Accidents management

Most of the discussions are presented here in the context of radionuclide behaviour during accidents at existing pressurised water reactors (PWRs) and boiling water reactors (BWRs). The basic principles in these discussions are applicable to all nuclear power plants. Readers may need to make some mental modifications of the specific details of the discussions to accommodate the imique features of other types of plants such as gas-cooled reactors, CANDU t5q)c reactors and RBMK reactors. 

Recent probabilistic risk assessments [In-5-9] establish that there is room for accident management to influence the consequences of reactor accidents. These risk assessments show there to be orders of magnitude uncertainty in the radionuclide releases as a result of accidents at nuclear power plants. A very significant portion of this uncertainty comes from uncertainty in the details of radionuclide behavior that can be influenced by accident management measures. The accident management measures taken to affect the radionuclide source term are not necessarily distinct from those taken to arrest or 

Radionuclides are released to the containment as gases and as aerosol particles by a variety of processes during severe accidents. Modem, mechanistic analyses of these radionuclide releases and the subsequent behaviour of aerosols and vapours under reactor accident conditions strive to be realistic. This realistic approach contrasts with the deliberate attempt to be conservative (which may not have been successful) in the definition of radionuclide behaviour for the design of nuclear power plant safety systems. A discussion of the various radionuclide release processes during severe reactor accidents is presented in Chapter II. Of primary interest in these discussions of release is the potential magnitude of radionuclide release and the radionuclides of most concern. Factors that most affect radionuclide release but can also be affected by accident management measures are discussed. 

Risk is used here to mean the sum over the products of accident frequency and consequences. Risk is, then, distinct from just the frequency of accidents. 

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The fourth level of defense-in-depth is activated if all of the previous levels fail and radioactivity is released from the power-generating system. This level consists of containment systems and accident management processes that prevent the dissernination of radioactivity to the atmosphere even if it is released from the nuclear systems. The fifth level is the provision for emergency planning outside the plant boundary in the highly unlikely event that all of the first four levels of defense were to fad. 

Risk-based information provides a foundation for regulation of severe accidents. Early PRAs, with large uncertainties, indicated risk that was above or below the Safety Goals depending on containment performance. Consequently the NRC developed an Integration Plan for Closure of Severe Accident Issues (SECY-88-47) with six main elements to this plan 1) individual plant examinations (IPE), 2) containment performance improvements, 3) improved plant oper itions, 4) severe accident research, 5) external event considerations, and 6) accident management. 

Anotlier act that lias Iiad a major impact on tlie general area of healtli, safety and accident management is tlie Pollution Prevention Act of 1990. The major tlieme of the act was to provide an importance to reduce tlie generation of wastes/pollutants/cheniicals tliat can create healtli, safety and accident management problems. Details of the act are provided later. 

HEALTH. SAFETY. AND ACCIDENT MANAGEMENT IN THE CHEMICAL PROCESS INDUSTRIES... 

The rapid growth and expansion of the chemical industry has been accompanied by a spontaneous rise in human, material, and property losses because of fires, explosions, hazardous and toxic spills, equipment failures, other accidents, and business interruptions. Concern over the potential consequences of catastrophic accidents, particularly at chemical and petrochemical plants, has sparked interest at both the industrial and regulatory levels in obtaining a better understanding of the subject of this book Health, Safety, and Accident Management (HS AM). The writing of this book was undertaken, in part, as a result of this growing concern. 

Health, Safety, and Accident Management in the Chemical Process Industries, Ann Marie Flynn and Louis Theodore... 

The third-layer recommendations shown in Figure 12-1 emphasize the importance of management systems for preventing accidents. Management systems are designed to continuously, and on a long-term basis, either prevent the accident or eliminate the hazardous conditions, that is, to break the link in the chain of events that led to the accident. Examples may be (1) a quar-... 

Health, Safety, and Accident Management in the Chemical Process Industries, Ann Marie Flynn and Louis Theodore Plantwide Dynamic Simulators in Chemical Processing and Control, William L. Luyben Chemical Reactor Design, Peter Harriott Catalysis of Organic Reactions, edited by Dennis G. Morrell Lubricant Additives Chemistry and Applications, edited by Leslie R. Rudnick... 

According to Coura and Dias (2009), the transmission mechanisms for Chagas infection can be divided into two groups (i) the principal mechanisms, by means of vectors (triatomines), blood transfusion, oral transmission, contaminated food and placental, or birth canal transmission and (ii) secondary mechanisms, by means of laboratory accidents, management of infected animals, organ transplants, sexual transmission, wounds, contact with sperm or menstrual fluid contaminated with T. cruzi and, hypothetically, deliberate criminal inoculation or contamination of food with the parasite (Coura and Dias, 2009). 

Altliough the design of a process is important, retrofit and temporary installations can play an important role in accident management. 

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