Monitoring of radioactivity in surface and underground water:
From sampling to dose assessment
Rosella Rusconi
ARPA Lombardia - Centro Regionale Radioprotezione (CRR)
Via Juvara 22 - 20129 Milano - Italyr.rusconi@arpalombardia.it

1

Contents
1. ARPA Lombardia – Presentation

2. Natural and artificial radioactivity in the environment
3. Emergency Quick Alert

4. European and National Environmental Radioactivity Network
5. Water Monitoring

6. Surface water
7. Environmental markers: Fish and Suspended Particles

8. Activity – Dose – Limit of detection
9. Conclusions

2

ARPA Lombardia – Presentationwww.arpalombardia.it

ARPA Lombardia• ARPA is a government Agency in charge ofpreventing and monitoring environmental
pollution• It is one of the 21 Italian Agencies operatingin the framework of the Network of Italian
Environmental Agencies (SNPA), coordinatedby the National Environmental Agency (ISPRA)
in RomeARPA Lombardia - Organization• Lombardia region: 9 Million people, 15% of Italian population,highest concentration of productive activities• ARPA Lombardia:• 13 offices in the main townsof the region• Around 1,000 people
employed: chemists,biologists, physicists,

engineers, etc.
• Headquarters: Milano

MilanoARPA Lombardia – Main fields of activity• Industrial emissions (air,water, wastes)• Environmental remediation• Noise• Non Ionizing Radiation• Hydrographic service•Geological Risk
•Meteorology•Weather Climatology

Environmental
Monitoring

Controls

Natural Risks• Radioactivity• Radon•IPA, As, Ni, Cd, Pb Samples•Annual and daily bulletins•Monitoring campaigns•Environmental impact
assessments•Strategic environmental
assessments

Air Quality

Environmental
Assessment• Air• Surface water• Groundwater• Biodiversity

Radiation
Protection

Radiation Protection Centre• 10 staff members: chemists, biologists andphysicists• 2 measurement labs (Milano andBergamo), 1 radiochemistry lab accredited
under ISO 17025

Bergamo
Milano• Equipment for alfa, beta and gamma measurement, both in field
and in lab• Tools for data evaluation and risk assessment

Radiation Protection Centre• Member of the National Network for Environmental
Radioactivity Monitoring• Member of IAEA ALMERA Network• Scientific advisors of National and Regional Health
Authorities for problems due to radioactive materials• Since 2000 member of ISO Committees

Natural and artificial radioactivity in the environment

Radioactivity in the environment
Map of Nuclear sites in Italy• Discharges from nuclear sites (10 NPP underdecommissioning)

Radioactivity in mushrooms in different areas - 2017
600 Bq/kg• Nuclear accidents (mainly Chernobyl)

Radioactivity in the environment
Contaminated wastes in incineration plants• Wastes from medical use of radioactivity• Areas contaminated as a result of past activities:– NORM industries (phosphogypsum
repositories)– Waste repositories from accidents occurredin the past (radioactive source melting infoundries)

Wastes from radioactive source melting in foundries

Radioactivity in the environment• Natural radioactivity– Underground waters (radon, radium, uranium, etc.)
Gross alpha activity in underground waters
25% of samples > 0,1 Bq/kg– Radon indoor(Regional mean value = 116 Bq/m3)

Emergency Quick Alert

Air monitoring – Gas and particulate• TSP monitoring: running since 1988
• Gas monitoring: running since 1997

Sampling point and frequency•

Milano city centre•

Particulate: Daily (continuous from 9 a.m. to 9 a.m.)•Gas: Weekly

Measurement frequency•

Particulate: Daily, Weekly, Monthly•

Gas: Weekly

Monitoring conditions
optimized for quick
alert of “relevant”
air contamination

Air monitoring – Sampling unit
• Housing: Commercial(Air Sampler GMWL-2000 H - General Metal Work Inc. US)• Flow counter: Commercial (Schlumberger; resolution 0,01 m3)
Uncertainty in flow rate measurement: 5%• Pumping system:
Flow: ≈ 100 m3/h ( ≈ 2400 m3/d)• Filtering unit:
Glass microfiber filter (Whatman GF/A CAT No. 1820-866,
203x254 mm) + iodine trap15

