Permissible hydrogen concentration

Hydrogen ignition as a threat to ALS integrity may be prevented if its concentration is kept below the flammability limit. 

There are two flammability limits for binary hydrogen and air mixtures a limit for a depleted mixture (with the H2 concentration below the stoichiometric level) and a limit for an enriched mixture (with the H2 concentration above the stoichiometric level). These limits are roughly estimated as 4.5 vol.% H2 and 74 vol.% H2, respectively, at standard temperature and pressure (i.e. 298 K and 100 kPa). The maximum permissible hydrogen concentration in any single ALS compartment is taken equal to 4 vol.% in the analysis. Should this criterion value be reached, H2 flammabiUty must be comprehensively assessed, taking into consideration the time dependence and the characteristic boundary conditions of the accident scenario for the ALS. 

According to the rules laid down by the national nuclear regulatory authority (see, for example, Ret [11]), the consequences of a DBA should never result in any population exposure that would require countermeasures to protect people in the early period of the radiation accident. 

The early phase (initial period) of an accident covers the time from its beginning to the time when the atmospheric release of radioactive substances is arrested. This period is assumed to be up to ten days. 

The design radius of the control area around an RBMK nuclear power plant is 3 km. 

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FIG. 40. The influence of deposition temperature on (a) the hydrogen concentration, (b) the microstructure parameter, and (c) the Raman half width P/2. The labels A and P refer to the ASTER and the PASTA deposition system. Series A1 was prepared from a SiH4 H2 mixture at 0.12 mbar. Series A2 and A3 were deposited from undiluted SiHa at 0.08 and 0.12 mbar. respectively. Series PI was deposited from undiluted SiHa. (From A. J. M. Bemtsen. Ph.D. Thesis. Universiteit Utrecht. Utrecht, the Netherlands, 1998, with permission.)... 

Computational and experimental hydrogen concentration histories at point (9.1, 0, 1) for the LH2 trial 6. (From Sklavounos, S. and Rigas, F., Energ. Fuel., 19, 2535,2005. With permission.)... 

Fig. 13.10 (a) Tapered optical fiber. p0 is the initial diameter, inset schematic cross section of the device p is the waist diameter, L0 is the length of the waist, t is the maximum thickness of the palladium film (shadowed area) and X is radiation wavelength, (b) Time response of the sensor to periodic cycles from a pure nitrogen atmosphere to a mixture of 3.9% hydrogen in nitrogen, (c) Time response of a sensor when it was exposed to different hydrogen concentrations, (d) Transmission versus hydrogen concentration sensor parameters p 1,300 nm, L 2 mm, and t 4 nm. Reprinted from Ref. 15 with permission. 2008 Optical Society of America... 

Figure 12. Hydrogen concentration versus temperature for silicon nitride layers deposited by PECVD. (seem is standard cubic centimeters per minute.) (Reproduced with permission from reference 221. Copyright 1985 The Electrochemical Society, Inc.)...

Figure 5.17. Simulated hydrogen concentration profiles at different values of the Thiele modulus. From [5.61], with permission from the American Chemical Society.

Figure 3.15 Initial rate data of benzene hydrogenation over Ni-kieselguhr. (a) rate of hydrogenation as a function of hydrogen concentration, P = 760 Torr (b) rate of hydrogenation as a function of benzene concentration, P = 760 torr (c) product inhibition effects at low conversions, P = 760 Torr, T = 124 °C. [After J.P.G. Kehoe and J.B. Butt, J. Appl. Chem. BiotechnoL, 23, with permission of the Society of Chemical Industry, (1972).]...

ALS Maximum permissible pressures in compartments, operating pressure difference of a safety device or maximum water temperature in the PSP Hydrogen concentration in any compartment no higher than 4vol.%... 

Fig. 2.35 Voltage signal, V.oftheTHSfor wide-range hydrogen concentration in air. The operating temperature of the THS was 80 °C (Reprinted with permission from Shin et al. (2003). Copyright 2003 Elsevier)...

FIGURE 1 Pressure-composition isotherms left) and van t Hoff plot right) tor the reaction of a metal or intermetallic compound with hydrogen. ph2. hydrogen pressure Ch. hydrogen concentration in the solid phase T, absolute temperature a, solid solution phase of hydrogen in the metal or Intermetallic compound metal hydride phase Peq, equilibrium pressure of metal hydride formation To, critical temperature AH, enthalpy of hydride formation. [From Schlapbach, L., Meli, R, and Zuttel, A. (1995). Intermetallic hydrides and their applications. In Intermetallic Compounds Principles and Practice (J. H. Westbrook and R. L. Fleischer, eds.), Vol. 2, pp. 475-488. Reproduced with permission from John Wiley Sons, New York.]... 

Fig. 40. EMF response of the following hydrogen concentration cell PH2(1 atm),Pt/CaZro, 980 103 /Pt,PH2(c). Dashed lines, theoretical value solid circles, 1000 C open triangles, 800 open circles, 600°C (Yajima et al. 1991). (Reprinted by permission of the publisher, Elsevier Science Publishers B.V)...

Figure 7. Hydrogen concentration profiles during charging and discharging (/>/ ) of a bulk specimen under potentiostatic pulse conditions with a constant concentration at the input side. (After Ref. 13. Reprinted with permission from Acta Metall, Copyright 1987, Pergamon Press pic.)...

Figure 15. Schematic of a high temperature aqueous hydrogen concentration cell. Reprinted from Ref. 32, Copyright (1973) with permission from Canadian Journal of Chemistry.

