The Series of Environmental Radioactivity Measuring Methods（Numerical Order）

Measurement samples are prepared using various methods such as the evaporation drying method, then their radioactivity is measured using β-ray measurement equipment. This method is to measure the total amount of β-rays emitted from a sample, and is unable to identify the radionuclides in the sample. However, it allows simple and rapid measurement of rough figures of radioactivity in samples through comparison with uranium beta standard.

This manual is an analysis method for environmental radiation monitoring at nuclear facilities, which specifies how to quantify Sr-90 and Sr-89 that are important in evaluating the environmental impact. Separation and refinement methods can be selected from the ion exchange method (Sr-90, Sr-89), fuming nitric acid method (Sr-90, Sr-89), oxalate method (Sr-90), and solvent extraction method (Sr-90), and the radioactivity is measured using a low-background beta counter. In the 4th revised edition, consideration is given to the conventional ion exchange method as a replacement for the fuming nitric acid method that requires special attention to the handling, and the method was made applicable to a wider range of environmental samples.

The nuclide to analyze is Cs-137. After adsorbing Cs-137 to ammonium phosphomolybdate, Cs-137 is separated and refined using the ion exchange resin method. Precipitate of cesium chloroplatinate is formed, and its radioactivity is measured using a low-background beta counter.

The nuclide to analyze is mainly I-131. A sample is measured, as is or after drying and crushing, by γ-ray spectrometry using a NaI(Tl) scintillation detector or germanium semiconductor detector to determine its radioactivity. For particulate matter and milk, it presents a radiochemical analysis method to measure β-rays of I-131 after separating and refining it.

The nuclide to analyze is mostly Co-60. Co-60 is separated and refined by the ion exchange resin method, and electrodeposited onto a copper plate. The gross radioactivity including a radioactive isotope Co-58 is measured using a low-background beta counter.

A sample is, as is or after drying and crushing, filled into a measurement container such as a Marinelli beaker. This method enables measurement of multiple kinds of γ-emitting nuclides at the same time. While a NaI(Tl) scintillation detector is poorer in energy resolution compared with a germanium semiconductor detector, it is high in the counting efficiency and easy to maintain and control since it does not require cooling the detector part using liquid nitrogen.

A germanium semiconductor detector is superior to a NaI(Tl) scintillation detector in energy resolution, and allows for measurement of multiple kinds of γ-emitting nuclides at the same time. This manual describes relevant measurement apparatuses and spectral analysis method.
In the 4th revised edition, several additions were made taking into account technological advancement and other changes. These additions include a technique to device peak efficiency using a numerical model such as a Monte Carlo simulation, evaluation of uncertainty of measurement pertaining to quality assurance, and calculation of lower limit of detection based on the technique described in ISO 11929.

A nuclear fission product Zr-95 becomes a radionuclide Nb-95 when it decays. Therefore, the nuclides to analyze by this method are Zr-95 + Nb-95. The nuclides are separated and refined by the solvent extraction method, adsorbed onto precipitate of iron(III) hydroxide, and the radioactivity of the precipitate is measured using a low-background beta counter.

This manual covers the measurement of tritium, a radioactive isotope of hydrogen, by liquid scintillation for water, air, and biological samples. The main revisions include the addition of the uncertainty required for proficiency tests such as intercomparison analysis between analytical laboratories and the calculation of detection limits, etc., based on ISO 11929. In addition, although the main focus is on methods for analyzing tritium in environmental samples under normal conditions, a wide range of related information and literature is also included for applications to other purpose of analysis, such as rapid analysis.

Ruthenium nuclear fission products come in Ru-103 and Ru-106, but in this method the target of analysis is Ru-106. Ru-106 is separated and refined by the distillation method, and oxide precipitate is formed. The radioactivity of the precipitate is measured using a low-background beta counter.

Cerium nuclear fission products come in Ce-141 and Ce-144, but in this method the target of analysis is Ce-144. Ce-144 is separated and refined by the solvent extraction method, and precipitate of cerium oxalate is formed. The radioactivity of the precipitate is measured using a low-background beta counter.

The nuclides to analyze are Pu-239 and Pu-240, but Pu-238 can also be measured at the same time. Pu-239 and Pu-240 are separated and refined by the ion exchange resin method or solvent extraction method, and electrodeposited onto a stainless steel plate. The radioactivity is determined by α-ray spectrometry using a silicon semiconductor detector.

