Type of neutron detector Proportional counter Type of signal cable Coaxial

Location of pulse preamplifier Source range detector thimble junction box Location of pulse amplifier Nuclear instrument cabinet Distance between pulse amplifier and preamplifier 1210 ft Distance between neutron detector and preamplifier 19 ft

Method of grounding A single point grounding system is used The grounding point is at the pulse-amplifier chassis. The pulse-amplifier chassis is grounded to the station grounding grid by bus bar and cable

Operating problems and modifications During preoperational checkout of the system, it was discovered that the majority of the coaxial connectors in the nuclear instrument system were assembled with poor workmanship The main problems were the preparation of the cable, the soldering of the pins, and the assembly of the connectors Many hours of rework were required to correct the problems When the system was put in operation, the source-range channels were very noisy, a check of the system revealed that induced voltage was causing ripple on the + 15-volt power supply to the preamplifier The leads carrying the + 15-volt power supply were changed from nonshielded to shielded conductors, which improved the condition but did not eliminate ripple sufficiently to not affect the operation of the source-range channels A RL filter was designed and installed at the preamplifier in the+15-volt supply This filter removed the ripple and corrected the noise problem