Factors Affecting Survey Instruments (6)

Question 1

Radiographic work should never be performed without a…

Answer 1

working, calibrated radiation survey meter.

Question 2

without a survey meter there would be no means of…

Answer 2

ensuring that the radiation source is in the fully shielded position

Question 3

Regulation for Troubleshooting Survey Meters

Answer 3

• battery check
  “all radiation survey meters must have some means of checking battery levels or strength prior to an during all radiographic work,”
  (NSRD: section 30.3 (a) (i) and (ii))

Question 4

Troubleshooting Survey Meters

Answer 4

• weak or dead batteries (last 100-200hours)
• short circuit from dirt, water or damage
• Extreme weather (-40°)
• expired or close to expired batteries
• loose wiring
• G-M tube can break (Geiger Mueller type)
• battery connections can come off
• intricate parts can be broken
• cracked casing
• salt causing corrosion
• chemical corrosion

Question 5

Remember, that meter is your…

Answer 5

lifeline and the most important piece of CEDO equipment!

Question 6

Calibration of survey meters regulation

Answer 6

NSRD: Section 31.1 (a) and 20
“Every survey meter used for radiography must have a legible label showing the last calibration date and a valid and current calibration certificate.

Question 7

How are meter calibrations performed?

Answer 7

Qualified personnel at a CNSC approved calibration facility.

• use of a known dose rate radiation source, meter is placed nearby and exposed.
• compare meter reading to known/true dose rate and make changes as needed.
• each range is calibrated independently, at two points on each range 1/4 full scale and 3/4 full scale, distance should be about 50%