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Commercial nuclear innovation "new space" age
In early 2006, a start-up company launched a small rocket from a tiny island in the Pacific. It exploded, showering the island with debris. A year later, a second launch attempt sent a rocket to space but failed to make orbit, burning up in the atmosphere. Another year brought a third attempt—and a third failure. The following month, in September 2008, the company used the last of its funds to launch a fourth rocket. It reached orbit, making history as the first privately funded liquid-fueled rocket to do so.
G. C. Pomraning
Nuclear Science and Engineering | Volume 136 | Number 1 | September 2000 | Pages 1-14
Technical Paper | doi.org/10.13182/NSE00-A2144
Articles are hosted by Taylor and Francis Online.
We consider the energy-dependent pencil beam problem for a thin slab with screened Rutherford scattering. Under certain approximations, this problem can be reduced to a monoenergetic problem with an effective depth-dependent scattering cross section [overbar]s(z). The z dependence of this cross section arises from the explicit z dependence of the true scattering cross section s(z,E), as well as from an induced z dependence associated with the energy dependence of s(z,E). Prior work led to a quadrature result for the scalar flux in the special case that [overbar]s is a constant, independent of z. In this paper, we generalize this result by allowing [overbar]s(z) to have an arbitrary z dependence. We use these considerations to show that simple homogenization, namely, replacing [overbar]s(z) by its average over the slab, can lead to significant errors in the scalar flux. A more detailed homogenization algorithm is suggested, involving an effective screening parameter in the screened Rutherford scattering phase function, as well as an effective depth coordinate z.