15/12/2017

15/12/2016

15/12/2015

15/12/2014

1,0E-01

15/12/2013

15/12/2012

15/12/2011

15/12/2010

1,0E-04

15/12/2009

15/12/2008

17/12/2007

15/12/2006

15/12/2005

15/12/2004

15/12/2003

15/01/2003

15/01/2002

15/01/2001

15/01/2000

15/01/1999

15/01/1998

1,0E-03

15/01/1997

15/01/1996

15/01/1995

15/01/1994

15/01/1993

15/01/1992

15/01/1991

15/01/1990

15/01/1989

15/01/1988

Air monitoring – Particulate
Bq/m3

1,0E+00

CS137 > MDA

CS137 < MDA

1,0E-02

Algeciras '98
Fukushima

1,0E-05

1,0E-06

1,0E-07

1,0E-0816

4,0E-03

3,5E-033,0E-03

21/09/2017
22/09/2017
23/09/2017
24/09/2017
25/09/2017
26/09/2017
27/09/2017
28/09/2017
29/09/2017
02/10/2017
03/10/2017
04/10/2017
05/10/2017
06/10/2017
07/10/2017
08/10/2017
09/10/2017
10/10/2017
11/10/2017
12/10/2017

Bq/m3

Air monitoring – Early detection of Ru-106
Ru-106 in air – September – October 2017
< MDA

> MDA

2,5E-032,0E-03

1,5E-03

1,0E-03

5,0E-04

0,0E+00

17

Air monitoring – Iodine trap

NORIT RKJ
* Granular activated carbon* Elemental, ionic and organic I retention* Pellet diameter: 1.3 – 1.5 mm* BET surface area: 900 – 1000 m2/g

Methylmetacrylate box

2 beds, each one:
19 x 24 x 2,4 cm≈ 500 g RKJ (≈ 1 L) (Marinelli)filling/empting holes
Beds separated by double metal grids(2 different meshes), silicon sealed18

Air monitoring – Iodine 131
1,20

I-131

1,00

FUKUSHIMA 2011
Radioactivity in Air (particulate)
Avg Igas/Iparticulate = 80 %

GAS

0,60

0,40

0,20

PTS
19-apr

17-apr

15-apr

13-apr

11-apr

9-apr

7-apr

5-apr

3-apr

1-apr

30-mar28-mar0,00

26-marmBq/mc0,80

Results comparable tothose obtained by otherEU laboratories (Masson
et al, 2011)19

European and National

Environmental
Radioactivity Network

Monitoring Network
ARPA is part of the National Environmental Radioactivity Network,
fulfilling requirements of European Union:• European Commission Recommendation 2000/473• European Council Directives (2013/51/EURATOM)
Environment Monitoring

Source Related Monitoring

No. of samples analyzed• Food and environmental samples, about 1000 samples per year
SampleAIR

Radionuclide
GROSS BETA
Cs-137

Minimum Detectable Activity
0,005 BQ/M3
0,03 BQ/M3

SURFACE WATERGROSS BETA
Cs-1370,6 BQ/L
1 BQ/LDRINKING WATER

H-3
Sr-90
Cs-137
NATURAL RADIONUCLIDES

100 BQ/L
0,06 BQ/L
0,1 BQ/LNOT SPECIFIED

MILK

Sr-90
Cs-1370,2 BQ/L
0,5 BQ/LMIX DIET

Sr-90
Cs-1370,1 BQ/DAY PER PERSON
0,2 BQ/DAY PER PERSON

as required by European Commission
Recommendation 2000/473

Monitoring Network

DOSE

23

Water Monitoring

Drinking water• According to European Council Directive 2013/51:– monitoring of major ground or surface water supplies andwater distribution networks
Parameter

