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Typical questions about measurement services

Here we have tried to answer the most common questions about our radiation measurement services.

Typical questions about measurement services

Typical questions about calibration
What is calibration?back to top

Calibration is the process of checking an instrument to ensure that it complies with the manufacturer's specification i.e. that it properly measures the radiation level to which it is exposed. This involves exposing the instrument to varying types and doses of radiation.

How is it done?back to top

Calibration of a radiation measurement instrument is carried out by taking a reading of a precise and known quantity of radiation which is traceable to international standards. Readings are compared to manufacturer’s specifications to ensure the instrument is functioning correctly.

Who is responsible for calibration?back to top

 All businesses and practices which are licensed to use sources of ionising radiation are obliged by law (Statutory Instrument 125 of 2000) to ensure measuring instruments are accurately calibrated. They must also be regularly checked to ensure that they are serviceable, and that they are being correctly used.

How frequently does my instrument need calibration?back to top

 Under Irish law, (SI 125 of 2000) radiation measurement instruments must be individually calibrated before first use and annually thereafter to ensure that they are in full working order. They should also be calibrated after any repair is carried out.

What instruments do you calibrate?back to top

The RPII’s Calibration Service calibrates all the most commonly-used radiation measurement instruments in Ireland, namely:

  • Surface Contamination Monitors
  • Gamma and X-Ray Survey Meters
  • External Doserate Monitors
  • Electronic Personal Dosemeters
  • Personal Alarms
  • Quartz Fibre Dosemeters.
How do I arrange a calibration?back to top

Please contact the Calibration Service in advance to arrange a suitable date for calibration. Download the application form and send it to us with the instrument for calibration.

You will be asked to supply contact details, delivery address for return of the instrument, and preferred payment method. You will also be asked to supply some details about the instrument(s) to be calibrated and your exact requirements.

For further information you can contact us directly at the RPII Calibration Service.

Where do I send the instrument?back to top

The instrument should be sent by courier in a suitable container, or personally delivered to the RPII Calibration Service.

Can I deliver the instrument by post?back to top

If the instrument is sent to us by post, it should be suitably packaged to prevent damage during transportation. It should also be prominently labelled with the words FRAGILE ELECTRONIC INSTRUMENT, or similar.

Do I receive a certificate to confirm the calibration?back to top

 A calibration certificate is returned along with the calibrated instrument.

How much does it cost to get an instrument calibrated?back to top

Find out more in Calibration Services

Can I pay by credit card?back to top

Yes, you can pay by credit card, cheque or postal order or you may provide a purchase order number for invoicing.

Can I buy a radiation measuring instrument from the RPII?back to top

The RPII does not sell radiation measurement or protection instruments.

Do you repair damaged or broken instruments? back to top

The RPII does not carry out repairs of electronic equipment. However, we are happy to advise you about possible solutions.

Typical questions about dosimetry
What is dosimetry?back to top

Dosimetry is the science of tracking and monitoring exposure to ionising radiation. 

It is used to monitor and measure the radiation dose received by people who work with ionising radiation.

How are radiation doses measured?back to top

The build-up of radiation in the human body, or in parts of the human body, is measured with a small device called a dosemeter, usually worn on the outer clothing in the form of a badge or film strip. They contain highly sensitive elements that measure the total amount of radiation to which the dosemeter has been exposed.

Do dosemeters only measure quantity of radiation?back to top

Some dosemeters are more sophisticated. As well as measuring quantity of radiation, these use special filters to measure the type of radiation (i.e. beta or gamma), and whether the energy emitted is high or low.

What types of dosemeter does the RPII supply?back to top

 The RPII supplies and processes the results of three types of dosemeter 

  • Wholebody Thermoluminescent Dosemeters (whole body TLD)
  • Extremity Thermoluminescent Dosemeters (extremity TLD)
  • Neutron Monitoring (PADC) Dosemeters. 
What are the differences between them?back to top

The wholebody TLD combines four elements and is used to measure not just the quantity, but also the type of radiation received. The extremity TLD consists of just one element and is specifically designed to monitor radiation to extremities, such as hands and feet. The PADC Dosemeter is insensitive to X-rays, gamma rays and beta radiation, and is used only to monitor radiation from neutrons.

How is the reading taken?back to top

The word ‘thermoluminescent’ derives from the ancient Greek words thermos and lumen, which mean heat and light. When crystalline materials are exposed to ionising radiation, then heated, they emit light. The basic element of a TLD comprises a sensitive crystal. When heated, the intensity of the light from the crystal reveals the quantity of energy which it has absorbed through exposure to radiation.

How accurate is the reading?back to top

All radiation dosemeters record a small quantity of background radiation. Background radiation is subtracted from the dosemeter reading. Reported doses of up to 0.3 millisieverts (mSv) can be seen on TLDs even when no dose has been received. This is due to the varying quantities of background radiation measured on the TLD.

At what level of radiation reading should advice be sought?back to top

If a dosemeter gives an unexpected net reading of 0.5 mSv or higher (after adjustment for background radiation) you may wish to telephone us for advice. You may also want to contact us as a precaution if one of your dosemeters regularly registers a significantly higher reading than the others (even if it is below 0.5 mSv).

What are the legal dose limits?back to top

The dose limit for an exposed worker over 18 years old is 20 mSv in any 12-month period. For those aged 16 to 18, the limit is 6 mSv in any given calendar year. For a member of the public, the legal dose limit is 1 mSv over one year.

Which workers are legally obliged to be monitored for radiation?back to top

Under Irish law (Statutory Instrument 125 of 2000), all exposed workers and students must be monitored for radiation by an approved dosimetry service or, as appropriate, by an approved radon measurement laboratory.  Workers who are likely to receive an effective dose greater than 6 mSv in a period of 12 months are designated ‘category A workers’. For this category of employee, personal monitoring and medical surveillance are compulsory.

Typical questions about certification
Do I need to send a sample for testing before I can get my certificate?back to top

This depends on whether you have previously had samples analysed and on the requirements of the importing country. You should contact our certification office and they will tell you.

How much does a product certificate cost?back to top

The current cost for the preparation and issue of a Certificate of Radioactivity Measurement provided in our Radiation Monitoring Services Price List. Any changes to previously issued certificates are charged at the same rate.

How much does it cost to have a sample analysed?back to top

The costs for sample analysis are provided in our Radiation Monitoring Services Price List. Unless otherwise specified, all samples received will be analysed by gamma spectroscopy for caesium-137 and caesium-134. 

How much sample do I have to send for testing?back to top

Where possible, 500g of sample is required for analysis. For meat and fish samples, a minimum of 300g of edible sample is required. Unless otherwise specified, all samples received will be analysed by gamma spectroscopy for caesium-137 and caesium-134. A test report detailing the activities of these radionuclides will be issued.

What information do I need to supply with my sample?back to top

You will need to fill out an Sample Analysis Request Form which requires

  • Your name and full contact details
  • A purchase order number
  • Information on the sample type being submitted
  • A unique batch or production code for each sample sent.
When can I expect results?back to top

We aim to get the analysis results back to you within seven working days.

When can I expect a Certificate of Radioactivity Measurement?back to top

Assuming there is no sample analysis required, and the RPII has all the correct information, we aim to get a Certificate of Measurement to you within three working days.

I have a query regarding my Certificate of Radioactivity Measurementback to top

Please do not hesitate to contact our certification office.

If your query has not been answered by our website, please do not hesitate to contact us.