The radiation dosage at the rear of the fuel magazine housing is 122 krad for a single fuel exchange (Lee et al., 2004). The manual drive mechanism is 3–4 m away from the fuel magazine housing.
Thus, the radiation level at the mechanism drops to one-tenth.
Thus, a motor controller was developed to stand radiation of up to 1 kGy using DSP. In addition, an emergency controller was also developed, which is composed of mechanical relays that are stronger to the irradiation than the semiconductors. Fig. 6 shows the DSP motor controller and the emergency controller.