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Radiological Impact Assessment for Near Surface Disposal of Thorium Waste

  • Faby SunnyEmail author
  • Manish Chopra
Conference paper

Abstract

Thorium (232Th) itself is not fissile and so is not directly usable in a thermal neutron reactor. However, it is fertile and upon absorbing a neutron will transmute to uranium-233 (233U), which is a fissile fuel material. The thorium fuel fabrication may lead to a low-level waste comprising of 232Th. This waste may be disposed of in the Near Surface Disposal Facility (NSDF). The very low probability event of leaching of the waste may lead to contamination of the groundwater system. This paper deals with the estimation of the radiological impact of thorium waste disposal in NSDF through groundwater drinking pathway using the Multiple Area Source Model (MASOM).

Keywords

Radiological impact Decay chain Dose Groundwater NSDF 

Nomenclature

B

is the width of the NSDF (m)

C

is the concentration of radionuclides in pore water (Bq m−3)

Ci

is the radionuclide concentration in the groundwater for instantaneous release of unit radioactivity (Bq m−3)

C1

is the concentration of parent radionuclide in the groundwater (Bq m−3)

Cn

is the concentration of the nth progeny in the groundwater (Bq m−3)

D

is the annual effective dose through groundwater drinking pathway (Sv y−1)

DFing

is the ingestion dose coefficient of the radionuclide (Sv Bq−1)

Dw

is the drinking water consumption rate (L day−1)

Dx

is the dispersion coefficient in x-direction (m2 s−1)

Dy

is the dispersion coefficient in y-direction (m2 s−1)

H

is the depth of the trench (m)

Ha

is the thickness of the aquifer (m)

Kd

is the distribution coefficient of the radionuclide for the aquifer material (m3 kg−1)

Kds

is the distribution coefficient of the radionuclide for the waste material (m3 kg−1)

KL

is the leach rate coefficient of the radionuclide from the NSDF (s−1)

L

is the length of the NSDF (m)

λ

is the radioactive decay constant of the radionuclide (s−1)

λ1

is the radioactive decay constant of the parent radionuclide (s−1)

λn

is the radioactive decay constant for nth progeny (s−1)

M

is the inventory of the radionuclide (Bq)

\( \nu \)

is the infiltration velocity (m s−1)

Q

is the disposal rate of the radionuclide into the NSDF (Bq s−1)

ρ

is the bulk density of the aquifer material (kg m−3)

ρs

is the bulk density of the waste material (kg m−3)

Rd

is the retardation factor in the aquifer

Rds

is the retardation factor in the waste material

ψ(t)

is the radioactivity release rate from the NSDF at any time t after disposal (Bq s−1)

T

is the period of dumping (s)

θ

is the porosity of the aquifer material

θS

is the porosity of the waste material in the trench

u

is the groundwater velocity (m s−1)

x

is the down-flow distance (m)

y

is the cross-flow distance (m)

Notes

Acknowledgements

The authors would like to thank Dr. K. S. Pradeepkumar and Dr. R. B. Oza of Bhabha Atomic Research Centre, Mumbai, India, for their help and support during the study.

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Copyright information

© Springer Nature Singapore Pte Ltd. 2019

Authors and Affiliations

  1. 1.Radiation Safety Systems DivisionBhabha Atomic Research CentreTrombay, MumbaiIndia

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