Dose distribution to a random walker moving in a two-dimensional surface around a radioactive source.

Background: Modeling of dose distribution of randomly moving population around a radioactive source is a complex problem.

Objective: The objective is to develop a model and solution techniques to estimate radiation absorbed dose to the population randomly moving around a radioactive source.

Methods: The problem is formulated using a second-order partial differential equation; different moments of the dose distribution function are defined related to physically realizable quantities, and solutions are obtained using standard moments methods.

Temporal evolution of activation products in a zircaloy-4 guide tube and the estimation of its external gamma dose rate for decommissioning activities.

The dismantling of structural objects during the decommissioning of nuclear facilities needs radioactive source characterisation for the planning of decommissioning strategies in compliance with the ALARA (as low as reasonably achievable) principle. The sources may arise from neutron activation of the structural components in the reactor core as well as contamination due to the radioactive release from the fuel occurred during normal operation or unplanned events in a nuclear power plant (NPP). In a pressurised heavy water reactor (PHWR), various in-core components are predominantly made of either zircaloy-2 or 4.

Effective dose conversion coefficient for gamma ray exposure from an overhead plume.

The external radiation exposure from an overhead plume containing gamma emitting radionuclides can contribute substantial dose to the ground receptor during normal operations as well as accidental release conditions of nuclear facilities. In order to estimate the effective dose conversion coefficients (DCCs) directly, a finite plume Monte Carlo model along with the reference phantom at the ground receptor location needs to be implemented. In the present study, a comprehensive simulation of radiation transport from the Gaussian plume source to the ICRP reference adult voxel phantoms (receptor) is carried out using the FLUKA Monte Carlo code.