In this article, to solve the problems about obsolescence of parts and unable to driving turret when internal components are failure, the DC-DC boost converter in the gun/turret drive system of mobile weapon was improved. The power converting circuit in converter is changed by applying the latest components, and the control circuit is changed from analog to digital. Also, the power converting circuits were modularized in three parallel so that it could be driven even when some components failed. The improved DC-DC boost converter secured stability such as converting to voltage in a linear manner in the entire section from the start of boosting to the end. Also, through the modular configuration, turret driving system can operates when some components failed.

Wolsong unit 1 (W1), which is a CANDU-6 type PHWRs that had been operated for 30 years since 1983, was shutdown in 2019. In this study, the radioactive waste levels of calandria and concrete structures were calculated to establish a decommissioning plan for W1. The specific systems within the scope of this study were grouped into 6 major categories as follows: Calandria, End Shield, Fuel Channel Assembly, Reactivity Control Device, End Shield Support, Vault. The main operating history of W1 is that the re-tubing project was performed. These characteristics and operation history were reflected in the evaluation. The neutron flux and energy spectrum of each structure were calculated by using MCNP code, and ORIGEN code is implemented to the calculation of radioactivity for each nuclide using the results from MCNP and the material information of the structure. As for the impurity information, ASTM B350, B351, B353 standard was used for zircaloy alloy. For other alloy, impurity information provided by NUREG/CR-3474 was applied. Since W1 is expected to be decommissioned immediately, the waste level was evaluated under cooling conditions for 5 years after permanent shutdown. Through the level evaluation of each component obtained as a result of the study, it can be used as basic data for the radioactive waste management of the decommissioning plan.