Safety in design and operation

The risk of an incident is based on potential severity (or consequence) and probability of occurrence. Both aspects should be thoroughly considered in design and operation for inherent safety. Potential severity can be reduced by ... 

The changing societal, governmental, and industrial perspectives of risk will require that more detailed attention be placed on process safety factors in design and operation of chemical processing plants. 

The difficulty in identifying and enforcing safety constraints in design and operations has increased from the past. In many of our older and less automated systems, physical and operational constraints were often imposed by the hmitations of technology and of the operational environments. Physical laws and the Umits of our materials imposed natural constraints on the complexity of physical designs and allowed the use of passive controls. 

Unlike the known designs of integral reactors being under development in many countries where either steam or steam-gas pressurizer is applied, the integral reactors developed by RDIPE use a gas pressurizer. Selection of such solution was motivated by several reasons, firstly, the intention to simplify and, consequently, enhance safety of the primary circuit pressure compensation system by elimination of heaters and sprinkler system. Secondly, this approach is based on our 40-year experience in designing and operation of ship-mounted NSSS with gas pressurizers in the primary circuit. It should be pointed out, however, that in the previous cases the pressurizes wee placed outside the reactor vessel. 

The nuclear and radiation safety system for nuclear industry facilities in Russia [1] was formed in the course of industrial development. The system is based on the longstanding experience in designing and operation gained by the plants, institutes, and agencies responsible for the reliable operation and safety of nuclear installations. The current safety system has the following elements ... 

The reliability performance of the SIS is referred to as safety integrity in the lEC-standards. This is the probability that the SIS satisfactorily performs the required SIFs, under stated conditions and for a stated period of time (lEC 61511 2003). In an early design phase, a hazards and risk analysis is performed to establish the required level of safety integrity of each SIF that is performed by the SIS, and in design and operation, it is necessary to demonstrate that this level of safety integrity is met. 

The National Aeronautics and Space Administration, a leader in the development and application of system safety methods and practices, has publications on system safety. The Nuclear Regulatory Commission uses some system safety methods in design and operation of nuclear power plants. The National Institute of Occupational Safety and Health published information about the use of system safety methods in occupational safety and health. ... 

A complementary approach to disseminating the knowledge and experience of Member States is to provide the lessons learned directly. The occurrence and recurrence of events, deviations from current international practice in design and operation, and results of PSA studies allow valuable insight into weaknesses in plant safety and into corrective measures to resolve them. 

Since safety issues are deviations from current safety practices in design and operation which are judged to be of safety significance, this TECDOC deals with those generic issues which are applicable to all LWRs, or to each particular type of BWR, PWR and WWER. Although WWERs are mentioned specifically in the text, they have been treated, for the most part, as a subclass of PWRs, for which most generic issues relevant to PWRs may have relevance. 

In the interim period between such assessments, program-level assessments will likely be needed. While more limited in scope, program-specific assessments account for the majority of reforms in the safety net sector. They tri er the adaptation of safety net programs to changing circumstances through incremental improvements in design and operations. 

Provisions measures implemented in design and operation such as inherent plant characteristics, safety margins, system design features and operational measures contributing to the performance of the safety functions aimed at preventing the mechanisms from occurring. 

Special safety constraints apply to equipment selection, design, and operation in nuclear reprocessing (269). Equipment should be reHable and capable of remote control and operation for long periods with minimal maintenance. Pulsed columns and remotely operated mixer—settlers are commonly used (270). The control of criticaHty and extensive monitoring of contamination levels must be included in the process design. 

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