Safety categories

U.S. (FDA) Category III for Safety and effectiveness Category I for safety, Category III for effectiveness Short-term use (0.24-3.75%) Category I for safety, Category III for effectiveness Long-term use Category III for safety and effectiveness... 

The existing systems (important for safety, categories A and B) to be modernised are the following ... 

The objective of this paper is to provide ( as an example) a set of staggered criteria for the qualification of pre-developed software to be used in different categories for safety critical I C. These qualification criteria appear in the form of requirements for the application of methods and measures in the different safety categories. The three safety categories are those from lEC 61226. 

Besides the safety categories, there are also usage categories which denote whether the predeveloped software is exeeuted directly online, or is used to directly generate online executed software, or is used to support the generation of online executed software. 

The ideal situation for pre-developed software would be that it has been developed for an exactly identical function as the envisaged one, according to the quality requirements of the safety category of this function. Usually, however, this is not the case, and one or more of the following issues must be tackled with ... 

Testing of the pre-developed software has of course to be performed for all safety categories. Even for non-classified software NC, tests will be necessary, as this is the state of practice to demonstrate that the software is suited for its purpose (as required by lEC 60880). 

The first step in the acceptance process is the identification of the environment within which the pre-developed software will have to work. This environment is determined by the system-level safety function as described in the system requirements specification. Also the interface and performance requirements, as well as the safety category should be contained in the system requirements specification. This means, that during the establishment of the plant safety design base a risk and hazards analysis has been performed which rendered the categories of safety functions to be implemented by pre-developed software. This risk and hazard analysis - in spite of being out of the scope of I C engineering - has been taken as the first of four acceptance criteria that should be applied to pre-developed software independently of its safety category. 

Table 2 Qualification Criteria Independent of Safety Categories...

Risk and hazard analysis shall have been performed to determine the safety category of the system-level safety function. LLNL [7], Table 4 EUR 19265 [3], 1.1.3.1... 

The second level qualification criteria are not grouped according to safety categories they should be regarded as a pool of requirements which are accessed from the first level. In many cases first level C criteria point to a smaller set of second level criteria than first level B criteria, and the same holds for the relationship between B and A first level criteria. 

As already mentioned, lEC 60880 describes the modification process for software in computer-based systems of the highest safety category. Taking into account, that most of the software-based systems important to safety are also to be installed in lower safety classes, the importance and necessity of... 

For the highest safety category operating experience can not replace a detailed documentation of... 

Figure 10.5 Classification of SOLVSAFE solvent candidates according to their elfects in five environmental, health and safety categories. Health adverse elfects according to Table 10.1. Toxicity for aquatic organisms based on LC50 96 h (fish) and ready biodegradability. VOC emission potential is considered when the vapour pressure at normal temperature is higher than 0.1 hPa. Low fire hazard is assigned whenever the flashpoint is higher than 55 °C. A low exposure potential in workplaces is considered when the vapour pressure is less than lOhPa.

Requirements on equipment and structures according to safety category... 

See Chapter 2.4, Section 2-4-5-9-2-1 for safety category 1 mechanical equipment, Table 5 for fuel and Chapter 2-9, Sections 2-9-3-1-4-5-3 and 2-9-3-1-4-5-4 for Primary Containment... 

Assignment of each item of equipment or each structure to a safety category, generally according to the highest safety level of function it has to perform. 

The designer shall assign each structure and each item of equipment to an appropriate safety category, primarily according to the highest level of the safety function they perform as follows ... 

Highest safety function level performed Safety category... 

Safety category II and non-safety category structures and equipment shall be designed to appropriate codes (Chapter 2-5 gives the general outline, which will be specified in more detail in Volume 3). 

Certain requirements are imposed on structures and equipment according to their safety category. These requirements are as follows ... 

The designer shall assign each safety category I structure and piece of equipment (mechanical, electrical, I C) to an appropriate class of the nuclear... 

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