~a we eT Rees wee neem ee wm mE = aa . “ - C corr i= paraffin. No particular troubles were encountered with these units, and, although they were used very little, they performed quite satisfactorily after calibration. 2.9.5 ate wee Laboratory Instruments These instruments, in general, included six Nuclear Instrument and Chemical Corp. scaling units with standard accessories (two equipped with gas flow alpha chambers) as well as two General Radio Co. counting rate meters and three Esterline-Angus Co., Inc., recorders. The instruments performed quite satisfactorily for this operation, although it was necessary to remove moisture from alpha chamber helium gas by passing it through chilled absolute alcohol before introducing it into the chamber. No major servicing was required other than an occasional ATION dosimeter. These two instruments were com- bined to form a single unit with one indicating meter. In operation, the meter normally in- dicates instantaneous intensities. However, at any time, a push button mounted on the handle may be pressed, and the meter will indicate the cumulative dose. This instrument proved to be most convenient and useful. Attention should be given to the production of similar models, perhaps built around different rate meter circuits and with dosimeter chambers having higher ranges than 200 mr, although the chamber may be charged at will. Also, a minimum of controls should be considered. Instruments of several types were supplied controls in the preamplifier of the alpha scaler. which were not used in this operation. In all cases they were left over from Operation Sandstone. They included Victoreen 356 alpha survey instruments, Beckman MX-7 pocket alarms, Cambridge 17609 chargers, etc. 2.9.6 2.9.7 tube replacement and changes to wire wound Special Instruments The only instruments supplied which were sensitive to beta radiation were low range Geiger tube units. A need for readings of beta intensities of a much higher order was found necessary, and for this purpose a modification of an AN/PDR-T1B instrument was made. An opening in the case below the chamber was made and covered with thin aluminum foil. Mechanical protection was provided by a protective wide mesh screen. The bottom of the General Comments At the start of this operation there was an inadequate supply of spare parts, as well as batteries, and some trouble was experienced in obtaining them. Delays in battery shipments were responsible for trouble with the Radiac training sets, but sufficient quantities were available later on. In general, sufficient num- plastic chamber was removed and replaced by bers of hand tools and supplies were available after the operation got under way, but at the start difficulty was experienced in obtaining them. It is suggested that future operations bration this instrument proved to be an excel- include some small power tools such as a grinder, drill press, small lathe, etc. These a thin Aquadag-coated plastic sheet. After calilent field survey meter for beta, with quite a linear response. To fill the need for a meter to measure 35-kv X rays, a 247A ion chamber instrument was employed, and an opening was cut in the case in front of the chamber. This opening was covered with a thin aluminum sheet and protected with a wide mesh screen. This modified instrument worked quite satisfactorily for the purpose for which it was intended. It is thought that, for convenience in monitoring, an instrument which would read both in- Stantaneous intensities of radiation as well as cumulative dose would be valuable. With this in mind, such an instrument was constructed. A 247A survey meter was used as the basis for the rate meter, and a Victoreen model 300 Proteximeter was used as the basis-for the “remy katie tier Te Tee were not available. It is suggested for future operations that the instrument laboratory be set up and staffed, instruments be unpacked and placed in operating condition, and a calibration range be set up be- fore monitors arrive. It is further suggested that all personnel in the instrument laboratory be given an oportunity to inspect all instru- ments to be used and to become familiar with them before the field operation starts. They should at least be given a list of instruments in advance along with instruction books describing their construction. In conclusion, it might be said that work in the instrument laboratory proceeded more efficiently and with less trouble by far than in any other operation with which the writer has ‘been associated. This probably was in great een ca eee WS Greener TORRENS Bedhhell aed TION