Operational safety criteria

Software hazard analysis (SWHA) is a system safety analytical technique whose primary function is to systematically evaluate any potential faults in operating system and applications software requirements, codes, and programs as they may affect overall system operation. The purpose of the SWHA is to ensure that safety specifications and related operational requirements are accurately and consistently translated into computer software programs. In this regard, the analysis will verify that specific operational safety criteria, such as failsafe or fail-passive, have been properly assimilated into operational software. The SWHA will also identify and analyze those computer software programs, routines, or functions that may have direct control over or indirect influence on the safe operation of a given system. Also, in the operation of the computer software command function, there is a potential that the actual coded software may cause identified hazardous conditions to occur or inhibit a desired function, thereby creating additional hazard potential. 

Under certain circumstances the safety criteria may be amended to suit the specific programme requirements (e.g. UAV safety criteria, or Military Operational Safety Criteria). However, this is subject to substantiation and agreement by the applicable regulatory authority, thus the declaration of the safety criteria (either in a separate safety criteria report, or as part of a safety plan or an early release of a preliminary system safety assessment). 

The tolerance for safety risks affecting civil aviation during peacetime is likely to be very different from the tolerance of safety risks to military aircraft during conflict (operational safety criteria may be less severe). In accordance with DEF STAN 00-56 (Part 1 Para 7.3.2.c), some systems have a defensive role whereby inaction under hostile circumstances may constitute a hazard. Safety targets for such systems shall address the requirements to reduce, to a tolerable level, the risk resulting from inaction under hostile circumstances. 

The flash point of a petroleum liquid is the temperature to which it must be brought so that the vapor evolved burns spontaneously in the presence of a flame. For diesel fuel, the test is conducted according to a closed cup technique (NF T 60-103). The French specifications stipulate that the flash point should be between 55°C and 120°C. That constitutes a safety criterion during storage and distribution operations. Moreover, from an official viewpoint, petroleum products are classified in several groups according to their flash points which should never be exceeded. 

This second approximation is somewhat problematic as it turns out to be part of an indirect procedure. Its justification is finally given by the safety criterion to be deduced. The application of the latter excludes operating conditions, for which the approximation is invalid. However, this procedure is the only one known so far and which has proven valid in practice. 

An additional sensitivity discussion is not necessary in this case. As shown in detail in reference [50], the sensitivity of all operating points which are in compliance with the safety criterion is equal to S = 1. 

A safety criterion has been defined which has enabled an operating condition to be evaluated as acceptable. This criterion is the operator has enough time (211 hour) to... 

Designs of units with WWER under operation in Ukraine were developed in 70-s. The basic safety criterion laid into these designs was to provide for safety under all the design basis accidents/at that time, exclusively deterministic approach to safety level assessment was adopted as the basis. 

The margin of safely from brittle fracture is therefore dependent on the stress level as well as the expected minimum temperature of operation. Some design codes use a single margin of safety criterion based on energy absorption in a Charpy test conducted at the minimum expected temperature of operation. ... 

As can be seen, in evaluation of the risk mitigation strategies for offshore wind power plants, the greatest weight is given to the safety criterion. This is perhaps in due consideration of the huge impact of operational hazards on grid safety. 

Some would say that this is the current state of the art. Much of the necessary library could be assembled from test systems that have been extensively evaluated and have already undergone extensive validation (Gad, 2000, 2001). Three critical steps must be taken for the eventual fulfillment of these objectives (1) acceptance of a scientific approach to the problem of safety assessment (2) development of an operative validation and acceptance process for new test procedures (3) clear enunciation of an acceptance criterion for new test designs by regulatory authorities. 

In the construction of the wet oxidation unit, several areas of safety were considered. Of utmost importance was that of personal safety. Since this type of operation demands the use of high pressures and temperatures, operator contact with the high pressure vessels had to be limited. To accommodate this criterion, a barrier was constructed to shield the operator from any unforeseen releases from the reactor. This barrier was constructed from 1/4 inch steel and is desig ied in a manner that will fully contain any releases. This barrier is also equipped with two explosion vents to direct the force of any explosions away from the main walls and into a safe area. To further maximize personnel safety, all operator assisted controls are mounted on the outside of the unit. 

