternative risk-informed performance based regulation was established in USA to resolve the challenges of the prescriptive rules. The review have revealed that both the prescriptive and risk-informed performance based approaches will not represent adequate design basis for new Nuclear Power Plants. The Japanese were pulled in the path of renew fire safety regulations and risk quantification after the Fukushima accident. It has been recognized that effective fire safety assessment, and culture, in concert with countermeasures to prevent, detect, suppress, and mitigate the effect of fires if they occur, will minimized NPP fire risk. Among the numerous recommendation the fire safety at NPP must be planned and engineered before construction begin using the state-of-the-arts technology. Also, the methods of fire risk assessment must integrate the state-of-the-arts deterministic and probabilistic approaches. Two methods are presented which serve to incorporate the fire-related risk into the current practices in nuclear power plants with respect to the assessment of configurations. The first method is a fire protection systems and key safety functions Unavailability Matrix (UM) which is developed to identify structures, systems, and components significant for fire-related risk. The second method is a fire zones and key safety functions (KSFs) fire risk matrix which is useful to identify fire zones which are candidates for risk management actions. The UM is an innovative tool to communicate fire risk. The Monte Carlo method has been used to assess the uncertainty of the UM. The analysis shows that the uncertainty is sufficiently bounded. The significant fire-related risk is localized in six KSF representative components and one fire protection system which should be included in the maintenance rule. The unavailability of fire protection systems does not significantly affect the risk. The fire risk matrix identifies the fire zones that contribute the most to the fire-related risk. These zones belong to the control building and electric penetrations building. The aggregation of Internal Events PSA model and Fire PSA model have shown that the Fire PSA contributes 38.4% to the Risk increase. The feasibility of developing Fire-related Risk Monitor from the FIRE PSA for the Spanish NPP was carried out. One of the main challenges is that RiskSpectrum® fire PSA has 384 fire cases and 384 CDF but in Risk Monitor one CDF is required. However, CAFTA is unable to convert a Sequential Fault Tree structure of the internal Event tree in the Fire PSA. The conversion fails to implement neither all of the sequences leading to core damage nor the Fault Tree selection of the frequency of fire. The proposal is to suppress exchange events and introduce the alignment of the consequences so that a unique result of core damage can be quantified. The detection and fire suppression Event Trees in the reference model were replaced by detection and fire extinction Fault trees. The frequency of each Fire Case of the conversion model and the reference model are quantified and the frequencies compared. The results shows that 90% of the cases are valid, however, the rest have challenges with MCS. A unique CDF of 7.65x10-7 is quantified compared with 9.83×10-6 of the reference. The conversion of the new model in CAFTA was not successful due to software incompatibility.La importància del incendi com un potencial iniciador de sistema múltiples fallides van agafar una nova perspectiva després del incendi al cable-safata de Browns Ferry el 1975. La revisió ha mostrat que la primera generació de seguretat contra incendis de centrals d'Energia Nuclear (NPP) no va ser àrea de alt risc, àrea que necessitava ser efectivament avaluada i quantificada. Això va resultar en el desenvolupament de normes de seguretat de incendi peculiar, estàndards i cares revisions. La manca d'una reglamentació adequada i mètodes eficaços d'avaluació de risc d'incendi, va fer que als USA foren instituïts mètodes d'adaptació de normativa preceptius, difícils i costós. L'alternativa de regulació informada per el risc es va establir als USA per resoldre els reptes de la regulació preceptiva. La revisió ha mostrat que tant als enfocaments de normativa preceptiva i regulació informada per el risc no representen bases de disseny adequades per a noves NPP. Ha estat reconeguda que la efectiva avaluació de seguretat al incendi i la cultura en concert amb mesures per prevenir, detectar, suprimir i mitigar l'efecte d'incendis, si es produeixen, minimitzarà el risc d'incendi en una NPP. Entre les nombroses recomanacions la seguretat contra incendis a una NPP s'hauran previst i dissenyat abans de començar la construcció i utilitzant estat del art de la tecnologia. També, els mètodes d'avaluació del risc d'incendi tindran que integrar el estat del art en els enfocaments de determinista i probabilístics. Dos mètodes són presentats que serveixen per incorporar el risc relacionats amb el foc a les pràctiques actuals en centrals nuclears en respecte a l'avaluació de configuracions. El primer mètode és un sistema de protecció contra incendis i una matriu de indisponiblitats de les funcions clau de seguretat (MU) que es desenvolupa per a identificar estructures, sistemes i components significatius per riscos relacionats amb els incendis. El segon mètode és zones de focs i matriu de risc d'incendi i funcions (KSFs) clau de seguretat que és útil identificar les zones de foc que són candidats per a les accions de gestió de risc. La MU és una eina innovadora per comunicar el risc d'incendi. El risc significatiu relacionats amb el incendi està localitzat en sis components representatius KSF i un sistema de protecció de foc que cal que figuri en la regla de manteniment. La manca de sistemes de protecció contra incendis no afecta significativament al risc. La matriu de risc d'incendi identifica les zones de foc que mes contribueixen al risc relacionats amb el incendi. Aquestes zones pertanyen a l'edifici de control i edifici de penetracions elèctriques. L'agregació del model de PSA de esdeveniments interns i model de incendis PSA han demostrat que el PSA de incendis aporta 38.4% a l'augment de risc. S'ha desenvolupat la viabilitat del Monitor de risc de incendis a partir del PSA de incendis per a una central nuclear espanyola. Un dels reptes principals és que RiskSpectrum® incendis PSA te 384 casos de incendis i te 384 CDF però en risc Monitor és necessària una CDF. Tanmateix, el CAFTA és incapaç de convertir una estructura seqüencial de arbre de fallida de l'arbre esdeveniment interna en el PSA de incendis. La conversió fracassa al posar en pràctica totes les seqüències de danys al nucli i la selecció de l'arbre de fallida de la freqüència de incendi. La descoberta i supressió de arbres de l'esdeveniment de incendi en el model de referència es van substituir per detecció i els arbres de fallades d'extinció d'incendi. La freqüència de cada cas de incendi del model de conversió i el model de referència son quantificades i les freqüències son comparades. Els resultats demostra que el 90% dels casos són vàlid, no obstant això, la resta té reptes amb MCS. Un únic CDF de 7.65x10-7 s'ha quantificat en comparació amb 9.83 × 10-6 de la referència. La conversió del nou model a CAFTA no va tenir èxit a causa de la incompatibilitat del programari.Postprint (published version

Final report for the REDUS project - Reduced Uncertainty in Stock Assessment

The REDUS project (2016-2020) has been a strategic project at the Institute of Marine Research (IMR) aimed at quantifying and reducing the uncertainty in data-rich and age-structured stock assessments (e.g., cod, herring, haddock, capelin). Work was organized in four topical work-packages: Fisheries-dependent (catch) surveys and assessment modeling (WP1), Fishery-independent (scientific) surveys (WP2), Evaluating and testing of long-term management strategies (WP3), and Communication of uncertainty, dissemination of project results and capacity building (WP4). The Norwegian Computing Center (NR) was contracted in as a strategic partner in statistical modeling and analysis, contributing mainly to WP1 and WP2, but found the research of fundamental interest therefore also allocating internal (NR) funding to develop the statistical science base of several of the methods.publishedVersio