ISO/TC 147/SC 3 - Radioactivity measurements

This document specifies conditions for the determination of 90Sr and 89Sr activity concentration in samples of environmental water using liquid scintillation counting (LSC) or proportional counting (PC). The method is applicable to test samples of drinking water, rainwater, surface and ground water, marine water, as well as cooling water, industrial water, domestic, and industrial wastewater after proper sampling and handling, and test sample preparation. Filtration of the test sample and a chemical separation are required to separate and purify strontium from a test portion of the sample. The detection limit depends on the sample volume, the instrument used, the sample count time, the background count rate, the detection efficiency and the chemical yield. The method described in this document, using currently available LSC counters, has a detection limit of approximately 10 mBq l−1 and 2 mBq l−1 for 89Sr and 90Sr, respectively, which is lower than the WHO criteria for safe consumption of drinking water (100 Bq·l−1 for 89Sr and 10 Bq·l−1 for 90Sr)[3]. These values can be achieved with a counting time of 1 000 min for a sample volume of 2 l. The methods described in this document are applicable in the event of an emergency situation. When fallout occurs following a nuclear accident, the contribution of 89Sr to the total amount of radioactive strontium is not negligible. This document provides test methods to determine the activity concentration of 90Sr in presence of 89Sr. The analysis of 90Sr and 89Sr adsorbed to suspended matter is not covered by this method. It is the user’s responsibility to ensure the validity of this test method selected for the water samples tested.

This document specifies a method for the measurement of 210Pb in all types of waters by liquid scintillation counting (LSC). The method is applicable to test samples of supply/drinking water, rainwater, surface and ground water, as well as cooling water, industrial water, domestic, and industrial wastewater after proper sampling and handling, and test sample preparation. Filtration of the test sample is necessary. Lead‑210 activity concentration in the environment can vary and usually ranges from 2 mBq l-1 to 300 mBq l-1 [27][28]. Using currently available liquid scintillation counters, the limit of detection of this method for 210Pb is generally of the order of 20 mBq l-1 to 50 mBq l-1, which is lower than the WHO criteria for safe consumption of drinking water (100 mBq l−1).[4][6] These values can be achieved with a counting time between 180 min and 720 min for a sample volume from 0,5 l to 1,5 l. Higher activity concentrations can be measured by either diluting the sample or using smaller sample aliquots or both. The method presented in this document is not intended for the determination of an ultra-trace amount of 210Pb. The range of application depends on the amount of dissolved material in the water and on the performance characteristics of the measurement equipment (background count rate and counting efficiency). The method described in this document is applicable to an emergency situation. The analysis of Pb adsorbed to suspended matter is not covered by this method. It is the user’s responsibility to ensure the validity of this test method for the water samples tested.

This document specifies a method for the physical pre-treatment and conditioning of water samples and the determination of the activity concentration of various radionuclides emitting gamma-rays with energies between 40 keV and 2 MeV, by gamma‑ray spectrometry according to the generic test method described in ISO 20042. The method is applicable to test samples of drinking water, rainwater, surface and ground water as well as cooling water, industrial water, domestic and industrial wastewater after proper sampling, sample handling, and test sample preparation (filtration when necessary and taking into account the amount of dissolved material in the water). This method is only applicable to homogeneous samples or samples which are homogeneous via timely filtration. The lowest limit that can be measured without concentration of the sample or by using only passive shield of the detection system is about 5·10-2 Bq/l for e.g. 137Cs.1 The upper limit of the activity corresponds to a dead time of 10 %. Higher dead times may be used but evidence of the accuracy of the dead-time correction is required. Depending on different factors, such as the energy of the gamma-rays, the emission probability per nuclear disintegration, the size and geometry of the sample and the detector, the shielding, the counting time and other experimental parameters, the sample may require to be concentrated by evaporation if activities below 5·10-2 Bq/l need to be measured. However, volatile radionuclides (e.g. radon and radioiodine) can be lost during the source preparation. This method is suitable for application in emergency situations. 1The sample geometry: 3l Marinelli beaker; detector: GE HP N relative efficiency 55 % ; counting time: 18h.

