Snelling

Ross Kinderman and J. Laurie Snell Markov fields and their applications. Contemporary Mathematics v. 1. American Mathematical Society, 1980. 

The physics of X-ray refraction are analogous to the well known refraction of light by optical lenses and prisms, governed by Snell s law. The special feature is the deflection at very small angles of few minutes of arc, as the refractive index of X-rays in matter is nearly one. Due to the density differences at inner surfaces most of the incident X-rays are deflected [1]. As the scattered intensity of refraction is proportional to the specific surface of a sample, a reference standard gives a quantitative measure for analytical determinations. 

The phase velocity is directly linked to the angles of incidence by the Snell-Descartes law ... 

The geometry of Fig. 10.3 leads to a result known as Snell s law, which relates the refractive index of the medium to the angles formed by two wave fronts with the interface. Defining 6q and 6, respectively, as the angles between the phase boundary and the wave front under vacuum and in the medium of refractive index n, show that Snell s law requires n = sin Oo/sind. 

P. D. Snell and C. L. Hilton, eds., Enyclopedia of Industrial Chemical Analysis, Wdey-lnteiscience, New York, 1968, p. 368. 

Reflection and refraction of X-rays follow the laws of optics (Fig. 4.2) The glancing angles of incidence (i) and reflection ( ) are equal. The respective refraction angles follow Snell s law for different phase velocities v in mediums 1 and 2 ... 

Charles A. Pinkow, Harvey Rosenhouse, John D. Snell,... 

Pressure-tubes allow the separate, low-pressure, heavy-water moderator to act as a backup hesit sink even if there is no water in the fuel channels. Should this fail, the calandria shell ilsdf can contain the debris, with the decay heat being transferred to the water-filled shield tank around the core. Should the severe core damage sequence progress further, the shield tank and the concrete reactor vault significantly delay the challenge to containment. Furthermore, should core melt lead to containment overpressure, the concrete containment wall will leak and reduce the possibility of catastrophic structural failure (Snell, 1990). 

Snell, V. G., et al., 1990, CANDU Safety under Severe Accidents, Nuclear Safety, 21,1, pp 20-36, January-March. 

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