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Nuclear Material Measurement Techniques and Equipment

Photo related to the term with caption below

The IAEA has its own experts and facilities, through its Safeguards Analytical Laboratory in Austria, experienced in sample measurement and analysis, including hundreds of samples from the 1990's Iraq inspections.

(Source: Dean Calma/IAEA)

Nuclear material verification depends on techniques and equipment for sampling, measurement and analysis of nuclear material. Physical standards are required for calibration of measurement equipment and provide a basis for determining the accuracy of measurements.

Alpha spectrometry : Quantification of alpha-particles being emitted by a nuclide or material that is being measured. More.
Assay: An investigative (analytic) procedure in a laboratory setting for qualitatively assessing or quantitatively measuring the presence or amount or the functional activity of a target entity (the analyte). More.
Bulk measurement: Quantification of an object, such as a container, to obtain the mass or some other property for recording. More.
Calibration: Operation that, under specified conditions, in a first step, establishes a relation between the quantity values with measurement uncertainties provided by measurement standards and corresponding indications with associated measurement uncertainties (of the calibrated instrument or secondary standard) and, in a second step, uses this information to establish a relation for obtaining a measurement result from an indication. More.
Calorimetry: The science or act of measuring changes in state variables of a body for the purpose of deriving the heat transfer associated with changes of its state due for example to chemical reactions, physical changes, or phase transitions under specified constraints. Can be used to determine the amount of an element by thermal power emission. More.
Cerenkov radiation detection: A technique used to verify the irradiation of nuclear fuel or materials in a storage pool or other potential irradiation zones. More.
Chemical titration : A common laboratory method of quantitative chemical analysis that is used to determine the unknown concentration of an identified analyte. More.
Controlled potential coulometry: An electrochemical method for measurement of element concentration whereby the element to be analyzed is selectively oxidized or reduced at a metallic electrode maintained at a controlled potential. The number of electrons (coulombs) used in the electrolysis is measured. The method is used at the Safeguards Analytical Laboratory to determine Pu. More.
Destructive analysis (DA): An assay of a material in which the physical form of the sample is destroyed. More.
Gamma ray scanning: Measurement of gamma ray emission as a function of position along an item. More.
Gamma ray spectrometry: Measurement of the energy spectrum and intensity of gamma rays incident upon a detector for the purpose of establishing the total amount of the source isotopes in the item measured and the identity and abundance of the contributing isotopes. More.
Gas mass spectrometry : A technique whereby gas samples (typically UF6) are introduced and multiple detectors are used to simultaneously collect ions of different masses and provide measurements of isotopic ratios with high precision. More.
Gravimetric analysis: A technique whereby the element to be analyzed is quantitatively separated and transformed to a well-defined and very pure chemical compound which is accurately weighed and related to the stoichiometric quantity of the element to be analyzed in the compound. At the Safeguards Analytical Laboratory, ignition gravimetry is used for determining U and Pu concentrations in oxides by converting them to stoichiometric U3O8 for U and PuO2 for Pu More.
Isotope dilution mass spectrometry (IDMS): Measurement of the total U or Pu in a sample by introducing a known quantity of a tracer isotope normally absent or of low abundance in the sample (e.g. 233U for U, 242Pu or 244Pu for Pu), measuring the abundances of all isotopes present in the sample with a mass spectrometer, and then determining the unknown by multiplying the isotope ratios observed by the quantity of tracer. This technique is generally used for highly radioactive reprocessing dissolver solutions. More.
K-edge densitometry: A technique for measuring the U or Pu concentration in solutions by determining the ratio of the transmission of photons whose energies closely bracket the K-electron absorption edge of the U or Pu. Hybrid instruments combining K-edge densitometry and X-ray fluorescence analysis are used for determining U and Pu concentrations in mixed solutions, including highly radioactive spent fuel solutions. More.
Mass spectrometry: Mass spectrometry (MS) is an analytical chemistry technique that helps identify the amount and type of chemicals present in a sample by measuring the mass-to-charge ratio and abundance of gas-phase ions. A mass spectrum (plural spectra) is a plot of the ion signal as a function of the mass-to-charge ratio. More.
Matrix: The non-nuclear part of nuclear material. More.
Network of Analytical Laboratories (NWAL): A group of laboratories in IAEA Member States that have been approved to analyze safeguards samples and to assist the Safeguards Analytical Laboratory in analysis of nuclear material and environmental samples. More.
Neutron coincidence counting: A technique that detects prompt neutrons from spontaneous or induced fission in a sample and distinguishes them from neutrons from other sources (such as α,n) reactions) by separating detected events that occur closely together in time (correlated events) from those that are randomly distributed in time. More.
Neutron counting: Quantification of neutron emission from nuclear material, and the ability to identify and measure the neutrons being emitted. More.
Neutron multiplicity counter : Variations in the neutron coincidence counting technique. More.
Non-destructive assay (NDA) : A wide group of analysis techniques used in science and industry to evaluate the properties of a material, component or system without causing damage. More.
Primary standard: A certified reference material that is designated or acknowledged to be of high metrological quality (i.e., traceable to a primary unit of measurement) and whose value is accepted without reference to other standards. More.
Random sampling: The process of selecting samples in such a manner that all items in a population have the same probability of being selected. More.
Reference material: Radioactive material is any material designated in national law, regulation, or by a regulatory body as being subject to regulatory control because of its radioactivity. More.
Representative sample: A sample that is intended to reflect the characteristics of a wider sampling such as the population or multiple containers. More.
Resin bead technique: Used to selectively absorb (isolate from fission products) U and Pu onto a resin bead (or beads) in preparation for isotopic analysis by thermal ionization mass spectrometry: one resin bead containing nanogram amounts of U and Pu is placed on a metal filament for the analysis. This method is suited to the measurement of reprocessing dissolver or highly active waste solutions. More.
Safeguards Analytical Laboratory (SAL): The IAEA's laboratory, located in Seibersdorf, Austria that is responsible for destructive analysis of nuclear material samples as well as for handling and analysis of environmental samples for safeguards purposes. The SAL also provides support to both destructive analysis and environmental sampling programs through the supply of sampling materials, quality assurance and training of IAEA inspectors. More.
Sample: A quantity that is selected for inspection and analysis. More.
Scintillation detector: A device which responds to incident gamma rays or neutrons by emitting light scintillations. The most common scintillator for gamma rays is sodium iodide (NaI); for neutrons, a variety of organic and inorganic liquid and solid scintillators can be employed. More.
Secondary standard: A standard which value is used to compare to the primary standard of the same quantity. More.
Semiconductor detector : A device which detects gamma rays by means of the induced charge displacement in a semiconducting material. More.
Systematic sampling: The process of selecting samples in a repeated pattern, such as every 11th item or at fixed time intervals, from a continuing process. More.
Thermal ionization mass spectrometry (TIMS) : A technique (also called surface ionization mass spectrometry) whereby picogram to microgram quantities of a sample are deposited on a metallic filament which is then heated to 1600-2000ºC in a high vacuum; this results in ionization of the sample. More.