Hydrogen damage potential

Concern about hydrogen damage has lead to much debate regarding limits for protection potentials of high-alloy steels. However, it is thought that under normal seawater service and cathodic protection conditions, these materials will not be adversely affected provided that the microstructure has at least 40% austenite present . This latter point is of particular importance to welds and their heat affected zone where careful control of heat input is necessary to maintain a favourable microstructure. 

The greatest damage potential is located in the fuel gas tank due to the largest amount of hydrogen found there. The failure modes that should be considered in the case of normal operation, and in collision as well, are the following ... 

Chapter I, Vapor Cloud Explosions, presents recent research on the safety hazards and explosion damage potential associated with the accidental release of combustible vapor clouds. Stock et al. report on experiments with explosive clouds formed by turbulent jets of propane, natural gas, or hydrogen released through various-sized orifices. They found significant scale effects, e.g., the maximum explosion pressure increased with the size of the vapor cloud and with the turbulence level in the jet. Desrosiet and coworkers have experimented with asymmetric explosions of vapoi clouds. They present results on how the ignition asymmetry of a hemi-... 

Corrosion hydrogen monitor Boiler tubes, feedwater system, and PWR steam generator corrosion Detect general corrosion vs. load and chemistry hydrogen damage, caustic gouging in boiler tubes, potential for impurity concentration... 

The rate of pressure build-up can be related to the potential for hydrogen damage occnrring in the vessel or piping materials. A period of stabilization is reqnired to enable the tnbnlar element to saturate with atomic hydrogen before meaningfnl data can be accnmnlated. 

The hydrogen concentration requirement was not addressed explicitly in the Action Plans. The staff considers that hydrogen release would be inhibited if WSRC can show that no DBEs will result in fuel damage. Potential hazardous... 

Cathodic protection of water power turbines is characterized by wide variations in protection current requirements. This is due to the operating conditions (flow velocity, water level) and in the case of the Werra River, the salt content. For this reason potential-controlled rectifiers must be used. This is also necessary to avoid overprotection and thereby damage to the coating (see Sections 5.2.1.4 and 5.2.1.5 as well as Refs. 4 and 5). Safety measures must be addressed for the reasons stated in Section 20.1.5. Notices were fixed to the turbine and the external access to the box headers which warned of the danger of explosion from hydrogen and included the regulations for the avoidance of accidents (see Ref. 4). 

It has been shown in many studies that protective effects of carotenoids can be observed only at small carotenoid concentrations, whereas at high concentrations carotenoids exert pro-oxidant effects via propagation of free radical damage (Chucair et al., 2007 Lowe et al., 1999 Palozza, 1998, 2001 Young and Lowe, 2001). For example, supplementation of rat retinal photoreceptors with small concentrations of lutein and zeaxanthin reduces apoptosis in photoreceptors, preserves mitochondrial potential, and prevents cytochrome c release from mitochondria subjected to oxidative stress induced by paraquat or hydrogen peroxide (Chucair et al., 2007). However, this protective effect has been observed only at low concentrations of xanthophylls, of 0.14 and 0.17 pM for lutein and zeaxanthin, respectively. Higher concentrations of carotenoids have led to deleterious effects (Chucair et al., 2007). 

---