Hazard defence

Measures of hazard defence are intended to mitigate the consequences of accidents. Among them figure the following measures, where of course only the active systems are triggered by PCE equipment. 

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Alarm and Hazard Defence Plans, Information of the Public... 

Alarm and hazard defence plans constitute a precaution which goes beyond the measures just described. They are to limit the damage after the occurrence of an accident. In the context of such plans the activities of the plant personnel in case of... 

Rapid and correct information of the public, if necessary accompanied by warnings, is to ensure the safety of the plant s neighbourhood. It is of use to plan the necessary information paths, to agree on them with the public safety forces and to integrate them into the works alarm and hazard defence plan. 

Figure 4.1 underlines the concept referring to technical devices needed to implement the different levels. Measures of alarm and hazard defence (vid. Sect. 4.1.6) are inscribed in mitigation . The terms used in Fig. 4.1 are now explained following [10]. 

Hazard defence using mitigation measures in case of releases of hazardous materials... 

Major accidents occurring despite preventative measures ( Dennoch Storfaiie ) stem from a progression of operational malfunctions which cause a serious danger despite the existence of accident preventing measures. They result from hazard sources which can reasonably be discarded or from the simultaneous impact of several independent sources of hazards. In order to hmit the consequences of such accidents plant specific measures and specific measures of hazard defence have to be taken. 

Because personal protection is limited to the user and the equipment must be worn for the duration of the exposure to the hazard, it should generally be considered as a last line of defence. Respiratory protection in particular should be restricted to hazardous situations of short duration (e.g. emergencies, maintenance, or temporary arrangements while engineering control measures are being introduced). Occasionally, personal protection may be the only practicable measure and indeed even a legal requirement. If it is to be effective, its selection, correct use and condition are of paramount importance. 

Careful attention to such detail is necessary as a second line of defence against the effects of reactive hazards. The level of protection considered necessary may range from the essential and absolute minimum of effective eye protection, via the safety screen, fume cupboard or enclosed reactor, up to the ultimate of a remotely controlled and blast-resistant isolation cell (usually for high-pressure operations). In the absence of facilities appropriate to the assessed level of hazard, operations must be deferred until such facilities are available. 

Ministry of Defence, UK, (1988) Explosive hazard assessment, Manual of tests, SCC No.3. 

There were probably no better-equipped forces in respect of anti-gas defence than those of the United Kingdom in the late 1930s. Britain had emerged from the First World War with a primitive respirator and basic techniques for gas-proofing dugouts, and little else. At the end of the 1930s, superior-quality anti-gas equipment was available to the armed forces to cater for all known hazards and a cheap, but efficient, respirator had also been developed for the civilian population.48 However, as far as offensive capabilities were concerned, investment had been limited and production had been minimal in terms of agents and weapons due to political unease and uncertainties. By 1938 the international situation was such that offensive research and development and the production of war reserve stocks of mustard gas were authorised by the British Cabinet, albeit that it was realised that a useful production output could not be obtained for at least 12-18 months. 

Bright, A.W., and Britton, L.G., Study of Hazards in Fuel Tanks of GRP Construction, Southampton University Applied Electrostatics Group, Final Report Ref No 7807/087 to Ministry of Defence Procurement Executive, February 1979. 

The technique may be said to combine the advantages of vacuum evaporation and sputtering, so that excellent qualities of adhesion are obtained without a limitation of maximum thickness of the coating—while at the same time the rate of deposition can be comparatively high. Many metals, alloys, and compounds may be deposited, on both metallic and non-metallic articles. However, its use at present is mainly for functional and protective applications, particularly where high resistance to corrosion is required. Thus, as examples, aluminium may be deposited on various types of steel and on titanium for uses in the aerospace and defence industries—and can be regarded as a less hazardous replacement for cadmium electroplating. 

Hazard Prevention Section, Hazard Prevention Dept., Tokyo Fire Defence Agency,... 

Noboru Nakagawa, Kimio Sato, and Kazutoshi Hasegawa, "Danger of Fire Breakout from Small Amount of Hazardous Sustances in an Earthquake and Measures Against It", Fire Defence Agency, Ministry of Home Affairs (1973)... 

Even if their absorption is high, the bioavailability of many compounds may be limited by an extensive metabolism that can affect the in vivo activity profile irrespective of its route of administration. Metabolism is vital since it transforms absorbed nutrients into endogenous substances required to maintain body functions for xenobiotics, including phytochemicals, metabolism represents the key body defence mechanism that converts them into less harmful, water-soluble, and thus excretable, compounds. Lipophilic, low molecular weight xenobiotics that are readily absorbed and distributed are difficult to eliminate and thus may accumulate to hazardous levels. Therefore, most lipophilic xenobiotics are metabolized into hydrophilic conjugates that are less likely to pass through membranes and, hence, can be more easily eliminated via the kidney. 

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