This manual describes sample pretreatment methods to prepare samples for γ-ray spectrum measurement using a germanium semiconductor detector. The purpose of pretreatment is to reduce the volume of the sample. The methods not to lose radionuclides to analyze by pretreatment and precautions for maintaining the homogeneity of samples are included.

The 2002 revised edition of the manual that specifies the uranium analysis method for the environmental monitoring around nuclear facilities such as nuclear fuel fabrication plants, nuclear power plants, and nuclear fuel reprocessing plants. It was established in 1982 and the first revised edition was released in 1996. In this 2002 revised edition, the ion exchange method, iron hydroxide coprecipitation method, and ICP mass spectrometry were newly adopted, and obsolete analysis methods were deleted.

This manual is a rapid measurement method for estimating and evaluating radioiodine concentrations in environmental samples in emergency situations. The main revisions include the description of I-132 and I-133, which can be evaluated simultaneously with I-131 in measurements with a germanium semiconductor detector, the addition of soil and other materials as sample types, and the establishment of priority levels. In addition to portable air samplers, iodine samplers with auto-sample changers and air monitors are also described for air sampling.

In surveys of environmental radioactivity, how to collect samples has a huge impact on the results of analysis, along with how to analyze them. Therefore, how to collect such samples is established in a separate manual. It specifies technical methods to collect samples on the field and process them into a storable condition (e.g., sampling amount, sampling device, sampling location, how to dry or incinerate).

A manual that describes the method for measuring environmental γ-rays using a continuous monitor, based on the advancement in measuring equipment in recent years and the lessons learned from the accident at the TEPCO Fukushima Daiichi Nuclear Power Plant. It provides explanations on the equipment configuration of continuous monitor, measurement systems using a continuous monitor, installation of measurement system, measurement and calibration, analysis and evaluation of measurement results, and spectral analysis by NaI monitor.

The amount of environmental γ-rays is measured using a thermoluminescent dosimeter (TLD), usually as three-month cumulative doses. The manual explains about the placement of TLD in a storage box, cleaning of TLD element, calibration of measurement equipment, evaluation of measurement results, and characteristics of TLD.

This manual handles analysis of Ra-226, one of the radionuclides that are most strictly regulated in terms of radiological protection. Ra is separated and refined by the barium sulfate coprecipitation method, and the radioactivity is measured using a low-background liquid scintillation counter.

The method to measure γ-ray spectra in the field environment. It can be utilized for the identification of radionuclides and the evaluation of contribution to the dose by nuclide. Two types of measurement equipment can be used, one is a NaI(Tl) scintillation spectrometer and the other is a Ge semiconductor spectrometer.

The nuclide to analyze is Am-241. Am-241 is separated and refined by the ion exchange resin method or solvent extraction-ion exchange resin method, and electrodeposited onto a stainless-steel plate. The radioactivity is determined by α-ray spectrometry using a silicon semiconductor detector.

A method to sequentially analyze plutonium (Pu-239 and Pu-240) and americium (Am-241) from the same sample. The methods of analysis and measurement are the same as those in the Series of Environmental Radioactivity Measuring Methods No. 12 Plutonium Analysis and No. 21 Americium Analysis.

The targets of analysis are radioactive strontium, iodine, cobalt, cerium, and plutonium. Chemical separation operations are the same as the relevant analysis method in the Series of Environmental Radioactivity Measuring Methods (No. 2, 4, 5, 11, or 12), and radioactivity is measured using a low-background liquid scintillation counter.

A sample pretreatment method for rapid measurement of radionuclides in environmental samples by γ-ray spectrometry in emergencies such as a nuclear accident. Based on the lessons learned from the accident at the TEPCO Fukushima Daiichi Nuclear Power Plant, food samples are treated assuming consumption and precautions are given for when handling contaminated samples.

The nuclide to analyze is C-14. A measurement sample is prepared by the carbon dioxide absorption method or benzene synthesis method, and its radioactivity is measured using a low-background liquid scintillation counter. Since carbon is the main componential element of the human body, C-14 is important in evaluating exposure doses.

The radiochemical analysis method with relatively easy analysis operations and the neutron activation analysis method with high detection sensitivity are available, selectable depending on the purpose. The former is to separate and refine I-129 and then measure β or γ rays of I-129. The latter is to separate and refine I-129, irradiate neutrons in a reactor to generate I-130 from I-129, and to measure γ rays of I-130 to derive the amount of I-129.

