Additional Protection Measures

Variable Concrete composition Condition Mean value 

Cover thickness (mm) Time to depassivation (y) Time to depassivation (y) 

Additional protection methods based on the control or characteristic of  

Metallurgical (e.g. to decrease the susceptibility to hydrogen embrittlement for high-strength steel) 

Control of environment humidity. CO2 and chloride conteni Control of quantity and type of de-icing salts 

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Frequently, measures for dc installations are not sufficient to limit stray currents. This applies particularly to dc railways. In many cases, additional protective measures for the affected installations are advisable [1] or even necessary [11]. 

Magnesium anodes are frequently used as an additional protection measure at a later stage for stainless steel tanks. In this case the anodes are connected through a 5- to 10-Q resistor to the tank to avoid an unnecessarily high current for the cathodic protection of the tank and simultaneous high consumption of the anodes. 

Easily sensitive (3 mj < MIE < 10 mj) Expert decision or Avoidance of effective ignition sources and additional protective measures. 

Figure 9 shows the spectra obtained from the application of the action spectrum for the global, diffuse and direct irradiances for the same case. It can be seen the change in the spectra and the increase of the importance of diffuse irradiance relative to global. In this context, it can be expected that UV diffuse radiation have an important role in the erithema formation. This result supports the idea that shadow is not enough to avoid a sunburn and that additional protection measures must be taken in order to avoid also the exposition to diffuse radiation (sunscreens, clothes, etc). 

Usually it is better and more effective to remove the hazard and make the facility more intuitively safe. If there is no practical method to remove the hazard, the likelihood (probability) for reducing the event consequences should be considered next. Finally if the probabilities cannot be reduced the consequences should be evaluated with additional protective measures. 

The use of genetic information to identify sensitive individuals raises difficult policy questions. For example, individuals with certain polymorphisms might be sensitive to a xenobiotic at concentrations below the TLV. Although this information could be used to recommend additional protective measures for sensitive workers, there is also concern that the identification of susceptible individuals could result in job discrimination. 

For an individual identified as having test results 30% or more below baseline, we examine his work history and plant production records to determine what product was being made in this work area on or just before the date blood was drawn. We also review industrial hygiene sampling results which will provide us with the actual level of exposure. These data then can be used to determine what additional protective measures need to be instituted to prevent a recurrence. 

Preventative measures, often referred to as additional protection measures, are employed as shown in Figure 11.5. They operate by hindering aggressive species from reaching the reinforcement, or by controlling the corrosion process through inhibition of the anodic process or the corrosion current flow in the concrete. 

Figure 11.6 Indicative values of the maximum chloride content % by mass of cement) that can be reached at the surface of reinforcement before corrosion initiates with some additional protection measures...

In general, reinforced concrete has proved to be successful in terms of both structural performance and durabiHty if the design mles (Chapter 11) and concrete technology (Chapter 12) were adequately considered. Additional protection measures will only be necessary in very aggressive environments or when a very long service life is required. As outlined in Section 11.8, corrosion inhibitors, thus chemical compounds added as admixtures to the fresh concrete, are one possible way to improve the durabiHty of concrete structures. 

The term conventional repair is used in this book to indicate a repair work made on a damaged reinforced concrete structure, which is aimed at restoring protection to the reinforcement by means of replacement of non-protective concrete with a suitable cementitious material. The durability of the repair work is due to the achievement and maintenance of passivity on the reinforcement by the contact with the protective repair material. The repair work can be divided in the following steps a) assessment of the condition of the structure b) removal of concrete in well-defined parts of the structure and for specific depths c) cleaning of the exposed rebars d) application of a suitable repair material to provide an adequate cover to the reinforcement [1-6]. Each of these steps must be carried out properly in order to guarantee the effectiveness of the whole repair work. Additional protection measures can be used to increase the durability of the repair, but they must not interfere with the protection provided by the alkahnity of the repair material. Strengthening may also be required to restore the structural safety of the structure. 

Reactivity insertion No additional protection measures required, cavity cooling system running on-line (L)... 

Station black out) No additional protection measures required, Passive decay heat removal by naturally governed heat transfer. No fission product release from the fuel elements (max. fuel temp, below IbOO C ) (L)... 

Provisions to promptly measure the amounts of radioactive material released and implement additional protective measures for the public if needed. 

Where greater stress is placed on the pipe coating (e.g., in placement in rocky areas) a coating with greater impact and penetration resistance is necessary without additional protection measures. The important factors (see Section 5.2.3) are ... 

Nonetheless, additional protective measures are necessary when bonding transparent or translucent materials. 

Unalloyed ferrous materials are used without additional protective measures to a strictly limited degree. The reason for their limited use is the lack of resistance of these materials to local attack, such as wide or deep pitting. In domestic installations, it is the brown discolouration and change in taste of drinking water (rusty water), above all, which are unacceptable to the public - although they are not a health hazard. 

Laboratory woikers can experience routine exposure to hazardous chemicals such as acetone, carbon monoxide, formaldehyde, hydrogen sulfide, mercury, nitric acid, and xylene. Many exposures occur annually in laboratories, resulting in chemical-related illnesses such as dermatitis, eye irritation, and even fatal pulmonary edana. Employers must include information on additional protective measures for work that involves carcinogens, reproductive toxins, and acutely toxic substances. 

For a floating NPP with the VBER-300, the following additional protection measures / features are provided ... 

Technical measures for risk minimalisation and additional protective measures... 

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