Measuring regional scale distribution of radiocaesium · 2013-12-03 · Measuring regional scale...
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Measuring regional scale distribution of radiocaesium
Measuring regional scale distribution of radiocaesium
David SandersonScottish Universities Environmental Research Centre
East Kilbride, Glasgow G75 0QF, UK
Caesium workshop : Fukushima recovery – understanding, modelling and managing radioacaesium decontamination, CORASSE, Fukushima, Japan
September 30 – October 3rd 2013
OutlineOutline
• Airborne and mobile gamma spectrometry
• Measurement technologies and small footprint systems
• Mapping radiocaesium (UK and European examples)
• Spatial resolution and reproducibility at regional and local scales
• International validation and ground to air comparisons
• Work conducted in Japan in 2012/13
• Future opportunities and needs
Airborne & Mobile Gamma Spectrometry for mapping radioactivity
Airborne & Mobile Gamma Spectrometry for mapping radioactivity
・ AGS is capable of rapid radiometric mapping of large areas Sensitive gamma-ray detector mounted on aircraft High volume NaI (or combined NaI/Ge system) Low altitude survey flights (30-100m) Large survey areas, high sampling density ~1000’s of observations per hour 104-105 m2 fields of view
・ Mobile Gamma spectrometry Geocoded gamma spectrometry operated from
backpacks, small vehicle, UAV’s, boats, hovercraft etc
More confined field of view – suited to detailed surveys of eg urban areas
Data capture rate 102 -103 per hour 10-102 m2 fields of view
・ AGS system used in ECCOMAGS Exercise ・ Fully validated performance
17 spectral input channels, multi-sensor capable High volume NaI arrays, HPGe detectors Stabilised power supply Upgraded (2005/6) to more powerful computers, larger
displays, revised power systems Software upgrades (2008-2010)
• ERS Format spectral input/output
HPGe analysis• Full spectral regridding
• Disjoint spectral windows
・ Real time mapping with differential “rainbow plots”・ Alarms
• Gross & stripped count rate
• Significance from differential analysis
• Intelligent digital filtering
・ 5Hz, EGNOS enabled GPS
SUERC AGS multispectrometer
SUERC AGS multispectrometer
・ Increased data throughput
Resolution maintained in high radiation fields (but could use HPGe)
・ (But summing multi-compton losses in detector arrays)
Digital SystemsDigital Systems
NaI
(Tl)
cp
s
0
200
400
600
800
HP
Ge
cps
0
2
4
6
8
10
12
・ Simple, compact systems
・ Self contained HV supply and DSP chips
・ USB connectivity
・ Ideally suited to weight limited platforms
・ Alternative detector geometries?
Digital systems have advantages
Belgoprocess Site 2Belgoprocess Site 2
BR3
201.2 201.4 201.6
400m0 200
201.0
212.0
200.8200.6
212.2
211.8
212.8
213.0
212.4
212.6
Calibration based on infiniteplanar source geometry
Measurement centre
BR3
201.2 201.4 201.6
400m0 200
201.0
212.0
200.8200.6
212.2
211.8
212.8
213.0
212.4
212.6
Measurement centre
BR3
201.2 201.4 201.6
400m0 200
201.0
212.0
200.8200.6
212.2
211.8
212.8
213.0
212.4
212.6
Calibration based on infiniteplanar source geometry
Measurement centre
・137Cs, 60Co activity from stored materials
・214Bi activity from 222Rn discharges from stored uranium & radium
GM
X C
ou
nt
rate
(cp
s)
0.1
1
10
NaI
(Tl)
Co
un
t R
ate
(cp
s)
1
10
100
1000
Energy (keV)
0 500 1000 1500 2000 2500 3000
0.1
1
10
1
10
100
1000
South of site
North of site
13
7C
s
60C
o
21
4B
i
13
7C
s
60C
o6
0C
o6
0C
o
・NaI Spectra show spectral distortion and coincidence summing
Backpack SystemBackpack System
March 2000 AGS June 2010 Backpack
Avril Weir and Catherine Mitchell survey the Scottish Enterprise Technology Park, in 2009 for their MPhysproject
“Demonstrating lightweight gamma spectrometry systems in urban environments”, Journal of environmental radioactivity, 2013, 124, 22-28
High resolution survey of Irish Sea beach in 2010
“Evaluating airborne and ground based gamma spectrometry methods for detecting particulate radioactivity in the environment: A case study of Irish Sea beaches” Science of the Total Environment 437 (2012) 285–296
3x3” NaI(Tl), digiBASE™, netbook, EGNOS enabled GPS
Regional scale mapping following the Chernobyl accident on 28th April 1986
Chernobyl 28th April 1986Chernobyl 28th April 1986
・ 28th April Chernobyl
・ UK fallout arrives early May
・ Initial deposition estimates based on limited ground sampling and meteorological modelling
・ Early SURRC surveys – SW Scotland, Western Isles, West Cumbria, North Wales
・ Later repeat surveys show long term migration of radionuclides
1988 MAFF Survey West Cumbria
2001 DETR study “Spatial andTemporal Aspects of airborne gammaspectrometry
Sanderson D.C.W., Scott E.M.,1989, Aerial Radiometric Survey In West Cumbria In 1988, MAFF Report N611 120
Sanderson D.C.W., Cresswell A.J., White, D.C., Murphy, S., McLeod J. 2001, Investigation of Spatial and Temporal Aspects of Airborne Gamma Spectrometry. DETR Report DETR/RAS/01.001.
