LIMITATIONS OF RADIAC INSTRUMENTS

Remember that although we have radiac equipment to detect and measure nuclear radiation, these instruments do have some limitations.

None of these instruments is capable of detecting and measuring alpha, beta, gamma, and neutron radiation at the same time. Even those that can detect both beta and gamma radiation do not automatically separate these two types of radiation for us. Instead, the operator keeps beta particles from entering the chamber by manually pulling a beta shield over the thin window in order to get a gamma reading only. Otherwise, you would get a combined reading. A separate instrument is used to measure alpha radiation.

CALIBRATION AND REPAIR OF RADIAC EQUIPMENT

Radiac equipment aboard ship is checked as required by the Ships' Maintenance and Material Management (3-M) Manual. Ashore, radiac equipment is checked at least once each month or at intervals specified by the applicable technical manual. This check is accomplished in accordance with instructions contained in the operator's section of the technical manual.

Radiac equipment must be temporarily transferred at regular intervals by shore activities to a radiac repair facility for maintenance and calibration. Ships, as far as practical within their operating schedules, also must transfer their radiac instruments to repair facilities for maintenance and calibration. When equipment requiring outside maintenance is found to be inoperative or is suspected of malfunctioning, it should be sent to the radiac repair facility immediately.

Routine maintenance should be performed on the radiac equipment as described in its technical manual. (See also any appropriate directives.) You may change the radiac's batteries if they are weak. However, changing batteries does not eliminate the need for routine maintenance. Some of these

Figure 8-17.-Cutaway diagram of an IM-143/PD pocket dosimeter. 8-21

instruments have complicated electronic circuits that may carry high voltages. Other instruments contain radioactive material inside that presents a potential hazard to untrained personnel who take them apart. All radiac equipment that operates on direct current is designed so you can replace the batteries without exposing the internal circuitry or making the radiation hazard more dangerous.

The following checks should be made at least monthly:

Battery check.

Function check.

Ensure instrument is turned off.

Ensure instrument is stored in cool. dry place. (Air-conditioning is not a requirement.)