Safety demonstration studies

The previous section served to recall some basic concepts (fault, error, and failure), but the systematic research of failures and the analysis of their effects on the system is achieved through activities such as preliminary hazard analysis (PHA), failure modes and effects analysis (FMEA), fault trees analysis (FTA), etc. 

Analyses related to dependability are now common (see [VIL 88] for example) and imposed by standards. All of these studies allow a demonstration of safety, which will be formalized through a safety case. The generic standard lEC 61508 [lEC 98], applicable to electronic-based systems and programmable electronics, covers this point and offers a general approach. 

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For a number of years during the 1970s studies in experimental animals and in the rat in particular caused concern about the safety of rapeseed oil for human use. Initially it was theorized that the oil might contain a toxic factor or substance. However, it has been demonstrated that vegetable oils contain no cardiopathogenic nontriglyceride compounds responsible for myocardial lesions in rats. Futhermore, it is now apparent that concerns about safety were unfounded since it is established that the rat is not suitable as an experimental model for safety assessment studies on vegetable oils intended for human use. The reasons why the rat is not a suitable model may be summarized as follow ... 

The first tests on the prototype demonstrated the efficiency of the system. Dysfunctional tests on the hardware and on the software made it possible to validate ruggedness and the high level of safety. The study also contributes towards controlling risks connected with hydrogen, the use of which is expanding. It shows the difficulty in certifying innovative products with present-day reference fi ames and standards. 

In addition to the procedural capability described in Section 7.3.1, a self-assessment will also need to demonstrate the completion of at least one project together with a safety-integrity study. 

The selected 23 chapters that are included in this volume on traffic safety demonstrate how technological innovations as well as new methodologies applied to transport safety can modify usual practices and offer efficient solutions to the ongoing challenges of safety considerations, needs of vulnerable road users, environmental issues and economical constraints. Both theoretical papers and practical case studies explore topics such as road safety management and policies, accident analysis and modeling, vulnerable road users safety, road infrastructure safety, ITS and railway safety. 

One of the principal advantages of hydrides for hydrogen storage is safety (25). As part of a study to determine the safety of the iron—titanium—manganese metal hydride storage system, tests were conducted in conjunction with the U.S. Army (26). These tests simulated the worst possible conditions resulting from a serious coUision and demonstrated that the metal hydride vessels do not explode. 

Two new female condoms, ie, vaginal pouches, are in early stages of development. These devices still require thorough preclinical and clinical studies to demonstrate safety and effectiveness before they reach the market (102). 

Noscapine [128-62-1] (45) is the second most abundant alkaloid found in opium. Unlike most opium alkaloids, however, it has an isoquinoline rather than a phenanthrene ting system. Noscapine was first isolated in 1817 but its antitussive activity was not demonstrated pharmacologically until 1952 (63). Clinical studies have confirmed its effectiveness. It is not a narcotic and has a wide margin of safety when given orally. Death could be produced in rats only with doses > 800 mg/kg (64). Noscapine is isolated from the water-insoluble residue remaining after processing opium for the manufacture of morphine. 

During regular operations to identify potential improvements for the next plant. Process improvement studies can then demonstrate the feasibility of inherent safety improvements so they can easily be incorporated into the design of the next plant or in major revamps of existing facilities. 

Experimental variance Permission granted by OSHA for the use of an alternative method of worker protection during an approved experiment to demonstrate or validate new safety and health techniques. The variance terminates upon study com pletion unless another type of variance is issued by OSHA. 

Modem behavior-modification programs rely on the identification and reinforcement of safe behaviors. Considerable improvements in measures of safety performance have been attributed to the introduction of these approaches (see McSween, 1993, for a petrochemical example). However, other studies have indicated that performance may return to its original level if the programs are withdrawn. It is therefore important to maintain a continuing program to ensure that the initial levels of improvements are maintained. Also, the benefits of behavior modification programs have mainly been demonstrated in the context of work activities where there is a high level of... 

In this study detailed fault trees with probability and failure rate calculations were generated for the events (1) Fatality due to Explosion, Fire, Toxic Release or Asphyxiation at the Process Development Unit (PDU) Coal Gasification Process and (2) Loss of Availability of the PDU. The fault trees for the PDU were synthesized by Design Sciences, Inc., and then subjected to multiple reviews by Combustion Engineering. The steps involved in hazard identification and evaluation, fault tree generation, probability assessment, and design alteration are presented in the main body of this report. The fault trees, cut sets, failure rate data and unavailability calculations are included as attachments to this report. Although both safety and reliability trees have been constructed for the PDU, the verification and analysis of these trees were not completed as a result of the curtailment of the demonstration plant project. Certain items not completed for the PDU risk and reliability assessment are listed. 

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