Structural analysis of the solid rocket case-grain system using experimentally determined propellant response properties may permit a complete description of the combined stresses and resultant deformations, but a statement expressing the ability of the propellant to withstand these stresses is also required. Such a statement, which relates the physical state at which failure occurs to some material parameters, is called a failure criterion. The criterion for failure permits a prediction of safety margins expected under motor operation and handling and defines the loading regimes where abnormal operations will occur with intolerable frequency. 

The goal of optimization is safety at maximum profit, but this can only be done if the market value of each product is known. This is not the case when the products of a column are not final products but feed flows to other unit processes. When the product prices are unknown, it is still possible to perform optimization, but the optimization goal changes. The criterion in that case becomes the generation of the required products at minimum operating costs. This can be called an optimum with respect to the column involved, but only a "suboptimum" with respect to the plant of which the column is a part. 

Low-poled motors with high speeds, in which the safety clutch located between motor and gear, can only be operated at maximum speed of the safety dutch, which has a limiting effect. Moreover, high motor speeds can lead to vibration problems. A further criterion that speaks against high-poled motors is their relatively high nominal current that demands the... 

The objective of the dynamic optimization is to determine, for a dynamic system, a set of decision variable time profiles (pressure, temperature, flowrate, heat duty etc.) that optimise a given performance criterion, subject to specified constraints (safety, environmental and operating constraints). 

Process simulation of several thousand operating conditions, covering the technically meaningful and industrially relevant parameter range, was applied to deduce empirically a safety technical assessment criterion. 

ABSTRACT By analyzing the hierarchy of safety factors in purification plant of natural gas, they are divided into personnel, equipment, environment and management. After the study of safety index, evaluation methods and fuzzy arithmetic method for each hierarchy, its fuzzy evaluation flow is given. During the evaluation, the weight of the factors and each hierarchy is decided by analytical hierarchical process, and the operational criterion adapts maximum membership degree. And this model is exemplified in purification plant of natural gas. The results show that the second fuzzy evaluation is effective to assess purification plant of natural gas. 

As an example for a subsequent level, the second level qualification criteria for criterion A 1 (suitability assurance) are given in table SI. Table S 2 gives the second level criteria of a part (namely the quality assurance part) of first level criterion A 2 (product assurance). The second part would be a table for V V, which has not been included, as only the principle of the qualification process is shown in this paper. For the same reason, also the further details of the first level criteria documentation, product safety, system safety, interface, compensation by operating experience, error reporting, and modification are not elaborated. Thus the GOTO. .. and other references in the description part of the tables, which are the pointers to the more detailed criteria are in most cases empty. 

The tables S 1 and S 2 in this example are dealing only with the first level criterion suitability assurance and one part of the aspects of the first level criterion product assurance , i.e. with software quality assurance. The other part of the criterion product assurance is verification and validation, V V, which also has to be broken down in more detailed criteria. Also the other first level criteria of tables 3, 4 and 5, i.e. dociunentation, product safety, system safety, interface, compensation by operating experience, error reporting, and modification should be detailed into appropriate levels of refinement. Examples for this process can be foimd in [7]. 

Section II of Appendix I also includes a numerical cost-benefit guideline to judge the necessity for additional improvements in radioactive waste treatment systems. This guideline has not been included as a top-level regulatory criterion as it is not a direct statement of acceptable health or safety consequence or risk to the public. Similarly, the other operative... 

Safety Mechanisms are identified by the hazard analyses in two ways either they are in support of an Operating Rule that has been identified in the analyses, or they can be shown to be a key instrument. A key instrument is one that if removed or permanently in the failed state would cause the estimated fault frequency to exceed the frequency target of a specified criterion. 

According to [6] the normal operation of a reactor is considered to be safe, if ATad < 50 K holds for the reaction occurring during normal operation and if there are no thermal instabilities of the reagents, the reacting mixture or the products in the temperature range [T, T + ATadl- However, this criterion should be used with care, since the time behaviour should be accounted for as well in assessing safety. Additionally, the uncertainties of the calculation should be observed [7]. 

A major and valid justification for OSHA to adopt the laboratory safety standard to supersede the general industry standards and the hazard communication standard for the laboratory environment was thatthe laboratory environment is radically different from industrial facilities and most other types of occupations. The organizational structure for research institutions is not nearly so structured, especially in the academic environment,and operations are different in size and character. The laboratory standard uses this difference as a criterion as to whether the laboratory standard is to be applied to a program. 

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