Parameter
value

Derivedconcentration

Limit ofdetectionrequired by UE
Directive

Indicative Dose < 0,1 mSv/y

RADON

100 Bq/L

10 Bq/LTRITIUM

100 Bq/L

10 Bq/L

INDICATIVE DOSE

0,1 mSv/yGross alpha and beta as
screening parameters
IF EXCEEDEDGross Alpha0,1 Bq/L

0,04 Bq/L

Gross Beta

1 Bq/L0,4 Bq/L

U-238

3 Bq/L0,02 Bq/L

Ra-2260,5 Bq/L

0,04 Bq/L

Cs-137

11 Bq/L

0,5 Bq/L

Single nuclides

Drinking water: Monitoring network•

Extensive monitoring of Gross Alpha and Beta (Gross Beta including possible
contribution of Cs-137):– Sampling about 0,5 L of water from tap– Measurement by Liquid Scintillation Counting with ISO
11704:2010
MEASUREMENT METHOD
100 mL of sample concentrated 1:10 by evaporation
pH adjusted to 2,5
8 mL sample + 12 mL liquid scintillation cocktail
1000 min counting with alpha/beta discrimination
20 mL Teflon
CoatedPolyethilene
Vials

Parameter

Screening
value

Limit of detection
Required by Law

Limit ofdetectionin our Lab

Gross Alpha0,1 Bq/L

0,04 Bq/L

0,008 Bq/L

Gross Beta

1 Bq/L0,4 Bq/L

0,08 Bq/L

Drinking water: Monitoring network•

In selected points, continuous sampling for high sensitivity monitoring by Gamma
Spectrometry
METHOD• Continuous elution, over 1 month, on a colum (1 kg) of ionicexchange resin• Measurement by Gamma Spec. for 4000 minutes
HPGe Detectors, 30% relative efficiency:
ParameterCs-137

Amount ofsampleCounting
Time

Limit ofdetection *1L1000 min

0,1 Bq/L

200 L

4000 min

0,0005 Bq/L

* Limit of detection required by EU: 0,5 Bq/L

Drinking water: Monitoring network
Results at a glance:– Gross Alpha:– 25% of samples > 0,1 Bq/L

Gross alpha activity in underground waters
25% of samples > 0,1 Bq/kg– Mainly due to Uranium isotopes(natural origin)– Gross Beta:– < Limit of Detection (0,08 Bq/L)– Artificial nuclides (Gamma Spec.) < L.D. (0,0005 Bq/L for Cs-137)

Surface waterSurface water• According to European Recommendation 2000/473:– monitoring of major inland waters for Residual beta and Cs-137
SAMPLING POINTS:
36 rivers, 17 lakes

SAMPLING POINTS:
7 rivers, 1 lake30

Surface water• For surface water samples:
Reporting Level as required by EU Commission (>= Detection limit):–
Residual beta: 0,6 Bq/L–
Cs-137: 1 Bq/L
In few cases more parameters are required (Pu isotopes, Sr-90)

Cs-137

Direct sampling (1 liter) andmeasurement by Gamma Spec.:
1 L, Marinelli Beaker, 1000 min
counting time, HPGe 30%
L.D. = 0,1 Bq/L

Beta

Pu

Sr-90

Radiochemistry:– ISO 11704 Gross beta
(L.D. = 0,08 Bq/L)– ISO 13167 Pu isotopes– ISO 13160 Sr-90

Surface water: results at a glance▪ Sampling point: Dervio (Como lake)▪ Sampling depth: 5 mt
▪ 2 samples per year (spring + autumn)
Gross alpha
Bq/kg

Gross beta
Bq/kg

Pu-239/40
Bq/kg

Pu-238
Bq/kg

Sr-90
Bq/kg

Cs-137
Bq/kg

Autumn0,0212 ± 0,0087< 0,091< 0,000047< 0,000042< 0,0057< 0,10Spring0,0238 ± 0,0092< 0,085< 0,00019< 0,00016< 0,0050< 0,10L.D.*