West Cumbria – Changes Between 1988 and 2000 - Livestock restriction
zone
West Cumbria – Changes Between 1988 and 2000 - Livestock restriction
zone
・ Total activity in area agrees to within 3% after decay correction・ Movement of activity from high to lower lying ground due to hydrological and colluvial
processes
1988 1988(decay corrected)
June 2000
Total Area (TBq) 9.35±0.02 7.01±0.02 7.22±0.02
Black Combe (GBq) 496±3 372±3 319±1
Corney Fell (GBq) 704±3 528±3 469±2
Loweswater Fell (GBq) 636±3 477±3 453±1
Lowlands (GBq) 851±16 638±12 732±8
Investigation of Spatial and Temporal Aspects of Airborne Gamma
Spectrometry
Investigation of Spatial and Temporal Aspects of Airborne Gamma
Spectrometry
Analysis of line spacing and environmental change
How reproducible is AGS?
How to measure change
D
A
Tielines
B
C
F
G
H
I
Barrow-in-Furness
Windermere
Windermere
ConistonWater
Carlisle
Wigton
RockcliffeMarsh
Annan
Allerbeck
Chapelcross
BassenthaiteLake
EnnerdaleWater
DerwentWater
Croasdale
Keswick
Cockermouth
Millom
DuddonEstuary
Moricambe
Silloth
Solway Firth
Sellafield
Ravenglass
WastWater
Caerlaverock
Workington
Maryport
St BeesHead
Whitehaven
5020 30 40
0 10 20km
3 000m1000
80
29
90
2 000m704 000m
80
40
50
60
70
00
10
20
30
5 000m
Geographic overlays reproducedfrom Ordnance Survey Strategi data with the permission of The Controller of Her Majesty's Stationary Office.(c) Crown Copyright 1998
Inner SolwayThe Solway Firth has extensive areas of salt marshContaminated by discharges from Sellafield
Survey areas6x11km, encompassing Rockcliffe and Burgh marshes and the tidal inlets of the Esk and the Eden30x20km, including Annan, Silloth and part of Carlisle
Survey dates and flight linesApril 1999: 50 and 250m line spacings ; June 2000: 250m line spacing, February 1992: 500m line spacing
West CumbriaUpland areas and coastal plainContaminated by Chernobyl and Windscale fire
Survey areasCoastline and Sellafield area (March 2000)40x40km (500m), northern Lakes and lower lying areas (June 2000)50x50km (2.5km), Lake District high ground (June 2000)Older data : Aug/Sept 1988: 500m line spacing; Sept 1990: Sellafield area
Inner Solway 137Cs Distributionand the landcover setting
Inner Solway 137Cs Distributionand the landcover setting
Hought
Harker
Sc
Blackford
Westlinton
Todhills
Moorhouse
Grinsdale
on-EdenKingstown
Cargo
Rockcliffe
Thurstonfield
Burgh by Sands
Kirkandrews
Beaumont
GretnaRigg
lasson
Drumburgh
astriggs
ort Carlisle
0 1 2km
36 37 38
3 0
00
m
32 33 34 3530 312928
66
65
64
63
62
61
60
59
26 27
3 0
00
m2
5
5 000m
5 000m67
58
Geographic overlays reproduced from Ordnance Survey Strategi data with the permission of The Controller of Her Majesty's Stationary Office.(c) Crown Copyright 1998
RockcliffeMarsh
Burgh Marsh
Sparse data for West Cumbria
Sparse data for West Cumbria
Barrow-in-Furness
Windermere
ConistonWater
Windermere
Wigton
Croasdale
EnnerdaleWater
DerwentWater
BassenthaiteLake
Silloth
Sellafield
Millom
Ravenglass
DuddonEstuary
WastWater
Workington
Whitehaven
Maryport
St BeesHead
40
0 10 20km
5010 20 303 000m90 0070
80
90
00
2 000m
4 000m
5 000m
40
10
20
30
50
Geographic overlays reproducedfrom Ordnance Survey Strategi data with the permission of The Controller of Her Majesty's Stationary Office.(c) Crown Copyright 1998
