AS 2365.4-1995

1 - AS 2365.4-1995 METHODS FOR SAMPLING AND ANALYSIS OF INDOOR AIR - DETERMINATION OF RADON
1 - PREFACE
1 - CONTENTS
2 - FOREWORD
4 - METHOD
4 - SECTION 1 SCOPE AND GENERAL
4 - 1.1 SCOPE
4 - 1.2 PRINCIPLE
4 - 1.2.1 Method A
5 - 1.2.2 Method B
5 - 1.2.3 Method C
5 - 1.3 REFERENCED DOCUMENT
6 - SECTION 2 COLLECTION IN SCINTILLATION CELLS AND MEASUREMENT OF ALPHA ACTIVITY (METHOD A)
6 - 2.1 APPARATUS
6 - 2.1.1 Scintillation cell
6 - 2.1.2 Vacuum pump
6 - 2.1.3 Photomultiplier tube (PMT)
6 - 2.1.4 Light-tight enclosure
6 - 2.1.5 Reference radon chamber or standard radium source
6 - 2.2 PROCEDURE
6 - 2.2.1 Calibration of scintillation cell
6 - 2.2.2 Sample collection
7 - 2.2.3 Measurement of alpha activity
7 - 2.3 CALCULATIONS
9 - SECTION 3 ADSORPTION ONTO ACTIVATED CHARCOAL AND MEASUREMENT OF GAMMA RADIATION (METHOD B)
9 - 3.1 REAGENT
9 - 3.2 APPARATUS
9 - 3.2.1 Sample container
9 - 3.2.2 Diffusion barrier
9 - 3.2.3 Lead-shielded NaI(Tl) gamma-ray detector
9 - 3.2.4 Pulse amplifier and multi-channel pulse height analyser (MCA)
9 - 3.2.5 Radium (Ra) standard solution
9 - 3.2.6 Radon test chamber
9 - 3.3 PROCEDURE
9 - 3.3.1 Preparation of radon monitor
10 - 3.3.2 Calibration
11 - 3.3.3 Sample collection
11 - 3.3.4 Measurement of gamma-ray peaks
12 - 3.4 CALCULATIONS
13 - SECTION 4 SOLID-STATE NUCLEAR TRACK MONITORING (METHOD C)
13 - 4.1 REAGENTS
13 - 4.1.1 Potassium hydroxide solution
13 - 4.1.2 2% acetic acid solution
13 - 4.1.3 Distilled water
13 - 4.2 APPARATUS
13 - 4.2.1 Detector
13 - 4.2.2 Marking tool
13 - 4.2.3 Sample containers
13 - 4.2.4 Sample holding block
13 - 4.2.5 Beakers or other suitable containers
13 - 4.2.6 Heating system
13 - 4.2.7 Desiccator or other low temperature drying device
14 - 4.2.8 Viewing system
14 - 4.3 PROCEDURE
14 - 4.3.1 Preparation of monitor
14 - 4.3.2 Sample collection
14 - 4.3.3 Etching of detectors
15 - 4.3.4 Counting of tracks
15 - 4.4 CALCULATION
16 - SECTION 5 PRECISION AND TEST REPORT
16 - 5.1 PRECISION
16 - 5.2 TEST REPORT
17 - APPENDIX A - URANIUM DECAY SERIES
19 - APPENDIX B - DETERMINATION OF RADON PROGENY CONCENTRATIONS BY MEMBRANE FILTER COLLECTION AND MEASUREMENT OF ALPHA ACTIVITY
19 - B1 SCOPE
19 - B2 PRINCIPLE
19 - B3 APPARATUS
19 - B3.1 Air pump
19 - B3.2 Filter holder
19 - B3.3 Membrane filters or supported membrane filters
20 - B3.4 Flowmeter
20 - B3.5 Stopwatch or other timing device of equivalent accuracy
20 - B3.6 Scintillation counter
20 - B4 PROCEDURE
20 - B4.1 Calibration procedure
20 - B4.2 Sample collection
20 - B4.3 Measurement of alpha activity
21 - B4.3.1 Single count method
21 - B4.3.2 Four count method
21 - B5 CALCULATIONS
21 - B5.1 Single count method
21 - B5.2 Four count method
21 - B5.2.1 Individual activity concentrations
22 - B5.2.2 Potential alpha energy concentration (PAEC)
22 - B6 PRECISION
22 - B7 TEST REPORT

Sets out three methods for the determination of the radon content in indoor air. Method A applies to grab samples and requires the collection of a grab sample in a scintillation cell followed by the measurement of its alpha activity. Method B is applicable for short-term sampling periods. The principle consists of adsorption of the radon onto activated charcoal followed by the measurement of the gamma radiation that is emitted. Method C applies to sampling periods of up to a year and employs solid state nuclear track monitoring.

This Standard sets out three methods for the determination of the radon content of indoor air. The methods are as follows:(a) Collection in scintillation cells and measurement of alpha activity (Method A)* Applicable for grab samples (sampling times of a few seconds) and providing a rapid means of obtaining a radon concentration at a particular time. Its detection limit is dependent on the background count rate. For a background count rate of 1 count/min and a counting period of 60 min, the lower detection limit is 40 Bq/m3. For a scintillation cell with a sampling volume of 140cm3, the sensitivity of the method is approximately 0.019 counts/min per Bq/m3in air.å(b) Passive adsorption onto activated charcoal and measurement of gamma radiation (Method B) Applicable for short term sampling (between 1 d and 7 d). The detection limit is approximately 15 Bq/m3for an exposure period of 4 d and counting period of 60 min.(c) Solid-state nuclear track monitoring (Method C) Applicable for sampling periods from one week to one year. The detection limit is 3 Bq/m3for an exposure period of one year and a counting area of 1.5 cm2.Methods for the determination of the concentrations of certain radon progeny, by membrane filter collection and measurement of alpha activity, and estimation of the total potential alpha energy concentration (PAEC) of radon progeny in indoor air are included in Appendix B. A sampling period of 5 min is used and, for the count intervals specified, this method should give a lower detection limit of 2.5 ¦ 10-8J/m3for the PAEC of the radon progeny.çNOTES:1 The recommended advisory level for radon in dwellings is expressed as a radon concentration in air, in becquerel per cubic metre, while actual radiation doses are calculated from the measurement of the concentration of the radon progeny in the air. The methods in Appendix B have been included for use in situations where measured radon concentrations are high enough to warrant further investigation.2 The detection limits for each method have been estimated using the procedure given by Currie (published in Analytical Chemistryº)

First published as AS 2365.4-1995.
Incorporating: Amdt 1-1996