This document specifies a method for the measurement of 14C activity concentration in all types of water samples by liquid scintillation counting (LSC) either directly on the test sample or following a chemical separation. The method is applicable to test samples of supply/drinking water, rainwater, surface and ground water, marine water, as well as cooling water, industrial water, domestic, and industrial wastewater. The detection limit depends on the sample volume, the instrument used, the sample counting time, the background count rate, the detection efficiency and the chemical recovery. The method described in this document, using currently available liquid scintillation counters and suitable technical conditions, has a detection limit as low as 1 Bq∙l−1, which is lower than the WHO criteria for safe consumption of drinking water (100 Bq·l-1). 14C activity concentrations can be measured up to 106 Bq∙l-1 without any sample dilution. It is the user’s responsibility to ensure the validity of this test method for the water samples tested.

This document specifies a test method for the determination of iron-55 (55Fe) activity concentration in samples of all types of water using liquid scintillation counting (LSC). Using currently available liquid scintillation counters, this test method can measure the 55Fe activity concentrations in the range from the limit of detection up to 120 mBq l-1. These values can be achieved with a counting time between 7 200 s and 10 800 s for a sample volume from 0,5 l to 1,5 l. Higher activity concentrations can be measured by either diluting the sample or using smaller sample aliquots or both. NOTE These performance indicators are wholly dependent on the measurement regimes in individual laboratories; in particular, the detection limits are influenced by amount of stable iron present. The range of application depends on the amount of dissolved material in the water and on the performance characteristics of the measurement equipment (background count rate and counting efficiency). It is the laboratory’s responsibility to ensure the suitability of this test method for the water samples tested.

This document provides guidelines for testing laboratories wanting to use rapid test methods on water samples that may be contaminated following a nuclear or radiological emergency incident. In an emergency situation, consideration should be given to: — taking into account the specific context for the tests to be performed, e.g. a potentially high level of contamination; — using or adjusting, when possible, radioactivity test methods implemented during routine situations to obtain a result rapidly or, for tests not performed routinely, applying specific rapid test methods previously validated by the laboratory, e.g. for 89Sr determination; — preparing the test laboratory to measure a large number of potentially contaminated samples. The aim of this document is to ensure decision makers have reliable results needed to take actions quickly and minimize the radiation dose to the public. Measurements are performed in order to minimize the risk to the public by checking the quality of water supplies. For emergency situations, test results are often compared to operational intervention levels. NOTE Operational intervention levels (OILs) are derived from IAEA Safety Standards[8] or national authorities[9]. A key element of rapid analysis can be the use of routine methods but with a reduced turnaround time. The goal of these rapid measurements is often to check for unusual radioactivity levels in the test sample, to identify the radionuclides present and their activity concentration levels and to establish compliance of the water with intervention levels[10][11][12]. It should be noted that in such circumstances, validation parameters evaluated for routine use (e.g. reproducibility, precision, etc.) may not be applicable to the modified rapid method. However, due to the circumstances arising after an emergency, the modified method may still be fit-for-purpose although uncertainties associated with the test results need to be evaluated and may increase from routine analyses. The first steps of the analytical approach are usually screening methods based on gross alpha and gross beta test methods (adaptation of ISO 10704 and ISO 11704) and gamma spectrometry (adaptation of ISO 20042, ISO 10703 and ISO 19581). Then, if required[13], test method standards for specific radionuclides (see Clause 2) are adapted and applied (for example, 90Sr measurement according to ISO 13160) as proposed in Annex A. This document refers to published ISO documents. When appropriate, this document also refers to national standards or other publicly available documents. Screening techniques that can be carried out directly in the field are not part of this document.

This document specifies the conditions for the determination of uranium isotope activity concentration in samples of environmental water (including sea waters) using alpha-spectrometry and 232U as a yield tracer. A chemical separation is required to separate and purify uranium from a test portion of the sample.

This document specifies a method for the measurement of 210Po in all types of waters by alpha spectrometry. The method is applicable to test samples of supply/drinking water, rainwater, surface and ground water, marine water, as well as cooling water, industrial water, domestic, and industrial wastewater after proper sampling and handling, and test sample preparation. Filtration of the test sample may be required. The detection limit depends on the sample volume, the instrument used, the counting time, the background count rate, the detection efficiency and the chemical yield. The method described in this document, using currently available alpha spectrometry apparatus, has a detection limit of approximately 5 mBq l−1, which is lower than the WHO criteria for safe consumption of drinking water (100 mBq l−1). This value can be achieved with a counting time of 24 h for a sample volume of 500 ml. The method described in this document is also applicable in an emergency situation. The analysis of 210Po adsorbed to suspended matter in the sample is not covered by this method. If suspended material has to be removed or analysed, filtration using a 0,45 μm filter is recommended. The analysis of the insoluble fraction requires a mineralization step that is not covered by this document [13]. In this case, the measurement is made on the different phases obtained. The final activity is the sum of all the measured activity concentrations. It is the user's responsibility to ensure the validity of this test method for the water samples tested.

