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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.
T. J. Hoffman, J. C. Robinson, P. N. Stevens
Nuclear Science and Engineering | Volume 48 | Number 2 | June 1972 | Pages 179-188
Technical Paper | doi.org/10.13182/NSE72-A22469
Articles are hosted by Taylor and Francis Online.
An important radiation transport problem is that of determining the effect of a geometrically complex object (vehicle) located in an otherwise geometrically simple system. The direct solution to this problem often requires a Monte Carlo calculation. If the vehicle is far removed from the radiation source, the calculation can be very costly or even impossible.To deal with this problem, a new method, the adjoint difference method, has been developed. This method decomposes the original problem into two independent calculations: 1. a geometrically simple (one- or two-dimensional) deep-penetration calculation that is independent of the vehicle 2. a localized three-dimensional calculation that is independent of the radiation source. The first calculation is suitable to deterministic methods of solution, such as discrete ordinates. The second, by nature of geometry, usually requires a Monte Carlo calculation; however, this is not a deep-penetration calculation. Therefore the dual complexity of geometry and statistics inherent in a deep-penetration Monte Carlo calculation is avoided. Since the above calculations are independent, only the coupling of these calculations depends on the relative position and orientation of the source and vehicle. Hence the effects of different sources and arbitrary vehicle orientations can be obtained from a single Monte Carlo calculation. The method was examined through application to several problems. All resuits were compared to those obtained from presently acceptable methods of problem solution. In these applications, the adjoint difference method was shown to be an efficient, versatile method of calculation.