HOW TO PMCS AND OPERATE RADIOLOGICAL DETECTOR

STANDARDS: Be able to perform a PMCS and operate AN/VDR-2 Radiac Set. Prepare Radiac Set in accordance with TM and stating the contamination reading obtained from an area survey, personnel monitoring, and equipment monitoring.

      DESCRIPTION: 1. Use to locate and measure gamma and beta particles.

2. Lightweight, battery operated, and self testing.

3. Measurement is in Gy (unit of Gray) 4. cGy - centigray, Gy – Gray, and uGy – microgray.

5. Negligible risk factor is 1 cGy.

 WARNING!!!!

• The high range detector contains one (1) nanocurie of Thorium (th) 232, and is controlled by U.S. Army Reg. 385-11.

    RADIACMETER PROBE POUCH STRAP

    1. Detects, measures, and displays level of gamma radiation dose rate from .01 uGy/hr to 100 Gy/hr.

2. Detects and displays level of beta particles dose-rate from .01 uGy/hr to 5 Gy/hr.

3. Measures, stores, and displays accumulated dose (total dose) from .01 uGy to9.99 Gy.

4. Flashing display to indicate reduced accuracy condition when measuring dose rate from 10 Gy/hr.

 1. Liquid Crystal Display (LCD): • • 3 digits decimal point Unit of measurement   • Indicates low batteries or fault 2. Can be vehicle mounted 3. Audible or visual alarm independently preset for dose rate and accumulated dose.

   1. Main power- 3 ea (9 volt batteries).

2. Vehicle power- 24 VDC.

3. Main power battery life- 100 hrs.

 Will retain memory for 5 min. after batteries are removed.

3- 9 volt batteries

    1. Low battery indicator (flashing/hr).

2. Decimal indicators.

3. Digits.

4. Dose units.

 Routine Checks: • • • • • A. All cables.

B. Loose or broken lights or covers.

C. Inspect panel.

D. Remove all foreign debris.

E. Inspect batteries and compartment.

    1. The AN/VDR-2 must be turned off when disconnecting/charging probes or batteries.

2. Install batteries.

3. Install meter in pouch.

4. Conduct pre-operational test.

    1. Set power to ON.

2. Set ALM to AUD.

3. Press and hold CLR/TEST button until alarm sounds for 2 seconds, then release.

4. When the segment displays, insure it is exactly as shown.

0.00 uGy

11.1 uGy 222 uGy .333 cGy 4.44 cGy

55.5 cGy

666 cGy 77.7 Gy 888 Gy 999 Gy

      5. Set ALM to off, then VIS. The dose rate lights will come on.

6. Once the segment test is complete the unit will automatically go through the unit/digit test and electrical test.

7. If all tests are ok, you will see a flashing “9”.

8. If there is a fault, you will see a flashing “8”.

9. Once you see the flashing “9”, press the CLR/TEST button.

10. Tests are complete.

 1. Surveying for beta/gamma contamination.

• • A. Stand in an open area, 10 meters from any shielding objects.

B. Hold unit waist high.

• • C. Slowly turn in a full circle.

D. Record highest reading received.

 There are 2 types of monitoring procedures.

• •  Direct Outside of any shielding objects.

 Indirect Stand in middle of room or area and do testing.

Step 1 (b) ° °

 Simplest and most precise type of monitoring.

 Consists of unshielded dose rate readings.

 Used when conditions and Operational Exposure Guidance (OEG) permit

360 ° Step 2 (b) Center

 Measure dose rates within an area shielded from radiation.

 Allows the unit to measure radiation levels and still keep exposure to a minimum.

 Preferred method when operating in a contaminated area.

 2. Determining Background Radiation.

• • • • • • A. Turn or walk away from the suspected contamination.

B. Open beta shield.

C. Observe reading for 5-10 sec. Record highest reading.

D. Multiply by 2.

E. If the reading is twice background or higher, contamination is present.

F. Report the results.

 4. Monitoring personnel.

• • • • • A. Take background.

B. Have the person being monitored stand with feet apart, and arms extended with palms upward.

C. Hold probe 1 inch from personnel.

D.. Pass over entire body, starting with the head.

E. Any reading above the background is contaminated.

Contamination: Before something can be considered contaminated, a reading 2 times higher than the background must be obtained.

 Your background reading is 2 uGy/hr; multiply by 2 which gives you 4uGy/hr. Your open shield reading is 3 uGy/hr and the closed shield reading is 3 uGy/hr . Both readings were not twice the background, therefore. No contamination is present.

 Beta Only • Your background reading is .2 uGy/hr times 2 is .4 uGy/hr. Your open shield reading is 2.5 uGy/hr which is more than twice the background reading. The closed shield reading is .2 uGy/hr. It is not twice the background, therefore, you have beta only.

 Both Beta & Gamma Contamination • Your background reading is .2 uGy/hr times 2 is .4 uGy/hr. Your open shield reading is 3.4 uGy/hr which is more than twice the background reading. The closed shield reading is 2.2 uGy/hr. It is also twice the background. Therefore, you have both beta and gamma radiation present.

QUESTIONS??