See the following references: https://ec.europa.eu/energy/sites/ener/files/documents/157.pdf

https://ec.europa.eu/energy/sites/ener/files/documents/122_part2.pdf

http://www-pub.iaea.org/MTCD/publications/PDF/Pub1213_web.pdf

http://www-pub.iaea.org/MTCD/publications/PDF/Pub1202_web.pdf

Florian Glodeanu,

Thank you so much for the important references you have provided above.  

I am already using/adopted the methodology in the book 'Practical Use of the Concepts of Clearance an Exemption-Part II. Application of the Concepts of Exemption and Clearance to Natural Radiation Sources. Radiation Protection No. 122...the one on that link https://ec.europa.eu/energy/sites/ener/files/documents/122_part2.pdf. 

I am not undestanding some of the values of the  equations for example Decay time for calculation of External Irradiation dose.

1. What is the Decay Time in this case? What can be the values for the Decay Time in this case?

2. How to change the Calculated Doses (µSv/a)/(kBq/kg) to exemption values in KBq/Kg?

3. Any clarification on the  procedure for rounding up the calculated values.

Those are the areas I want clarfication.

Thank you!!!

Dear Gamulani,

before give my opinion i would tell you that the references indicated by Dr. Glodenau are the best way to understand how to calculate CL level. Other important document is the RP135, but you can use it only to give the dose by liquid and gas effluent by NORM/TENORM activities.

About your questions:

A: you must know what radionuclides are present in your material and the concentration (Only Uranium? Or all elements of Uranium chain? And again, the elemento of uranium chain are in secular equilibrium?).

B: you must know what kind of exposure way at the radionuclides (external, internal, or both), time exposure

1)i'm not sure to understand the core of the question...but i try.  If you have a short half life radionuclide you can understand that the exposure decrease during the time...normally with NORM and TENORM you a have a continuous exposure...

2)The conversion factors (µSv/a)/(kBq/kg) are given by technical documents (ICRP, IAEA or in RP122 for example), you must use these values to determinate the effective dose. f you want change it...you must make studies to give the new conversion factors...

3) In my experience when i must give the effective dose by NORM or TENORM material i want know: radionuclides, secular euqilibrium, concentrations, exposure pathway understanding the scenario (transport, stock ecc...), exposure time and other factors. So i'm able to calculate the effective dose.

In RP122 you can use the table 2 (values or Sum index given by CL) if you have a concentrations, Bq/kg, of your materials, to understand if you have a effective dose < 0,3 mSv/y.

But you can create your scenario reading the RP122 part II §4-5-6.

Remember the radon/thoron inhalation of you work in indoor place...

Mattia Taroni,

Thank you so much for your explaination. In my project, I already worked out the radiounuclides, the exposure scenario and the exposure pathways involved. 

My main problem is to undestand what is the Decay Time (fdec) used in the formula for calculating Dose from External Exposure.  

This is the equation: Hext = Dext. te. fd. fdec

Where: 

Hext       individual annual dose from external irradiation per kBq/kg,

Dext       average dose rate during the exposure year.

te          exposure time 

fd          dilution factor for the NORM waste

fdec         decay time.

So what is the Decay Times (fdec) and how can we calculate/find the Decay Time???

On my other question number 2 'How to change the Calculated Doses (µSv/a)/(kBq/kg) to exemption values in KBq/Kg?'. I think the solution is dividing the Dose Criterion with the Calculated doses when finally deriving the exemption values.

On my question 3 on the procedure for rounding up the calculated values. I still need clarification on this. 

I hope I have made my questions clear.

Please your assistance is always appreciated.

Best regards,