14.11.2018

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 13.12.2016

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

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

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)

Some Examples of Users

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)

Radionuclides in Drinking Water

Typical Uranium concentrations in natural water

Typical Radium concentrations in natural waters

Typical Radon concentrations in natural waters

Human radiation exposure Typically about 1 – 10 mSv/a

Liquid Scintillation Counting principles 14.11.2018 Liquid Scintillation Counting principles

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)

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

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

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)

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.

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.

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

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.

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

Sample preparation

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

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

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

Conventional Double Coincidence Counters Perkin Elmer Wallac Aloka Hitachi Beckman

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

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

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

14.11.2018 The Performance and Advantages of Hidex 300 SL / 600 SL TDCR Liquid Scitillation Counters in detection of radioactivity in Drinking water

- 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

14.11.2018 H-3 detection Comparison of Hidex 300 SL to Quantulus and use of luminescence free counting mode

Stabile conditions and low level materails 14.11.2018 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

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

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

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

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

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

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

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) 201.64 +/- 0.32  CPM Hidex (lum. free mode) 195.94 +/-0.13 CPM (no outliers)

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.

14.11.2018 Gross alpha/beta measurement Optimization of a/b separation using Hidex counters and 2D graphical tool

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.

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

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

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

Conditions to meet EURATOM requirements Radioactive substance Ld requirement European Union Ld 300/600 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 = 3.92. 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 = 3.92. Counting simultaneously with gross alpha.

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.

Detection of Sr-90 by TDCR-Cerenkov method 14.11.2018 Detection of Sr-90 by TDCR-Cerenkov method

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 28.79 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

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

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)

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

Sr-90 Radioactive substance Ld requirement European Union Ld 300/600 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!

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

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

Thank You! risto.juvonen@hidex.com Mustionkatu 2, Turku - Finland www.hidex.com Tel. +358 10 843 5570