For their advantages over TLD, fluorescent glass dosimeters are rapidly spreading in recent years. They were mentioned in the Guidelines for Environmental Radiation Monitoring in Emergencies (Nuclear Safety Commission, March 2001), and establishment of a measurement manual was desired as a dosimeter to replace TLD. A fluorescent glass dosimeter is a cumulative dosimeter characterized in little variations in the sensitivity between elements, ability to read repeatedly different from TLD, and extremely little fading. This manual is a summary of various characteristics tests conducted on fluorescent glass dosimeters to investigate their basic performance and applicability to environmental monitoring.

If an accident occurs at a nuclear fuel reprocessing plant, α-emitting nuclides such as plutonium are expected to be released to the environment, and indexes for plutonium and transuranium elements are newly added to the indexes related to the restrictions on food and drink intake provided in the Disaster Prevention Measures for Nuclear Facilities, Etc. (Nuclear Safety Commission, November 1998). In such an emergency situation, an analysis method that has a much lower limit of detection than the indexes and is able to obtain results rapidly for long half-life nuclides such as plutonium will be required. For this manual, we established an analysis method that allows for carrying out pretreatment, chemical separation, measurement, calculation, and reporting within about 24 hours by adopting ICP-MS as the measurement equipment and speeding up the process from pretreatment through separation and refinement.

Gamma-ray spectrometry using a germanium semiconductor detector is widely applied for environmental radiation monitoring in emergencies, but has issues specific to emergency situations such as misrecognition of γ-ray peaks since it requires analysis and evaluation of complicated γ-ray spectra. This manual provides explanations on these emergency-specific issues and how to address them using actual examples, while giving consideration to broadly sharing findings from the accident at the TEPCO Fukushima Daiichi Nuclear Power Plant.

If an accident occurs at a reprocessing plant, the types of radionuclides released to the environment may be different from those in the reactor facility. For that reason, a method to rapidly quantify transuranium elements such as plutonium, americium, and curium in particular will be required. This manual specifies a rapid analysis method using alpha-ray spectrometry to quantify americium and curium in environmental samples within 24 hours after starting the analysis.

If an accident occurs at a reprocessing plant, the types of radionuclides released to the environment may be different from those in the reactor facility. For that reason, a method to rapidly quantify alpha-emitting nuclides of transuranium elements such as plutonium, americium, and curium in particular will be required. This manual stipulates a rapid analysis method in which plutonium and transuranium elements in environmental samples are separated and refined by extraction chromatography and the gross alpha radioactivity is measured distinguishing from natural alpha-emitting nuclides such as uranium and thorium.

Iodine-129 is a radionuclide that may be released from reactor facilities and reprocessing facilities. Its half-life is very long with 1.57 × 107 years, and once taken into a human body it migrates mostly to the thyroid. Therefore, it is considered important to understand its radioactivity level in the environment and assess the impact. This manual presents a rapid analysis method using the solid-phase extraction method and ICP-MS measurement as a simplified method to rapidly grasp iodine-129 concentrations.

It explains the measurement and analysis method for in-situ (on-site) measurement using germanium semiconductor detectors. It also includes the results of the study on the factors (e.g., geographical features around the measuring point, height of detector) that affect analysis results and how to make corrections.

Neptunium-237 has been specified as an important nuclide to analyze in terms of reprocessing of spent fuel and treatment and disposal of high-level radioactive waste.
This manual shows a rapid analysis method in which neptunium is separated and refined by the rapid and simple solid-phase extraction method and quantified using ICP-MS within about 24 hours.

This manual describes the basic matters and procedures of environmental sample collection in emergencies, based on the experience of emergency monitoring after the accident at the TEPCO Fukushima Daiichi Nuclear Power Plant.
Common matters on sampling procedure include prevention of contamination of materials and tools and protection of monitoring personnel. Sample types are divided into the samples (atmosphere, soil, and drinking water) that are to be collected with priority to make a decision on implementing protective measures based on the Nuclear Emergency Response Guidelines, and other samples. It also gives an example check list of materials and tools that will be needed and example sampling record forms.

This manual consists of two parts, the first one for use in normal situation and the second one for use in emergent situation, and each part can be used as a stand-alone manual. Part 1 describes the procedures for continuous measurement by dust monitors and for collecting and analyzing air samples using a dust sampler. Part 2 describes the procedures for continuous measurement by air monitors and for collecting and analyzing air samples using an iodine sampler.