2. Risto Juvonen, product manager/Hidex Oy 13.12.2016
Detection of radionuclides in drinking water with Hidex 300 SL and 600 SL
- Implementation of EURATOM Drective 2013/51
Risto Juvonen, product manager/Hidex Oy

3. Hidex Oy Family owned company founded 1993
Manufacturing analytical instrumentation for bio- and health sciences, nuclear industry and for monitoring radioactivity in environment
Hidex staff has long engineering know- how since 70’s
Located in Turku, Finland
Instruments are delivered and supported globally through an independent distributor network

4. Main Products
Hidex 300 SL & 600 SL - automatic TDCR scintillation counters
Triathler – manual scintillation and gamma counters
Hidex AMG – automatic gamma counters

5. Examples of applications Environmental radioactivity
H-3, C-14, Sr-90, Rn-222, gross alpha/beta,...
Biotechnology, bilology, pharmacology
H-3, C-14, P32 etc. Used as labels e.g. In metabolism studies
Industry
Nucler power plants cooling water and emission gases
Safety
Terrorism threads, accidents
Clinical diagnostics
C-14 Helicobacteria test
Verification of biomaterials and dating
Determination of biobased carbon content based on C-14
Contamination control
Swipe tests, internal contamination (biotests)

6. Some Examples of Users

7. Radioactivity in general
-Ionizing radiation
, , , X-rays, neutrons
-Unit: [Bq] Becquerel
(old unit [Ci] Curie, 1 Ci = 3.7 · 1010 Bq)
-Activity is decaying by time
Half life T1/2 = time the activity is halved
-Radioactivity is present in nature naturally and due to hiuman actions, e.g. accidents
-Elements consist often on stabile and unstabile (radioactive) elements, e.g. H (1H, 2H and 3H)

8. Radionuclides in Drinking Water

9. Typical Uranium concentrations in natural water

10. Typical Radium concentrations in natural waters

11. Typical Radon concentrations in natural waters

12. Human radiation exposure
Typically about 1 – 10 mSv/a

13. Liquid Scintillation Counting principles
Liquid Scintillation Counting principles

14. General The most sensitive method for detection of radioactivity
The sample is mixed with scintillation cocktail which converts the radioactive decay energy to visible wavelength photons.
The photons are detected with photomultiplier tubes (PMT) and analyzed with multichannel analyzer (MCA
As result there is an energy spectra typical to each different isotope
H-3, C-14 and P-32 spectra (Emax 18 keV, 158 keV ja 1700 keV)

15. General
LSC method is used typically for detection of the activity of beta isotopes such as H-3, C-14, P-32, I-129, Sr-90 etc.
Can be used very well also detection of alpha emitting isotopes such as Rn-222 or Ra-226
Can be used also for detection of gamma emitting isotopes
LSC is the only sensitive enough method for detection of environmental activity concentrations of the lowest energy isotope H-3

16. General Beta decay is a multiphoton event (about 7 photons/keV)
In LSC we are detecting Coincidence pulses (2 or more photons are detected simultaneously with PMTs)
Single pulses are considered background and disgarded

17. General The result: Observed counts per minute (CPM)
CPM is corrected to absolute activity DPM (disintegrations per minute) by deviding CPM with counting efficiency (Eff.)
DPM = CPM/Eff.
(Becquerel, Bq = DPS = DPM/60)

18. Main interferences Background
Environnmental radiation (cosmic, soil, materials, K-40 in PMT photocathodes)
Luminescence
Electronic noise (from the instrument itself)
Static electricity
Quenching
Color quenching
Chemical quenching and water
Physical quenching
Three PMTs bring a very high effieciency. Over 70% for unquenched tritium.

19. Quench Correction – determination of counting efficiency
Intrernal standard method
Counting efficiency is determined by adding known amount of activity (standard) in the sample
Eff. = CPM2-CPM1/DPM
CPM1 the count rate of the sample without the standard
CPM2 the count rate of the sample with the standard
DPM is the known amount of activity added in the sample
Excellent quench correction method when the quenching is constant from sample to sample, e.g. Distilled water samples.
Three PMTs bring a very high effieciency. Over 70% for unquenched tritium.

