Category 2. Normal Operation

Category 1. Abnormal situation handling (includes startup and shutdown) Category 2. Normal operation (most utilized role)... 

Electrical switches, relays, and other devices are described for safety reasons by several general categories. Since these devices are potential sources of ignition during normal operation (for example, arcing contacts) or due to malfunction, the area classification limits the types of devices which can be used. 

The first type of monitoring Sis are constructed from actual safety related deviations from normal operation like small releases of hazardous substances, failures of safety related hardware, near misses, etc. This category of monitoring Sis are typified as the safety deviations category. 

This example shows that the focus was put on deviations that have direct safety related consequences ( high consequence category), such as violation of safety procedures or shortfalls in safety training. However, the normal operation in which this ( indirect safety related) overheating deviation occurred had not been identified as relevant ( low consequence category). Finally this re-occurring deviation caused a similar accident only this time with more severe consequences. 

When performing chemical reactions it is necessary to consider conceivable deviations (e.g., upsets, abnormal situations, failures) from the normal operation of a process and equipment and their possible effects on the reaction enthalpy AHr, the gas volume M produced and the rate of gas production (dM/dt), the heat flow balance (dQR/dt) - (dQ /dt) and the maximum permissible temperature TeXo for thermal stability under the applicable process conditions. Upsets (abnormal situations, failures) can be divided into two categories, and their consequences can be assessed using the following tables3 ... 

The spark test apparatus shall be inserted in the circuit under test at each point where it is considered that an interruption or interconnection may occur. Tests shall be made with the circuit in normal operation, and also with one or two faults, as appropriate to the category of electrical apparatus..., and with the maximum values of the external capacitance (C0) and inductance (L0) or inductance to resistance ratio (LJR0) for which the apparatus is designed. 

The calculation of population radiation effects is performed on the basis of different atmosphere stability categories. The estimated maximum annual effective dose for Severodvinsk population at the boimdary of the Sanitary Protection Area (500 m from radioactive release point) will be 0.1 pSv. It is considerably less than ImSv (the population dose limit under normal operation conditions in accordance with Radiation Safety Codes -NRB-99). 

The trend analysis strategy will be shown to be able to differentiate between normal and abnormal responses of the coolant flow rate and is similar to the example used in the paper by Whiteley and Davis [325]. Here, three categories of classification are considered normal, intermediate and abnormal. An intermediate class represents a window of data that can move into the normal or abnormal classes in the next window and no definitive decision between normal and abnormal can be made during that specific time period. For normal operation, the system is able to handle a 5%... 

Using information provided by the enrollees and exposure stratification assignment at the time of enrollment, those enrolled in the study were categorized into one of four groups. The exposure categories were based on the probability of JP8 exposure in the completion of normal operational duties. The exposure categories and decision tree for enrollee categorization are listed below. 

Different categories apply to the hydrogen issue in nuclear reactor containments. During normal operation, small quantities of H2 are generated by radiolysis of the coolant, 44 H2 and 22 O2 molecules per 10 eV of neutron radiation energy. Under accident conditions, significant amounts of hydrogen could be produced due to radiolysis and corrosion reactions. 

TA-V Standard Operating Procedure (TA-V SOP) Operations procedure which implement the Technical Safety Requirements (TSR), to address specific topics (e.g. isotope processing, maintenance, normal operations), or required by the SNL ES H manual to address special hazard categories. TA-V SOPs are reviewed by the appropriate HCF safety committee and are approved by line management prior to implementation. 

In the 1970s, there was a series of unanticipated operational events that occurred in commercial operating pressurized water reactors (PWRs) in the USA (NRC, 2012).These events resulted in pressures and temperatures in the RPV that were outside the P-TUmits specified for normal operation. The conditions associated with these unanticipated events could be placed into two categories. Rrst, there were approximately 30 transient events where the pressure in the RPV exceeded the allowable pressure at relatively low temperature. These events were isothermal pressure transients that generally occurred at temperatures below approximately 93 C (200°F) during reactor start-up. In many instances, the transient pressures were several times the allowable pressure. Typically, the transients occurred while the reactor coolant system was filled with water and were a result of operators failing to follow appropriate procedures to control and prevent... 

The second category addressing cell level safety is the abuse tolerance. The term abuse refers to using of product in a way that is not intended by the supplier but which may result from unreasonable or malicious human behavior or unreasonably extreme conditions or environments [8]. Cell designs that are tolerant to abuse conditions without venting or self-destruction are imperative. But that does not ensure the complete safety of cells when operated under normal specified conditions. It has to be noted that almost the entire field failure reported for Li-ion cells was not due to any abuse situation, but occurred during use under normal operating conditions. 

The third category is the PPB (Parts Per Billion) level safety that refers to the field incidents of Li-ion cells that were subjected to normal recommended operating conditions. This category is the most concerning one and corresponds to the cells not categorized in bulk safety and the failure mode in most cases is a thermal runaway during normal operating conditions. 

This category can be said to inclnde qnantum tunnelling composites which are cnrrently nnder development. These unusual materials are insulators under normal operating conditions but become metal-like conductors when pressure is applied. Such materials can be used for sensors and switch substrates for example. They can be cast, extruded, moulded, machined or screen printed by standard processes. 

Category 3 Effective ignition sources are hkely to occur at anticipated disturbances or equipment failures, but not during normal operation. 

A listing of safety categories and classes associated with normal operation and DB fault conditions for all plant SSCs are presented in the APIOOO UK Safety Categorisation and Classification of Structures, Systems and Components report (Reference 4.2). 

The Level 1 defence in depth features are the duty systems that control and monitor the plant during normal operation and during expected operational deviations. On the APIOOO, the following SSCs are in this category ... 

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