Cutting operation of simulated fuel assembly heating examination by AWJ

Abe, Yuta; Nakagiri, Toshio; Watatani, Satoshi*; Maruyama, Shinichiro*

JAEA-Technology 2017-023, 46 Pages, 2017/10

JAEA-Technology-2017-023.pdf:8.01MB

This is a report on Abrasive Water Jet (AWJ) cutting work carried out on specimen, which was used for Simulated Fuel Assembly Heating Examination by Collaborative Laboratories for Advanced Decommissioning Science (CLADS) molten core behavior analysis group in February 2016. The simulated fuel assembly is composed of Zirconia for the outer crucible/simulated fuel, stainless steel for the control blade and Zircaloy (Zr) for the cladding tube/channel box. Therefore, it is necessary to cut at once substances having a wide range of fracture toughness and hardness. Moreover, it is a large specimen with an approximate size of 300 mm. In addition, epoxy resin has high stickiness, making it more difficult to cut. Considering these effects, AWJ cutting was selected. The following two points were devised, and this specimen could be cut with AWJ. If it was not possible to cut at one time like a molten portion of boride, it was repeatedly cut. By using Abrasive Suspension Jet (ASJ) system with higher cutting ability than Abrasive Injection Jet (AIJ, conventional method) system, cutting time was shortened. As a result of this work, the cutting method in Simulated Fuel Assembly Heating Examination was established. Incidentally, in the cutting operation, when the cutting ability was lost at the tip of the AWJ, a curved cut surface, which occurs when the jet flowed away from the feeding direction, could be confirmed at the center of the test body. From the next work, to improve the cutting efficiency, we propose adding a mechanism such as turning the cutting member itself for re-cutting from the exit side of the jet and appropriate traverse speed to protect cut surface.

Applicability of AWJ technique for dismantling reactor of the Fukushima Daiichi Nuclear Power Station; Cutting test of imitation of fuel debris and optimization of the cutting condition

Maruyama, Shinichiro*; Watatani, Satoshi*

Mitsui Sumitomo Kensetsu Gijutsu Kenkyu Kaihatsu Hokoku (CD-ROM), (14), p.21 - 26, 2017/02

https://www.smcon.co.jp/company/development-center/report-2016/

Based on findings made during recovery works that followed the accident at Three Mile Island Station2, we assume that the reactor internals at the Fukushima Daiichi Nuclear Power Station (1F) have intermixed with melted fuel and confined in limited spaces, they are likely to have complex geometries. Accordingly, abrasive water jet (AWJ) cutting method is considered to be a candidate technique that can be safely and reasonably used for cutting and removing reactor internals. We conducted tests to examine the potential of this technique. We have test for solving the problems of this technique. They are using imitation of fuel debris and optimization of the cutting condition. Based on the results, we confirmed the plan for some of the associated issues, and that AWJ cutting method would be assumed as a candidate technique for removing reactor internals.

Evaluation method using material analysis of specimen in plasma heating experiment, 3; Cutting of simulated fuel assembly heating examination by AWJ

Maruyama, Shinichiro*; Abe, Yuta; Nakagiri, Toshio; Watatani, Satoshi*; Takashima, Yuji*

no journal, , 

no abstracts in English