Figure 41. Response of the W/WOs-Pt combination sensor to changes in oxygen and hydrogen concentrations in pure water at 300 °C. Reprinted from Ref 5, Copyright (1997) with permission by Elsevier.

Figure 12.6 The structural model of KH-GIC, with stoichiometry C4KH, constructed at jc = 1. The actual hydrogen concentration x ranges from 0.67 to 0.8. (Reproduced by permission of Elsevier Science, from ref 118.)...

Fig. 1.15 a Evolution of the transition temperature, Tc, with change in hydrogen concentration b temperature dependence of the thermoelectric figure of merit for monoclinic VO2 (M), hydric VO2 (M-R), and hydric V02(R), Reprinted with the permission from Ref. [161], copyright 2011 American Chemical Society... 

Fig. 6.1.2 Absorption spectra of Latia luciferin (1), the product of catalytic hydrogenation (2), the product of ammonolysis (3), and the product of hydrolysis (4), all in ethanol at the same molar concentration (89 pM). Latia luciferin has an e value of 13,700 at 207nm, and a bioluminescence activity of approximately 7.6x 1015 photons/mg. From Shimomura and Johnson, 1968b, with permission from the American Chemical Society.

Fig. 7. Dependence of relative molar concentrations n-Jn of reaction components on reciprocal space velocity W/F (hr kg mole-1) in the consecutive hydrogenation of phenol. Temperature 150°C, catalyst Pt-SiCh (1% wt. Pt), initial molar ratio of reactants G = 9. The curves were calculated (1—phenol, 2—cyclohexanone, 3—cyclohexanol) the points are experimental values. From Ref. (61). Reproduced by permission of the copyright owner.

FIG. 3. Absolute atomic concentrations in units of 10 al./cm. determined by ERD. RBS, and optical reflection and transmission spectroscopy, of (a) hydrogen, (b) carbon, and (c) silicon as a function of the carbon fraction. v. Results are presented for the series ASTI (filled circles), AST2 (filled triangles), ATLl (open circles), and ATL2 (open triangles). (From R. A. C. M. M. van Swaaij. Ph.D. Thesis, Universiteit Utrecht. Utrecht, the Netherlands, 1994. with permission.)... 

Fig. 14.13 (a) Bubble temperatures estimated using the MRR method as a function of thermal conductivity for the rare gases, (b) Hydrogen peroxide concentration following sonication of pure water as a function of gas solubility in different rare gases ( ) He ( ) Ne (a) Ar ( ) Kr ( ) Xe ( ) He/Xe mixture [42] (reprinted with permission from the American Chemical Society)... 

Hydrogenation rate as a function of catalyst concentration. [Adapted from M. Zajcew, J. Am. Oil Chem. Soc., 37 (11), 1960. Used by permission of American Oil Chemists Society.]... 

FIGURE 2.18 Potential-current density curves for the Ni electrodes in hydrogen fuels containing different concentration of Ff20. (From Nakagawa, N. et al., J. Electrochem. Soc., 142 3474-3479, 1995. Reproduced by permission of ECS-The Electrochemical Society.)... 

FIGURE 1. The variation in the initial rate of disappearance of hydrogen chloride (g) in the reaction of HC1 with 1,3-butadiene as a function of the surface-to-volume ratio at 295 K. The initial concentrations of hydrogen chloride and 1,3-butadiene are 3.4 x 1CU4 M and 1.6 x 1CU4 M, respectively. (Reprinted from Reference 44, copyright 1991, with permission Elsevier Science)... 

FIGURE 4-43 Hydrogen peroxide concentrations at Riverside, California, in August 1970. Reprinted with permission from Bufalini et al. ... 

Fig. 4. The concentration of n-syloio dimethyl aceta. in the reaction between D-xyloso (1%) and methanolic hydrogen chloride (0 5%) at 25 . From Carbohyd. Res. d, 75 (1368) (by permission)...

Figure 2.5 The response of an MISiC sensor, (a) At 600°C to gas mixtures containing different hydrocarbons (butane, propene, ethane) and concentrations. (From [56]. 1997 Elsevier B.V. Reprinted with permission.) (b) To hydrogen in different oxygen concentrations at 300°C and at T> 600°C plotted versus the ratio of reducing to oxidizing species, a, as defined in (2.6). Inset the pulse response at 620°C to 0.1, 0.2, and 0.3% Hj in 0.1% Oj/Ar. (From [57]. 1 988 The Electrochemical Society. Reprinted with permission.)...

Figure 4,56 Schematic representation of concentration profiles of hydrogen diffusing through a composite wall. Reprinted, by permission, from D. R. Gaskell, An Introduction to Transport Phenomena in Materials Engineering, p. 498. Copyright 1992 by Macmillan Publishing.

Models of the interiors of the giant planets depend on assumed temperature-pressure-density relationships that are not very well constrained. Models for Jupiter and Saturn feature concentric layers (from the outside inward) of molecular hydrogen, metallic hydrogen, and ice, perhaps with small cores of rock (rocky cores are permissible but not required by current data). Uranus and Neptune models are similar, except that there is no metallic hydrogen, the interior layers of ice are thicker, and the rocky cores are relatively larger. 

Fig. 7. Absorption spectrum of hydrogen peroxide vapor. The absorption coefficient, a, is defined by the equation / = 70 exp (— atcd), where c is the concentration in molecules/cc. and d is the length of the light path in cm. Curve (a) and point O after Holt et al. (45,46). Curve (b) after Urey et al. (85). This figure based on refs. (46) and (85) with the permission of The Journal of Chemical Physics and the Journal of the American Chemical Society.

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