Radioactive contamination measurements

RTEC (Radon Track Etch Count)

aim

to determine the average concentration of radon in the air

typical use

• characterisation of average indoor radon levels in dwellings or working places

basic mechanism

• exposure of a passive polycarbonate detector in a special recipient during a long time ( e.g. 3 months to one year) to the air
• electrochemical etching and counting the number of tracks present on the detector

type of samples

• living rooms, bedrooms, cellars, etc.
• production halls, storage rooms, outdoor environment, ...

applicability range

• depending on exposure time
• from 10 Bq/m³ (outdoor background levels) up to tens of kBq/m³

turn-around time

• after exposure and return of the detectors to the laboratory, results can be available typically after one week

advantages

• simple, reliable ( within 10 to 15% ), independent from instantaneous changes in conditions

disadvantages

• no immediate results

contact

Dr. Vanmarcke Hans
Dr. Paridaens Johan

RAC (Radon Active Charcoal)

aim

to roughly estimate the average concentration of radon in the air

typical use

• first rough estimate of average indoor radon levels in dwellings or working places

basic mechanism

• exposure of a recipient containing a few grams of active charcoal to the air during 24 hours
• measurement with liquid scintillator upon return to the laboratory

type of samples

• living rooms, bedrooms, cellars, etc.
• production halls, storage rooms, outdoor environment, ...

applicability range

• from 10 Bq/m³ (outdoor background levels) up to tens of kBq/m³

turn-around time

• after exposure and return of the detectors to the laboratory, results can be available typically after one week

advantages

• simple, quicker results than track etch, first rough estimate

disadvantages

• strongly dependent on instantaneous variations

contact

Dr. Vanmarcke Hans
Dr. Paridaens Johan

RAMM (Radon Active Measuring Methods)

aim

to determine the instantaneous concentration of radon in the air

typical use

• real time characterisation of instantaneous indoor radon levels in dwellings or working places

basic mechanism

• use of Lucas scintillation device or alpha guard in combination with active pumping; immediate read-out of radon concentration

type of samples

• living rooms, bedrooms, cellars, etc.
• production halls, storage rooms, outdoor environment, ...

applicability range

• from 10 Bq/m³ (outdoor background levels) up to tens of kBq/m³

turn-around time

• instantaneous

advantages

• even quicker than active charcoal, almost immediate results

disadvantages

• more complicated, equipment has to be taken to the measurement site and operated by qualified personnel
• strongly dependent on instantaneous variations

contact

Dr. Vanmarcke Hans
Dr. Paridaens Johan

RISEM (Radon in situ exhalation measurement)

aim

to determine, in situ, the radon exhalation rate of soil

typical use

• in situ characterisation of radon exhalation rates out of the ground

basic mechanism

• a special canister containing active charcoal, is placed in situ on the terrain under investigation
• after typically 24 hours of exposure, the radon content is determined through gamma-analysis and the exhalation rate is determined from this

type of samples

• on top of waste piles, on outdoor terrain of almost any type
• in cellars

applicability range

• minimum detectable exhalation rate : 0.1 mBq/(m²s)

turn-around time

• after exposure and return of the detectors to the laboratory, results can be available typically after one week

advantages

• in situ measurement, soil need not be disturbed or transported, representative for the real conditions on the terrain

disadvantages

• difficult in very wet conditions

contact

Dr. Vanmarcke Hans
Dr. Paridaens Johan

REM (Radon Exhalation Measurement)

aim

aim to determine the radon exhalation rate of building materials, soil samples, etc.

typical use

• determining radon exhalation characteristics of building materials

basic mechanism

• a sample (large enough for low exhalations) is placed in a closed experimental radon chamber and the radon build-up is monitored

type of samples

• all kinds of building materials, soils, etc.

applicability range

• depending on quantity of sample available

turn-around time

• about two or three weeks, depending on availability of radon chambers

advantages

• no humidity problems, good for characterising material itself

disadvantages

• less information on real in situ conditions

contact

Dr. Vanmarcke Hans
Dr. Paridaens Johan

aim

delivery of standardised radionuclide solutions or solid state sources

typical use

• calibration of α, β and γ detection apparatus

basic mechanism

• solutions are calibrated for specific activity by means of activity determination of quantitatively deposited drops in the measurement samples
• precision weighings, buoancy corrected, are carried out on a calibrated microbalance applying the picnometer technique
• measurements are performed on either a 4pi proportional counter, using the coïncidence method or on a 4pi NaI well type detector for integral γ counting
• activity determination of a electrodeposition sources is done by measurements in a 2pi windowless proportional counter

type of samples

depending on applied measurement technique

• 4pi proportional counting:
  thin (~ 30 µg/cm²) gold coated sandwiched plastic foils
• 4pi gamma counting:
  cylindrical perspex boxes Φ 19 mm with 1mm absorption thickness
• 2π a counting:
  Al or s.s. backing sources: Φ = 15 and 40 mm

