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.

The Selection of the cutting technologies for dismantling the FUGEN reactor

Nakamura, Yasuyuki; Iwai, Hiroki; Mizui, Hiroyuki; Sano, Kazuya

JAEA-Technology 2015-045, 137 Pages, 2016/03

JAEA-Technology-2015-045.pdf:27.77MB

FUGEN is 9 m outer-diameter and 7m height, and characterized by its tube-cluster construction that contains 224 fuel channels arranging both the pressure and the calandria tubes coaxially in each channel. And the periphery part of the core has the laminated structure composed of up to 150 mm thickness of carbon steel for radiation shielding. The structure of the reactor, which is made of various materials such as stainless steel, carbon steel, zirconium alloy and aluminum. The reactor is planning to be dismantled under water in order to shield the radiation ray around the core and prevent airborne dust generated by the cutting, the temporary pool structure and the remote-operated dismantling machines needs to be installed on the top of reactor. In consideration of above the structure of Fugen reactor, the cutting method was selected for dismantling the reactor core in order to shorten the dismantling term and reduce the secondary waste.

Applicability cutting test for the dismantlement of the internal core of Fukushima Daiichi NPS, 3-2; The Results and consideration of the validation test by abrasive water jet cutting technology

Nakamura, Yasuyuki; Tezuka, Masashi; Iwai, Hiroki; Sano, Kazuya; Maruyama, Shinichiro*; Watatani, Satoshi*

no journal, , 

no abstracts in English