UGT Noise Minimization Techniques.
Final rept. Apr-Nov 76,
MISSION RESEARCH CORP LA JOLLA CA
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The high-intensity radiation delivered by a nuclear explosion during an underground test produces large, fast current pulses on conductors and in the earth as a direct result of the interaction of the fast radiation pulse with the earth and test configuration. These currents can produce transient voltages in experiment measuring circuits that interfere seriously with the experiments to be performed. Experimenters have dealt with such interference by combinations of electrical and radiation shielding, grounding or electrical isolation, filtering, modulating and demodulating. The following grounding and cabling practices are preferred 1 the cables should be enclosed in a conducting shield zipper tube or pipe until the cable run escapes from the radiation field and the electric field induced in the tunnel air and wall. This shield should be earth grounded at its end. 2 The uphole cables should have their outer shields shorted together at the gas seal bulkhead, alcove splice rack and mesa splice rack. 3 The transfer impedance for low-noise experiments should be minimized by using solid-shield cables and conducting foil bridges over connectors. 4 Electrically pulsing the transmission line between cable shields and enclosing shield e. g., zipper is an effective means of quality control on the transfer impedance. 5 The direct photon-induced cable currents should be minimized by using radiation shielding and solid-dielectric cables in the irradiated region.
- Electrical and Electronic Equipment
- Nuclear Radiation Shielding, Protection and Safety