This document specifies the determination of radium-226 (226Ra) and radium-228 (228Ra) activity concentrations in drinking water samples by chemical separation of radium and its measurement using liquid scintillation counting. Massic activity concentrations of 226Ra and 228Ra which can be measured by this test method utilizing currently available liquid scintillation counters go down to 0,01 Bq/kg for 226Ra and 0,06 Bq/kg for 228Ra for a 0,5 kg sample mass and a 1 h counting time in a low background liquid scintillation counter[8]. The test method can be used for the fast detection of contamination of drinking water by radium in emergency situations.

This document specifies a method for the measurement of 99Tc in all types of water by inductively coupled plasma mass spectrometry (ICP-MS). The method is applicable to test samples of supply/drinking water, rainwater, surface and ground water, as well as cooling water, industrial water, domestic, and industrial wastewater after proper sampling and handling and test sample preparation. A filtration of the test sample is necessary. The detection limit depends on the sample volume and the instrument used. The method described in this document, using currently available ICP-MS, has a detection limit of approximately 0,2 ng·kg−1 to 0,5 ng·kg−1 (0,1 Bq·kg−1 to 0,3 Bq·kg−1), which is much lower than the WHO criteria for safe consumption of drinking water (100 Bq·l−1)[3]. The method presented in this document is not intended for the determination of ultra-trace amount of 99Tc. The mass concentration values in this document are expressed by sample mass unit instead of sample volume unit as it is usually the case in similar standards. The reason is that 99Tc is measured in various matrix types such as fresh water or sea water, which have significant differences in density. The mass concentration values can be easily converted to sample volume unit by measuring the sample volume. However, it increases the uncertainty on the mass concentration result. The method described in this document is applicable in the event of an emergency situation, but not if 99mTc is present at quantities that could cause interference. The analysis of Tc adsorbed to suspended matter is not covered by this method. It is the user's responsibility to ensure the validity of this test method for the water samples tested.

This document specifies a method for the measurement of 99Tc in all types of waters by liquid scintillation counting (LSC). The method is applicable to test samples of supply/drinking water, rainwater, surface and ground water, as well as cooling water, industrial water, domestic, and industrial wastewater after proper sampling and handling, and test sample preparation. A filtration of the test sample is necessary. The detection limit depends on the sample volume and the instrument used. The method described in this document, using currently available LSC instruments, has a detection limit of approximately 5 Bq·kg−1 to 20 Bq·kg−1, which is lower than the WHO criteria for safe consumption of drinking water (100 Bq l−1)[3]. These values can be achieved with a counting time of 30 min for a sample volume varying between 14 ml to 40 ml. The method presented in this document is not intended for the determination of ultra-trace amount of 99Tc. The activity concentration values in this document are expressed by sample mass unit instead of sample volume unit as it is usually the case in similar standards. The reason is that 99Tc is measured in various matrix types such as fresh water or sea water, which have significant differences in density. The activity concentration values can be easily converted to sample volume unit by measuring the sample volume. However, it increases the uncertainty on the activity concentration result. The method described in this document is applicable in the event of an emergency situation, but not if 99mTc is present at quantities that could cause interference and not if 99mTc is used as a recovery tracer. The analysis of Tc adsorbed to suspended matter is not covered by this method. It is the user's responsibility to ensure the validity of this test method for the water samples tested.

This document specifies a method by liquid scintillation counting for the determination of tritium activity concentration in samples of marine waters, surface waters, ground waters, rain waters, drinking waters or of tritiated water ([3H]H2O) in effluents. The method is not directly applicable to the analysis of organically bound tritium; its determination requires additional chemical processing of the sample (such as chemical oxidation or combustion). With suitable technical conditions, the detection limit may be as low as 1 Bq·l−1. Tritium activity concentrations below 106 Bq·l−1 can be determined without any sample dilution.

