radiation safety training survey meters.pps

7/29/2019 Radiation safety training survey meters.pps

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Radiation Safety TrainingSurvey Meter Use

Washington State University

Radiation Safety Office


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What is a Survey Meter?

A survey meter is a portable handheld, electronicinstrument used to detect radiation, often called aGeiger counter.


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Choosing a Survey Meter

Portable survey instruments can be very useful inaiding workers in locating radioactive contamination.However, the type of detector (or probe) must be

chosen according to the kind of radioactive materialthat is being used.


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Choosing a Survey Meter(cont.)

Generally, thin window Geiger-Mueller (GM) probesare best suited to detect beta radiation with energiesabove 70 keV

while sodium iodide (NaI) scintillators are best for

gamma radiation.


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Choosing a Survey Meter(cont.)

Radioisotope Half-life PrincipalEmission

Average Energy(KeV)

Hand-heldinstrument.

H-3 12 years Beta 18.6 None

C-14 5730 years Beta 157 Geiger-Mueller (GM)

P-32 14 days Beta 1709 Geiger-Mueller (GM)

P-33 24.4 days Beta 249 Geiger-Mueller (GM)

S-35 83 days Beta 167 Geiger-Mueller (GM)

I-125 60 days Gamma 35 sodium iodide(NaI) scintillators

I-131 8 days Gamma 364 (NaI) or (GM)

Ensure that the probe you are using is capable of detecting

the isotope you are using. If you are unsure, consult with the

manufacturer, your Authorized User or the Radiation Safety

Office.


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Know Your Meter!

Unless you know exactly what you are measuring andunderstand the limitations of detection instruments, itis possible to draw misleading conclusions from yourreadings.


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Know Your Meter!

Here is one example. The radiation from some isotopes can cause a Geiger-

Mueller (GM) tube to overexcite and indicate a higher

level of radiation than is actually present. Americium241 is an example of this phenomenon.


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Know Your Meter!

Read the meter's operating manual to gainfamiliarity with the controls and operating

characteristics of your meter.


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Meter Parts.

The detector or probe is the device which produceselectrical signals when exposed to radiation. It usuallyhas a window through which radiation can penetrateits cavity.


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Meter Parts. (Cont.)

The dial or readout is the gauge which indicates the

amount of radiation exposure present. It often has twoscales, mR/hr and/or CPM. The selector switch is aswitch to turn the meter on-off, check the meterbatteries, and/or select a scale multiplier.


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The reset button allows the meter reading to be zeroed.

When the level of radiation or the number of countsexceeds the highest reading at a particular scale multiplier,switch the scale multiplier to a higher range and push thereset button. This causes the readout needle to reset to zero

so the user can accurately determine the count rate.


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The response button adjusts the response time of the

meter. When this switch is on F the meter will have afaster response but, the meter readings will be lessstable. For routine work set the response button to theslow mode S.


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The speaker is an audible device connected to the

radiation monitor. It may be located outside or insidethe meter and may have its own battery. The speaker isin-line with the detector so each count produces anaudible click on the speaker.


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Listen! Always use the instrument's audible response while

conducting surveys. The audible response is much fasterthan the meter indication. While scanning areas, listen tothe "clicks" of the instrument rather than relying on meterdeflection. What you are listening for is any increase in the

rate of "clicks" above normal background levels. When younote any increases, stop and scan that area morethoroughly. Any sustained increase above backgroundlevels should be investigated.


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Survey meter use.

1) Check the meter for any physical damage. Check thecord for damage or wear. Make sure the probe windowhas not been punctured.


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Survey meter use.

2) Before using your meter, check the calibration sticker.

Most meters are calibrated once a year. Be sure your meteris in calibration. If it is not, do not use it and contact theRadiation Safety Office.


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Survey meter use. 3) Perform a battery check. This is performed differently

on different meters. So please become familiar with yourmeter. Turn the selector switch to BATT position. Theneedle must be within BATT OK range. If not, the

batteries are weak and must be replaced.


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Survey meter use.

4) Check the background radiation levels. Remember

there is always background radiation. Record thebackground reading in the Survey Meter Quality

Assurance Notebook.


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Survey meter use. 5) Check your meters response to a known radiation

source. This meter has an attached check source. Ifyours does not, use the source in the meter notebook.


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Survey meter use.

Be sure the cover page of your note book is filled in properly.Every survey meter should have a Survey Meter Quality Assurance Notebook.

Fill in meter manufacturer and serial number.

Ludlum 3 111111111

44-9 22222222

Fill in probe model number and serial number.

Fill in Meter storage location.

Fulmer 123Fill in Authorized User or Equipment Coordinators name and

contact phone number and the same for an alternate contact.Arthur Dent

555-4242

Ford Prefect555-5883


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Survey meter use.

This is the Response Check Source page in the notebook.

Place the meter probe over the check source to get the

check source reading. Record this reading on the next page

of the notebook.


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Survey meter use.

Be sure the information has been filled in on this page. Meter

and serial number. Probe and serial number.

Ludlum 3 1111111111

44-9 222222222

The Expected response to check source, should have been

filled in by the Radiation Safety Office.

450

Record the date and your name.

1/1/11 Dr. Who

Verify the calibration status of the meter.Record the background reading and the response check reading.

50 450

The meter is now ready to be used for the radiation safety

survey.


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Survey meter use.

Use of Survey Meter review.

Check for Calibration Sticker

Check battery

Check background radiation

Check meter response to a known

radiation source.

Record the check source results and

background readings in the meter notebook.


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Start the Survey.

The detector's "window" (probe) should be held asclose as possible (within about 1 cm (1/2 ")) to thesurface being measured. Use extreme care to avoidactually touching surfaces and spreading radioactive

contamination to the detector. Remove plasticcoverings, if present, from the detector window as thiswill effectively shield out lower energy radiations andpreclude their detection.


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The Survey (Cont.)

Scan surfaces slowly enough to detect the presence oflow levels of radioactive contamination. Typically, therate of detector movement should not exceed about 1"

to 2" per second.


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The Survey (Cont.)

Ensure that you select the proper scale on theinstrument for conducting the survey. Wheneverscanning surfaces for radioactive contamination,always use the lowest scale (i.e., x0.1 or x1 scale)available. Select higher range scales as necessary toobtain maximum readings if contamination or othermeasurable radiation is detected.


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The Survey (Cont.)

Be sure to survey all areas of the lab. That have topotential for radioactive contamination and other areas

that you might not think are contaminated. Such as

Telephones, door knobs, and lab coat sleeves. Always

survey the bench tops, floors, and equipment used in the

experiment.

Everyone uses survey meters.


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Test Time!

Follow this link to the test.https://myresearch.wsu.edu

Use your WSU user name and password to sign in.

Click on the training tab.

Then click on the available training tab

Find the radiation safety training Survey Meters

course, in the OR section, click on it and take thetest.
https://myresearch.wsu.edu/https://myresearch.wsu.edu/

radiation safety training survey meters.pps

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