0,6 Bq/L* L.D.: Limit of Detection as required by EU Commission Recommendation 2000/473

1 Bq/LSurface water• In few cases lower limits of detection (Gamma emitters, Cs-137) are
requiredCs-137

Direct sampling of 5 liters followed by sample concentration:– Absorption on ion exchange resins– Sample evaporation with SiO2

Absorption on ion exchange resins• Resin: Amberlite MB6113 (mixed bed) with saturation
indicator• Resin capacity: ~ 35 ml resin / g dry residue(depending on dissolved salts)• Resin amount: ~ 0,1 L• Sample amount: ~ 5 L• Elution rate: ~ 40 mL/min• Contact time: ~ 2,5 min• Resin uptake: tested by atomic adsorption analysis on
eluate (stable Ca) – 100%34

Sample evaporation with SiO2
• Sample evaporated on a hot plate• Water samples is acidified (nitric acid, pH 2 c.a.) to
avoid salts precipitations and adhesion on beakerwalls• Inert material (silica-gel – SiO2) is added (~ 25 g)• Sample is evaporated to dryness, silica gel istransferred in a beaker and measured• No filtration required• Up to 10 liters can be easily treated (3-7 days)

METHOD TESTED BY SPIKED SAMPLES,YIELD = 100%
35

ADVANTAGES• Works well independent on theamount of dissolved salts• Once dried is still dusty (no crusty
scales, no residues left on beaker)• The residue recovery (powder) iseasy and complete• Very easy to attain correct
geometry and density• Silica gel is easily available andin high purity• Relatively cheap: ~ 0,1 €/g of
SiO2

SiO2 30ml

DISADVANTAGES• Not very quick
36Limit of Detection of different methods for Cs-137
HPGe detector, 30% relative efficiency
Water as is

Resin absorption

1L

Sample evaporation(SiO2)
Resin absorption
5L

Geometry

Marinelli 1 L

Beaker 30 cc

Marinelli 1 L

Counting time1000 min1000 min4000 min

MDA Cs-137

0,1 Bq/L

0,01Bq/L

0,0005 Bq/L

Amount of sample

200 L

37

Methods comparison – IAEA PT 2016
1. Water analysis (as is)
2. Sample evaporation (SiO2)
3. Absorption on ion exchange resins – low volume

Bq/kg

Sample 3 - Spike
0,70
0,60
0,50
0,40
0,30
0,20
0,10
0,00

0,5 Bq/kg

Water sample t.q.

SampleResin absorption
evaporation (SiO2)

Cs-137QC
SAMPLE
Expected value:
0,5 Bq/kg
Measured value:Cs-137: 0,495 ± 0,017 Bq/kg
Cs-134: 0,502 ± 0,078 Bq/kg

Cs-13438

Methods comparison – IAEA PT 2016
1. Water analysis (as is)
2. Sample evaporation (SiO2)
3. Absorption on ion exchange resins – low volume

JAPAN
RIVER

Bq/kg

Sample 1 - River water from Japan
0,35
0,30
0,25
0,20
0,15
0,10
0,05
0,00

0,29 Bq/kg

Expected value:Cs-137: 0,29 ± 0,02 Bq/kg
Cs-134: 0,045 ± 0,005 Bq/kg

0,045 Bq/kg

Measured value:
Water sample t.q. Sample evaporation Resin absorption
Cs-137: 0,279 ± 0,019 Bq/kg(SiO2)
Cs-134: 0,0387 ± 0,0062 Bq/kg
Cs-137

Cs-13439

Methods comparison – IAEA PT 2016
1. Water analysis (as is)
2. Sample evaporation (SiO2)
3. Absorption on ion exchange resins – low volume
0,10