This document specifies a method for the determination of gross alpha and gross beta activity concentration for alpha- and beta-emitting radionuclides. Gross alpha and gross beta activity measurement is not intended to give an absolute determination of the activity concentration of all alpha and beta emitting radionuclides in a test sample, but is a screening analysis to ensure particular reference levels of specific alpha and beta emitters have not been exceeded. This type of determination is also known as gross alpha and gross beta index. Gross alpha and gross beta analysis is not expected to be as accurate nor as precise as specific radionuclide analysis after radiochemical separations. Maximum beta energies of approximately 0,1 MeV or higher are well measured. It is possible that low energy beta emitters can not detected (e.g. 3H, 55Fe, 241Pu) or can only be partially detected (e.g. 14C, 35S, 63Ni, 210Pb, 228Ra). The method covers non-volatile radionuclides, since some gaseous or volatile radionuclides (e.g. radon and radioiodine) can be lost during the source preparation. The method is applicable to test samples of drinking water, rainwater, surface and ground water as well as cooling water, industrial water, domestic and industrial wastewater after proper sampling, sample handling, and test sample preparation (filtration when necessary and taking into account the amount of dissolved material in the water). The method described in this document is applicable in the event of an emergency situation, because the results can be obtained in less than 1 h. Detection limits reached for gross alpha and gross beta are less than 10 Bq/l and 20 Bq/l respectively. The evaporation of 10 ml sample is carried out in 20 min followed by 10 min counting with window-proportional counters. It is the laboratory's responsibility to ensure the suitability of this test method for the water samples tested.

This document specifies a method for the determination of gross alpha and gross beta activity concentration for alpha- and beta-emitting radionuclides using liquid scintillation counting (LSC). The method is applicable to all types of waters with a dry residue of less than 5 g/l and when no correction for colour quenching is necessary. Gross alpha and gross beta activity measurement is not intended to give an absolute determination of the activity concentration of all alpha- and beta-emitting radionuclides in a test sample, but is a screening analysis to ensure particular reference levels of specific alpha and beta emitters have not been exceeded. This type of determination is also known as gross alpha and beta index. Gross alpha and beta analysis is not expected to be as accurate nor as precise as specific radionuclide analysis after radiochemical separations. The method covers non-volatile radionuclides below 80 °C, since some gaseous or volatile radionuclides (e.g. radon and radioiodine) can be lost during the source preparation. The method is applicable to test samples of drinking water, rain water, surface and ground water as well as cooling water, industrial water, domestic and industrial waste water after proper sampling and test sample preparation (filtration when necessary and taking into account the amount of dissolved material in the water). The method described in this document is applicable in the event of an emergency situation, because the results can be obtained in less than 4 h by directly measuring water test samples without any treatment. It is the laboratory's responsibility to ensure the suitability of this test method for the water samples tested.

This document specifies a test method for the determination of gross beta activity concentration in non-saline waters. The method covers non-volatile radionuclides with maximum beta energies of approximately 0,3 MeV or higher. Measurement of low energy beta emitters (e.g. 3H, 228Ra, 210Pb, 14C, 35S and 241Pu) and some gaseous or volatile radionuclides (e.g. radon and radioiodine) might not be included in the gross beta quantification using the test method described in this document. This test method is applicable to the analysis of raw and drinking waters. The range of application depends on the amount of total soluble salts in the water and on the performance characteristics (background count rate and counting efficiency) of the counter used. It is the laboratory's responsibility to ensure the suitability of this method for the water samples tested.

