Analysis of a radioactive waste package fall into
a rainwater channel in the site of Almirante
Alvaro Alberto Nuclear Power Plant
Antônio Sérgio M. Alves
Erivaldo M. Passos
Juliana P. Duarte
P. F. Frutuoso e Melo
August 2012 I International Symposium of Nuclear Engineering 2
Introduction
Radioactive waste
Accident analysis
Results
Conclusions
August 2012 3
Rainwater channel
Point of outflow of the rain channel
into the sea
Fall point
IntroductionIntroductionIntroductionIntroduction
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August 2012 4
Figure 2. 200 liter drum (Angra 2) [1]
Figure 1. 200 liter drum
(Angra 1) [1]
Primary resin (PR) and Compacted waste (CW)
Radionuclide WasteRadionuclide WasteRadionuclide WasteRadionuclide Waste
[1] Eletronuclear S/A, Environmental Impact Assessment of the Waste Management Center (in Portuguese),Rio de
Janeiro, 2003
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Typical radionuclides and activities
[2]
[3,4]
[5]
[2] Passos, E. M. e Alves, A. S., Radiological Analysis for the Choice of Packages for Angra 2 Solid Radioactive Waste of
Low and Mean Activities (in Portuguese), Technical Report ETN GSN.T – 017/05, Rio de Janeiro, RJ.
[3] ELETRONUCLEAR S/A, Angra 1 Final Safety Analysis Report, Rev. 34, Rio de Janeiro, 2005.
[4] ELETRONUCLEAR, Angra Waste Data Bank (in Portuguese) – REJAN, Angra dos Reis, Rio de Janeiro, Brasil, 2005.
[5] Alves, A. S., Radiological Analysis of Angra 2 Exhausted Resin, Report ETN BN/2/0068/1170/08040, Rio de Janeiro,
RJ, 2008.
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Figure 3. Side view
Figure 4. Bridge view
Figure 5. Front view
Accident AnalysisAccident AnalysisAccident AnalysisAccident Analysis
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The following assumptions were taken into account:
The rainwater channel has enough water to cover the package;
The protection due to package external metal part is not considered;
For the waste immobilized in solid matrix, the released activity is modeled by a
leaching mechanism;
For the non immobilized waste, we considered that the entire drum activity contents is
released into the channel during a year;
The concentration of activity dissolution in the sea was not considered;
The dose was calculated for an individual from the public due to the ingestion of
contaminated seafood.
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Mathematical Model
Once the channel parameters and the release rate (Bq/yr) were estimated, the
concentration along the channel, Cw,tot, were calculated by equation (1), based on
dispersion effects of radionuclides in a river [6].
(1)
where Qi is the channel activity release rate (Bq/yr), λi is the decay rate of the i-th
radionuclide ( yr-1), U is the average water velocity in the channel (m/yr) and qr is equal
to one third of the average flow rate calculated from Manning equation [7]. The use of a
third of the average flow rate is in accordance with Ref. [6].
⋅−=
U
x
q
QC i
r
i
totw
λexp,
[6] IAEA - Safety Report Series No.19, Generic Models for Use in Assessing the Impact of Discharges of Radioactive
Substances to the Environment, Vienna, Austria, 2001.
[7] Tomaz, P., A Course on Rainwater Management – Chapter 50 – Manning’s Formula and Channels, www.pliniotomaz.com.br, accessed on Fev, 29th, 2012.
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Mathematical Model
The leaching rate may be defined by equation (2) [8].
(2)
where Inf is the rate infiltration, H is de drum’s diameter, θω is the porosity, ρb is the
density and Kd is the distribution coefficient.
)( dbKH
InfALF
ρθω +=
[8] IAEA - Safety Assessment Methodologies for Near Surface Disposal Facilities - Volume 1, Vienna, Austria, 2004.
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Mathematical Model
The activity concentration in seafood, Cp,i, and the effective dose, Eing,p, was calculated
by equations (3) and (4) respectively [6]:
(3)
(4)
where Bp is the bioaccumulation factor and Hp is the consumption rate and DFing is the
ingestion dose coefficient.
1000/,, piwip BCC ⋅=
ingpipping DFHCE ⋅⋅= ,,
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The highest activity concentration at the channel outflow in the sea corresponds to the
case of compacted waste total washing, and it is equal to 18.1 Bq/m3.
This concentration provides the highest levels found through consumption of
contaminated seafood, equal to
0.0050 mSv for children 1-2 years old,
0.0022 mSv for children 7-12 years old and,
0.0015 mSv for adults.
The total activity released in the first year by leaching mechanisms of the primary circuit
resin, immobilized in cement matrix of Angra 1, is equal to 5.17 ×××× 106 Bq and in bitumen
matrix of Angra 2, 1.53 ×××× 105 Bq, corresponding to 2.6 ×××× 10-4% and 7.7 ×××× 10-5% of the
total activity, respectively.
ResultsResultsResultsResults
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Activity released by leaching
0.0 0.2 0.4 0.6 0.8 1.02.80
2.82
2.84
2.86
2.88
2.90
Time Hyr L
Re
lea
sed
act
ivity
HMB
qêy
rL
137Cs
0.0 0.2 0.4 0.6 0.8 1.0
0.086
0.088
0.090
0.092
0.094
Time Hyr L
Re
lea
sed
act
ivity
HMB
qêy
rL
137Cs
Angra 2 primary circuit resin drum (200 liter drums with
bitumen matrix)
Angra 1 primary circuit resin drum (200 liter drum with cement matrix)
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The highest dose found for an individual from the public, via ingestion of
contaminated seafood, is equal to 0.005 mSv. This corresponds to only 2% of the
annual limit prescribed dose to the normal operation of each plant (Angra 1 and 2),
which is equal to 0.25 mSv [9].
The activities of the resin drums are up to 363 times higher than those of the
compacted waste drums. However, the highest dose calculated for an individual from
the public is due to the fall of a compacted waste drum, indicating the effectiveness of
solid matrices on the containment of radioactive waste in the case of an accident;
The fall of solid radioactive waste into a rainwater channel during its transfer from
Angra 1 and Angra 2 to the Waste Management Center (CGR) showed no significant
radiological impact on an individual from the public.
ConclusionsConclusionsConclusionsConclusions
[9] Dias, W. B., Angra 2: Environmental Radiological Control Handbook – MCRMA (in Portuguese). Technical Report ETN
CP/2/1170/000001, Rio de Janeiro, RJ, 2002.
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