Bq/kg

0,08

DANUBE
WATER

Sample 2 - Danube water
0,070 Bq/kg

Expected value:Cs-137: 0,070 ± 0,005 Bq/kg

0,06

Measured value:Cs-137: 0,0732 ± 0,0054 Bq/kg

0,04
0,02
0,00
Water sample t.q. Sample evaporation (SiO2) Resin absorption

40Surface water – Environmental markers
Fish and Suspended Particles

Surface water - Fish
• Fish monitoring provides direct data of food contamination
Fish - Herbivore and carnivorous species

Limit value: 600 Bq/kg (Cs-137+Cs-134)

Persico (Perca Fluviatilis)
Cavedano (Squalius squalus)
Lavarello (Coregonus lavaretus)
Scardola (Scardinius erythrophthalmus)

Higher Cs-137 values
in carnivorous species
1986

2017

Surface water - Fish
• Source of information about environmental dynamics of different waterbasinsBq/kg

Fish – “Perca Fluviatilis” from Ceresio and Lario lake

10000

Ceresio Lake

Persico Ceresio
1000

100

10

1

2012

43

2010

2008

2006

2004

2002

2000

1998

1996

1994

1992

1990

1986

1988

0
1986

Lario Lake

Persico Lario

Retention time:
Ceresio = 8,2 yLario = 4,5 y2017

Surface water – Suspended particles“Cartene shells” time-integrating method:• Point and time integrating system• Sampling period: from 5 to 7 days
ADVANTAGES: easy and cheap

DISADVANTAGES: can’t be referred to a

specific volume of water, just a relative marker
Successfully tested during the “Intercomparisonof freshwater and suspended particles
sampling” held in 1999

Surface water – Suspended particles“Cartene shells” time-integrating method:• Consist of a cartene envelope inserted in a second
one. A grid is made on these plastic bags to trap theparticulate matter in suspension. Inside these 2
envelopes at least 3 PVC strips are inserted, after
being balled up to effectively collect the suspended
particles.

• In these 2 envelopes, secured by tying
together the handles, are inserted
some stones as ballast

“Cartene shells”
7 days sampling
Possible sampling points
Cartene sampler*“Slow flow side”“Slow flow side”

*

≈3-4m

≈ 0,5 - 1 m

“Cartene shells”• At the end of the sampling time the systems arepulled out and brought to the laboratory• The particles collected are sieved at 1 mm andleft to settle during one night• The supernatant water is removed and thesample homogenized

Raw sample

1 mm sieve• The solid fraction is analysed by gamma
spectrometry• The activity concentration is referred to the dryweight, determined on 40 g aliquot, 1 night at
105° C

decanted (1 day)solid fraction: toradiometric analysis

Suspended particles: results at a glance
Sampling points:• Lambro river, south of Milano• Mincio river, south of CremonaCs-137
I-131

48

Suspended particles«allowed» to detecta serious accident in
an aluminum foundrythat melted
contaminated scraps
and discharged intoa river contaminatedwaste waters

wate«Excess» Cs-137 in river flow
(suspended particles and sediments)
49

Activity
Dose
Limit of detection

Which method? Which Detection Limit?
STEPS:•

Define the exposure scenario•

Define the “Target Dose” (T.D.)•

Define the relationship between dose and Cs-137 concentration (C)•Calculate the Cs-137 concentration (CT.D.) corresponding to the target dose•

Assume as Detection Limit a fraction (e.g. 1/10) of CT.D.

