Safety significance

Arzhaev A T, Kiselyov V.A., Bougaenko S E., Strelkov B.P, Badalyan VG, Vopilkin, A.Kb. Safety significance of Augur-4.2 on-site applications at RBMK NPPs. In NDE Techniques Capability Demonstration and Inspection Qualification, U. EstorffandP. Lematre (Eds ), 1997, pp, 251-259. 

March-Leuba (1990) presented radial nodalization effects on the stability calculations. March-Leuba and Blakeman (1991) reported on out-of-phase power instabilities in BWRs. BWR stability analyses were reported by Anegawa et al. (1990) and by Haga et al. (1990). The experience and safety significance of BWR core-thermal-hydraulic stability was presented by Pfefferlen et al. (1990). 

Pfefferlen, H., R. Raush, and G. Watford, 1990, BWR Core Thermal-Hydraulic Stability Experience and Safety Significance, Proc. Int. Workshop on BWR Instability. Hottsville, NY, CSNI Rep. 178, OECD-NEA, Paris. (6)... 

Assessing the safety significance of proposed changes is generally more difficult when dealing with chemical reactivity hazards. New test data may need to be obtained, and experts may need to be consulted. Changes in process quantities, rates or conditions—especially temperature—or the introduction of new or modified materials must be carefully reviewed. 

From the viewpoint of safety, information about the flash point is of most significance at or slightly above the maximum temperatures [30 to 60°C (86 to 140°F)] that may be encountered in storage, transportation, and use of liquid petroleum products, in either closed or open containers. In this temperature range the relative fire and explosion hazard can be estimated from the flash point. For products with flash points below 40°C (104°F), special precautions are necessary for safe handling. Flash points above 60°C (140°F) gradually lose their safety significance until they become indirect measures of some other quality. 

Indicate if the substance or mixture is stable or unstable under normal ambient and anticipated storage and handling conditions of temperature and pressure. Describe any stabilizers which are, or may need to be, used to maintain the product. Indicate the safety significance of any change in the physical appearance of the product. 

The Notification Convention applies in the event of any accident involving facilities or activities of a State Party, or those under its jurisdiction or control, from which a release of radioactive material occurs or is likely to occur, and which has resulted or may result in an international transboundary release that could be of radiological safety significance for another State. A State Party involved in an accident covered by the Convention is obliged to immediately notify, directly or through the IAEA, those States which are or may be physically affected. 

An attribute related to physical capacity is the perceptual/motor skUls of an individual, such as eye-hand coordination. These skUls vary widely among individuals and may have more health and safety significance than strength or endurance because they come into play in the moment-by-moment conduct of work tasks. While strength may influence the ability to perform a specific component of a task, perceptual/motor skills are involved in all aspects of manuM tasks. Thus, perceptual/motor skills affect the quality with which a task is carried out as well as the probability of a mistake that could cause an exposure or accident. 

The Sellafield MOX Plant has been designed such that it remains safe under plant shutdown conditions without the need for the provision of any services to maintain safety-significant equipment. 

Inspections by the regnlatory body should be concentrated on areas of safety significance. These are those SSCs and activities affecting safety or processes important to safety which are identified as such in the safety documentation snbmitted by the operator or in the findings of the regulatory body s review and assessment, or which are stipulated in the conditions attached to the licence. 

This requires a continuing introspection concerning their knowledge and skills and keeping current with the evolving technology in the practice of safety. Significantly, they must assess the perceptions others have of the substance and worth of the consultancies they provide. 

In order to get a realistic picture of the nature and safety significance of a LPS event, it is sometimes necessary to do a very detailed and comprehensive analysis. A good example of this is a boron dilution event for which models of mixing and 3D neutron kinetics are needed in combination with modelling of primary circuit thermal hydraulics. 

Currently the analysis for LPS has been performed only for a small number of cases. However, because of their safety significance, there is a need to perform these analyses for inclusion in final safety analysis reports, for development of emergency operating procedures, and for further development of technical specifications. Due to their potential impact, LPS analyses need to be carried out with the same care as those for full power conditions. 

Factors important to safety, such as the ageing of safety significant components, as well as maintenance history and operating experience should be taken into account in the long term planning. 

Deviations from, or violations of, requirements [of the authorization], or unsatisfactory situations which have minor safety significance, may be identified at facilities or in the conduct of activities. In such circumstances, the regulatory body shall issue a written warning or directive to the operator which shall identify the nature and regulatory basis of each violation and the period of time permitted for taking remedial action (Ret [1], para. 5.19). This is the most common form of enforcement action and will, in most cases, suffice to remedy the safety issue. 

Prioritisation of the safety significance of hnman errors, bearing in mind the potential for detection and recovery of errors. The process FMEA (refer Step 3d and Table 5.7) is usefnl in this regard. 

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