Barrow-in-Furness
Windermere
ConistonWater
Windermere
Wigton
Croasdale
EnnerdaleWater
DerwentWater
BassenthaiteLake
Silloth
Sellafield
Millom
Ravenglass
DuddonEstuary
WastWater
Workington
Whitehaven
Maryport
St BeesHead
40
0 10 20km
5010 20 303 000m
90 0070
80
90
00
2 000m
4 000m
5 000m
40
10
20
30
50
Geographic overlays reproducedfrom Ordnance Survey Strategi data with the permission of The Controller of Her Majesty's Stationary Office.(c) Crown Copyright 1998
137Cs Activity for Areas C and D
137Cs Activity for Areas C and D
L in e S p a c in g (k m )
0 .0 2 .5 5 .0 7 .5 1 0 .0 1 2 .5
To
tal A
cti
vity
(T
Bq
)
3 4
3 5
3 6
3 7
3 8
3 9
4 0
4 1
L in e S p a c in g (k m )
0 1 0 0 0 2 0 0 0 3 0 0 0 4 0 0 0 5 0 0 0 6 0 0 0
To
tal A
cti
vity
(T
Bq
)
1 4
1 5
1 6
1 7
1 8W e s t C u m b ria
(a re a s C + D )N o rth W e s t C u m b ria
(a re a C )Inventories of large features relative to line spacing are robust (shapes less so)
for dimensions perpendicular to lines >2x line spacing
smaller features subject to significant uncertainties for wider line spacing
Even 10km line spacings show broad distribution pattern and inventory of Chernobyl derived activity on uplands
Sanderson, D. C. W., Cresswell, A. J. and White, D. C. (2008) 'The effect of flight line spacing on radioactivity inventory and spatial feature characteristics of airborne gamma-ray spectrometry data', International Journal of Remote Sensing, 1 – 16 DOI: 10.1080/01431160701268970
ECCOMAGSECCOMAGS
・ Protocols for dose rate and radionuclide deposition mapping using AGS
・ Exercise design documentation
・ Unique data base of airborne & ground based measurements
・ Exercise report – 387p book published
・ Journal articles
・ European Capability for AGS Radiation Protection Dosimetry
・ Vol. 73, Nos 1–4, pp. 213–218 (1997)
・ European Bibliography Journal of Environmental Radioactivity
・ 53 (2001) 411-422
・ International validation of deposition and dose rate determination under conditions of cooperative trials Radiation Protection Dosimetry (2004), Vol. 109, Nos 1-2, pp. 119-125
Exercise Aims and Outcomes
Exercise Aims and Outcomes
・ Aims Validation of AGS protocols for deposition
and dose rate quantification Traceable comparisons between AGS, in-
situ spectrometry, field dose rate measurements and laboratory analysis of core samples
Demonstration of composite mapping capability
・ Venue SW Scotland May 24th-June 3rd 2002 Pre-characterisation fieldwork in
November 2001・ Organisation
International steering Committee (ISC) National Organising Committee, (NOC)
Design and Evaluation Group (DEG)
Outcomes
Participants150 participants from 18 institutions in 10 countriesObservers and visitors
Activities and achievementsAGS >120,000 measurements in common areas and composite mapping zones~150 In-situ and field dose rate measurements from calibration sites and 42 common area sites>750 laboratory gamma spectrometry results from ~130 core samples and reference materialsCGS data from 3 teams
Inch Farm
WigtownMerse
CastleKennedy
Dumfries
Stranraer
Solway Firth
Dumfries and Galloway Region
0 10 20km
ECCOMAGS Exercise : Calibration Sites
137Cs : 20.8 ± 1.0 kBq m-2
Dose rate : 0.057 ± 0.003 µGy h-1
137Cs : 224.7 ± 10.9 kBq m-2
