Development and evaluation of an innovative cold spray nozzle for reactor pipe inner wall repair technology

福岛第一核电站完全退役还需要几十年的时间。为保证电厂退役期间的安全运行，需要开发合适的维修技术。研究开发了低压冷喷涂技术，该技术具有工作温度低、涂层强度高、柔韧性好等优点。首先，设计了用于管道内壁涂覆的螺旋形LPCS喷嘴。实验结果表明，螺旋喷嘴可以在管道内壁上制备全氟烷氧基烷烃涂层。结果表明，所设计的LPCS喷嘴具有提高核管使用寿命的潜力。然后探索了两个创新应用：1)漏水管道修复和2)水下涂层制造。结果表明，LPCS应用于管道漏水和水下涂层现场修复是可行的。基于这些令人振奋的结果，对传统的LPCS喷嘴进行了重新设计，以实现304L不锈钢的高沉积效率，从而提高涂层强度。

It still needs several decades until the Fukushima Daiichi nuclear power plant is completely decommissioned. To ensure the safe operation of the power plant during decommissioning, suitable maintenance technology needs to be developed. This research develops the low-pressure cold spray (LPCS) technique for nuclear piping maintenance, which has the advantages of low working temperature, high coating strength, and high flexibility.First, a spiral-shaped LPCS nozzle for coating the pipe's inner wall was designed. The experimental results demonstrated that the spiral nozzle could be used to fabricate the Perfluoroalkoxy Alkane coatings on the pipe's inner wall. This results indicated that the designed LPCS nozzle has the potential of improving the service life of the nuclear pipe. Then, two innovative application was explored: 1) water-leaking pipe repair and 2) underwater coating fabrication. The results demonstrate the feasibility of applying LPCS for on-site pipe repair regarding water leaks and underwater coating. Based on these exciting results, the conventional LPCS nozzle was redesigned to realize the high-deposition efficiency of 304L stainless steel for enhancing the coating strength.