Review of dynamical models for external dose calculations based on Monte Carlo simulations in urbanised areas.

After an accidental release of radionuclides to the inhabited environment the external gamma irradiation from deposited radioactivity contributes significantly to the radiation exposure of the population for extended periods. For evaluating this exposure pathway, three main model requirements are needed: (i) to calculate the air kerma value per photon emitted per unit source area, based on Monte Carlo (MC) simulations; (ii) to describe the distribution and dynamics of radionuclides on the diverse urban surfaces; and (iii) to combine all these elements in a relevant urban model to calculate the resulting doses according to the actual scenario. This paper provides an overview about the different approaches to calculate photon transport in urban areas and about several dose calculation codes published.

Modeling of an industrial environment: external dose calculations based on Monte Carlo simulations of photon transport.

External gamma exposures from radionuclides deposited on surfaces usually result in the major contribution to the total dose to the public living in urban-industrial environments. The aim of the paper is to give an example for a calculation of the collective and averted collective dose due to the contamination and decontamination of deposition surfaces in a complex environment based on the results of Monte Carlo simulations. The shielding effects of the structures in complex and realistic industrial environments (where productive and/or commercial activity is carried out) were computed by the use of Monte Carlo method.

The monetary value of the averted dose for public exposure assessed by the willingness to pay.

The monetary value of the unit averted collective dose at an individual reference dose (as alpha(base)-value) and the aversion against the high individual exposure were assessed by the WTP (Willingness To Pay) method. The original questionnaire and methodology were developed by the CEPN, France, for specialists in the nuclear field. Modifications to the questionnaire were introduced in 2000 to take into account the Hungarian aspects.

Assessment of the aversion coefficient in nuclear safety in Hungary.

The key elements of the optimization practice as applied to radiation protection are the monetary value of the averted person-sievert and the aversion coefficient. Determination of the monetary value of the unit averted person-sievert (as alpha(base)-parameter) in Hungary was presented in a previous paper. The estimation of this parameter was carried out by the willingness-to-pay (WTP) method associated with averted occupational exposure (at the NPP Paks/Hungary).