Radiation Levels Governing Nuclear Roce Ground Instrumentation

A rocket vehicle with a nuclear propulsion system assumes the environment of the reactor: specifically, the high intensity neutron and gamma radiation fields. The rocket system considered here is a booster-type vehicle of approximately 1.25 million pounds. Reactor power requirements for the specified mission and the necessity of minimum shielding result in a neutron flux in excess of 6 × 1013 n/cm2-sec ten meters from the reactor core, and a gamma flux of approximately 1015 ¿/cm2-sec at the same distance. The environment at the launch site is affected by intense gamma radiation from the reactor during reactor run-up, hold-down for systems check, and also for a short time after lift-off. In addition, there will be fission product release resulting in ground contamination, and gamma radiation in the air both vicinal to and remote from the launch site. Assuming that the reactor and booster vehicle are to be recovered, activation radiation induced in the structure, and fission product release from the shutdown reactor must be evaluated. The requirements for instrumentation around a nuclear rocket launch site are, indeed, many and diverse. The demands upon a monitoring and measurement system are constant at all times, and during nuclear operations are severe. Although the magnitudes of nuclear radiations shown here are prodigious, the problems presented by them are not insurmountable. This paper analyzes the various radiation environments, and outlines on-site and off-site radiation instrumentation requirements.