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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

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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

I International Symposium of Nuclear Engineering

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

I International Symposium of Nuclear Engineering

August 2012 5

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.

I International Symposium of Nuclear Engineering

August 2012 6

Figure 3. Side view

Figure 4. Bridge view

Figure 5. Front view

Accident AnalysisAccident AnalysisAccident AnalysisAccident Analysis

I International Symposium of Nuclear Engineering

August 2012 7

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.

I International Symposium of Nuclear Engineering

August 2012 8

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.

I International Symposium of Nuclear Engineering

August 2012 9

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.

I International Symposium of Nuclear Engineering

August 2012 10

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 ⋅⋅= ,,

I International Symposium of Nuclear Engineering

August 2012 11

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

I International Symposium of Nuclear Engineering

August 2012 12

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)

I International Symposium of Nuclear Engineering

August 2012 13

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.

I International Symposium of Nuclear Engineering

Thank you

Antônio Sérgio M. Alves

Erivaldo M. Passos

Juliana P. Duarte

P. F. Frutuoso e Melo