The team led by Feng Chang, from Institute of Optics and electronics (IOE), Chinese Academy of Sciences(CAS) applied the underwater binocular measurement technology to three-dimensional measurement system for large underwater strong radioactive fuel assemblies under high temperature. Depended on multi-year expertise in special photoelectric intelligent equipment R&D and after several systematic field tests in lack of pool of nuclear power station, the team took 6 months to solve the problem successfully. 

The system was recently used at a nuclear power station in China for the first time to obtain high-precision measurement data of nuclear fuel assemblies and passed the acceptance of users and relevant departments. This technology filled the domestic gaps of multi-parameter three-dimensional measurement in the nuclear engineering submerged fuel assemblies applications, providing accurate data for China's nuclear fuel components life extension plan. 

The total length of the nuclear fuel assemblies of the domestic nuclear power station is over 4000mm. The more than 10 key parameters include the length and deformation of the components, the width of the grid, the distance between the upper and lower headers, etc. The whole measurement process is carried out under high temperature, high radiation and heat disturbance conditions. The measurement accuracy of the assemblies’ length and deformation, and the distance between the upper and lower nozzle achieved 0.2mm at the range of 3800mm, reaching the highest level in China. 

In order to achieve multi-parameter high-precision nuclear fuel assemblies measurement results, the team combined the underwater radiation imaging with underwater thermal disturbance image restoration, underwater binocular measurement and other key technologies which was developed by the team independently. The success of research and development of the system provides a reliable data source for the health status and nuclear safety assessment of nuclear power station fuel assemblies, which will wide applications and commercial prospect. 

At present, the IOE’team is making effors to research on measurement technology underwater laser three-dimensional reconstruction technology. Subsequently, based on the underwater binocular measurement technology, they will develop a new equipment to measure underwater conformations, underwater topography and other parameters in the marine and lake environment. In future, this technology will provide technical support for the marine resource exploration of China and bring affluent society and economic benefits.