Safety analysis containment systems

LESF (Figure 3.4.5-5), exemplified for the large LOCA, is compared with SELF. Event tree headings are the refueling water storage tank (RWST) a passive component, an engineered safety system (SA-1) and four elements of the containment system. Other examples of the LESF method show human error in the event tree while the criteria for system success is usually in the tan It tree analysis. 

Large safety factors have been built into the design of the EDS vessel and the procedures for its operation. The mechanical integrity of the vessel was evaluated by Sandia National Laboratories using a combination of small-scale failure analysis tests and computer simulations. This evaluation indicated that the EDS-1 containment vessel could withstand several thousand detonations with more than 1 pound of explosive, providing a significant margin of safety for a system with an intended life of 500 detonations (SNL, 2000). 

In the nuclear field grading is tied to the consequences of the failure of a system in most of the national and international categorization/classification models An attempt to develop a standard where the probability of occurrence of a failure is also included, i.e. a risk based categorization, was made in lEC. This resulted, however, not in a standard but in a report [10] which contains four examples for a categorization using probabilistic safety analysis PSA. 

The MRX simplified passive safety system can ensure safety of the reactor, which is confirmed by the safety analysis. It is noteworthy that the MRX never uncover the core by help of the water-filled containment even in a LOCA. 

OTEC plant system characteristics OTEC plant system overall layout Land-hased containment system (LCBS) design Power system design Water ducting design Asset acquisition Project achedule OTEC plant system deployment LBCS deployment Inspection, maintenance and repair Safety analysis... 

As illustrated in Fig. 3.2, before proceeding with a detailed System Safety Assessment (SSA), the FHA is often used to determine the need for and scope of any subseqnent analysis. An FHA may contain a high level of detail in some cases (such as for a Flight Guidance and Control System with many functional modes), but many installations may need only a simple review of the system design [AMC25.1309 para 10b(3)]. If further safety analysis is not required, then the FHA could itself be used as a complete safety assessment. 

A piece-part FMEA is similar to a functional FMEA, except that the failure modes of each individual component contained in the item or function are analysed instead of the failures of a block of components. A piece-part FMEA is used to determine the failure effects of potential electrical, electronic or mechanical failures. Piece-part FMEAs are typically done when the more conservative failure rates from a functional FMEA will not allow the system or item to meet the FTA probability of failure budget. A piece-part FMEA may also be useful for systems that rely on redundancy, since a functional FMEA may not reveal single component failures affecting more than one redundant element. Piece-part FMEAs are also useful for safety analysis of mechanical items and assemblies. 

The database information consists of the thermal-hydraulic/radiological variables of the core, reactor coolant system, containment system, and safety systems which are generated from integrated severe accident analysis code, such as MAAP or MELCOR program. 

The safety analysis should establish the design capabilities and protection system set points to ensure that the fundamental safety functions are always maintained. The design basis events are the basis for the design of the reactivity control systems, the reactor coolant system, the engineered safety features (for example, the emergency core cooling system, the containment system and containment protection... 

The data in this handbook can be used in a variety of applications, such as safety and environmental analyses, and to provide information relevant to system and experiment design. However, these data and the analyses of the data contained herein need to be critically evaluated for applicability in each situation in which they are used, and they represent only one source of information in a complete safety analysis or design process. 

The design, development and safety analysis of computer-based systems is well treated within both standards and the literature within the computer science domain. Many of these standards are based upon the requirements of large customers such as military or government projects. These projects range in size from small self-contained systems to large projects including submarines or social... 

How many an ytical systems are there The second edition of the System Safety Analysis Handbook (1999) fills 626 pages and contains a compilation of 101 analysis techniques and methodologies. This Handbook serves as a desk reference for the highly accomplished system safety specialist who may have to resolve highly complex or infrequently encountered or unusual situations. 

Some variants of the LOPA methodology determine the harm more precisely in terms of harm caused to people and harm to the environment. This approach, which is required by the tolerability of risk framework for human safety. Reducing risks, protecting people, requires consideration of additional factors such as the probability of ignition, the performance of containment systems, and the probability of fatality. For a similar perspective of environmental issues assessors should consult the relevant Environment Agency sector BAT guidance. All of these factors may be subject to considerable uncertainty, and the way the LOPA is carried out needs to reflect this uncertainty. Uncertainties are present in all calculations but sensitivity analysis can be used to help understand the uncertainty. 

In the system safety analysis process, you will come across IT-driven or microprocessor-based systems. While performing any of the system safety analyses, numerous hazardous situations will be discovered. The first step is to decide whether there are any software controls in those particular subsystems. If there are, then it can be considered a safety-critical subsystem. More formally, a safety-critical subsystem is one in which the operations must work properly or a hazardous situation will result. Safety-critical software is a software within a control system that contains one or more hazardous or safety-critical functions. 

The licensee s submittal for any proposed modifications to emergency ac sources, battery capacity, condensate inventory, compressed air capacity, ventilation systems, containment isolation valves, and primaiy coolant make-up capability is reviewed. The information available in the Final Safety Analysis Report is also reviewed. 

The applicative case-study that supports the evaluation of the methodology and its associated tools is a system function called Compute traction orders . While being limited to one single system function, this case-study is representative of the system since it contains both critical and non-critical sub-functions and considers both realtime and operational constraints. The use-case will allow to structure and strengthen the development platform and framework of such systems, especially in the scope of multi-viewpoint system modelling (e.g. operational, functional, constructional, dysfunctional...). A simplified view of interoperability needs between system model, safety analysis and requirement management is represented in the following workflow ... 

The required degree of leaktightness of the reactor building or of other buildings and structures containing radioactive material and the requirements for the ventilation system shall be determined in accordance with the safety analysis of the reactor and its utilization. 

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