(2017/11/27@Kiev) I NSI GHTS OBTAI NED FRO M ENVI RONMENTAL D Y N A MI CS STUDY FOR FU KUSHI MA REMEDI ATI ON Fukushima Environmental Safety Center Sector of Fukushima Research and Development Japan Atomic Energy Agency Akihiro Kitamura
(2017/11/27@Kiev)
I N S I G H T S O B T A I N E D F R OM E N V I R O N ME N T A L
D Y N A MI C S S T U D Y F O R F UK U S H I MA
R E ME D I A T I O NFukushima Environmental Safety Center
Sector of Fukushima Research and DevelopmentJapan Atomic Energy Agency
Akihiro Kitamura
Outline of the talk
• Purpose of research
• Researches on transport behavior of radionuclides• Forest, river system, estuary
• Predictive modeling• Mechanistic approaches• Radiocesium behavior in the Ukedo river system• Comprehensive Evaluation System
2
Contaminated Area- Chernobyl and Fukushima -
3Ministry of Economy, Trade and Industry (2013)
kBq/m2
Contaminated area (km2)
Chernobyl Fukushima ratio
1,480 - 3,100 200 6%
555 - 1,480 7,200 400 6%
185 - 555 18,900 1,400 7%
37 - 185 116,900 6,900 6%
Total 146,100 8,900 6%
Surface contamination density [kBq/m2]
3,700 –1,480 – 3,700 555 – 1,480 185 – 555 37 – 185
4 Initial Cs distribution: Forests occupied the most
WastelandPaddy fieldBeachOceanRiver and LakeForestBuilt-up arearoad / railwaysGolf fieldCrop fieldOther land use
Land use distribution in eastern Fukushima
Land use
Area (km2)
Initial Cs (TBq)
Forest 5,330 920
Total 8,370 1,300
Forest% 64% 69%
Kitamura et al, Anthropocene (2014)
Redistribution and evolution of concentration of radioactive CsRedistribution and evolution of concentration of radioactive Cs
Consequence of redistribution and evolutionConsequence of redistribution and evolution
Background of the project 5
dissolutiondissolutiondissolved
Cs
particulateCs
desorptiondesorption
transfer to agricultural / aquatic products and drinking water
sedimentation near living sphere
transport to the ocean
erosionerosion
run-off / river transportrun-off / river transport
sedimentationsedimentation
Internal exposure
External exposure
wash offwash off
transfer to forest products
accumulation in forests near living sphere
Redistribution and evolution of concentration of radioactive CsRedistribution and evolution of concentration of radioactive Cs
Consequence of redistribution and evolutionConsequence of redistribution and evolution
Objectives of the F-TRACE project 6
Developing calculation tools for;• predictive modeling of transport,• evaluation of transfer, and • evaluation of external / internal
dose, and database.
Establishing the system supplying information to the government, regional municipalities and habitants; • on future dose, future concentration of products, etc., • by showing analytical results visually and clearly,• with scientific understandings obtained in various investigations.
Obtaining data on Cs behaviors in the environment of each river system.
Understanding the processes of generation of dissolved Cs, transport of particulate Cs.
Kitamura et al, Nucl Sci Eng (2015)
Research area
1F NPP
Odaka
Ukedo/TakaseMaeda
Kuma/Ogawara
Tomioka/Oginosawa
Kido
Ohta
7
Ide
・ Systematic research on each river system from forests to estuary makes it possible to evaluate the behavior in whole catchment.
・ Comparing behaviors in several river systems with different characteristics is useful to clarify factors dominate transport of Cs.