•

Select the measurement method

1. Exposure scenario: Drinking water• Target Dose: 0,1 mSv/y according to EU Directive 51/2013• Relationship between dose (D) and Cs-137 concentration (C):D (Sv/a) = C (Bq/kg) x I (kg/y) x h(g) (Sv/Bq)

C (Bq/kg) = D (Sv/a) / I (kg/y) x h(g) (Sv/Bq)
Where:I (kg/y) = Water consumption rate – Adults: 730 kg/yh(g) = Dose coefficient for ingestion – Cs-137, adults: 1,3E-08 Sv/Bq

1. Exposure scenario: Drinking water• Cs-137 concentration (CT.D.) corresponding to the target dose of 0,1 mSv/y:CT.D. (Bq/kg) = D (Sv/a) / I (kg/y) x h(g) (Sv/Bq) == 1E-04 (Sv/a) / 730 (kg/y) x 1,3E-08 (Sv/Bq) = 10,5 Bq/kg• Desired Detection Limit: 1/10 of CT.D. = 10,5 / 10 = 1 Bq/kg• Measurement method: direct Gamma Spec. on 1 L (typical L.D. = 0,1 Bq/L)

2. Exposure scenario: Fishing• Target Dose: 1 mSv/y• Relationship between dose (D) and Cs-137 concentration (C):D (Sv/a) = C (Bq/kg) x I (kg/y) x h(g) (Sv/Bq)

C (Bq/kg) = D (Sv/a) / I (kg/y) x h(g) (Sv/Bq)
Where:I (kg/y) = Fish consumption rate – Adults: 16 kg/y (Italian Diet)h(g) = Dose coefficient for ingestion – Cs-137, adults: 1,3E-08 Sv/Bq

2. Exposure scenario: Fishing• Cs-137 concentration in Fish (CF) corresponding to the target dose of 1 mSv/y:

CF (Bq/kg) = D (Sv/a) / I (kg/y) x h(g) (Sv/Bq) == 1E-03 (Sv/a) / 16 (kg/y) x 1,3E-08 (Sv/Bq) = 4800 Bq/kg

Relationship between Dose and Fish contamination

2. Exposure scenario: Fishing
Relationship between Fish and Water contamination?
• Cs-137 concentration in water (CW) corresponding to CF (4800 Bq/kg):
Hypothetical* relationship between Cs-137 in surface water (CW) and in fish (CF):CF (Bq/kg) = CW (Bq/m3)* Bp (Bq/kg per Bq/L) / 1000
where Bp = Bioaccumulation factor = 30 ÷ 10000 Bq/kg per Bq/L
CW (Bq/m3) = CF (Bq/kg) *1000 / Bp (Bq/kg per Bq/L) == 4800 (Bq/kg) *1000 / 10000 (Bq/kg per Bq/L) = 480 Bq/m3 = 0,48 Bq/L
* IAEA Safety Reports Series No.19 - Generic Models for Use in Assessing the Impact of Discharges of Radioactive Substances to the Environment.
* IAEA Technical Reports SeriEs No. 472 - Handbook of Parameter. Values for the Prediction of Radionuclide Transfer in Terrestrial and Freshwater
Environments.

2. Exposure scenario: Fishing
Desired Detection Limit: 1/10 of CW = 0,48 / 10 = 0,05 Bq/kg
HPGe detector, 30% relative efficiency
Water as is

Resin absorption

1L

Sample evaporation(SiO2)
Resin absorption
5L

Geometry

Marinelli 1 L

Beaker 30 cc

Marinelli 1 L

Counting time1000 min1000 min4000 min

MDA Cs-137

0,1 Bq/L

0,01Bq/L

0,0005 Bq/L

Amount of sample

NO

200 L

3. Exposure scenario: Waste waters from waste repository• Surveillance around contaminated sites• Phosphogypsum repositories: gross activity, Uranium, Radium,Po-210 and Pb-210• Foundry slag repositories contaminated by artificial nuclides:
Cs-137, Am-241

Foundry slag repository
contaminated by Cs-137

3. Exposure scenario: Waste waters from waste repository
Which monitoring plan?
• Well providing drinking water to animals and human• Groundwater below the repository• Pond water outside therepository, potentiallycontaminated bygroundwater

