Radiochemical measurement techniques

aim

analysis of metallic compounds in solids

typical use

• semi-quantitative determination of impurities in solids
• panoramic analysis of unknown samples

basic mechanism

• the sample, together with a suitable carrier, is brought into a graphite electrode and is arced or sparked
• the optical emission spectrum is recorded on a photographic film and measured by microdensitometry

type of samples

• solids (metal, powders)

applicability range

• for most elements from percent to ppm range
• depends on the refractory properties of the elements

turn-around time

• depends on the nature of the sample; typically, two hours are needed for the exposure of the film
• the overall time, including microdensitometry and calculations, is about 1/2 to 1 day

advantages

• multi-element analysis (panoramic analysis)
• medium sensitivity, traceability
• suited for hazardous materials like nuclear fuels (fitted in glove box)

disadvantages

• poor accuracy (30 - 50 % relative)
• not suited for strong refractory materials

contact

Dr. Gysemans Mireille
Dr. Dobney Andrew

aim

qualitative and quantitative determination of alpha emitting radionuclides

typical use

• characterisation of actinides in reactor waste streams, conditioned wastes, fresh and spent nuclear fuels, etc.

basic mechanism

• plateafter the necessary sample preparation, such as dissolution and/or radiochemical separation and/or dilution, a measurement source is prepared by evaporation or co-precipitation
• total alpha counting is performed using ZnS scintillation detectors
• the alpha spectrum is recorded in a vacuum chamber with a semiconductor detector and analysed by a multichannel Tracor Northern analyser or Genie2000 software

type of samples

• radioactive wastes (aqueous solutions, resins, evaporator concentrates, ashes,…)
• fuels (mixed oxides, uranium oxides, spent fuels, …)
• other medium to highly radioactive samples (irradiated materials, reactor dosimeters,…)

applicability range

• down to the Bq range

turn-around time

• typically, 2 to 8 hours are needed for the measurement depending on the activity of the source
• sample preparation depends strongly on the nature of the sample
• the overall time, including preparation and calculations, is about 1 to 3 days

advantages

• high sensitivity - rather accurate method (5 % or more)
• suited for hazardous materials such as nuclear fuels
• simultaneous identification and determination of radionuclides
• detector efficiency is isotope independent

disadvantages

• very thin sample geometry is required because of the strong alpha-ray attenuation
• interfering alpha emitters ought to be separated
• time consuming sample preparation is needed for complex matrices

contact

Dr. Gysemans Mireille
Dr. Dobney Andrew

aim

qualitative and quantitative determination of beta emitting radionuclides

typical use

• characterisation of beta emitting radioinuclides in reactor waste streams, conditioned wastes, spent fuels, etc.

basic mechanism

• after the separation of the radionuclide under investigation a purified sample fraction is mixed with a scintillation cocktail in a standard vial
• the sample vial is placed in the scintillation counter and measured

type of samples

• radioactive wastes (aqueous solutions, resins, evaporator concentrates, ashes,…)
• spent fuels
• other medium to highly radioactive samples (irradiated materials, reactor monitors,…)

applicability range

• down to 0.1 Bq/g

turn-around time

• typically, a few minutes are needed for the measurement
• sample preparation depends strongly on the nature of the sample
• the overall time, including preparation and calculations and a repetition, is about 2 days

advantages

• high sensitivity
• rather accurate method (5% or more)
• 100 % efficiency for not too low beta-ray energies

disadvantages

• preliminary radiochemical separation required in many cases
• difficulty to measure more than two beta-ray emitters simultaneously
• identification is harmed because of the continuous energy distribution up to a maximum energy

contact

Dr. Gysemans Mireille
Dr. Adriaensen Lesley

aim

qualitative and quantitative determination of gamma emitting radionuclides

typical use

• characterisation of gamma emitting radionuclides in reactor waste streams, in conditioned wastes, fresh and spent nuclear fuels, etc.

