ae te ate BB igen te + SSepeeny CHAPTER 6 LABORATORY GROUP The laboratory procured, repaired, and maintained various radiological-safety instruments for the Task Group and furnished technical assistance to the instrument-repair stations of the Army, Navy, and Air Force task groups. It also processed and recorded film -badge exposures for all JTF 132 personnel. In addition it collected, interpreted, and disseminated radiochemical data for radiological~safety operations and documentation. 6.1 . WARY EReee get Ne : ELECTRONICS SECTION The instrument-repair shop was located in the Rad-Safe Building on Parry Island when the Unit was ashore and in the Aviation Electronics Workshop when the Unit was aboard the USS Rendova. The monitoring load fell on 50 TIB instruments that were on loan from AFSWP, These instruments had previously been switch modified at the Nevada Proving Grounds. This switch modification consisted in replacing the “leaf” type switch with a “two-wafer” rotary switch. Also, a flexible coupling was installed on the switch shaft between the electrometer section of the switch and the switch wafers. In addition, the electrometer section of the switch had the porcelain fingers between contacts removed and the electrometer switch rotor fastened to the shaft by means of a lucite ring. This eliminated switching transients resulting from change in scale. Attempts to modify the electrometer switch wafers during this operation met with moderate success. One feature of significance was noted, j.e., the flexible shaft coupling is required to provide maximum stability and ‘reedom from transients. The solid shaft extending to the switching knob from the electrometer switch wafer results in transients when handling the in- erroee apaarenyPER]TE SL” Raei erteata strument case. Major failures were experienced with the electrical meter movement. Of the 25 instruments consistently used in the field, 18 meter replacements were required. Minor failures of the lucite screw mounts, holding the chamber and electrometercircuit to the instrument panel, were noted. When the instrument was dropped or jarred, the lucite screw mounts carried away. It was necessary to; covide metal stops from the panel tv the chamber and to the electrometer e circuit section to maintain maximum stability. No major difficulties were experienced with the MX-5 instcuments used for personnel monitoring and decontamination work. Several light-sensitive Geiger-Mueller (G-M) tubes were corrected. vee The new lightweight type of ion-chamber instrument, IM-71/PD(XE-1),called the “Jas- wogte per,” sponsored by the Army Signal Corps, initially developed humidity leaks but, after repair, functioned satisfactorily and was used as a replacement for the T1B. One T1B was modified by cutting cut a portion of the metal box and replacing the portion with aluminum foil: This permitted high-range measurement of the low-energy radiation, 4 eeete + eneee eect: dni taierh titan Ay carteonot 29