A. PRS-1 When the PRS-1 is operated in the ratemeter mode with the calibration factor enabled the dpm detected by the probe will be multiplied by a Calibration Factor, This process allows epm detected to be converted to and displayed in more useful units such as mR/h, dpm or 27 dpm (impinging cpm). It is important to understand the unit's disintegration per minute (dpm) and counts per minute (epm). An activity level is measured in pCi or dpm. One dpm equals 2.22 times the number of pCi. The amount of radiation emitted in the 2n direction is labeled the impinging epm. The number of counts detected by a given probe is labeled "Detected epm." Detected epm divided by impinging epm is the probe efficiency. The reciprocal of probe efficiency is the PRS-1 Calibration Factor (CF). Perform the following procedure at three-month intervals (using the MP-1 Mini Pulser): 1. Inspect and clean the input connector as necessary and put calibration switch to OUT. 2. Using an electrostatic voltmeter verify that the PRS-1 HV is within +5% of the indicated value at 500, 1000 and 1400 volts. 3. Check the Battery OK circuit. Battery OK must be ON at 5.75 volts and OFF at 5.6 volts. 4. Check for proper operation of all display legend switches. 5. In the PHA mode with the threshold and window both set to 1.00 and HV set to minimum, check that pulse amplitudes between approximately 12 and 24 mV are detected. 6. Check the A, B, C and D ratemeter scales at 1000 epm. 7. Check the 0.5-, 1-, 2- and 5-minute scaler pre-set times. 8. Check the Manual, Stop and Reset functions for operation. Note on Probe Calibration: The HV indications of the PRS-1 used for calibrating probes must be calibrated immediately prior to use. Unless otherwise noted, set PRS-1 controls as follows for the calibration of probes: PHA—Gross Threshold Window Calib. Gross 1.00 1.00 Out It is assumed that rate multiplier boards will be installed in all PRS-1's, B. AC-3 General: The AC-3 probe is a large area alpha scintillation probe that is useful as a personnel and equipment survey instrument and for obtaining a preliminary estimate of alpha activity in soil. A-29-3