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A Radiation Estimation Method for use in the Initial and Intermediate
Stages of a Nuclear AccidentStages of a Nuclear AccidentShi k K t R hji Ohb Mi ik Ki (Th U i it f T k )Shinsuke Kato, Ryohji Ohba, Minsik Kim (The University of Tokyo)
Jiro Yoneda(Mitsubishi Heavy Industries)
Masayuki Takigawa(Japan Agency for Marine-Earth Science and Technology)
Paul Bieringer(National Center for Atmospheric Research)
Bent Lauritzen(Denmark Technical University)
Today’s main topicsy p1. Introduction of the MEXT 2012-2014 project2. Verification and Validation study of STE method
MEXT: Ministry of Education, Science, Culture, Sports and TechnologySTE: Source Term Estimation
1
Initial and Intermediate stages of nuclear accident
Initial stage (for a few weeks) Intermediate stage (for a few years)
(a)Source Term
Radiation exposure calculation by ERMIN code
Internal exposure(b) AtmosphericDispersion
Estimation(c) Deposition (2) re-suspension in
outdoor and indoor
Gas
(5) Internal and external exposure
Dry
WetParticle
(1) Weathering effect (3) Mass balance of indoor concentration& (4) De-contamination effect
in outdoor and indoor
ERMIN: European Model for Inhabited areas code, developed by EU, after Chernobyl accident 2
References: Emergency response system of EU/ARGOS(integration system of STE and Decontamination )(integration system of STE and Decontamination )
3
Difficulties Developed technologiesShortage of monitoring data Application of mobile monitoringShortage of monitoring data Application of mobile monitoring
by car and airplane Unsteady wind and release Operational Source Term conditions Estimation methodSeparation of cloud and ground shines
Data filtering technique
Monitoring post: D
4000
5000
Gy/
h)
80
100
hour)
Red:gamma radiation dose
Blue: Precipitaion
shines
Time history of Gamma-ray dose rate data
0
1000
2000
3000
Rad
iation d
ose
(nG
0
20
40
60
Pre
cip
itat
ion(m
m/h
Ground-shineCloud-shine
0
3/1 3/23/33/4 3/53/6 3/73/83/93/103/113/123/133/143/153/163/173/183/193/203/213/223/233/243/253/263/273/283/293/303/31
0
Cloud shine
G d hiGround shine
Flow Chart of Source Term Estimation (STE)Observation Simulation model Uncertainty of STE
Availability and ReliabilityAssumed source intensity
Meteorological data
(Air flow)Air flow condition
•Availability and Reliability of observed data
Air Concentration
Dispersion model
•Air flow condition
•Turbulent diffusivity
STEConcentration
Soil concentration Deposition model •Deposition velocity
•Particle diameter
STE
STE
Radiation dose Radiation model
Particle diameter
•Content of radioactive STE
STE
1)Cloud-shine
2)Ground-shine
materials
•Distribution of radioactive materials
STE
3)Sky-shineradioactive materials on the ground surfaceMain object of this study
5
Operational STE methodusing the Transfer Coefficient Matrix(TCM) DataBaseusing the Transfer Coefficient Matrix(TCM) DataBase
Assumption of application1)Steady state of meteorological condition
Input typical meteorological conditions) y g
2)Short time release (< few hours)3)Nearfield monitoring points(< few kms)
conditions(Ex. 16 wind directions & 3 atmospheric stabilities = 48 cases)
Calculation of air field and dispersion under unit release rate
Example of monitoring points &TCM in Fukushima
DataBase of TCMBefore accidentDataBase of TCM
Monitoring data of gamma radiation dose STE using TCM DB
accident
g g STE using TCM DBMonitoring post: D
3000
4000
5000
ose
(nG
y/h)
60
80
100
n(m
m/hour)
Red:gamma radiation dose
Blue: Precipitaion
After accident
0
1000
2000
3/1 3/23/33/4 3/53/6 3/73/83/93/103/113/123/133/143/153/163/173/183/193/203/213/223/233/243/253/263/273/283/293/303/31
Rad
iation d
o
0
20
40
Pre
cip
itat
ion
Ground-shineCloud-shine
6
Data filtering technique of Gamma dose rate to obtain just the cloud-shine
a) Raw data)
1day
2011/3/1 3/313/11 3/15
γ-raylevel in air
se (n
Gy
/h)
b) HPF data
3/11
Normal background level γ-ray level from ground
γ-ra
yd
os
Through the HPF
3/11 3/15
γ-raylevel in air
Through the LPF
c) LPF data
3/11 3/15
Normal background level γ-ray level from ground
7
Verification & Validation Study of STE based on the Wind Tunnel data (1st step)
・Observed data: W/T data (concentration)・TCM:Gaussian Plume model(fitting with W/T data) a)
b)
2.50E‐05
Concentration Distribution at a Distance of 2000m Downwind
)
1.00E‐05
1.50E‐05
2.00E‐05
C/Q(m
‐2)
TransferCoefficient
Observation
Estimation
a) Wind direction: NAccuracy of estimated Source rate:97%
5 00E 06
0.00E+00
5.00E‐06