Dose rate 0.09 ± 0.01 µGy h-1
137Cs : 6.3 ± 0.35 kBq m-2
Dose rate : 0.033 ± 0.005 µGy h-1
Calibration sites
・Sampled in November 2001
・Reference values distributed to participants
・AGS hover manoevres and in-situ measurements used for data levelling
・In-situ checks for environmental change
0.1
1
10
100
Channel
0 100 200 300 400 500
Co
un
t R
ate/
Ch
ann
el (
cps)
0.1
1
10
100
<10 m
50 - 65 m
Wigtown Merse
Inch Farm
Castle Kennedy
Ground Based Data sets – Key points for ground to air comparisons
Ground Based Data sets – Key points for ground to air comparisons
・ Laboratory Gamma spectrometry Laboratory performance Different behaviours observed between
IAEA reference materials and common bulk samples
Results provide basis for ground to air comparisons
・ In-situ data Necessary to re-standardise data sets to
common mass-depth profiles Also to re-level them to the Inch Farm site Relationships between in-situ and cores
bring mass-depth into play・ Dose Rate measurements
Field instruments showed considerable differences
Dose Rates re-estimated from in-situ spectra and cores
・ CGS biased by field of view differences
1 (S
tir)
2 (S
UE
RC
)
3 (E
RC
)
4 (B
GS
)
5 (N
RP
B)
6 (C
EH
)
7 (G
C)
8 (B
fS)
9 (S
SI)
10 (
CE
A)
1 (S
tir)
3 (E
RC
)
4 (B
GS
)
5 (N
RP
B)
6 (C
EH
)
7 (G
C)
8 (B
fS)
11 (
Ris
o)
12 (
DS
TL)
Sta
nd
ard
ised
Dif
fere
nce
-15
-12
-9
-6
-3
0
3
6
9
12
15WG BS1 WG BS2 IF BS1 IF BS2 CK BS1 CK BS2
Laboratory
1 (S
tir)
2 (S
UE
RC
)
3 (E
RC
)
4 (B
GS
)
5 (N
RP
B)
6 (C
EH
)
7 (G
C)
8 (B
fS)
9 (S
SI)
10 (
CE
A)
1 (S
tir)
3 (E
RC
)
4 (B
GS
)
5 (N
RP
B)
6 (C
EH
)
7 (G
C)
8 (B
fS)
11 (
Ris
o)
12 (
DS
TL)
Sta
nd
ard
ised
Dif
fere
nce
-15
-12
-9
-6
-3
0
3
6
9
12
15SOIL 6SOIL 375SL-2
137 Cs – Bulk samples
137 Cs – IAEA reference materials
Main Common area AGS findings
Main Common area AGS findings
・ All teams identify the main radiometric features
・ Data levelling between teams using single common measurement point
Applicable to emergency response
Further corrections and analysis lead to only minor changes
・ Considerable agreement between teams
Definition of spatial features
Point to point regressions
Ground to Air ComparisonsGround to Air Comparisons
・ Ground to air comparisons
Agreement is broadly consistent with the internal consistency of each data set
AGS and in-situ sensitive to depth distribution
AGS observations are consistent with ground based results
But are spatially more numerous and representative
The data sets provide a basis for protocol validation
In-situ 137Cs (kBq m-2)
0 5 10 15 20 25 30 35
AG
S 13
7C
s (k
Bq
m-2
)
0
5
10
15
20
25
30
35
In-situ 137Cs (kBq m-2)
0 5 10 15 20 25 30 35
AG
S 13
7C
s (k
Bq
m-2
)
0
5
10
15
20
25
30
35
In-situ 137Cs at measured mass depth (kBq m-2)
0 20 40 60 80 100 120
AG
S 1
37C
s (
kBq
m-2
)
0
20
40
60
80
100
120
137Cs from cores (kBq m-2)
0 5 10 15 20 25 30 35
AG
S 1
37C
s (k
Bq
m-2
)
0
5
10
15
20
25
30
35
137Cs from cores (kBq m-2)
0 25 50 75 100 125 150 175 200
AG
S 13
7C
s (k
Bq
m-2
)
0
25
50
75
100
125
150
175
200
Assuming 8.5 g cm-2 relaxation depth Assuming measured depth profile
In-situ 137Cs (kBq m-2)
0 20 40 60 80 100
AG
S 1
37C
s (
kBq
m-2
)
0
20
40
60
80
100
I JF G HC D EA B
Dumfries
Stranraer
ECCOMAGS Exercise : Composite Mapping Areas
