The application of a two-dosemeter system with its algorithm, as well as a test of its use in an inhomogeneous high-radiation field, is described in this study. The goal was to improve the method for estimating the effective dose equivalent during maintenance periods at Korean Nuclear Power Plants (NPPs). The use of this method in Korean and international NPPs, including those NPPs in the USA and Canada, was also investigated. The algorithms used by the the American National Standards Institute, Lakshmanan, the National Council on Radiation Protection and Measurements (NCRP), the Electric Power Research Institute and Kim were extensively analysed as two-dosemeter algorithms. Their possible application to NPPs was evaluated using data for each algorithm from two-dosemeter results that were obtained from an inhomogeneous high-radiation field during maintenance periods at Korean NPPs. The NCRP algorithm (55:50) was selected as an optimal two-dosemeter algorithm for Korean NPPs by taking into account the field test results and the convenience of wearing two dosemeters.