Measurement Principles

Applications Solutions Technologies
Applications

1. Environmental monitoring

Radiation Detection and Environmental Monitoring instruments determine radioactivity in the environment by gamma ray measurement. ANTECH Radiation Detection and Environmental Monitoring systems include:

  • Contamination vehicle and pedestrian portal monitors
  • The RadSearch gamma camera
  • Mobile environmental laboratories
  • Technology for in-field soil measurements

2. Homeland security

ANTECH Homeland Security systems are sensitive dual technology measurement instruments (neutron and gamma ray measurement technologies). They are designed to detect:

  • Illegal and contraband radioactive sources
  • Improvised radioactive weapons (dirty bombs)

3. Radioactive waste measurement

Radioactive Waste Measurement instruments use different technologies to quantify the radionuclide content or the mass of a radionuclide (or radionuclides) in waste.

ANTECH Radioactive Waste Measurement instruments cover a range of waste density and waste container sizes including small samples and small cans, drums of different sizes and large boxes and containers.

3.1 Gamma ray waste assay

Gamma ray waste assay systems include gross gamma based instruments to measure the total activity of low-density waste and gamma spectroscopy based instruments to measure specific radionuclide activity of medium density waste. Both types of instrument use density correction based on container weight. More sophisticated gamma spectroscopy segmented scanning instruments (including SGS and TGS) use gamma transmission sources for density correction and can measure more heterogeneous and higher density waste containers.

3.2 Neutron waste assay

Neutron waste assay systems measure the uranium or plutonium content of waste containers or objects. They can be either passive (measuring spontaneous fission neutrons) or active (measuring induced fission neutrons). Neutron counting technologies include: Total neutron counting (the total neutron count rate arising from a sample), Coincidence neutron counting (the rate of emission of two neutrons in coincidence) and Neutron multiplicity counting (the rate of emission of three neutrons in coincidence).

3.3 Calorimetry waste assay

Calorimeters perform waste assay by measuring the thermal energy generated by radioactive decay. Calorimeters are typically used to measure waste materials that produce significant amounts of heat by alpha particle decay (plutonium, americium), or beta particle decay (tritium).

3.4 Combined waste assay

Combined waste assay systems use multiple assay techniques to quantify waste and produce a complete assay result. It is common to combine a gamma system (to determine plutonium isotopic ratios) with a passive neutron coincidence system (to determine 240Pueffective mass). Analyzing the data in a combined technology assay instrument determines the individual mass of all of the plutonium isotopes and provides a complete assay result.

4. Safeguards

Nuclear Safeguards instruments employ gamma ray, neutron and calorimetry measurement technologies to verify and quantify the presence of Special Nuclear Materials (SNM). Safeguards instruments either verify the radioactive fingerprint or signature of SNM and fission products (for example in spent nuclear fuel), or quantify SNM in bulk form (for example in unused nuclear fuel for verification purposes).

Safeguards instruments are sometimes used for nuclear materials assay for inventory and materials quantification purposes as well as for safeguards, for example in a nuclear fuel production plant.

Solutions

1. Homeland security

ANTECH Homeland Security systems are sensitive dual technology measurement instruments (neutron and gamma ray measurement technologies). They are designed to detect:

  • Illegal and contraband radioactive sources
  • Improvised radioactive weapons (dirty bombs)

2. Safeguards

Nuclear Safeguards instruments employ gamma ray, neutron and calorimetry measurement technologies to verify and quantify the presence of Special Nuclear Materials (SNM). Safeguards instruments either verify the radioactive fingerprint or signature of SNM and fission products (for example in spent nuclear fuel), or quantify SNM in bulk form (for example in unused nuclear fuel for verification purposes).

Safeguards instruments are sometimes used for nuclear materials assay for inventory and materials quantification purposes as well as for safeguards, for example in a nuclear fuel production plant.

3. Integrated measurement

ANTECH integrated measurement solutions provide a complete measurement solution for Safeguards and Waste Assay applications. These systems include various combinations of gamma ray, neutron and calorimetry measurement technologies to provide integrated measurement results.