Sampling every 9 month59

3. Exposure scenario: Waste waters from waste repository
Which Limit of Detection?
Well providing drinking water to animals and human• Drinking water (EU Directive 51/2013): 0,1 mSv/y• Corresponding derived concentration for Cs-137: 10,5 Bq/L
• Dose constraint put to 10 microSv/y (radiological non relevance)• Corresponding derived concentration for Cs-137: 1,0 Bq/L
Required sensitivity:• For radioprotection purposes: 0,1 Bq/L (1/10 of 1,0 Bq/L)• To assure early detection of contamination release: 0,01 Bq/L
60

3. Exposure scenario: Waste waters from waste repository

Bq/kg
1000
100
10

Pz 2

ID

Frequency

Lastsampling

Next
Amount Treatment
sampling

MDA(Bq/kg)PZ 1

9 mesifeb-16

nov-166L

5 liters silica gel

0,01

PZ 2

9 mesifeb-16

nov-166L

5 liters silica gel

0,01

PZ 4

9 mesifeb-16

nov-166L

5 liters silica gel

0,01

PZ 10

9 mesifeb-16

nov-166L

5 liters silica gel

0,01

PZ 11

9 mesifeb-16

nov-166L

5 liters silica gel

0,01

PZ 12

9 mesifeb-16

nov-166L

5 liters silica gel

0,01

Cs-137
K-40

1
0,1
0,01
0,001
gen-12 gen-13 gen-14 gen-15 gen-16 gen-17 gen-18 gen-19

61

3. Exposure scenario: Waste waters from waste repository

Further problem: production of big amounts of waste watercontaminated by Cs-137
Definition of exposure scenario:• waste collected by tanks• sent for waste processing to an
ordinary sewage• sludge (which concentrate Cs) used inagriculture62

3. Exposure scenario: Waste waters from waste repository«Clean»Waste water

Clean
water

Cs-137: 100 Bq/kg
Contaminatedwaste water1000 ton/year
102 Bq/kg * 106 kg/y
= 108 Bq/y108 Bq/y

Sewagetreatment plant

River
Agriculture

Sludge2000 ton/y

108 Bq/y / 2*106 kg/y
= 500 Bq/kg

63

3. Exposure scenario: Waste waters from waste repository
Sludge (500 Bq/kg Cs-137) in agriculture:• Max amount per area: 0,75 kg/m2 of agricultural land (National Regulation)• Cs-137 (Bq/m2) = 500 Bq/kg * 0,75 kg/m2 = 375 Bq/m2• Sludge mixed with soil (10 cm depth -1500 kg/m3) :375 Bq / (1m2 * 0,1m * 1500kg/m3) = 2,5 Bq/kg
10 cm of soil
contaminated by
Cs-137 – 2,5
Bq/kg

1 µSv/y,mainly due
to external irradiation (97%)
RESRAD - Argonne National Laboratory - http://resrad.evs.anl.gov/
Exposure pathways: external irradiation, food ingestion, etc.
64

RESRAD - Argonne National Laboratory - http://resrad.evs.anl.gov/

653. Exposure scenario: Waste waters from waste repository
To resume:
Exposure scenario: use in agriculture of slags contaminated by watercontaminated by Cs-137

Waste water: 100 Bq/kg of Cs-137

1 µSv/y to the most exposed group“Specific clearance level” for waste water corresponding to 10 µSv/y:1000 Bq/kg of Cs-137
Required sensitivity: 1/10 of 1000 Bq/kg = 100 Bq/kg
66

Conclusions

Conclusions• The choice of the method to be used for the measurement of Cs-137 in water

depends on the desired Limit of Detection• The Limit of Detection can be fixed by law (especially for drinking water)• In most cases, the Limit of Detection must be evaluated taking into account the

specific exposure scenario and dose limit
Limit of Detection
EU Legislation
Specific exposure scenarios

Drinking water
0,1 - 0,5 Bq/L

Surface water
1 Bq/L

Waste water--

1 Bq/L

0,05 Bq/L

100 Bq/L• In surface water monitoring the use of “contamination markers” provides reliable

and useful data68