applicability range

• precision depends upon decay scheme and the presence of isotopical impurities typically 2 % 3σ

turn-around time

• about 1 week after receipt or preparation of non standardised primary product

advantages

• standards available in almost any geometrical form
• traceability with International Laboratories
• considerable price reduction if several standards derived from a freshly calibrated radionuclide solution are to be furnished
• availability of ⁵⁶Co

disadvantages

• no standards directly available from stock
• activity range of standards limited to about 10 MBq
• calibration of gases and radionuclides decaying by EC and emission of low energy photons not possible

contact

Bruggeman Michel

aim

global alpha and beta activity

typical use

activity measurements in

• air dust sample
• water (rainwater, surface water, underground water ...)
• filter
• nose-blow

basic mechanism

• the filter samples are directly placed in the counters
• 250cc of water or more is evaporated on a tray and placed in the counters the nose-blow after destruction with acid is evaporated on a tray and placed in the counters
• alpha measurements are performed with ZnS or proportional counters beta measurements are performed with proportional counters

type of samples

• filters maximum size 100 cm²
• water sample from 250cc to 1000cc
• nose-blow

applicability range

• from detection limit to....

turn-around time

varies from type and size of sample and from counting time
typical value for

• filters of 100 cm²: alpha 10 mBq/filter, beta 12 mBq/filter
• 250cc of water : alpha 22 mBq/l, beta 50 mBq/l
• nose-blow : alpha 0.02 Bq/sample

advantages

• in case of emergency relatively fast
• inexpensive

disadvantages

• global measurements

contact

Dr. Hurtgen Christian
Dr. Verrezen Freddy

aim

¹³¹I, ^89-90Sr activity

typical use

activity measurements in

• milk
• water (rainwater, surface water, underground water ...)
• filter

basic mechanism

• after chemical separation of the element to be measured and preparation of a counting tray,beta measurements are performed with proportional counters

type of samples

• milk, filters, water samples, soil

applicability range

• from detection limit to....
• high activity samples are not appreciated in our laboratories

turn-around time

varies from type and size of sample and from counting time typical value for

• filters: ⁹⁰Sr 10 mBq/filter, ⁸⁹Sr 20 mBq/filter
• 250cc of water : ⁹⁰Sr 40 mBq/l, ⁸⁹Sr 60 mBq/l
• 5l milk sample : ⁹⁰Sr2 mBq/l, ⁸⁹Sr 3 mBq/l, ¹³¹I 10 mBq/l

advantages

• specific measurements
• low detection limitre
• relatively fast measurement for ¹³¹I

disadvantages

• destructive measurements
• 1 week delay for Sr measurements

contact

Dr. Hurtgen Christian
Dr. Verrezen Freddy

aim

³H, ¹⁴C, ⁶³Ni, ⁹⁹Tc ... activity

typical use

activity measurements in

• water (rainwater, surface water, underground water ...)
• aqueous samples (milk, ...)
• biological samples (urine, faeces)
• organically bound ³H, ¹⁴C in environmental samples

basic mechanism

• either directly mixed with liquid scintillator for the measurements or after chemical separation of the element to be measured and preparation with liquid scintillator
• low energy beta measurements are performed in a liquid scintillator counter

type of samples

• any liquid sample or solid samples for organically bound ³H, ¹⁴C

applicability range

• from detection limit to....
• high activity samples are not appreciated in our laboratories

turn-around time

varies from type and size of sample and from counting time
typical value for

• aqueous sample: ³H10 Bq/l, ¹⁴C 5 Bq/l

lower detection limit can be obtained by special treatment of the samples

advantages

• more or less specific measurements
• relatively low detection limit
• relatively fast measurement

disadvantages

contact

Dr. Hurtgen Christian
Dr. Verrezen Freddy

aim

²²⁶Ra & ²²²Rn activity

typical use

activity measurements in

• water (rainwater, surface water, underground water ...)
• soil, sediment, ....
• air sample

basic mechanism

• after dissolution of the solid sample the solution is placed in a flask and flushed with nitrogen to remove all traces of radon, the solution is stored for at least one week to allow radon ingrowth
• the radon is then transferred to a counting bell and then counted
• for ²²²Rn in air, the sample is directly transferred to a counting bell and counted

type of samples

• any environmental or biological samples

applicability range

• from detection limit to....
• high activity samples are not appreciated in our laboratories

turn-around time

varies from type and size of sample and from counting time
typical value for

• 500cc of water: ²²⁶Ra < 1 mBq/l
• solid sample: ²²⁶Ra < 0.5 mBq/sample
• air sample: ²²²Rn < 0.25 mBq/l

advantages

• specific measurements
• solution can always be used for other type of measurements
• low detection limit

