Real-time On-line Decision Support Research Articles

Emergency Decision Support Techniques for Nuclear Power Plants: Current State, Challenges, and Future Trends

Emergency decision support techniques play an important role in complex and safety-critical systems such as nuclear power plants (NPPs). Emergency decision-making is not a single method but a framework comprising a combination of various technologies. This paper presents a review of various methods for emergency decision support systems in NPPs. We first discuss the theoretical foundations of nuclear power plant emergency decision support technologies. Based on this exposition, the key technologies of emergency decision support systems in NPPs are presented, including training operators in emergency management, risk assessment, fault detection and diagnosis, multi-criteria decision support, and accident consequence assessment. The principles, application, and comparative analysis of these methods are systematically described. Additionally, we present an overview of emergency decision support systems in NPPs across different countries and feature profiles of prominent systems like the Real-Time Online Decision Support System for Nuclear Emergencies (RODOS), the Accident Reporting and Guiding Operational System (ARGOS), and the Decision Support Tool for Severe Accidents (Severa). Then, the existing challenges and issues in this field are summarized, including the need for better integration of risk assessment, methods to enhance education and training, the acceleration of simulation calculations, the application of large language models, and international cooperation. Finally, we propose a new decision support system that integrates Level 1, 2, and 3 probabilistic safety assessment for emergency management in NPPs.

JRODOS customization for Pakistan and assessment of the consequences of a hypothetical nuclear accident

Since the Chernobyl disaster in 1986, decision support systems and modelling tools have been utilized in response to nuclear and radiological emergencies. The java-based real-time online decision support system (JRODOS) is a decision support tool that can be utilised in response to an emergency in managing off-site radiological consequences. This article documents the customization and use of JRODOS for Pakistan. JRODOS was tailored to the local Pakistan conditions, and a case study of a theoretical nuclear power plant accident was used to assess JRODOS’s feasibility as a decision support tool. A worst-case probabilistic accident scenario was used to identify zones and areas where urgent protective actions, early protective actions and food restriction and other response actions could be required. The areas and distances identified for the implementation of protective and response actions for such a hypothetical accident were found to be in agreement with the emergency planning zones and distances suggested by the International Atomic Energy Agency (IAEA). Additionally, the implications of meteorological and source term input parameters on predicting the radiation doses to members of the public were investigated. It was identified that the output of such tools strongly depends on the availability and accuracy of the input parameters, such as radioactive release and meteorological data. Limitations and uncertainties associated with these tools need to be considered in deciding on protective and other response actions in response to a nuclear accident. As established by the IAEA, protective and other response actions need to be applied on a graded approach, taking into account the protection strategy and uncertainties and limitations in the available information and criteria, based on the conditions at the facility and off-site.

Verification of the NACAC atmospheric dispersion calculation using a hypothetical accident in a neighboring nuclear power plant

Calculating atmospheric dispersion in a hypothetical nuclear accident plays an essential role as a predictive tool in nuclear emergency planning. The Nuclear Accident Consequence Analysis Code (NACAC) has been developed as an in-house code by the Thailand Institute of Nuclear Technology to develop its capability for understanding the transboundary radiological effect of a hypothetical nuclear accident. To verify the performance of the NACAC, a comparison between the calculated results using the NACAC with those from the well-developed Java-based Real-time On-line Decision Support (JRODOS) code is performed with representative cases of all seasons in a year. Two hypothetical severe accidents at the Fangchenggang pressurized water reactor, namely, (i) a loss of off-site power and (ii) a large-break loss of coolant, are utilized as the initial boundary conditions. The air concentration characteristic maps obtained from both codes are analyzed, revealing that the dominant radionuclide dispersion pathways are similar in all study cases. The air concentration, ground concentration, and total effective dose rate at several locations up to 500 km away from the release point are directly compared. Typically, the calculated results from the two codes are in reasonable agreement. However, for specific locations and directions, the NACAC predictions of the concentrations and total effective dose rate are lower than those from the JRODOS. These differences may be influenced by the different trajectory calculations between the two codes, which resulted in varying plume densities in certain areas. However, it does not significantly affect the radiation effect assessment. The NACAC still provides a total effective dose rate corresponding to the JRODOS, lower than one mSv throughout the main dispersion direction.

