Study on water stopping, repair and stabilization of lower PCV by geopolymer, etc. (Contract research); FY2022 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; The University of Tokyo*

JAEA-Review 2024-021, 126 Pages, 2024/11

JAEA-Review-2024-021.pdf:6.51MB

The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2022. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2021, this report summarizes the research results of the "Study on water stopping, repair and stabilization of lower PCV by geopolymer, etc" conducted in FY2022. The present study aims to propose a construction method to stop jet deflectors by improved geopolymer and ultra-heavy muddy water, and to repair the lower part of the dry well. In addition, in order to increase the options for on-site construction in unknown situations such as deposition conditions, we will examine a wide range of construction outside the pedestal, and evaluate the feasibility of the construction method by the latest thermal flow simulation method.

Experiments of melt jet-breakup for agglomerated debris formation using a metallic melt

Iwasawa, Yuzuru; Sugiyama, Tomoyuki; Abe, Yutaka*

Nuclear Engineering and Design, 386, p.111575_1 - 111575_17, 2022/01

https://doi.org/10.1016/j.nucengdes.2021.111575

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.

Nitrogen K-edge X-ray absorption near edge structure (XANES) spectra of purine-containing nucleotides in aqueous solution

Shimada, Hiroyuki*; Fukao, Taishi*; Minami, Hirotake*; Ukai, Masatoshi*; Fujii, Kentaro; Yokoya, Akinari; Fukuda, Yoshihiro*; Saito, Yuji

Journal of Chemical Physics, 141(5), p.055102_1 - 055102_8, 2014/08

https://doi.org/10.1063/1.4891480

Improvement of high-voltage performance of acceleration tubes by cleaning the walls with a high-pressure water jet

Takeuchi, Suehiro; Nakanoya, Takamitsu; Kabumoto, Hiroshi; Yoshida, Tadashi

Nuclear Instruments and Methods in Physics Research A, 513(3), p.429 - 438, 2003/11

https://doi.org/10.1016/S0168-9002(03)02080-1

At the JAERI Tandem accelerator, an acceleration tube replacing plan is proceeding to increase the acceleration voltage toward 20 MV. Lengthy conditioning is generally necessary for a large tube system. We had an idea to clean the tubes with high-pressure water-jet rinsing before installation. We cleaned tubes and tested them at 1 MV and 3 MV. The both results exhibited that the voltages went beyond the rated voltages and discharge activities were much less than the old records. During the test of new tubes at 3 MV, the conditioning proceeded well and an extremely stable condition was fulfilled within 24 hours. In conclusion, the cleaning was found to be a very promising way to improve high-voltage performance of the tubes in a large tube system.

Research on the fundamental process of thermal-hydraulic behaviors in severe accident; Numerical simulation of fundamental process of vapor explosion using particle method, JAERI's nuclear research promotion program, H10-027-5 (Contract research)

Koshizuka, Seiichi*; Ikeda, Hirokazu*; Liu, J.*; Oka, Yoshiaki*

JAERI-Tech 2002-013, 60 Pages, 2002/03

JAERI-Tech-2002-013.pdf:3.16MB

no abstracts in English

Experimental study on the effect of nozzle surface finishing in high-speed water jet

Nakamura, Hiroshi; Ida, Mizuho*; Nakamura, Hiroo; Nakamura, Hideo; Ezato, Koichiro; Akiba, Masato

JAERI-Research 2000-068, 30 Pages, 2001/02

JAERI-Research-2000-068.pdf:3.88MB

no abstracts in English

Experimental and analytical studies on high-speed plane jet along concave wall simulating IFMIF Li target flow

Nakamura, Hideo; Ito, Kazuhiro*; Kukita, Yutaka*; ; ; Maekawa, Hiroshi; Katsuta, Hiroji

Journal of Nuclear Materials, 258-263, p.440 - 445, 1998/00

https://doi.org/10.1016/S0022-3115(98)00235-9

no abstracts in English

Radiation effects and safety control of tritium, 2; Status of tritium use and source term

Noguchi, Hiroshi

Nihon Genshiryoku Gakkai-Shi, 39(11), p.915 - 916, 1997/00

no abstracts in English

Techniques and experiences in decommissioning of Japan Power Demonstration Reactor

Fujiki, Kazuo; ; ;

Proc. of the Int. Conf. on Dismantling of Nuclear Facilities; Policies-Techniques, p.219 - 232, 1992/00

no abstracts in English