Kawamata(Forest only)
Outline
• Purpose of research
• Researches on transport behavior of radionuclides• Forest, river system, estuary
• Predictive modeling• Mechanistic approaches• Radiocesium behavior in the Ukedo river system• Comprehensive Evaluation System
8
Observation issues and points (examples of Namie town) 9
Forest Deposition behavior using lichens River ( continuous monitoring system) Dose rate and weather condition Dam reservoir Mountain Estuary
10
Stem
flow
Thro
ughf
all
Mineral soil
Organic layerBasement
Infil
trat
ion
Rain fall
Surface runoff Soil loss
Litt
er fa
ll
Forest: Cs transport processes in forests
11
Stem
flow
Thro
ughf
all
Mineral soil
Organic layerBasement
Infil
trat
ion
Rain fall
Surface runoff Soil loss
Litt
er fa
ll
Forest: water, litter and soil movement
Washoff rates were quite low in all observation areas.
Niizato et al, J Environ Radioact (2016)
2013(duration)
2014(duration)
Kawauchi (KA)Evergreen
(Japanese cedar) Steep slope
0.10%(6.10-11.18)
0.06%(4.11-10.8)
Kawamata (KE)Deciduous
Gentle slope
0.02%(3.29-11.19)
0.10%(4.7-10.20)
Kawamata (KW)Deciduous
Steep slope
0.05%(6.28-11.19)
0.11%(4.7-10.20)
Cs-137 washoff rate accompanied by the transportation of particulate matter.
12
Stem
flow
Thro
ughf
all
Mineral soil
Organic layerBasement
Infil
trat
ion
Rain fall
Surface runoff Soil loss
Litt
er fa
ll
Forest: water, litter and soil movement
Evolution of depth profiles of Cs in the topsoil of forest floor (KA).
Infiltration of Cs was quite slow.
Cs deposition (kBq/m2/cm)
Dep
th (
cm)
•Ridge•Slope: 8°•Sampling Jan. 2013
Oct. 2014
•Bottom of valley•Slope: 20°•Sampling
Jan. 2013Oct. 2014
Dep
th (
cm)
Cs deposition (kBq/m2/cm)
Dissolved Cs in a mountain stream
Stream waterGroundwaterPore water collected by suctionPore water naturally oozing out
a. well for groundwater b. natural lysimeter c. suction lysimeter
Well for GW
Depth of suction lysimeter
Water table
observation of flow rate
observation of flow rate
Flowing out point of stream
13
Observation equipments set up in the evergreen forest in Kawamata.
Dissolved Cs in a mountain stream
Water table
Depth of suction lysimeter
July 2015
Sept. 2015
14
• Concentration of dissolved Cs drastically increased near the flowing out point. => Concentration of Cs was controlled by dissolution from litter or desorption
from soil near the flowing out point.
Stream waterGroundwaterPore water collected by suctionPore water naturally oozing out
Numbers indicate dissolved Cs-137 concentration in mBq/L;
Onda, results of commissioned study by JAEA
Ukedo river system
Ukedo river- Dam at middle- Upper: Highly contaminated
Takase river- No dam- Upper: Less contaminated
15
Ogaki dam lake
FDNPS
Dissolved Cs in the Ogaki dam lake 16
2014.3.22014.9.182015.4.62015.10.230,0
0,1
0,2
0,3
0,4
0,5
0,6
0,7 流入水(請戸川)流入水(小出谷川)放流水
Diss
olve
d 13
7Cs [
Bq/L
]
Evolution of concentration of dissolved Cs in inflow and outflow waters of Ogaki dam lake (Ukedo river).
Inflow 1
Inflow 2
Outflow
< 1 Bq/L in 2014. Seasonal change ← Biodegradation? Less decreased ← Any buffering processes? Outflow concentration was defined by inflows.
Inflow 1Inflow 2
Outflow
Funaki et al, J Environ Radioact (submitted)
Cs discharged to the ocean in FY 2015 17
River
Estimated amount of discharge
Annual discharge Discharge at the high water event on Sept.
Amount(TBq)
Ratio to initial
deposition
Amount(TBq)
Ratio to annual
discharge
Odaka 0.074 0.5 % 0.053 72 %
Ukedo > 0.224
> 0.1 % 0.089 48 %
Takase 1.185 0.4 % 0.811 79 %
Maeda 0.057 0.1 % 0.035 73 %
Kuma 0.312 0.5 % 0.233 79 %
Tomioka 0.022 0.1 % 0.013 58 %
with dam
with dam
Discharge rates of Cs to the ocean were extremely low, especially in rivers with dams.