basic mechanism

• a sample fraction is introduced in a standard container or sealed ampoule
• the sample container is placed at a standard distance from the detector
• the gamma spectrum is recorded thewith an energy and efficiency calibrated HP Ge detector and analysed by Genie2000 software

type of samples

• liquids, solids
• from mg level to several grams
• interfering gamma emitters ought to be separated

applicability range

• down to the 1 Bq range depending on the measuring geometry and possible interferences

turn-around time

• typically, 2 to 8 hours are needed for the measurement
• sample preparation depends strongly on the nature of the sample
• the overall time, including preparation and calculations, is about 1 to 3 days

advantages

• high sensitivity, non destructive (if no preparation is needed)
• gamma attenuation in the sample is in most cases small
• rather accurate method (3 % or more)
• suited for hazardous materials like nuclear fuels
• simultaneous identification and determination of many radionuclides is possible (specific mono-energetic gamma rays and high energy resolution of the HPGe detectors)

disadvantages

• sensitive to sample geometry
• interfering gamma emitters ought to be separated

contact

Dr. Gysemans Mireille
Dr. Adriaensen Lesley

aim

Qualitative and quantitative determination of N₂, O₂, Ar, CO₂, He, H₂, CH₄, Kr, Xe

typical use

• Characterisation of fission gasses in spent fuels

basic mechanism

• A portion of the gaseous sample is introduced in the ionisation chamber
• Collisions between the gas and electrons, originating from a Re filament, cause the formation of ions
• The positive ions are separated by a quadrupole analyzer and are consequently detected by a faraday cup or an electron multiplier

type of samples

• (radioactive) gasses in closed ampoules with a preferred pressure of ~ 0.200 bar

applicability range

• Normal mass range: 1 - 150 amu
  Minimal concentration: 0.04%

turn-around time

• The measurement takes ~ 2 hour (upto 4 ampoules per day)
• Overall time, including preparation, calibration and reporting ~ 4 days

advantages

• Good sensitivity
• Measurement of multiple m/z values per analysis

disadvantages

• Sensitive to the inlet pressure
• Time consuming

contact

Ind.Ir. Vos Liliane
Dr. Adriaensen Lesley

aim

analysis of dissolved cations (metallic, semi-metallic)

typical use

• characterisation of the composition, from percent level to trace level, of any type of matrix provided it can be dissolved
• particularly suited for the determination of trace elements in diluted solutions

basic mechanism

• the sample solution is nebulized in a spray chamber
• the finest aerosol particles are blown through an argon plasma (T°: 6000 - 8000 °K) maintained in a quartz torch by RF-induction
• the aerosol particles are desolvated, dried, decomposed and excited by the plasma
• the emitted light is analysed either sequentially by a monochromator with a PM-tube, or simultaneously with an echelle spectrometer and a CCD detector

type of samples

• solutions

applicability range

• for most elements from ppm to ppb range
• not suited for H, C, N, O, S and halogens
• depends on the specific emission of the elements measured and the main concentration of the matrix

turn-around time

• depends on the number of elements to determine and of the routine character of the analysis (typical measuring time, 1 - 2 min. per element and per sample)
• the overall time, including calculations, is about 1/2 to 1 day

advantages

• multi-element analysis
• sensitivity, traceability, good accuracy over large dynamic range of concentrations (4 to 5 decades)
• accuracy (5 % rel. at 95% confidence level)

disadvantages

• spectral interferences possible
• partly dependent from the matrix (sample matching standardisation is often necessary)

contact

Dr. Gysemans Mireille
Ing. Thomas Peter

aim

analysis of dissolved cations (metallic, semi-metallic)

typical use

• characterisation of the composition, from percent level to trace level, of any type of matrix
• particularly suited for the determination of ultra-trace elements in solutions