4. Materials inventory

ANTECH provides a range of instruments for determining the inventory of radioactive and nuclear materials. The function of ANTECH Material Inventory Measurements range from determining the quantity of radionuclides to establishing that radioactive materials containers are empty and contain very little radioactivity.

5. Measurement automation

ANTECH measurement automation solutions are used to position detectors, samples, cans, drums, boxes and containers for measurement. Measurement Automation solutions include:

  • Drum loading beams
  • Roller conveyors
  • Rail systems
  • Gantry robot cranes for automating the movement of sample cans, drums and boxes

6. Radiation detection

Radiation Detection and Environmental Monitoring instruments determine radioactivity in the environment by gamma ray measurement.

ANTECH Radiation Detection and Environmental Monitoring systems include:

  • Contamination vehicle and pedestrian portal monitors
  • The RadSearch gamma camera
  • Mobile environmental laboratories
  • Technology for in-field soil measurements

7. Radioactive Waste Measurement

Radioactive Waste Measurement instruments use different technologies to quantify the radionuclide content or the mass of a radionuclide (or radionuclides) in waste. ANTECH waste assay instruments cover a range of waste density and waste container sizes, including small samples and small cans, drums of different sizes and large boxes and containers.

7.1 Exempt and VLLW

Sensitive detection instruments are required to measure waste at the lowest subcategories of Exempt and Very Low Level Waste (VLLW).

UK: These categories generally correspond to maximum specific activities of:

  • Exempt:    0.4 Bq/g (10.8 pCi/g)
  • VLLW:       4 Bq/g (108 pCi/g)

7.2 LLW and greater than class C waste

LLW waste is measured using a range of techniques depending on the volume and homogeneity of the waste.  ANTECH provides a range of options for LLW measurement, which range from far field to segmented. Shielding is sometimes included in measurement instruments to reduce background radiation. Low Level Waste (LLW) upper thresholds vary.

UK: LLW upper thresholds correspond to:

  • 12,000 Bq/g (324 nCi/g) for waste with beta-gamma activity
  • 4,000 Bq/g (108 nCi/g) for waste with alpha activity

US: The upper threshold for LLW waste with alpha activity is:

  • 100 nCi/g (3,700 Bq/g)

NOTE: In the USA, Class C LLW represents waste with higher beta-gamma activity and is generally equivalent to UK ILW with higher beta-gamma activity.

7.3 ILW and high activity waste measurement

UK: Waste is generally categorised as ILW because it has high activity above the beta-gamma activity threshold or it has higher alpha activity (or both), as detailed below:

  • Beta-gamma activity: > 12,000 Bq/g  (324 nCi/g), or
  • Alpha activity:             > 4,000 Bq/g (108 nCi/g)

ILW and higher activity waste is measured using a range of technologies and techniques depending on the density, homogeneity and the amount of alpha activity present.

7.4 Transuranic waste and ILW measurement

USA: Transuranic waste (TRU) is waste with a specific alpha activity greater than 100 nCi/g (3,700 Bq/g). ANTECH offers a range of assay instruments and technologies for segregating and characterising this type of waste.

7.5 Plutonium and uranium waste assay

ANTECH provides a range of instruments for uranium and plutonium waste assay. These are based on a range of technologies, including gamma ray measurement, neutron measurement and calorimetry. In addition, ANTECH provides gamma ray instruments for determining the ratio of plutonium isotopes, which are used with neutron and calorimetry assay methods.

7.6 Remote handled (RH) waste assay

Remote Handled (RH) waste is defined in the USA as waste that has an external dose rate of grater than 200 milli-rem/hr (2 mSv/hr). The term is often used for all radioactive waste with a high surface dose rate. Depending on dose rate, the category may include low level waste, intermediate level waste, transuranic waste and high level waste (including spent fuel). There are special safety and handling considerations that must be taken into account when dealing with RH waste. ANTECH provides general purpose far-field gamma ray measuring instruments and special neutron measuring instruments for the measurement and characterisation of RH waste.

