~3~3 d X 3S,LN V NO dFU3 SLE I-X-3XN SECTION I INTRODUCTIONThis report is a compilation of two previous sets of pretest calculations, references 1 and 2 and the grounding and shielding report, reference 3. The calculations performed in reference 1 were made for the baseline system, with the instrumentation trailers not isolated from ground, and wider ranges of ground conductivity were considered. This was used to develop the grounding and shielding plan included in the appendix. The final pretest calculations of reference 2 were performed for the modified system with isolated trailers, and with a better knowledge of the ground conductivity.The basic driving mechanism for currents in the model is the motion of Compton electrons, driven by gamma rays, in the air gaps and soil. Most of the Compton current is balanced by conduction current which returns directly along the path of the Compton electron, but a small fraction will return by circuitous paths involving current flow on conductors, including the uphole cables.The calculation of the currents is done in a two step process -first the voltages in the ground near the conducting metallic structures is calculated without considering the presence of the structures. These are then used as open circuit drivers for an electrical model of the conductors which is obtained from loop integrals of Maxwell's equations. The model which is used is a transmission line model, similar to those which have been used to calculate EMP currents on buried and overhead cables in other situations, including previous underground tests, although on much shorter distance and time scales, and with more controlled geometries. The behavior of air gaps between the conducting structure and the walls of the drift is calculated using an air chemistry model which determines the electron and ion densities and uses them to calculate the air conductivity across the gap.Section II of this report discusses the EMP driver terms, and basic physical parameters of the air and soil models. Section HI discusses the basis of the transmission line electrical model, including the special models which had to be developed to account for the air gaps, rockbolts and isolated trailers. In section IV, the calculational results are presented, including both the scoping calculations of reference 1 and the pretest calculations of reference 2. In this section, the pretest predictions are also compared with the experimental data. DISCLAIMERThis report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thmeof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not ...
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