Session: 04-06-01 Underwater Vehicles & Subsea Communications I

Submission Number: 175169

Development and Application of an Underwater Crawler Vehicle for Cleaning Nuclear Power Plant Cooling Pools 

This study presents the development of an underwater crawler vehicle designed for cleaning and maintaining cooling water pools in nuclear power plants. In these facilities, sediment and debris often accumulate on the pool floor due to continuous water circulation and suspended particles. If not removed, these deposits can reduce cooling efficiency and compromise long-term safety. Conventional cleaning methods previously relied on divers, but this approach has been largely replaced by remotely operated vehicles (ROVs). However, ROVs are not ideal for this task because they cannot easily carry heavy cleaning tools, and maintaining stable, precise positioning for localized cleaning requires advanced control systems and skilled operators.

The vehicle is permanently stationed within the facility and can be deployed or retrieved using an overhead crane adjacent to the pool. It is powered by a shore-based power supply (110–220 V AC) through a 70-meter hybrid cable that integrates power delivery, Ethernet control, and video transmission. The cable connects to a shore-based control box equipped with a monitor and joystick, allowing for remote operation and real-time video monitoring.

The vehicle incorporates three in-house-developed high-torque underwater motors: two independently drive the left and right tracks, while the third powers the front-mounted rotating brush. The brush effectively removes sediment from the pool floor, resuspending particles that are subsequently extracted via a rear-mounted suction pipe and delivered to a shore-based filtration system. The brush ground clearance can be adjusted by a linear actuator, allowing the brush to be lifted up to 50 mm off the pool floor. This adjustability, combined with the high-torque drive motors, enables the vehicle to climb over obstacles up to 50 mm in height on the pool bottom. During development, the team tackled the challenge of underwater motor sealing by using a simplified design. Unlike conventional underwater motors that require the entire housing to be filled with pressurized oil to prevent water ingress at the rotating shaft, the developed motors only require oil filling in the shaft seal region. This approach successfully enabled the motors to pass operational tests under pressure equivalent to 100 m water depth.

The vehicle is equipped with two in-house-developed underwater cameras: a forward-facing camera mounted on a pan-tilt unit for navigation and operation monitoring, and a fixed rear camera for pre- and post-cleaning observations. The pan-tilt mechanism utilizes commercially available, waterproof, miniature servo motors to provide a wider viewing angle in water. Video signals from both cameras are transmitted through the hybrid cable, with each camera assigned to an individual twisted pair to maintain independent transmission paths separate from the control signal. An Analog High-Definition (AHD) camera system is employed to achieve high-quality video capture, characterized by minimal latency and enhanced real-time monitoring capabilities.

The results confirm the system's cleaning efficiency and structural reliability in pool environments, highlighting its potential for practical application in nuclear power plant maintenance. Beyond nuclear facilities, the design approach can be adapted to other industrial applications that require continuous sediment management in water pools or reservoirs. This paper presents the mechanical design, power system configuration, control system development, and experimental validation results.

Presenting Author: Jia-Pu Jang Department of Electrical Engineering, NKUST & Taiwan Ocean Research Institute, NIAR

Presenting Author Biography: Jia-Pu Jang received an M.E. degree in Engineering from the Institute of Undersea Technology, National Sun Yat-Sen University, Kaohsiung, Taiwan, in 2009. And pursue a Ph.D. degree in the Department of Electrical Engineering at the National Kaohsiung University of Science and Technology. He has held an engineering position at the Taiwan OceanResearch Institute of the National Applied Research Laboratories since 2009, responsible for the development of marine instruments and deep-sea equipment mechanical mechanisms.

Authors:

Jia-Pu Jang Department of Electrical Engineering, NKUST & Taiwan Ocean Research Institute, NIAR
Po-Chi Chen Taiwan Ocean Research Institute, NIAR
Hsu-Kuang Chang Taiwan Ocean Research Institute, NIAR
Yu-Lin Sung Taiwan Ocean Research Institute, NIAR
Yu-Hung Hsiao Taiwan Ocean Research Institute, NIAR
Ming-Yuan Cho Department of Electrical Engineering, NKUST