20. Quench Correction – determination of counting efficiency
External Standard Method
1. Sample is measured using an extrenal standard source 133Ba, 137Cs or 152Eu
-> the position of the resulted compton spektra is proportional to quenching -> a parameter proportional to the position e.g. the end point of the spectra (QPE) is printed
-> QPE is fitted to the Quench curve to read Efficiency
2. Sample is measured without the satnadrd and CPM is recorded
Result: DPM = CPM/Eff
Three PMTs bring a very high effieciency. Over 70% for unquenched tritium.
Challenges: every isotope and every type of sample condition requires it’s own quench curve
Advantages compared to internal std method: can be used for variable quenching

21. Quench Correction – determination of counting efficiency
TDCR (= Triple to Double Coincidence Ratio ≈ Counting Efficiency)
Requires triple coincidence detector (3 PMTs)
Can be used for varibale quenching and no need for extrenal radioactive standard source = Absolute counting method
DPM= CPM/Eff.
As Eff. ≈ TDCR
=> DPM ≈ CPM/TDCR
Three PMTs bring a very high effieciency. Over 70% for unquenched tritium.

22. Triple detector array and coincidences
R S: Double Coincidence Counts
R T: Double Coincidence Counts
S T: Double Coincidence Counts
R S T: Triple Coincidence Counts
Sample S T
Counts are collected as Triple coinciences and three double pairs.
R S T
R S
R T
S T
Ct = triple counts
Cd = double counts
Call = All coincidence counts

23. Sample preparation

24. Sample preparation
Sample is mixed with cocktail in a scintillation vial (5 mL, 7 mL, 20 mL) - > homogenous emulsion
Filters (e.g. swipes or air filters) can be measured directly
Biological samples require solubilization

25. Scintilation cocktail
Organic aromatic solvent+ fluorescent molecules+ emulsifiers
Solubility in water max 10 ml water/10ml cocktail
Salts, acids, bases reduce solubility
Temperature affects on solubility which affects on efficiency
– optimum about 15 C – 20 C
Various manufacturers, e.g.. Meridian, Perkin Elmer, Zinsser, who hav ecocktails optimized for various different sample types. e.g. UltimaGold, GoldiSol, Hisafe etc.
Hidex is offering few cocktails with AquaLight and MaxiLight trade marks which have been found the best ones to few most typical applications

26. Vials
Plasti (“polyvials”)
+ Material is fossil based polyethylene or -propene ->LOW BACKGROUND
- Plastic and it’s components may dissolve in cocktail causing quenching and radioactive molecules may adsorb in the surface
Teflon coated plastic
+ low background/inert to solvents
- Cost
Glass + Inert material - Relatively high background due to K-40 radioactive isotope in borosilicate

27. Conventional Double Coincidence Counters
Perkin Elmer
Wallac
Aloka Hitachi
Beckman

28. Hidex TDCR counters and manual Triathler
Hidex 300 SL and 600 SL – automatic TDCR LSC counters
Hidex Triathler – manual LSC and gamma counter

29. Hidex 300 SL and 600 SL Automatic TDCR Liquid Scintillation Counter
Automatic vial counter with triple-PMT detector facilitating:
exceptionally high counting efficiency,
automatic quench correction by TDCR method without external radioactive standard source
Luminescence free counting mode
a/b separation with 2D graphical calibration & validation tool
Pb shielded Triple- coincidence detector

30. MikroWin 300 & 600 SL Software - compatible with latest win 10 OS - complies with FDA requirements

31.
The Performance and Advantages of Hidex 300 SL / 600 SL TDCR Liquid Scitillation Counters in detection of radioactivity in Drinking water

32. - Manufcturing of the old ”Wallac” Quantulus is discontinued - How Hidex 300 SL super low level counter model can meet the requirements - Examples in drinking water detection: H-3, Sr-90, Gross alpha/beta

33.
H-3 detection Comparison of Hidex 300 SL to Quantulus and use of luminescence free counting mode

34. Stabile conditions and low level materails
Optimization of the conditions
Stabile conditions and low level materails
Stabile temperature preferably between 15 – 20 C
Plastic/teflon coated platic vials & low level cocktails
Bkg water sample – ”dead water”
Dark adapt of the samples
Use delay options and repeat counting if necessary allowing to disgard samples with high bkg luminescence

35. Comparison of Hidex 300 SL super low level model to Quantulus at IAEA Vienna
Samples: natural H-3 TRIC intercomparison test samples electrolytically enriched from 500 mL to 15 mL, Counting time 10 x 50 min
Digital Pb shield was used - reduction of bkg in open 35 % efficiency window was from 5.7 CPM to 4 CPM (FOM > 300)
The results showed perfect agreement with Hidex 300 SL and Quatulus
Key factors for equal resuts were
higher counting efficiency and
exceptionally stabile background