-1700 -1200 -700 -200 300 800 1300
UC
Uncertainty factor of wind direction
‐5.00E‐06
y :Crosswind(m)
2 00E‐05
2.50E‐05
Concentration Distribution at a Distance of 2000m Downwind
b) Wind direction: N +11.25 degA f ti t d S t
1.00E‐05
1.50E‐05
2.00E 05
UC/Q(m
‐2)
TransferCoefficient
Observation
Estimation
Accuracy of estimated Source rate:3%
‐5.00E‐06
0.00E+00
5.00E‐06
-1700 -1200 -700 -200 300 800 1300
C i d( )
8
Verification & Validation Study of STE based on the Wind Tunnel data (1st step)
・Observed data: W/T data modified by the meandering factor of 1 hour・TCM:Gaussian Plume model(fitting with W/T data and modified by the meandering factor of 1 hour)
a)b)
the meandering factor of 1 hour)
2 00E 05
2.50E‐05
Concentration Distribution at a Distance of 2000m Downwind
a) Wind direction: N+11.25 deg without meandering factor
Accuracy of estimated Source rate:3%
1.00E‐05
1.50E‐05
2.00E‐05
UC/Q(m
‐2)
TransferCoefficient
Observation
Estimation
Uncertainty factor of wind direction ‐5.00E‐06
0.00E+00
5.00E‐06
-1700 -1200 -700 -200 300 800 1300
y :Crosswind(m)
b) Wind direction: N +11.25 deg with d i f t f 1 h
with meandering
2.00E‐05
2.50E‐05
Concentration Distribution at a Distance of 2000m Downwind
y C oss d( )
meandering factor of 1 hourAccuracy of estimated Source rate:94%
5.00E‐06
1.00E‐05
1.50E‐05
UC/Q(m
‐2)
TransferCoefficient
Observation
Estimation
‐5.00E‐06
0.00E+00
5.00E 06
-1700 -1200 -700 -200 300 800 1300
y :Crosswind(m)
1 hour averaged data are desirable for STE9
Verification & Validation Study of STE based on the Field test data (2nd step under preparation)
Test site: MOL test reactor in
( p p p )
Belgium・Released gas: Ar41(2001.10.)・Observed data: Gamma dose
Release rateObs. data
(Q/U)Release height
Est. databy RISO g
Wind direction
RISO
10
10
Long term radiation exposure modelTarget:to improve the ERMIN(European Model for Inhabited areas) code
Input data Output data
・Ground Surface condition
S il t i ti
・Long term exposure
(External and internal)・Soil contamination
・De-contamination measures
・Effect, cost and waste amount
of de-contamination
R i ff ( 1)
of de contamination
Tasks of 2012 Re-suspension coeff.(m-1)= Soil contamination (Bq/m2)/Air concentration (Bq/m3)
Tasks of 2012
・Analysis of re-suspension coefficient
・Analysis of weathering factor
・Installment of Japanese database
Weathering factor(washout effect et al.) 11
Database installed into ERMIN code
Ground surface categories in Fukushima
Soil contamination map
12
Calculated results by ERMIN code
・Calculated results decrease with the passed time and the living time inside a house.More calculations are planned to check the・More calculations are planned to check the
effect of the ground surface, house and de-contamination conditions.
13
Validation of ERMIN code with Fukushima dataF k hi ERMIN
0.8
1
1.2
/h
Fukushima ERMINOBS_Ave.Ref.1Ref.1-1Ref 2 1(10%)
F0.2
0.4
0.6
0.8
μSv/ Ref.2_1(10%)
Ref.2_2(Ave.)Ref.2_3(95%)
M 0
0.2
0 365 730 1095 1460 1825 2190 2555 2920 3285 3650
time(days)
1
1.2Motomiya ERMIN
OBS_Ave.Ref.1Ref.1-1
0.4
0.6
0.8
μSv/h Ref.2_1(10%)
Ref.2_2(Ave.)Ref.2_3(95%)
0
0.2
0 365 730 1095 1460 1825 2190 2555 2920 3285 3650
time(days)
Ref.1 : Dt(t)=Di(0)・exp(-ln2/τw ・ t) ・ exp(-λi ・ t), Ref.1_1: Dt(t)=Di(0)・ exp(-λi ・ t)τw: Weathering factor (137Cs:18.4 Years, Komamura(2006)), λi: Radioactive decay factor(137Cs:0.0231), Ref.2: Golikov(1993)
14
time(days)
Summaryy
1. The operational Source Term Estimation method was developed using the database of the Transfer Coefficient Matrix based on the wind tunnel data.
2. Verification & Validation study of STE method was conducted using the wind tunnel data
3. EU-ERMIN code was applied for the estimation of long term radiation dose in Fukushima area.of long term radiation dose in Fukushima area.
15
Annual schedule of each subjectsua sc edu e o eac subjec sSubjects FY2012 FY2013 FY2014
(Development of fundamental tech.)
(Validation test) (System integration)
(1)Source Term Programing Validaiton test System integration(1)Source Term Estimation(Tokyo Univ.)
g g
(2)D
Validaiton test
P i
y g
Integration testI t lli i t d t
InitialStage( Few(2)Data pre-
processing(MHI)
Programming Integration testInstalling input data ( FewWeeks)
(3)Re-suspension(Tokyo Univ )
Data analysisImprovement of ERMIN code
Estimation of radiation dose
Long term(3)Long term exposure
LateStage( Few
(Tokyo Univ,.)International collaborations
a)Kick-off meetingsb)Invitations from
a)Visiting at RISOb)Participation into
a)Closing meetings
years)
LLNL and NCAR international conf.16