basic mechanism

• the sample solution is nebulized in a spray chamber
• the finest aerosol particles are blown through an argon plasma (T°: 6000 - 8000 °K) maintained in a quartz torch by RF-induction
• the aerosol particles are desolvated, dried, decomposed and ionised by the plasma
• the ions are analysed with a quadrupole mass spectrometer

type of samples

• solutions or solid samples (the latter can be analysed after dissolution)

applicability range

• for most elements from ppm to ppt range
• not suited for H, He, C, N, O, F, S, Cl
• depends on possible isobaric interferences from the matrix

turn-around time

• depends on the number of elements to determine and of the routine character of the analysis (typical measuring time, 1 - 2 min. per element and per sample)
• the overall time, including calculations, is about 1/2 to 1 day

advantages

• multi-element analysis
• suited for hazardous materials like nuclear fuels (fitted in glove box)
• high sensitivity, traceability, good accuracy over large dynamic range of concentrations (4 to 5 decades)
• accuracy (5 - 10 % rel. at 95% confidence level)
• yields information about the isotopic composition

disadvantages

• isobaric interferences possible (necessitates a good isotope library)
• partly dependent on the matrix (sample matching standardisation is often necessary)

contact

Dr. Gysemans Mireille
Ing. Van Bree Peter

aim

analysis of dissolved anions

typical use

• characterisation of the anionic composition, from percent level to trace level

basic mechanism

• a known volume of the solution is injected on a ion chromatographic column
• the anionic species are separated by elution and measured by conductimetry

type of samples

• solutions
• solid samples need to be dissolved either directly in water, or after a carbonate fusion

applicability range

• for most anions from ppm to ppb range
• depends on possible interferences from the matrix

turn-around time

• depends on the number of anions to determine and of the routine character of the analysis (typical measuring time, 20 min. per sample)
• the overall time, including calculations, is about 1 day.

advantages

• high sensitivity, traceability, accuracy (5 % rel. at 95% confidence level)
• easy to use vs. classical wet methods
• suited for hazardous materials like nuclear fuels (fitted in glove box)

disadvantages

• heavily loaded solutions need to be diluted
• organic anions need a gradient elution

contact

Dr. Gysemans Mireille
Ing. Thomas Peter

aim

quantitative determination of dissolved ions

typical use

• determination of F^-, NH⁴⁺, pH

basic mechanism

• a suitable volume of sample is poured in a beaker and, if necessary, conditioned with appropriate reagents
• the measurement is performed with a dedicated ion selective electrode

type of samples

• aqueous solutions

applicability range

• down to 10-5, 10-6 M

turn-around time

• typically, 20 minutes are needed for the measurement
• preparation depends on the nature of the sample
• the overall time, including preparation and calculations, is about 2 hours.

advantages

• rather good sensitivity
• rather accurate method (5 - 10% rel.)
• easy to implement

disadvantages

• the selectivity is generally poor, except for a few ions
• restricted to F-, NH4+, pH

contact

Dr. Gysemans Mireille
Ing. Thomas Peter

aim

Determination of the total open porosity and of the pore size distribution

typical use

• (non) irradiated and irradiated solid fuel materials without cladding

basic mechanism

• A holder, containing the sample, is filled with Hg
• The pressure is increased (stepwise) up to 4000 bar
• The intrusion volume is measured as a function of pressure (AUTOPORE software)

type of samples

• (non) irradiated solid materials

applicability range

• Pore diameter: 0.003 – 360 µm
• Maximum volume: 5 cc

turn-around time

• Overall time, including reporting ~ 3 days

advantages

disadvantages

• Destructive measurement

contact

Ind.Ir. Vos Liliane
Dr. Adriaensen Lesley

aim

Determination of the bulk density

typical use

• (non) irradiated fuels

basic mechanism

• The weight of the sample is determined
• The sample is placed in the measurement chamber and the chamber is filled with Hg by means of a plunger until a pressure of 1 bar is reached
• The volume of the sample is calculated