ESTIMATION OF RADIOLOGICAL CONSEQUENCES FOR A HYPOTHETICAL RADIOACTIVE RELEASE AT CERNAVODA NPP

An analysis regarding the release and atmospheric transport ofradionuclides in case of a hypothetical nuclear incident at Cernavoda Nuclear Power Plant was performed in the present paper. For that purpose, the computer code JRodos (Real-Time Online Decision Support System for Offsite Emergency Management in Europe) was implied.

MODELING OF DOSE RATES IN CASE OF A RADIOLOGICAL INCIDENT AT THE IFIN-HH INTERMEDIARY GRAPHITE STORAGE

The low and intermediate level activity wastes resulted from decommissioning of the VVR-S nuclear research reactor belonging to the “Horia Hulubei” National Institute for R&D in Physics and Nuclear Engineering (IFIN-HH), are kept in an intermediary storage facility. The storage is located on the premises of the Institute near Bucharest, Romania and includes activated graphite from the reactor thermal column. In case of a very low probability hypothetical atmospheric radiological dispersal incident such as an unexpected fire, despite all the implemented safety measures, there is a certain radiological risk for the workers and general public due to potential ingestion or inhalation or contact with the radioactive aerosols released on a certain range from the storage building. For estimating the total gamma dose intake and adequate countermeasures for workers and public members, the JRODOS (Real-time On-line Decision Support) code system for off-site emergency management after nuclear accidents was used in the paper.

An approach for radiological consequence assessment under unified temporal and spatial coordinates considering multi-reactor accidents

The current approaches and computer code systems for radiological consequence assessment of nuclear accidents have still gaps in assessing consequences of nuclear accidents involving multiple reactors, since multi-reactor accidents should be treated in one unique temporal and spatial system. This paper presents an approach to unify and generalize temporal and spatial coordinates for the consequence assessment of multi-reactor accidents. A code system named Advanced Radiological Consequence Assessment Toolkit (ARCAT) was developed accordingly. ARCAT is intended to support in particular emergency preparedness studies at the nuclear power plant level.To verify ARCAT, an analysis was carried out comparing ARCAT with MELCOR Accident Consequence Code System (MACCS), and the Java-based Real-time Online Decision Support System (JRodos). The results indicate that ARCAT is comparable to MACCS. This means that ARCAT is suitable for offsite radiological consequence assessment and able to support emergency preparedness including cliff-edge effects. Further to this, the effects of a unified temporal and spatial coordinate system are discussed to better recognize the impact of such special characteristics of multi-reactor accidents. A preliminary application based on ARCAT is presented, in which the plume emergency planning zone (PEPZ) for a hypothetical site with two reactors is developed. Finally, potential challenges and further research plans are discussed.

Nuclear accident consequence assessment in Hong Kong using JRODOS

The JRODOS (Java-based Real-time Online DecisiOn Support) is a decision support system for off-site emergency management for releases of radioactive material into the environment. This paper documents the application of JRODOS by the Hong Kong Observatory in accident consequence assessment and emergency preparedness studies. For operational considerations, the most computational efficient dispersion model in JRODOS, ATSTEP, is adopted. Verification studies for JRODOS's ATSTEP model have been conducted. Comparison with tracer experiment results showed that under neutral atmospheric conditions and distances up to 50 km, the JRODOS simulation outputs were in general of the same order of magnitude with the tracer data. To further evaluate the capability of JRODOS in short-range simulation, a case study on the Fukushima nuclear power plant accident was also carried out. JRODOS was able to produce realistic simulation results which were comparable to the actual airborne monitoring data of the Cs-137 ground deposition from the Fukushima accident.Furthermore, the results of a comprehensive study to assess the potential consequences of accidents at a nearby nuclear power station are presented. Simulation using the French S3 source term for the Guangdong Nuclear Power Station at Daya Bay showed that the projected effective doses within Hong Kong remain far below the IAEA generic criteria of projected dose for urgent protective actions in sheltering/evacuation, while the projected equivalent dose in thyroid may meet the IAEA generic criteria for use of thyroid blocking agent at some areas in the northeastern part of Hong Kong, at distances of up to about 40 km from Daya Bay depending on the prevailing weather conditions in different seasons.

Treatment, logistical, and cost burden of prior authorization in community practice.

