Accident prevention and mitigation

In the second phase, lasting from about 1982 to about 1985, studies of severe accident prevention and mitigation were more systematic. Additional probabilistic studies were performed and mechanistic models, more elaborate than the Rasmussen report ones, were developed. 

All safety factors are important to operational safety, including accident prevention and mitigation of the consequences of accidents. The safety factors are subdivided into groups to facilitate the review however, the order and numbering of the safety factors do not indicate an order of importance. 

Level 2 PSA, which identifies ways in which radioactive releases from the plant can occur and estimates their magnitude and frequency. This analysis provides additional insights into the relative importance of accident prevention and mitigation measures such as the use of a reactor containment. 

The safety valves and relief valves at the pressurizer are capable of relieving steam, steam-water mixture, and water. These valves have been upgraded in the frame of the severe accident prevention and mitigation concept. One of the measures of this concept is primary feed and bleed. As a consequence, the valves and the corresponding pipes have been upgraded to cope with water loads. 

The CAREM concept greatly enhances accident prevention and mitigation by simplicity, reliability, redundancy and passivity. Nevertheless, in case of the extremely low probability of... 

European Major Accidental Reporting System (EMARS) is selected to recover the historical data of accidents for 30 years from 1983 to 2013. The EMARS was established by the EU s Seveso Directive 82/501/EEC in 1982. The purpose of this reporting system is to facilitate the exchange of lessons learned from accidents and near misses involving dangerous substances in order to improve chemical accident prevention and mitigation of potential consequences (EMARS). At the moment, only accidents are considered in this analysis with a possibility to add near misses in future. 

Kletz emphasized an extra effort to generate three levels of recommendations for preventing and mitigating accidents ... 

Inherent safety is an approach to chemical accident prevention that differs fundamentally from secondary accident prevention and accident mitigation [1-9]. Sometimes also referred to as primary prevention [1-3], inherent safety relies on the development and deployment of technologies that prevent the possibility of a chemical accident1. By comparison, secondary prevention reduces the probability of a chemical accident2, and mitigation and emergency responses seek to reduce... 

Secondary prevention and mitigation, by themselves, are unable to eliminate the risk of serious or catastrophic chemical accidents, although improved process safety management can reduce their probability and severity. Most chemical production involves transformation processes, which are inherently complex and tightly coupled. Normal accidents are an unavoidable risk of systems with these characteristics [11]. However, the risk of serious, or catastrophic, consequences need not be. Specific industries use many different processes. In many cases, alternative chemical processes exist which completely or almost completely eliminate the use of highly toxic, volatile, or flammable chemicals [12]. 

Inadequate information about the potential for catastrophic accidents, the significant costs of secondary prevention and mitigation and the costs of chemical accidents, and the existence of inherently safe[r] alternatives. 

Zhou, YF Liu, M. 2011. Risk analysis of major accidents in chemical industry areas. Journal of Disaster Prevention and Mitigation Engineering, 31(l) 68-73. 

The second element is the safety analysis and technology. It determines the conditions to meet the safety requirements, such as evaluation of source terms and consequences, engineering design to prevent and mitigate an accident. 

Level 4 Control of the severe accident conditions of the plant, including the prevention of accident progression and mitigation of consequences. Additional measures and accident management. 

The hazard analysis considers the complete spectrum of accidents that may occur due to operations at the facilities, analyzes potential accident consequences to the public and workers, estimates the likelihood of accidents occurring, identifies and assesses associated preventive and mitigative features, and identifies bounding accident scenarios. Subsequent accident analysis evaluates the bounding accident scenarios for comparison vwth DOE Evaluation Guidelines. The scope and format of this chapter is consistent with DOE-STD-3009-94. 

Two distinctly different, yet complementary, perspectives of hazards for the HCF and associated radioactive material storage locations are obtained for the overall hazard analysis of Chapter 3 by using both PHA and failure mode effects analysis (FMEA) techniques. FMEA is a complementary type of evaluation that utilizes a system failure-based form of analysis. Unlike PHA, the first objective of FMEA is to subdivide the facility Into several different (and, to the maximum extent possible, independent) system elements. Failure modes of each system element are then postulated and a structured examination of the consequences of each failure mode follows. However, similar to PHA, FMEA documents preventive and mitigative features (failure mechanisms and compensation) and anticipated accident consequences (failure effects). Appendix 3D contains the FMEA for the HCF. 

The report is rather general and fully applies to SMRs, the majority of which are already designed to achieve a very high level of prevention and mitigation of severe accidents. 

Generic Safety Issue (GSI) I.C.l in NUREG-0933 (Reference 1), addresses the need for improvement in the quality of operational information provided to plant operations and staff personnel in order to enhance normal plant operation and the prevention and mitigation of plant transients or accidents. 

American Institute of Chemical Engineers (AlChE) to focus on engineering practices to help prevent and mitigate catastrophic hazardous chemical accidents. 

Level 3 Control of severe plant conditions, including prevention of accident progress and mitigation of the consequences. 

National Research Coimcil. 1983. Ship Collisions with Bridges - The Nature of the Accidents, their Prevention and Mitigation, National Academy Press, Washington, D.C. 

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