type of samples

• (non) irradiated solid materials

applicability range

• Solid particles of 3 – 5 cc

turn-around time

• Overall time, including reporting ~ 2 days

advantages

• Good accuracy ~ 0.2%

disadvantages

• Sensitive to contamination

contact

Ind.Ir. Vos Liliane
Dr. Adriaensen Lesley

aim

Qualitative and quantitative determination of N₂, O₂, Ar, CO₂, He, H₂, CH₄, Kr, Xe from solids

typical use

• Determination of gasses present in irradiated, solid materials

basic mechanism

• The sample is cleaned in a suitable way
• The sample is heated in a tungsten holder (up to 2300°C, but below the melting point of the sample compounds)
• The released gas is analyzed with a gas mass spectrometry

type of samples

• (non) irradiated solids

applicability range

• Maximum dimensions: 22 mm x 33 mm
• Thickness < 3 mm
• Activity < 2 mSv/h

turn-around time

• Overall time, including calibration and reporting ~ 5 days (without preparation)

advantages

• Good sensitivity
• Measurement of multiple m/z values per analysis

disadvantages

• Sensitive to the inlet pressure
• Time consuming

contact

Ind.Ir. Vos Liliane
Dr. Adriaensen Lesley

aim

analysis of impurities in solids

typical use

• semi-quantitative determination of impurities in solids
• panoramic analysis of unknown samples

basic mechanism

• two electrodes are prepared from the sample and are sparked in the sampling chamber of a high resolution mass spectrometer
• the mass spectrum is recorded on a photographic plate and measured by microdensitometry

type of samples

• solids (metal pieces, powders)
• non conductive solids previously need to be mixed with graphite or silver powder

applicability range

• for most elements from ppm to ppb range
• depends on the maximum exposure time

turn-around time

• depends on the expected sensitivity; typically, half a day is needed for the exposure of the plate
• the overall time, including microdensitometry and calculations, is about 2 days

advantages

• multi-element analysis (panoramic analysis)
• high sensitivity, traceability
• suited for hazardous materials like nuclear fuels (fitted in glove box)

disadvantages

• poor accuracy (50 % relative or less)
• very sensitive to a heterogeneous distribution of the impurities

contact

Dr. Gysemans Mireille
Dr. Dobney Andrew

aim

determination of the isotopic composition of dissolved samples

typical use

• isotopic analysis of fresh and spent nuclear fuels
• burn-up determination of spent fuels
• general isotopic analysis
• determination of concentration by isotopic dilution technique

basic mechanism

• a sample fraction is evaporated on the source filament(s)
• the sample filament is heated and electrons generated by another filament ionise the atoms
• the isotopic mass intensities are measured by Faraday or Daly detectors

type of samples

• liquids
• interfering elements (isobaric interferences) ought to be separated

applicability range

• for most elements from percent to ppb range

turn-around time

• typically, two hours are needed for the measurement
• preparation (separation) depends strongly on the nature of the sample
• the overall time, including preparation and calculations, is about 4 to 5 days

advantages

• high sensitivity
• accurate method (up to 0.1 % depending on the abundance)
• suited for hazardous materials like nuclear fuels
• quantitative determination possible with isotopic dilution technique

disadvantages

• often needs a separation to avoid isobaric interferences
• tedious sample preparation

contact

Dr. Gysemans Mireille
Dr. Dobney Andrew

aim

quantitative determination of organic carbon in solution

typical use

• determination of organic carbon in liquids

basic mechanism

• a known amount of sample is injected in a hot furnace and burned
• the evolved CO₂ is measured by I.R.

type of samples

• surface water, clay water, etc.

applicability range

• down to 1 ppm

turn-around time

• typically, 0.5 hour is needed for the measurement
• preparation depends on the nature of the sample
• the overall time, including preparation and calculations, is about 2 hours.

advantages

• good sensitivity
• rather accurate method (5 - 10% rel.)

disadvantages

• restricted to liquid samples

contact

Dr. Gysemans Mireille
Dr. Thomas Peter