164 Background: Prior authorization (PA) process is complicated and labor intensive and with limited resources available to community practices, significant opportunity to reduce the costs of therapy exists by transforming this decision support process while being compliant with guidelines Methods: We retrospectively evaluated 123 patients between November 2016 and June 2016 across our three rural oncology practices with no dedicated in-house pharmacy. An established PA workflow involved two physicians, 1 nursing staff and 2 clerical staff involved in the process to manage PA for high cost imaging (PET/CT/MRI) or after a high-risk/cost prescription was initiated by a medical provider to a local pharmacy, specialty or mail-order pharmacy. Two Physicians determined strength of concordance with National Comprehensive Cancer Network (NCCN) guidelines. We examined approval rates, method of communications, time to approval and whether these variables were associated treatment delay and insurance provider Results: Eight decision steps were necessary to obtain a PA. Forty-nine Medicare (39%), 21 managed Medicaid (17%), 29 commercial insurance (23.5%) and 14 commercial insurances (11%) required PA mostly for targeted therapy (29%), oral chemotherapy (28%), PET/CT (24%). Approval rate was 94.3% on first attempt with only 1.6% being denied after an appeal process. 89% concordance with NCCN guidelines was seen. Median time to start treatment was 4 working days (Mean 4.7; Range 0-18 days). PA requests were associated with greatest delay in approval time with managed Medicaid (7 v 1.51 days; p < 0.0001) compared to Medicare, when specialty pharmacy was used (5.2 v 2.3 days p < 0.03) and when fax was used versus online (4.1 v 2.3 days p < 0.02). Conclusions: The impact of the PA process on care delivery and cost reduction are not clear. Current process is particularly burdensome on small practices especially given the high approval rates. Significant opportunity exists to reduce the inefficiency of this system using a computer algorithm-based PA using real-time online decision support system using NCCN guideline concordance

Automatic plume episode identification and cloud shine reconstruction method for ambient gamma dose rates during nuclear accidents

Ambient gamma dose rate (GDR) is the primary observation quantity for nuclear emergency management due to its high acquisition frequency and dense spatial deployment. However, ambient GDR is the sum of both cloud and ground shine, which hinders its effective utilization. In this study, an automatic method is proposed to identify the radioactive plume passage and to separate the cloud and ground shine in the total GDR. The new method is evaluated against a synthetic GDR dataset generated by JRODOS (Real Time On-line Decision Support) System and compared with another method (Hirayama, H. et al., 2014. Estimation of I-131 concentration using time history of pulse height distribution at monitoring post and detector response for radionuclide in plume. Transactions of the Atomic Energy Society of Japan 13:119–126, in Japanese (with English abstract)). The reconstructed cloud shine agrees well with the actual values for the whole synthetic dataset (1451 data points), with a very small absolute fractional bias (FB = 0.02) and normalized mean square error (NMSE = 2.04) as well as a large correlation coefficient (r = 0.95). The new method significantly outperforms the existing one (more than 95% reduction of FB and NMSE, and 61% improvement of the correlation coefficient), mainly due to the modification for high deposition events. The code of the proposed methodology and all the test data are available for academic and non-commercial use. The new approach with the detailed interpretation of the in-situ environment data will help improving the ability of off-site source term inverse estimation for nuclear accidents.

Assessment of off-site early countermeasures in the event of a LOCA in a research reactor

Off-site early emergency management actions due to a potential release from the Greek Research Reactor-1 are assessed with the aid of a modern decision support tool. To this end, a hypothetical loss-of-coolant accident has been assumed under two distinct ventilation schemes of the reactor building. Five, site-typical, meteorological scenarios have been applied based on observed conditions that demonstrate the effects the released radioactive plume has on the surrounding urban area. The JRODOS (Java-based Real-time On-line DecisiOn Support) system has been used to calculate gamma radiation doses, estimate the affected areas and assess early countermeasures in accordance with national legislation. The results indicate that the suggested countermeasures may need to be applied only to a very limited area in a few of the considered weather scenarios.

Comparative Analysis of Calculation Possibilities of MACCS and RODOS Computer Codes for Emergency Response and Analysis of Radiation Consequences of Severe Accidents at NPPs

The paper presents a brief description of the Real-time On-line Decision Support System (RODOS) and MELCOR Accident Consequence Code System (MACCS) and evaluates the application of these codes for assessment of radiation impact on the public and environment in case of a severe accident at NPP in real time mode. The experts performed comparative analysis of results obtained from calculations using RODOS, WinMACCS and HotSpot codes. In the framework of the research, the chosen comparative criteria were assessed: total effective dose, thyroid equivalent dose, skin equivalent dose, I-131 and Cs-137 ground concentration at different distances up to 50 kilometers from the source of release.