8. Special measurement applications

Measurement instruments that do not fall into the categories of Safeguards, Waste Measurement, Environmental Monitoring or Remote Handled Waste Measurement are considered to be Special Measurement Applications.

ANTECH develops radiometric measuring instruments and analysis software for special requirements and bespoke applications. ANTECH uses a variety of radiation detectors and imbedded microprocessor technology. Solutions to Special Measurement Applications include multi-detector microprocessor based counting systems and the QuickSort system for LLW-TRU sorting.

Technologies

1. Gamma ray measurements

Most radionuclides decay by gamma ray emission. Gamma ray measurement is the most common and widely used method for measuring nuclear material. It can be used to determine three different qualities of a sample:

  1. Total dose rate (commonly used for medical purposes)
  2. Ratio of the constituents of the sample
  3. Total radionuclide content of a source, either in terms of activity of the mass of a particular radionuclide

The gamma ray measurement process can be passive or active. In PASSIVE measurement the gamma rays emitted form radioactive decay are measured by appropriate detectors and counting electronics. In ACTIVE measurement gamma rays are used to interrogate samples and the attenuation of these interrogating gamma rays is measured. This is used to determine the ability for transmission through samples and thus the degree of attenuation in the sample material and the matrix in which it is contained.

ANTECH instruments perform gross gamma counting using ion chambers and plastic scintillators, and spectroscopy using low-resolution spectrometers (sodium iodide scintillators) or medium and high-resolution spectrometers (LaBr3scintillators and high purity germanium detectors). ANTECH instruments are configured to perform far field measurements to view entire objects, and segmented and tomographic gamma scanning for more complex samples.

2. Neutron measurements

Neutrons are emitted by the decay of Special Nuclear Materials (SNM) and transuranic elements. Neutron measurement is the process of counting the neutrons emitted in nuclear fission. It is normally used to quantify uranium and plutonium. It is a sensitive technique that can be used to measure large or small quantities. The neutron measurement process can be passive or active. In PASSIVE measurement neutron emissions from the sample are measured by the detector and counting system. In ACTIVEmeasurement the sample is interrogated with neutrons from a neutron source or a neutron generator. The neutrons emitted from this induced fission are measured by the detector and counting system. ANTECH neutron counting electronics record the three different rates of neutron emission.

  1. Singles: the total neutron count rate arising from a sample (neutron totals counting)
  2. Pairs: the rate of emission of two neutrons in coincidence (neutron coincidence counting)
  3. Triples: the rate of emission of three neutrons in coincidence (neutron multiplicity counting)

ANTECH neutron instruments employ neutron detectors including fission chambers, boron proportional counters and helium-3 (He3) detectors.

3. Calorimetry measurements

Calorimetry measures the thermal energy released from a sample. It is applied in two areas:

  1. The measurement of plutonium in relatively large quantities. Thermal energy is generated through alpha particle decay.
  2. The measurement of tritium in relatively large quantities. Thermal energy is generated through beta particle decay.

Alpha and beta particles have a relatively short range inside the sample materials so the bulk of the energy released in the decay process is deposited locally in the sample. ANTECH calorimeters determine the rate of energy release by the samples through these decay processes.

Calorimeters are configured as single instruments, unlike gamma ray and neutron instruments in which the detector and counting electronics can be separated. The thermal element (or detector component) uses temperature sensitive materials such a nickel wire or thermocouples as a means of measuring temperature. It uses electrical heating elements as a means of depositing thermal energy for temperature control. The electronic coupling components are similar to electrical voltage and current measuring devices.

ANTECH employs two different calorimeter technologies: Isothermal calorimeters employ the power replacement method and achieving adequate measurement precision. Twin-cell heat-flow calorimeters are applied where high accuracy and precision measurement are required.

4. Combined technology measurements

ANTECH instruments often combine different measurement technologies to provide an optional measurement solution.

These combined instruments usually include neutron and gamma measurements in a single system for waste assay and nuclear safeguards measurement applications.