Third Symposium on Use of Nuclear Techniques in Environmental Studies
Download
1 / 18

Design of Radon Surveys, Data Interpretation and Measurement of Equilibrium Factor - PowerPoint PPT Presentation


  • 122 Views
  • Uploaded on

Third Symposium on Use of Nuclear Techniques in Environmental Studies CTAPS, Yarmouk University, Irbid, Jordan. Design of Radon Surveys, Data Interpretation and Measurement of Equilibrium Factor. Lluís Font. Grup de Física de les Radiacions Edifici Cc. Universitat Autònoma de Barcelona. Spain.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Design of Radon Surveys, Data Interpretation and Measurement of Equilibrium Factor' - edolie


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

Third Symposium on Use of Nuclear Techniques in Environmental Studies

CTAPS, Yarmouk University, Irbid, Jordan

Design of Radon Surveys, Data Interpretation and Measurement of Equilibrium Factor

Lluís Font. Grup de Física de les Radiacions

Edifici Cc. Universitat Autònoma de Barcelona. Spain


Third Symposium on Use of Nuclear Techniques in Environmental Studies

CTAPS, Yarmouk University, Irbid, Jordan

Contents

Radon surveys: design and data interpretation

The long-term measurement of the equilibrium factor


Third Symposium on Use of Nuclear Techniques in Environmental Studies

CTAPS, Yarmouk University, Irbid, Jordan

Radon surveys

The design of the radon survey strongly depends on the main goal:

  • To obtain the annual averaged dose.

  • To identify radon prone areas or houses.

  • To check the usefulness of a given detection technique.

  • To set up the methodology (to be used in a larger survey)

The results obtained have to be interpreted according to the main

goal of the survey

The dosemeter used has to be well calibrated. Intercomparison

exercises.


Third Symposium on Use of Nuclear Techniques in Environmental Studies

CTAPS, Yarmouk University, Irbid, Jordan

Radon surveys

Elements of a survey design

Type of dosemeter

Exposure time

Selection of houses. Information to the inhabitants.

Procedure for installing and collecting the dosemeters


As long as possible! Environmental Studies

The whole year is the best option.

Installation/collection in the living room and bedrooms of the houses by trained people.

Third Symposium on Use of Nuclear Techniques in Environmental Studies

CTAPS, Yarmouk University, Irbid, Jordan

Radon surveys

If the main goal is to obtain the annual average of indoor radon levels:

Passive. Nuclear Track Detector (NTD) of closed type

Dosimeter type

Exposure time

  • According to the distribution of population

  • Randomly (for big sampling)

  • Taking into account census data

  • 1 in 10000 of the housing stock (UNSCEAR,93)

  • Information sheet to the inhabitants

Selection of houses.

Information

Procedure


Third Symposium on Use of Nuclear Techniques in Environmental Studies

CTAPS, Yarmouk University, Irbid, Jordan

Radon surveys

If the main goal is to identify radon prone areas or houses:

Any: NTDs, charcoal cannisters, grab sampling, etc.

Dosimeter type

From few hours to several months

Short-term may require confirmation

Exposure time

According to the distribution of population and to any geologycal, industrial, etc. reason that may suggest the possibility of high radon levels.

Information sheet to the inhabitants

Selection of houses.

Information

Procedure

Installation/collection in the living room and bedrooms of the houses by trained people.

Installation in basements, low-ventilated areas


Third Symposium on Use of Nuclear Techniques in Environmental Studies

CTAPS, Yarmouk University, Irbid, Jordan

Radon surveys

If the main goal is to check the usefulness of a given detector:

The one that has to be tested

Other types if possible

Dosimeter type

Exposure time

According to the dosimeter type(s) used

According to the distribution of population.

Among known people is also possible (optimum losses)

Information sheet to the inhabitants

Selection of houses.

Information

Procedure

Installation/collection in the living room and bedrooms of the houses by trained people.

Installation in basements, low-ventilated areas


Third Symposium on Use of Nuclear Techniques in Environmental Studies

CTAPS, Yarmouk University, Irbid, Jordan

Radon surveys

If the main goal is to set up the methodology

The one that will be used

Other types if possible

Dosimeter type

Exposure time

Different exposure times (to avoid saturation)

According to the distribution of population.

Among known people is also possible (optimum losses)

Information sheet to the inhabitants

Selection of houses.

Information

Procedure

Installation/collection in the living room and bedrooms of the houses by trained people.

