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.