Solway Firth
Dumfries and Galloway Region
0 10 20km
AGS Composite mapping task
・10 contiguous areas of approximately 250-270 km2
・Each presenting diverse environments from topographic and radioecological perspectives
・Allocated to individual AGS teams to demonstrate collective mapping abilities
137Cs Map with terrain model
137Cs Map with terrain model
ECCOMAGS exercise composite mapping task 200290x40 km area; 69000 spectra; data acquired in 3 days, published on-line within a
week
Airborne Gamma Spectrometry maps • US DOE team (March), MEXT/JAEA teams April
Ground clearance 300m initiallyDose rate maps, followed by apportioned Cs maps
Visits to Japan 2012/13• March 2012 – Tsukuba,
Fukushima, Exclusion zone, Prefecture research institutes, JAEA, UK Embassy, EU delegation (DS/YT)
• May 2012 – SRRCE inaugural conference Fukushima Izaka (DS)
• July 2012 Fukushima (AC, BS)• September 2012 (SF,XS) visit
AMS labs• Oct/Nov 2012 UK Nuclear Safety
workshop (FCO) (DS)• Jan 2013 Biomass investigation
Iwaki (AC DS)
7th March 2012 Road Trip
7th March 2012 Road Trip
Energy (keV)
0 500 1000 1500 2000 2500 3000
Cou
nts
/s
0.01
0.1
1
10
100
1000
10000
13
4C
s 60
5 k
eV
134C
s 7
95
keV
13
7C
s 6
62
keV
134C
s 1
365
keV
Okuma Daycare Centre 7th March 2012
Fukushima University Kanayagawa Campus
6th March 2012
Fukushima University Kanayagawa Campus
6th March 2012
Can we use this to direct remediation?
Apportionment of dose rateApportionment of dose rate
The charts show the relative proportions of dose rates due to individual nuclides • Can we use this type of information to set and evaluate targets for remediation ?
Play Park
Shrine
Conference Hotel
Conference Venue
Gamma dose rate map Iizaka 20th May 2012 Conducted during the SRRCE meeting
University of Fukushima : areas subject to remediation July 2012
University of Fukushima : 137Cs map showing remediated areas
0
5
10
15
Per
cent
age
of a
rea
0
5
10
15
0
5
10
137Cs kBq m-2
5 5010 1000
10
20
30
All data
Un-remediated areas
Remediated areas(exc. tennis courts)
Tennis courts
University of Fukushima : Gamma dose rate showing remediated areas
Remediated areas are on average 4 times lower than untreated areas
0
5
10
Per
cent
age
of
are
a
0
10
20
0
5
10
15
Gamma Dose Rate µGy h-1
0.05 0.5 50.1 10
10
20
30
All data
Un-remediated areas
Remediated areas(exc. tennis courts)
Tennis courts
University of Fukushima : 134Cs map showing remediated areas
0
5
10
15
Per
cent
age
of a
rea
0
5
10
15
0
5
10
134Cs kBq m-2
5 501 10 1000
10
20
All data
Un-remediated areas
Remediated areas(exc. tennis courts)
Tennis courts
134Cs (kBq m-2) 137Cs (kBq m-2) Dose Rate (μGy h-1)
Remediated Unremediated Remediated Unremediated Remediated Unremediated
Mean 23.8 80.0 36.9 121.4 0.20 0.58
Std dev 21.8 34.6 32.9 51.9 0.15 0.24
Percentiles
10th 4.9 37.8 9.2 56.7 0.08 0.30
50th 17.2 76.8 27.7 117.2 0.15 0.56
90th 48.6 124.3 76.2 189.9 0.36 0.87
Analysis of the effectiveness of remediation
Remediated areas are on average 4 times lower than untreated areas
137Cs
FU Bq kg-1
101 102 103 104 105
SU
ER
C B
q k
g-1
101
102
103
104
105
Slope: 0.965 ± 0.015Intercept: 58 ± 24R2: 0.989
Calibration site at Fukushima University
• Sampled in July 2012• Tyler et al 1996,J. Environ.