disadvantages

• 1 week delay for ²²⁶Ra measurements

contact

Dr. Hurtgen Christian
Dr. Verrezen Freddy

Natural uranium measurements

aim

natural uranium concentration

typical use

concentration of natural uranium in

• water (rainwater, surface water, underground water ...)
• urine

basic mechanism

• after evaporation of the sample in a platinum disk and preparation of a flux, natural uranium is measured in a fluorimeter

type of samples

• water or urine samples

applicability range

• from detection limit to....
• too high concentrations need dilution before measurement

turn-around time

• typical value 1 µg/l for water and urine samples

advantages

• very fast measurements
• low detection limit
• inexpensive

disadvantages

• non specific measurement other element can also give fluorescence

contact

Dr. Hurtgen Christian
Dr. Verrezen Freddy

aim

Th, U, Pu, Am, Cm ...activity

typical use

activity measurements in

• environmental samples (water, soil, sediment ...)
• biological samples (urine & faeces) for routine or incident control

basic mechanism

• after chemical separation of the element to be measured and preparation of a counting tray, this is counted in ZnS counter or by alpha spectrometry
• alpha spectrometry measurements need the use of a tracer

type of samples

• environmental samples (water, soil, sediment ...)
• biological samples (urine & faeces)

applicability range

• from detection limit to....
• high activity samples are not appreciated in our laboratories

turn-around time

varies from type and size of sample and from counting time
with a counting time of 250000 sec typical value

• 1l of water: 0.15 mBq/l for Pu, Am, U or Th
• urine sample of 36h: 0.1 mBq/24h for Pu, Am, U or Th
• faeces sample: 1 mBq/sample for Pu, Am, U or Th

advantages

• very specific measurements by alpha spectrometry
• very low detection limit

disadvantages

• lengthy preparation (3-4 days) and counting time (3 days)

contact

Dr. Hurtgen Christian
Dr. Verrezen Freddy

Neutron activation analysis

aim

bulk average element concentrations, independent of chemical state

typical use

• characterisation of the composition of any type of matrix, from percent level to trace level
• particularly suited for organic materials (absence of interference from the matrix main components in the activation spectrum)
• indispensable tool for the characterisation of reference materials (because it is only dependent on nuclear properties, unlike other techniques)

basic mechanism

• the sample is integrally placed in neutron field of research reactor
• radioactive nuclides are produced and their typical (delayed) γ-ray emission is detected off-line in a HPGe γ-detector
• peaks in activation spectra allow identification and quantification of the corresponding element

type of samples

• solid, powder, liquid, slurry, gas
• from mg level to several grams (and more)
• NAA is a good alternative method when e.g. the matrix is difficult to dissolve

applicability range

• for most elements in the ppb-ppm range
• not suited for light elements (from H to O)
• depends on the matrix activity (i.e. the presence of other activated elements in the matrix that add "background" counts to the spectrum)

turn-around time

• with rabbit system, in particular for short-lived products, the result can be obtained within a few minutes/an hour. In practice, the client will get his result within a week
• with the traditional off-line set-up for long lived products, the measurements can be spread over days/weeks. The client gets his results within a few weeks up to a month.

advantages

• non-destructivity: the sample is analysed in its original state and can be recuperated after some decay period
• sensitivity, traceability, high accuracy over large dynamic range of concentrations
• allows large dynamic range of sample weights
• limited matrix effects, simplicity of chemical preparations, freedom from analytical blank and dissolution problems
• independence of molecular or electronical state
• multi-element capability

disadvantages

• high turn-around time for long-lived products
• radioactive waste

contact

Sneyers Liesel
Vermaercke Peter

In-situ gamma-spectrometry

aim

activity of gamma-emitters in-situ

typical use

• characterisation of gamma field from radionuclides in soil: natural radioactivity (homogeneous distribution in soil) or radioactive fallout (surface contamination)
• characterisation of large area contamination, radioactive cloud, ...

basic mechanism

• gamma spectrum is taken with a portable HPGe detector (with Multi Attitude Cryostat + portable data acquisition system)
• radionuclides are identified from peaks in gamma spectrum
• activity derived from gamma peak area in spectrum and the assumed geometric distribution of the emitters

type of samples

• flat soil, meadow,...
• contaminated hot spot in nuclear site
• radioactive cloud

applicability range

• typically 1 Bq/kg for natural activity in soil

turn-around time

• highly contaminated spots can be characterised in a few minutes
• low activity, like natural activity in soil, takes 1/2-1 hour

advantages

• better sample representativity then laboratory measurements on small samples
• measurement on-site
• non-destructive, does not disturbe the site

disadvantages

• calibration difficult for non-homogeneous or unknown distribution of radioactive matter