36. Average values and one sigma uncertainties
The poster presented at IAEA hydrogeology meeting on May 2015

37. How we met the criteria of the intercomparison
sample
(TU)
Hidex-expected (TU)
Z-Score
Acceptance
(fiktiv)
T20
-0,01 -
acceptable
T21
0,43
0,446
0,16
T22
1,121
1,31
1,92
T23
2,741
2,86
1,20
T24
4,37
4,48
0,87
T25
7,51
7,54
0,13
Z-Scores: z = (x-xa)/sp)
-2 < z < 2: Acceptable
-3 to -2 / 2 to 3: Questionable
< -3 / > 3: Unacceptable

38. Issues/interferences
Hidex background higher than the background of Quantulus
Hidex bkg about 5 – 10 times higher than that of Quantulus
Compensated by higher counting efficiency and high stability
-> Detection limit only about twice as high

39. Issues/interferences
Stability of the samples
Luminescence and static electricity causes instability
Luminescence decays by time (hours – days)
Solved usually
by waiting luminescence decay (hours-days)
By counting samples repeatedly and by removing outliers
Hidex triple-coincidence detector allows an additional tool: Luminescence Free counting mode
Counting of all triple counts + pure double counts above the luminescence region
Reasonable high counting eff. 20 – 25 %
low and extremely stabile background –> Low risk on outliers

40. Luminescence free counting
Luminescence do not interfere with triple counts
Even highly luminescence samples can be counted w/o dealy using triple-coincidence counting mode

41. Comparison of outliers 8 + 12 ml samples, 10 x 50 min counting time
Outlier CPM Overall:
Quantulus
13 out of 24 samples had from 1-3 CPM “outliers” removed (means reduced counting time too for some). 11 had no CPM outliers.
Hidex (lum. free mode)
no CPM outliers
Tritium Standards
Quantulus
(1 outlier CPM was removed)
/- 0.32  CPM
Hidex (lum. free mode)
/-0.13 CPM
(no outliers)

42. H-3 performance comparison
8+12 ml, 4 h measurement time, 3 s uncertainty
Normal mode Lum free mode Quantulus
Bg 4.7 CPM 2.8 CPM 0.5 CPM
Eff 37 % 24 % 25 %
Ld 2.4 Bq/L 2.8 Bq/L 1.7 Bq/L
Outliers High risk Low risk High risk
Luminescence mode allows immediate start of the measurement after sample prep.
Detection limit only slightly higher than that in normal count mode.
High stability and reliability of the results
No need to exclude outliers after the measurement
Ld < 10 Bq/L required by EURATOM directive can be reached with 60 – 120 min counting time even in luminescence free counting mode
Sample preparation by distillation.

43.
Gross alpha/beta measurement Optimization of a/b separation using Hidex counters and 2D graphical tool

44. Alpha Beta separation Pulse anatomy:
Ionizing particle excites several scintillator molecules to mixture of
Singlet states  fast decay or prompt component
Triplet states  long decay or delayed component
Alpha particles produce denser ionization which favors formation of triplet states, hence more delayed component.
Alphas
Betas
Crudely, the pulse shape is sum of prompt and delayed components:
 In LSC cocktails, the prompt component has life-time typically 1-10 nanoseconds; the delayed component some tens of nanoseconds.
It’s often just said that alpha pulses are “longer” than beta pulses.

45. Conventional calibration procedure
Optimization of the pulse decay discriminator (PDD, PSA,..) using a pure alpha and a pure beta emitter (typically Am-231, Pu-239/Sr-90, Cl-36)
Optimum PDD varies based on the isotope energies and degree of quenching
Betas
90Sr/241Am, 90Sr/239Pu
3 mL of 0.5M HCl in 17 mL of Ultima Gold AB and Low 40K glass vial.
(Ref: RRMC 2015)
-> PSA is different for different isotopes
-> uncertainty of the results if the isotopes are not the same as in the unknown samples

46. Calibration procedure with 2D graph
- Applicable for Hidex Triathler and 300 SL & 600 SL counters
Measure a sample with alphas & betas
(can be the same isotopes as you use in the misclassification run or just a typical unknown sample with some alphas)
Print out 2D spectra
Alphas
Optimize the conditions if separation is not good
Select discriminator (PLI)
(visually or by performing conventional misclassification run)
Measure the unknowns using selected PLI
PLI
Betas

47. Example: optimization of 90Sr/241Am measurement w/Hidex 300 SL
(3 mL of 0.5M HCl in 17 mL of cocktail)
UG ab / glass
UG ab / teflon
AL ab / teflon
Optimum PLI
Alpha and beta regions merged together
-> misclassification of alphas as betas and vice versa
-> high uncertainty
2. Separation improved by selecting better vial type
3. Separation improved even more by selecting cocktail with higher separation efficiency
-> almost zero misclassification
-> low uncertainty
! 2D graph can be used also as a results verification tool for the unknowns

