Detection of space reactors by their gamma-ray and positron emissions

A ban on nuclear reactors in orbit could be verified using the tremendous flux of gamma rays and positrons that such reactors emit when operating. Indeed, these radiations already constitute a significant background for orbiting gamma-ray astronomical satellites. In this paper, we estimate the gamma-ray flux from reactors on spacecraft, using the design parameters for the US SP-100 space reactor as an example. We then summarize the sensitivities of several existing and planned gamma-ray detectors. We give special attention to the COMPTEL Compton telescope, one of the four instruments that will be included on the US Gamma Ray Observatory (GRO) satellite, which is scheduled for launch in 1990. We show that the gamma flux from an SP-100 could be detected at thousands of kilometers with COMPTEL, and demonstrate that COMPTEL would typically detect a reactor in low earth orbit several times per day. Finally, we briefly discuss positrons from orbiting reactors both as a signal for verification and as an undesirable background for gamma-ray astronomy.

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