Outline
• Purpose of research
• Researches on transport behavior of radionuclides• Forest, river system, estuary
• Predictive modeling• Mechanistic approaches• Radiocesium behavior in the Ukedo river system• Comprehensive Evaluation System
18
Mechanistic approaches for future predictions 19
Suspended solid
Dissolved RCs
SS-bound RCs
advection dispersion inflow/outflow sedimentation/resuspension
advection dispersion decay inflow/outflow sorption/desorption to SS and river bed
advection dispersion decay inflow/outflow sorption/desorption sedimentation /resuspension
20 Prediction of Cs migration in dam reservoir
20
TODAM: 1D transport model for contaminant in rivers
Inflow 1
Inflow 2
Concentration of137Cs in the inflows (input of calculation) and outflow (output) of Ogaki dam lake in the typhoon in 2013.
outflow
Calculated values of outflow agreed well to those of observed . Around 90% of Cs in inflows could be accumulated in the lake.
Conc
entr
atio
n of
Cs-
137
(Bq/
L)
Inflow 1 (obs.)Inflow 2 (obs.)Outflow (obs.)Inflow 1 (input)Inflow 2 (input)Outflow (output)
Inflow 1
Inflow 2
outflow
Kurikami et al, J Enviorn Radioact (2014)
21 3D grid-block system for watershed modeling
・ Horizontal resolution of the grid-blocks was between 30-250 m (average 100 m).・ Subsurface geology in the vertical direction consisted of 28 layers・ Plus one air layer and one surface layer. ・ Thickness of the vertical layers varied. ・ Total number of grid-blocks created was 4,224,000.
Kitamura et al, ESPL (2016)
Prediction of Cs discharge from the river
It can be applied to predict the behavior of Cs depending on precipitation.
Wa
ter
flow
[m
3 ]
137C
s d
isch
arg
e [
GB
q]
Water flow, soil loss and Cs-137 discharge for 3 days during each high water event.
Relationship to precipitation
0,0E+0
1,0E+7
2,0E+7
3,0E+7
4,0E+7
5,0E+7
6,0E+7
0,0E+0
2,0E+6
4,0E+6
6,0E+6
8,0E+6
1,0E+7
0,0E+0
1,0E+2
2,0E+2
3,0E+2
4,0E+2
5,0E+2
6,0E+2
0 50 100 150 200 250 3000,0E+0
2,0E+6
4,0E+6
6,0E+6
8,0E+6
1,0E+7
0 50 100 150 200 250 3000,0E+0
1,0E+2
2,0E+2
3,0E+2
4,0E+2
5,0E+2
6,0E+2
0 50 100 150 200 250 3000,0E+0
1,0E+7
2,0E+7
3,0E+7
4,0E+7
5,0E+7
6,0E+7
Precipitation per event [mm]
22
3 d
ays
so
il lo
ss [
kg]
3 d
ays
wa
ter
flow
[m
3]
3 d
ays
dis
cha
rge
of
137C
s [G
Bq]
Precipitation per event [mm] Precipitation per event [mm]
So
il lo
ss [
kg]
Sakuma et al, J Enviorn Radioact (2017)
RCs distribution in soil(input data)
Air dose rate evaluation
Depth distribution of RCs in soil
Agreement of predictions with measurements
Prediction model for ground-shine dose rate 23
Malins et al, J Environ Radioact (2016)
Top soil removal Layer interchange Reverse tillage
Remediation method
Decrement of air dose rate
Observations Simulations (center)
Topsoil removal
40 - 70% 73%
Layer interchange
- 64% 68%
Reverse tillage 30 - 60% 54%
Remediation simulations: Comparison with measurements
Change to depth distributions
Prediction of decontamination efficiencies 24
Malins et al, Health Phys (2016)