Development of Point-Kernel Code for Skin Dose Calculation

The new computer code K-SKIN has been developed for use in skin dose assessment. The K-SKIN code calculates the dose distribution over the contaminated area using point kernels of monoenergetic electrons. These kernels are averaged over the beta spectra of contaminated radionuclides to obtain the dose distributions. Then, beta dose rates to the skin are calculated by numerical integration of point-kernel data over the contaminated area. Photon dose rates, if involved, are calculated using the specific gamma-ray constant for the radionuclides. Three predefined source types are arranged: point, disk, and cylinder. Backscattering correction, source self-shielding of a volume source, and reduction by the shielding material and air gap are considered during dose calculation. K-SKIN employs MATLAB as the coding tool and provides a graphical user interface. To verify K-SKIN, the dose rates from the point and disk source of several radionuclides over 1.0-cm² area at 70 m skin depth were calculated and compared with results obtained from another point-kernel code VARSKIN 3 and the Monte Carlo simulation code MCNPX. The calculated results agreed within ±20%. The skin dose at various depths showed that the inclusion of energy-loss straggling in the point kernel improves the accuracy of the beta dose calculation at the deep region. The K-SKIN computer code will facilitate assessment of skin exposure at nuclear facilities.