contact

Bruggeman Michel
Lebacq Anne Laure
Daniëls Eddy

TLD dosimetry

aim

dose equivalent or absorbed dose

typical use

• personal dosimetry
• extremity dosimetry
• ambient dosimetry
• other single measurements of dose

basic mechanism

• thermoluminescence (TL): energy, coming from radiation, is stored in metastable phases of TL-materials; the reading out of the detectors is done by heating them, so that the energy is released as measurable light

type of samples

• single detectors
• badges containing several detectors and filters

applicability range

• 50 µSv to 1000 Sv

turn-around time

• ± 1 day to 1 week

advantages

disadvantages

contact

Vanhavere Filip
Maes Ludo

Laboratory for Nuclear Calibrations

Irradiation facilities

• panoramic irradiations with ⁶⁰Co and ¹³⁷Cs γ-sources
• panoramic irradiations with ²⁵²Cf neutron sources
• horizontal collimated beam with ⁶⁰Co and ¹³⁷Cs γ-sources
• vertical collimated beam with ⁶⁰Co γ-sources
• X-ray irradiation equipment (420 kV)
• ¹⁴⁷Pm, ²⁰⁴Tl and ⁹⁰Sr-⁹⁰Y β-sources

applicability range
(02/97)

• ⁶⁰Co: max. 13 Gy/h
• ¹³⁷Cs: max. 2 Gy/h
• ²⁵²Cf : max. 20 mSv/h
• ¹⁴⁷Pm: activity 5.107 Bq
• ²⁰⁴Tl: activity 4.106 Bq
• ⁹⁰Sr-⁹⁰Y: activity 1.109 Bq

contact

Vanhavere Filip
Lebacq Anne Laure

aim

radioactive body or organ burdens

typical use

• control of workers (in Nuclear power plants, in laboratories manipulating radioactive samples, near to particle accelerators), people manipulating thorium (lamp factories), nuclear medicine,...
• in-vivo measurements of radioactive burdens in case of contamination accidents.
• study of metabolisms
• follow up of contamination in case of surgical interventions
• measurements of wounds

basic mechanism

• the person is placed in an environment free of radiation (shielding room when necessary) to reduce the background
• a detector (scintillator , gas or semiconductor) is placed near to the body (or near to an organ to be measured) during a period of time between one minute and one hour
• a γ-ray or X-ray spectrum is collected allowing the identification and the quantification of the body or organ burden

type of samples

applicability range

• for most isotopes, the detection limits are low enough to answer to directives and recommendations

turn-around time

advantages

• very sensitive in most of the cases (a one minute counting detects and quantifies an internal contamination not detectable by radiation control procedures)
• fast results within half an hour after measurement
• does not require chemical procedures
• applicable to all γ-emitters, to most of high energetic β-emitters (bremmstrahlung) and to many α-emitters (by measuring the daughters γ-rays.
• not expensive technique
• no radioactive wastes
• Stress is reduced with fast results

disadvantages

• detection limits are sometimes too high
• some isotopes are not directly detectable

contact

Lebacq Anne Laure

Gamma and alpha spectrometry

aim

activity or specific activity of radionuclides emitting gamma-, X- and/or alpha radiation

typical use

• radiological surveillance of the environment: control of water, sediment, biological indicators etc.
• radiological safety: control of releases, cooling waters etc.
• support to research activities, e.g. of radioecology projects
• control of contamination of consumer products, e.g. foodstuffs, feeding stuffs, construction materials etc.

basic mechanism

• the sample is placed close to a radiation sensitive detector (High purity Germanium, Si(Li), NaI(Tl) or silicon detectors)
• these detectors have a sufficient resolution to obtain spectra that allow identification of the nuclides as well as quantitative results if the sample geometry corresponds sufficiently well to the geometries used for calibration of the detectors

type of samples

• water or aqueous solutions, environmental samples, powders or solids, feeding stuffs
• in our laboratory the sample dimensions for gamma spectrometry vary between 0,7 ml and 2.5 liter Marinelli
• most of the samples have low specific activities in our laboratory

applicability range

• typically 0,1 Bq - 100 000 Bq/sample

turn-around time

• samples of low activity are counted overnight, yielding a turn-around time of 1 to 2 days
• samples of higher activity can be treated within a few hours

advantages

• sensitive method
• sufficient accuracy for all relevant applications
• relatively fast method
• allows quantification of a large number of radioisotopes
• in case of gamma spectrometry: very simple sample handling

disadvantages

• some radionuclides can not or only with great difficulty be determined
• sample preparation complex for pure alpha- or X-ray emitters
• detection limits for one isotope are dependent of the activity of other isotopes present in the samples
• for complex spectra: interference's may increase uncertainties; short-lived radionuclides may increase detection limits or uncertainties for longer lived nuclides, often requiring repetitive analyses for mixed samples

contact

Dr. Bruggeman Michel