Probabilistic risk assessment from potential exposures to the public applied for innovative nuclear installations

Potential exposures are those that may occur as a result of unanticipated operational performance or accidents. Potential exposure situations are probabilistic in nature because they depend on uncertain events such as equipment failure, operator errors or external initiators beyond the control of the operator. Consequently, there may exist a range of possible radiological impacts that need to be considered. In this paper a Level 3 Probabilistic Safety Assessment (PSA) for a hypothetical scenario relevant to Innovative Nuclear Energy Systems (INS) was conducted using computer code MACCS (MELCOR Accident Consequence Code Systems). The acceptability of an INS was analyzed taking into account the general requirement that relocation or evacuation measures must not be necessary beyond the site boundary. In addition, deterministic modeling of the accident consequences for the critical meteorological conditions was carried out using the JRODOS decision support system (Real-time On-line Decision Support system for off-site emergency management in Europe). The approach used for dose and risk assessment from potential exposure of accidental releases and their comparison with acceptance criteria are presented. The methodology described can be used as input to the licensing procedure and engineering design considerations to help satisfy relevant health and environmental impact criteria for fission or fusion nuclear installations.

Functions of decision support systems (JRodos as an example): overview and new features and products

Under the auspices of its Euratom Research Framework Programmes, the European Commission (EC) has supported the development of the RODOS (Real-time Online DecisiOn Support) system for off-site emergency management after nuclear accidents for more than a decade. Significant additional funds have been provided by many national research programmes, research institutes and industrial collaborators. In particular, the German Ministry of the Environment, Nature Conservation and Reactor Safety financially contributed to the project with an emphasis on early emergency response. The final result of these collaborative actions, the comprehensive RODOS system, can be applied generally within and across Europe. It can be used in national or regional nuclear emergency centres, provides coherent support at all stages of an accident, and includes the long-term management and restoration of contaminated areas. Within the NERIS-TP project, several model improvements have been developed, covering the worldwide applicability of the system, the coupling with the early notification system of the IAEA, improved countermeasure modelling and model adaptation for the new ICRP 103 recommendations. Several of these new tools were also integrated into the ARGOS system (Hoe S., Muller H., Gering F., Thykier-Nielsen S., Havskov Sorensen J. (2002) ARGOS 2001: A decision support system for nuclear emergencies. In: American Nuclear Society Transactions . Winter Meeting Vol. 87, pp. 574-579).

Knowledge database and case-based reasoning

Nuclear emergencies are characterised by severe disruptions in society's functionality and adverse impacts on human, environment and economy. Decision-making in times of such crises is complex and usually accompanied by acute time pressure. Environment can change rapidly and decisions may have to be made based on uncertain information. IT-based decision support can systematically help to identify response and recovery measures, especially when time for decision-making is sparse, when numerous options exist or when events are not completely anticipated. This paper reviews the case- and scenario-based approach implemented in the so-called analytical platform to support the management of nuclear events in different accident phases. Important information needed for decision-making as well as approaches to reusing experience from previous events and the fictitious scenarios calculated by Java version of the Real-time On-line Decision Support System are discussed. Suitable management options based on similar historic events and scenarios might be identified to support disaster management.

A Framework Design of Automatic Fault Diagnosis System

To resolve a lasting suitable cabin environment for the astronauts, this paper proposes an effective framework design for automatic fault diagnosis system. This framework can implement a real-time online diagnosis and decision support for fault, and carry out an early diagnosis for weak fault. Finally, this paper achieves an online automatic fault diagnosis system by using neural networks self-learning characteristics and expert knowledge. In two-men-two-days simulated manned space flight test, the software of diagnosis system framework worked well, which has been assessed and verified comprehensively.