This document specifies methods used to determine the concentration of plutonium and neptunium isotopes in water by inductively coupled plasma mass spectrometry (ICP-MS) (239Pu, 240Pu, 241Pu and 237Np). The concentrations obtained can be converted into activity concentrations of the different isotopes[9]. Due to its relatively short half-life and 238U isobaric interference, 238Pu can hardly be measured by this method. To quantify this isotope, other techniques can be used (ICP-MS with collision-reaction cell, ICP-MS/MS with collision-reaction cell or chemical separation). Alpha spectrometry measurement, as described in ISO 13167[10], is currently used[11]. This method is applicable to all types of water having a saline load less than 1 g·l−1. A dilution of the sample is possible to obtain a solution having a saline load and activity concentrations compatible with the preparation and the measurement assembly. A filtration at 0,45 μm is needed for determination of dissolved nuclides. Acidification and chemical separation of the sample are always needed. The limit of quantification depends on the chemical separation and the performance of the measurement device. This method covers the measurement of those isotopes in water in activity concentrations between around[12][13]: — 1 mBq·l−1 to 5 Bq·l−1 for 239Pu, 240Pu and 237Np; — 1 Bq·l−1 to 5 Bq·l−1 for 241Pu. In both cases, samples with higher activity concentrations than 5 Bq·l−1 can be measured if a dilution is performed before the chemical separation. It is possible to measure 241Pu following a pre-concentration step of at least 1 000.

This document specifies the measurement method for the determination of total activity concentration of uranium isotopes in non-saline waters by extraction and liquid scintillation counting. This method covers the measurement of soluble uranium isotopes in water in activity concentrations between approximately 2·10−3 Bq/kg and 10 Bq/kg when analysing a 1 l test sample volume with a 60 000 s counting time with a typical alpha LSC instrument. The ratio 234U/238U can also be determined. This method has not been tested for the measurement of other uranium isotopes.

ISO 9696:2017 specifies a method for the determination of gross alpha activity in non-saline waters for alpha-emitting radionuclides which are not volatile up to 350 °C. The method is applicable to raw and potable waters. The range of application depends on the amount of total soluble salts in the water and on the performance characteristics (background count rate and counting efficiency) of the counter. It is the laboratory's responsibility to ensure the suitability of this method for the water samples tested.

ISO 13165-3:2016 specifies the determination of radium-226 (226Ra) activity concentration in all types of water by coprecipitation followed by gamma-spectrometry (see ISO 18589‑3). The method described is suitable for determination of soluble 226Ra activity concentrations greater than 0,02 Bq l−1 using a sample volume of 1 l to 100 l of any water type. For water samples smaller than a volume of 1 l, direct gamma-spectrometry can be performed following ISO 10703 with a higher detection limit. NOTE This test method also allows other isotopes of radium, 223Ra, 224Ra, and 228Ra, to be determined.

ISO 13167:2015 specifies a test method for measuring actinides (238Pu, 239+240Pu, 241Am, 242Cm, 243+244Cm and 237Np) in water samples by alpha spectrometry following a chemical separation. The method can be used for any type of environmental study or monitoring. The volume of the test portion required depends on the assumed activity of the sample and the desired detection limit. The detection limit of the test method is 5 × 10−3 to 5 × 10−4 Bq/l for a volume of the test portion of 0,1 l to 5 l with a counting time of two to ten days.

ISO 13168:2015 describes a test method for the simultaneous measurement of tritium and carbon-14 in water samples by liquid scintillation counting of a source obtained by mixing the water sample with a hydrophilic scintillation cocktail. This is considered a screening method because of the potential presence of interfering nuclides in the test sample. The method can be used for any type of environmental study or monitoring. ISO 13168:2015 is applicable to all types of waters having an activity concentration ranging from 5 Bq/l to 106 Bq/l (upper limit of the liquid scintillation counters for direct counting). For higher activity concentrations, the sample can be diluted to obtain a test sample within this range.

ISO 13164-4:2015 describes a test method for the determination of radon-222 (222Rn) activity concentration in non-saline waters by extraction and liquid scintillation counting. The radon-222 activity concentrations, which can be measured by this test method utilizing currently available instruments, are at least above 0,5 Bq l−1 for a 10 ml test sample and a measuring time of 1 h. This test method can be used successfully with drinking water samples and it is the responsibility of the laboratory to ensure the validity of this test method for water samples of untested matrices. Annex A gives indication on the necessary counting conditions to meet the required detection limits for drinking water monitoring.

ISO 13165-2:2014 specifies the determination of radium-226 (226Ra) activity concentration in all types of water by emanometry. The method specified is suitable for the determination of the soluble, suspended, and total 226Ra activity concentration in all types of water with soluble 226Ra activity concentrations greater than 0,02 Bq l−1. In water containing high activity concentrations of 228Th, interference from 220Rn decay products can lead to overestimation of measured levels.