Radioactivity, 33(3), 213-235.• Soil cores analysed at
Fukushima and SUERC• Relative to international
standards• Results in good agreement for
137Cs• Reference values can be used
to check dose rate and in-situ instruments and by local groups
Mean mass depth : 0.9 ± 0.1 g cm-2
137Cs 265 ± 20 kBq m-2
134Cs 165 ± 20 kBq m-2
Dose rate 1.24 ± 0.13 µGy h-1
Calibration site at Fukushima University
• Depth Profiles from 13 cores
• Above 10 g cm-2 the profiles are approximately exponential with mean mass of 0.9 g cm-2
• But do the data below 10 g cm-2 belong to the same distribution?
• Why not?• Sample handling?• Multiple components?
134 C
s B
q kg
-1
10
100
1000
10000
100000
Mass depth (g cm-2)
0 2 4 6 8 10 12 14
137 C
s B
q kg
-1
1
10
100
1000
10000
100000
Fukushima Prefecture Fruit Tree Research Institute
Fukushima Prefecture Fruit Tree Research Institute
Do radiometric data from experimental orchards help to understand the pathways and impacts of fruit cultivation in the presence radiocaesium?
Can we use this to evaluate solutions?
Mapping in March, May, July and Nov 2012 with training
Calibration site sampled
Mass depth (g cm-2)
0 2 4 6 8 10 12 14
13
7 Cs
Bq
kg-1
10
100
1000
10000
100000
13
4C
s B
q kg
-1
10
100
1000
10000
100000
Reference Value Backpackmeasurement
134Cs kBq m-2 135 ± 20 171 ± 3137Cs kBq m-2 245 ± 30 263 ± 6
Reference value for 3rd November 2012. Mean mass depth 0.70 ± 0.05 g cm-2. Calculated from gamma spectrometry at SUERC, no comparison with FU yet.Backpack measurements calibrated to FU calibration site, mean mass depth 0.9 g cm-2.
Citrus cultivation near Mount Shinobu
July 2012
November 2012
“Yuzu” fruit from 2012 shows higher levels of radioactivity (by an order of magnitude) than apples, pears, peaches and grapes cultivated in Fukushima
Why?
IAEA Technical report 472Interception?Translocation?Root uptake?Soil immobilisation?Contamination levels?
We think that the clue lies in evergreen nature of the tree, coupled to local topography
Biomass energy harvesting and phytoremediation ?Can they be used synergistically?
FCO prosperity funded investigation with Mitsubishi Morgan Stanley, Suncare, University of Tsukuba, NNL, and input from SUERC
January 2013 fieldwork near Iwaki using a collimator to establish the proportions of total Cs radiation originating in forest canopy
Remapping following forest litter removal to determine remediation factor
Control area to account for environmental change
Cedar Deciduous
Uncollimated Collimated Reduction Uncollimated Collimated Reduction
Number 459 174 35 18
134Cs kBq m-2 25.8 ± 0.2 24.7 ± 0.2 1.1 ± 0.3 14.4 ± 0.3 13.5 ± 0.4 0.9 ± 0.5
137Cs kBq m-2 53.0 ± 0.4 53.0 ± 0.4 0.0 ± 0.6 28.7 ± 0.7 27.8 ± 0.7 0.9 ± 1.0
Dose RateµGy h-1
0.258 ± 0.001 0.253 ± 0.002 0.005 ± 0.002 0.157 ± 0.002 0.150 ± 0.003 0.007 ± 0.004
Discussion points and conclusions
• Both low and high resolution spectrometry can be used for quantitative AGS, CGS and ground based mapping of radiocaesium and gamma dose rate
• Post Chernobyl experience, and experience of measuring the footprint of nuclear sites, and the impact of discharges to the Irish sea have provided a framework for validation of methods
• AGS is well suited to detailed regional scale investigations providing low ground clearance and close line spacings are used
• Protocols and data exchange formats have been defined in EU research, and quantitative international validation studies performed
• For more detailed work ground based approaches yield greater spatial resolution, appropriate to site specific evaluations
• Last year’s visits have confirmed the utility of radiometrics as a means of targetting and evaluating remediation, and helping to understand the distribution and dynamic behaviour of radiocaesium in important urban and rural systems
• Calibration sites were sampled and analysed in two locations providing an initial basis for cross-validation of Japanese and international teams
• It is hoped that this work can be extended in the future with the aim of helping to improve confidence in the long term recovery of Fukushima