25 Years of MCDA in nuclear emergency management

Radiation accidents such as those at Three Mile Island, Chernobyl and, more recently, Fukushima have emphasized the need for supporting all phases of emergency management from the early phases in which a threat is detected to years and decades after the accident. Several decision-aiding tools have been developed to prevent and mitigate the effects of a radiation accident. This work reviews a range of mathematical models, computing tools and, particularly, multi-criteria decision-making techniques that have been applied in the last 25 years to help politicians, health officials, local authority representatives and emergency planning officers devise better countermeasure strategies in the event of a radiation accident. The paper discusses all phases of a nuclear emergency as well as emergency training and planning. It highlights what has been achieved in the application of multi-criteria decision analysis, mainly through initiatives such as the EU-funded real-time online decision support projects. It examines how such tools that have been developed fit into the formulation, evaluation and appraisal stages of the emergency management process and discusses the complex socio-technical issues that arise from radiation accidents.

APPLICATION OF DECISION SUPPORT SYSTEM JRODOS FOR ASSESSMENTS OF ATMOSPHERIC DISPERSION AND DEPOSITION FROM FUKUSHIMA DAIICHI NUCLEAR POWER PLANT ACCIDENT

After the Chernobyl accident, the European Commission – under the auspices of its Research and Technological Development Framework Programme – has supported the development of the RODOS (Real-time On-line DecisiOn Support) system for off-site emergency management. The multiplatform version of RODOS was recently redesigned as a user friendly system applicable for various computational platforms and easy customizable for different sites of nuclear power production. This new version was named JRODOS as its software implementation base is Java language. In March 2011 JRODOS was customized for the site of Fukushima Daiichi Nuclear Power Plant (NPP). JRODOS was applied to perform atmospheric dispersion and deposition calculations and to assess the doses to the public in the vicinity of the NPP. From the second half of March 2011 onwards, results of the assessments were presented to the public and mass media on the web site of the Karlsruhe Institute of Technology. The Numerical Weather Forecast model WRF has been implemented for the region around the NPP to produce 3D fields of the meteorological parameters that were further used by the JRODOS system. Prognostic and diagnostic assessments of the radiological situation in the vicinity of the site have been performed at least once per day with various source terms. Taking into account the high uncertainties in the source term estimation, the simulated results show a reasonable fit to the monitoring data obtained later. The study demonstrated the flexibility of JRODOS for the assessment of the consequences of nuclear accidents at different nuclear energy production sites.

JRODOS: Platform for improved long term countermeasures modelling and management

One of the major objectives of the 6th Framework EC RTD EURANOS (European Approach to Nuclear and Radiological Emergency Management and Rehabilitation Strategies) project was to improve the RODOS (Real-time on-line decision support) system in its operational applicability. In the first phase of the project two possibilities for the main system development has been discussed: either to carry out refinements in the current version of RODOS or to consider a complete software re-engineering. The RODOS Users Group (RUG) finally concluded that the latter option was one to be realised. As a result a JAVA based version named JRODOS has been developed introducing a cross-platform solution capable to run on most operation systems, including Windows, Macintosh and the main UNIX derivates. The re-engineered system preserves computational models from RODOS, adding a powerful GIS support and applying modern database technologies with flexible configuration possibilities. Furthermore, these new GIS functionalities allowed implementing advanced simulation models for simulating countermeasures in inhabited areas (ERMIN - European Model for Inhabited Areas) and food production systems (AGRICP – Agricultural Countermeasure Program). Both simulation models have been part of the EURANOS project and represent state of the art modelling capabilities in their respective area.

A radio frequency identification and sensor-based system for the transportation of food

The damage caused by the degeneration of the quality of perishable products usually results in a great loss to transportation enterprises. To improve the delivery system for perishable products, a real-time monitoring and online decision support system with Radio frequency identification (RFID), a sensor network and a decision rule base has been developed in this study. First of all, the value degeneration process is described, using several mathematical models for handing different ways of perishing. Based on the mathematical models, and data from RFID and the sensor network, the quality of the goods can be predicted by the forecast module. When something abnormal occurs, the warning function will send an alarm signal to the users, then, the rule-based decision module will provide the user with suggestions as how to cope with the abnormality. The results from the simulation have shown that the monitoring and decision support system is an efficient tool for reducing the transportation losses of perishable products for the enterprises in cold chain.

MATCH development during the EURANOS project

The Multi-scale Atmospheric Transport and Chemistry Model (MATCH) is used in the RODOS (Real-time On-line decision Support) system since more than 10 years for the long range atmospheric transport and dispersion calculations. With the start of the EURANOS project, several functionalities of the model at that time should be further enhanced. This included the better use of the meteorological information available in the numerical forecast data and the coupling to the source term data base of the RODOS system.