ISO 13164-2:2013 specifies a test method for the determination of radon-222 activity concentration in a sample of water following the measurement of its short-lived decay products by direct gamma-spectrometry of the water sample. The radon-222 activity concentrations, which can be measured by this test method utilizing currently available gamma-ray instruments, range from a few becquerels per litre to several hundred thousand becquerels per litre for a 1 l test sample. This test method can be used successfully with drinking water samples. The laboratory is responsible for ensuring the validity of this test method for water samples of untested matrices. An annex gives indications on the necessary counting conditions to meet the required sensitivity for drinking water monitoring.

ISO 13164-1:2013 gives general guidelines for sampling, packaging, and transporting of all kinds of water samples, for the measurement of the activity concentration of radon-222. The test methods fall into two categories: a) direct measurement of the water sample without any transfer of phase (see ISO 13164‑2); b) indirect measurement involving the transfer of the radon-222 from the aqueous phase to another phase (see ISO 13164‑3). The test methods can be applied either in the laboratory or on site. The laboratory is responsible for ensuring the suitability of the test method for the water samples tested.

ISO 13164-3:2013 specifies a test method for the determination of radon-222 activity concentration in a sample of water following its transfer from the aqueous phase to the air phase by degassing and its detection. It gives recommendations for rapid measurements performed within less than 1 h. The radon-222 activity concentrations, which can be measured by this test method utilizing currently available instruments, range from 0,1 Bq l−1 to several hundred thousand becquerels per litre for a 100 ml test sample. This test method is used successfully with drinking water samples. The laboratory is responsible for ensuring the validity of this test method for water samples of untested matrices. This test method can be applied on field sites or in the laboratory. Annexes A and B give indications on the necessary counting conditions to meet the required sensitivity for drinking water monitoring

ISO 13165-1:2013 specifies the determination of radium-226 (226Ra) activity concentration in non-saline water samples by extraction of its daughter radon-222 (222Rn) and its measurement using liquid scintillation counting. Radium-226 activity concentrations which can be measured by this test method utilizing currently available liquid scintillation counters goes down to 50 mBq l−1. This method is not applicable to the measurement of other radium isotopes.

ISO 9697:2015 specifies a test method for the determination of gross beta activity concentration in non-saline waters. The method covers non-volatile radionuclides with maximum beta energies of approximately 0,3 MeV or higher. Measurement of low energy beta emitters (e.g. 3H, 228Ra, 210Pb, 14C, 35S, and 241Pu) and some gaseous or volatile radionuclides (e.g. radon and radioiodine) might not be included in the gross beta quantification using the test method described in ISO 9697:2015. This test method is applicable to the analysis of raw and drinking waters. The range of application depends on the amount of total soluble salts in the water and on the performance characteristics (background count rate and counting efficiency) of the counter used. It is the laboratory's responsibility to ensure the suitability of this method for the water samples tested.

ISO 13166:2014 specifies the conditions for the determination of uranium isotope activity concentration in samples of environmental water (including sea waters) using alpha-spectrometry and 232U as a yield tracer. A chemical separation is required to separate and purify uranium from a test portion of the sample. Plutonium isotopes can interfere, if present, with detectable activities in the sample. The detection limit for measurement of a test portion of about 500 ml is approximately 5 mBq · l−1 with a counting time of about 200 000 s.

ISO 13163 specifies the determination of lead-210 (210Pb) activity concentration in samples of all types of water using liquid scintillation counting (LSC). For raw and drinking water, the sample should be degassed in order to minimize the ingrowth of 210Pb from radon-222 (222Rn). Using currently available liquid scintillation counters, this test method can measure the 210Pb activity concentrations in the range of less than 20 mBq⋅l-1 to 50 mBq⋅l-1. These values can be achieved with a counting time between 180 min and 720 min for a sample volume from 0,5 l to 1,5 l. Higher 210Pb activity concentrations can be measured by either diluting the sample or using smaller sample aliquots or both. It is the laboratory's responsibility to ensure the suitability of this test method for the water samples tested.