Installation in basements, low-ventilated areas


Third Symposium on Use of Nuclear Techniques in Environmental Studies

CTAPS, Yarmouk University, Irbid, Jordan

Radon surveys

Interpretation of the results obtained

Fit to a lognormal distribution

Be cautious. Before getting a conclusion:

Did you check any other explanation to your findings?

Rely on your own results when possible.

Did you check if seasonal variations are important?

Do not be too ambitious. Look for the conclusions related to the goals of your survey and that can be demonstrated from your experimental results.


Third Symposium on Use of Nuclear Techniques in Environmental Studies

CTAPS, Yarmouk University, Irbid, Jordan

Equilibrium factor measurement

The equilibrium factor

The equilibrium factor between radon and radon daughters is defined as:

where Ceq is the equilibrium-equivalent radon concentration.

It can be obtained from the expression:

where

is the disequilibrium degree of the i daughter


Third Symposium on Use of Nuclear Techniques in Environmental Studies

CTAPS, Yarmouk University, Irbid, Jordan

Equilibrium factor measurement

Interest

The measurement of the equilibrium factor is a direct measurement of the PAEC, which is related to the dose received.

Most of the equilibrium factor measurements have been carried out with active detectors. No possibility of using them in radon surveys

The results obtained show high variations on F values

In the conversion factor from radon concentration to dose, a mean value of F = 0.4 is assumed.

Measuring F with NTDs will mean going one step further in the dose estimation.


Third Symposium on Use of Nuclear Techniques in Environmental Studies

CTAPS, Yarmouk University, Irbid, Jordan

Equilibrium factor measurement

Review of existing passive methods

Conventional

Frank and Benton Nucl. Track Det. 1 149 (1977)

One NTD within a diffusion chamber

One NTD open

214Po method

Dörschel and Piesch. Radiat. Prot. Dosim.48, 145 (1993)

One NTD within a diffusion chamber

One NTD open

Assuming ventilation rate as the only free parameter


Third Symposium on Use of Nuclear Techniques in Environmental Studies

CTAPS, Yarmouk University, Irbid, Jordan

Equilibrium factor measurement

Review of existing passive methods

The measurement of the equilibrium factor by means of NTDs is problematical:

Out of 30 measurements carried out by 5 passive detectors, only one result agreed with those obtained with active measuring systems.

Miles et al. Results of the 1995 European Comission intercomparison of passive radon detectors, European Comission, Directorate-General XII, Report EUR 16949 (1996).

However, the conventional or the Po-214 methods are being used to estimate equilibrium factor in some radon surveys.


Third Symposium on Use of Nuclear Techniques in Environmental Studies

CTAPS, Yarmouk University, Irbid, Jordan

Equilibrium factor measurement

The concept of the Reduced Equilibrium Factor

Amgarou, Font and Baixeras Nucl. Instr. and Meth. A 506, 186-198 (2003)

Some more previous definitions

u and a for unattached and attached to the airborne aerosol particles respectively

and

li (decay constant), pi-1 (recoil factor or desorption probability), la (attachment rate) ld (deposition rate)


Third Symposium on Use of Nuclear Techniques in Environmental Studies

CTAPS, Yarmouk University, Irbid, Jordan

Equilibrium factor measurement

The concept of the Reduced Equilibrium Factor


It is possible to measure Environmental StudiesF with a good accuracy if independent measurements of Po-218 and Po-214 are carried out.

Third Symposium on Use of Nuclear Techniques in Environmental Studies

CTAPS, Yarmouk University, Irbid, Jordan

Equilibrium factor measurement

The concept of the Reduced Equilibrium Factor


Third Symposium on Use of Nuclear Techniques in Environmental Studies

CTAPS, Yarmouk University, Irbid, Jordan

Equilibrium factor measurement

Comparison with experimental results

From Reineking and Porstendörfer Health Phys. 58, 715 (1990)

Concentration values in Bq/m3


Third Symposium on Use of Nuclear Techniques in Environmental Studies

CTAPS, Yarmouk University, Irbid, Jordan

Equilibrium factor measurement

How to measure Po-214 and Po-218 with NTDs?

Open question.

Some kind of alpha spectrometry is required:

- Electrochemical etching

- Measurements of alpha-track geometry.

A multi-component dosimeter has been set up in our group to measure independently 222Rn, 214Po and 218Po consisting of 3 Makrofol foils: 1 enclosed within the Fzk diffusion chamber and 2 open. It is being currently tested.

If you try it,…..GOOD LUCK!!


ad