48. Conditions to meet EURATOM requirements
Radioactive substance
Ld requirement European Union
Ld /600 SL
Description of the method
Gross alpha
0.04 Bq/L
< 0.04 Bq/L
< 0.02 Bq/L*
Concentration of the sample to 1:10 by evaporation: 8 ml sample + 12 ml AquaLight cocktail in 20 ml teflon coated plastic vial in open alpha energy window using alpha beta separation option Measurement time 500 min, k1-a + k 1-b = Counting simultaneously with gross beta.
*sample preparation by freeze drying
Gross beta
0.4 Bq/L
< 0.3 Bq/L
Concentration of the sample to 1:10 by evaporation: 8 ml concentrated sample + 12 ml AquaLight coktail in 20 ml teflon coated plastic vial in open alpha energy window using alpha beta separation option Measurement time 500 min, k1-a + k 1-b = Counting simultaneously with gross alpha.

49. Summary 2D graph can be used as a tool:
for optimizing measurement conditions
for quality control of the results
How to optimize the conditions:
selecting optimum vial materials and cocktail with best possible separation efficiency
reducing quenching using different sample to cocktail ratio
optimizing instrument alpha/beta parameters
Same procedure can be applied for detection of specific alphas e.g. Rn-222, Ra-226, Am-241, etc.

50. Detection of Sr-90 by TDCR-Cerenkov method
Detection of Sr-90 by TDCR-Cerenkov method

51. Rapid detection of Sr-90 in water by Tayeb et
Rapid detection of Sr-90 in water by Tayeb et.al, Atomic Energy Canada, Chalk River J. Radioanal. Nucl. Chem. (2014) 300:263–267
Why has Sr-90 such an importance?
Strontium-90 (90Sr) is a contaminant found everywhere at nuclear sites, resulting from nuclear fission of plutonium and uranium.
-> found in high concentrations in spent nuclear fuel and waste.
World-wide nuclear weapons testing in the 1950s and 1960s also resulted in widespread distribution of Sr-90
With its long half-life of years, Sr-90 persists in the environment and if released into soil, can form subsurface groundwater plumes that could eventually discharge to surface waters
It is biochemically similar to calcium and can therefore be accumulated in the bones
-> potentially leading to cancers of the bone marrow and the soft tissues surrounding the bone

52. Detection of 90Sr
Most of the conventional methods require time consuming and complex radiochemical sample pretreatment methods with subsequent detection e.g. with GPC or by LSC once 90Sr has reached equilibrium with it’s daughter 90Y.
90Y can be detected by Cerenkov method with very low interference of 90Sr and no interference of low energy betas.
The absolute activity determination of Cherenkov radiation has been a problem
TDCR counting method, which is well established in absolute counting of beta emitters by LSC has been used succesfully also on absolute activity determination of 90Y
TDCR-Cerenkov method allows reduction of measurement times by several days compared to commonly used standard methods

53. TDCR correlates more or less linearily with Cerenkov efficiency
TDCR correlates more or less linearily with Cerenkov efficiency. (conventional extrenl std method do not correlate with Cerenkov efficiency and cannot be used) Example: Y-90 Cerenkov TDCR vs. Real efficiency (PTB, Germany)

54. Rapid detection of Sr-90 in water by Tayeb et
Rapid detection of Sr-90 in water by Tayeb et.al, Atomic Energy Canada, Chalk River
Conclusions:
The measurements obtained from counts following direct TDCR Cherenkov counting and radiochemical separation agreed very well.
This confirmed that direct TDCR Cherenkov counting can serve as a rapid screening method with reliable results.
However, the radiochemical separation method may yield more accurate results in cases where other interfering radionuclides are present in the samples

55. Sr-90
Radioactive substance
Ld requirement European Union
Ld /600 SL
Description of the method
Gross alpha
0.4 Bq/L
< 0.2 Bq/L
Direct counting after radiochemical separation: 8 ml of prepared water sample in Cerenkov-TDCR counting mode in 20 ml plastic vial for Y-90 activity. Subsequent addition of 12 ml of AquLight Beta cocktail to count Y-90 + Sr-90 activity on LSC mode. Sample volume 2 L, measurement time 30 min, k1-a + k 1-b = 3.92.
Note! conventional methods require waiting for Sr-90/Y-90 eqilibrium which takes about 1 week.
Cerenkov-TDCR method reduces the total analysis time by several days!

56. Summary on measurement of radiounuclides in drinking water with Hidex 300 SL 600 SL

57. Summary on detection of radionuclides from drinking water with Hidex 300 SL/600 SL

58. Thank You! risto.juvonen@hidex.com Mustionkatu 2, Turku - Finland
Tel