ISO 13160:2012 specifies the test methods and their associated principles for the measurement of the activity of 90Sr in equilibrium with 90Y, and 89Sr, pure beta-emitting radionuclides, in water samples. Different chemical separation methods are presented to produce strontium and yttrium sources, the activity of which is determined using a proportional counter (PC) or liquid scintillation counter (LSC). The selection of the test method depends on the origin of the contamination, the characteristics of the water to be analysed, the required accuracy of test results and the available resources of the laboratories. These test methods are used for water monitoring following, past or present, accidental or routine, liquid or gaseous discharges. It also covers the monitoring of contamination caused by global fallout. When fallout occurs immediately following a nuclear accident, the contribution of 89Sr to the total amount of strontium activity is not negligible. ISO 13160:2012 provides the test methods to determine the activity concentration of 90Sr in presence of 89Sr.

ISO 13162:2011 specifies the conditions for the determination of 14C activity concentration in samples of environmental water or of 14C-containing water using liquid scintillation counting. The method is applicable to the analysis of any organic molecule soluble in water that is well mixed with the scintillation cocktail. It does not apply to micelles or "large" particles (lipids, fulvic acid, humic acid, etc.) that are inadequately mixed with the scintillation cocktail and the water. Some beta energy is lost without any excitation of the scintillation cocktail and the results are underestimated. The method is not applicable to the analysis of organically bound 14C, whose determination requires additional chemical processing (such as chemical oxidation, combustion). It is possible to determine 14C activity concentrations below 106 Bq l-1 without any sample dilution.

ISO 13161:2011 specifies the measurement of 210Po activity concentration by alpha spectrometry in all kinds of natural waters. The detection limit of this method depends on the volume of the sample, the counting time, the background count rate and the detection efficiency. In the case of drinking water, the analysis is usually carried out on the raw sample, without filtration or other pretreatment. If suspended material has to be removed or analysed, filtration at 0,45 µm is recommended. The analysis of the insoluble fraction requires a mineralization step that is not covered by ISO 13161:2011. In this case, the measurement is made on the different phases obtained. The final activity is the sum of all the measured activity concentrations.

ISO 9698:2010 specifies the conditions for the determination of tritium activity concentration in samples of environmental water or of tritiated water using liquid scintillation counting. The choice of the analytical procedure, either with or without distillation of the water sample prior to determination, depends on the aim of the measurement and the sample characteristics. Direct measurement of a raw water sample using liquid scintillation counting has to consider the potential presence of other beta emitter radionuclides. To avoid interference with these radionuclides when they are detected, the quantification of tritium will be performed following the sample treatment by distillation. Three distillation procedures are described. The method is not applicable to the analysis of organically bound tritium; its determination requires additional chemical processing (such as chemical oxidation or combustion). With suitable technical conditions, the detection limit may be as low as 1 Bq l-1. Tritium activity concentrations below 106 Bq l-1 can be determined without any sample dilution. A prior enrichment step can significantly lower the limit of detection.

ISO 11704:2010 specifies a method for the determination of gross alpha and gross beta activity in waters for radionuclides which are not volatile at 80 °C. Radon isotopes and their decay products of short half life are not included in the determination. The method is applicable to raw and potable waters with a dry residue less than 5 g/l and when no correction for colour quenching is necessary.

ISO 10704:2009 specifies a method for the determination of gross alpha and gross beta activity in non‑saline waters for alpha- and beta‑emitting radionuclides. The method is applicable to raw and potable waters containing a small quantity of dissolved matter. It can, after adaptation, apply to other kind of waters. The range of application depends upon the amount of dissolved material in the water and on the performance characteristics of the measurement equipment (background count rate and counting efficiency).

ISO 9697:2008 specifies a method for the determination of gross beta activity in non-saline waters. The method covers non-volatile radionuclides with maximum beta energies > 0,3 MeV. Measurement of very low energy beta emitters, such as 3H; 14C, 35S and 241Pu, is not included in ISO 9697:2008. The method is applicable to the analysis of raw and potable waters.

ISO 9696:2007 specifies a method for the determination of gross alpha activity in non-saline waters for alpha‑emitting radionuclides which are not volatile at 350 °C. It is possible to determine supported volatile radionuclides measured to an extent determined by half-life, matrix retention (of the volatile species) and the duration of measurement (counting time). The method is applicable to raw and potable waters.

ISO 10703:2007 specifies a method for the simultaneous determination of the activity concentration of various radionuclides emitting gamma rays with energies between 40 keV and 2 MeV in water samples, by gamma‑ray spectrometry using germanium detectors with high energy resolution in combination with a multichannel analyser.