Establishing an evaluation method for the aging phenomenon by physical force in fuel debris

Suzuki, Seiya; Arai, Yoichi; Okamura, Nobuo; Watanabe, Masayuki

Journal of Nuclear Science and Technology, 60(7), p.839 - 848, 2023/07

https://doi.org/10.1080/00223131.2022.2159559

The fuel debris, consisting of nuclear fuel materials and reactor structural materials, generated in the accident of Fukushima Daiichi Nuclear Power Plant can become deteriorated like rocks under the changes of environmental temperature. Although the fuel debris have been cooled by water for 10 years, they are affected by seasonal and/or day-and-night temperature changes. Therefore, in evaluating the aging behavior of the fuel debris, it is essential to consider the changes in environmental temperature. Assuming that the fuel debris are deteriorated, radioactive substances that have recently undergone micronization could be eluted into the cooling water, and such condition may affect defueling methods. We focused on the effect of repeated changes in environmental temperature on the occurrence of cracks, and an accelerated test using simulated fuel debris was carried out. The length of the crack increases with increasing number of heat cycle; therefore, the fuel debris become brittle by stress caused by thermal expansion and contraction. In conclusion, it was confirmed that the mechanical deterioration of the fuel debris is similar to that of rocks or minerals, and it became possible to predict changes in the length of the crack in the simulated fuel debris and environmental model.

Weinberg operator contribution to the -odd nuclear force in the quark model

Yamanaka, Nodoka*; Oka, Makoto

Physical Review D, 106(7), p.075021_1 - 075021_15, 2022/10

https://doi.org/10.1103/PhysRevD.106.075021

The contribution of the violating three-gluon interaction, proposed by Weinberg, to the short-range -odd nuclear force is evaluated in the nonrelativistic quark model. We first show that the naive leading contribution generated by the quark exchange process vanishes at sufficiently short distance within the resonating group method, by considering the one-loop level gluon exchange -odd interquark potential induced by the Weinberg operator with massive quarks and gluons. We then estimate the true leading contribution by evaluating the gluonic correction to the -odd interquark potential in the closure approximation. It is found that the resulting irreducible -odd nuclear force is comparable to that generated by the chiral rotation of the -even short-range nuclear force, where the -odd mass calculated with QCD sum rules is used as input. The explicit calculation of the electric dipole moment (EDM) of the He nucleus yields MeV. The total EDM, accounting for the intrinsic nucleon EDM, the pion-exchange and the short- range -odd nuclear force, is MeV, with the dominant effect coming from the intrinsic nucleon EDM.

Quantitative evaluation of long-term state changes of contaminated reinforced concrete considering the actual environments for rational disposal (Contract research); FY2020 Nuclear Energy Science & Technology and Human Resource Development Project

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

JAEA-Review 2021-047, 127 Pages, 2022/01

JAEA-Review-2021-047.pdf:5.57MB

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 FY2020. 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 FY2020, this report summarizes the research results of the "Quantitative evaluation of long-term state changes of contaminated reinforced concrete considering the actual environments for rational disposal" conducted in FY2020. The present study aims to construct a database for quantitative prediction of contaminated reinforced concrete inside the reactor building. In FY2020, in chapter 3.1, in order to obtain the data for the evaluation of mesoscale cracking behavior, the equipment for the making and the measurement of the test specimens were prepared, the evaluation method was confirmed, and preliminary experiments were carried out.

Development of semantic survey map building system using semi-autonomous mobile robots for surveying of disaster area and gathering of information in nuclear power station (Contract research); FY2018 Center of World Intelligence Project for Nuclear Science/Technology and Human Resource Development

Collaborative Laboratories for Advanced Decommissioning Science; Tokyo Polytechnic University*

JAEA-Review 2019-022, 35 Pages, 2020/01

JAEA-Review-2019-022.pdf:2.71MB

CLADS, JAEA, had been conducting the Center of World Intelligence Project for Nuclear Science/Technology and Human Resource Development (hereafter referred to "the Project") in FY2018. The Project aims to contribute to solving problems in nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. 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 FY2018, this report summarizes the research results of the Development of Semantic Survey Map Building System Using Semi-autonomous Mobile Robots for Surveying of Disaster Area and Gathering of Information in Nuclear Power Station. The objective of the present study is to research and develop semi-autonomous mobile robot systems (multi-sensor fusion system, semantic simultaneous localization and mapping (SLAM), system for traversable-route learning and safe traversable-route presentation, etc.) that simply, safely, and rapidly make semantic survey maps including multiple information (air dose rate, temperature, obstacles, etc.). The system will be applied to the investigation of the situation inside the building of the nuclear power station where people cannot access at the time of disaster.

Radiation exposure estimates on production and utilization of recycled items using dismantling waste

Nakamura, Hisashi; Nakashima, Mikio

JAERI-Tech 2002-006, 58 Pages, 2002/03

JAERI-Tech-2002-006.pdf:2.56MB

Radiation exposure was estimated on production and utilization of recycled items using dismantling waste by assuming that their usage are restricted to nuclear facilities. The radiation exposure attributed to production of a steel-plate cast iron waste container, a receptacle for slag, and a drum reinforcement was calculated to be in the range of several Sv to several tens of Sv even in recycling contaminated metal waste of which radioactivity concentration of Co-60 is higher than the clearance level by a factor of two figures. It is also elucidated that casting of a multiple casting waste package meets the standards of dose equivalent rate for the transport of a radioactive package and the weight of the package will be able to kept around 20 tons for the convenience of the handling, in case of disposal of metal waste less than 37MBq/g with the steel-plate cast iron waste container. As the results, from the radiological exposure's point of view, it should be possible to use slightly contaminated metal for recycled items in waste management.

Improvement of the effective nuclear charge model for triatomic molecules, VII

Spectrochimica Acta, Part A, 39(2), p.181 - 187, 1983/00

no abstracts in English

Measurement of Void Behavior in NSRR Forced Convection Tests(1) (Exreactor Mockup Test Results)

; *;

JAERI-M 9825, 37 Pages, 1981/12

JAERI-M-9825.pdf:1.38MB

no abstracts in English

Prediction of heteronuclear diatomic force constants from atomic shielding factors

Journal of Chemical Physics, 75(3), p.1309 - 1312, 1981/00

https://doi.org/10.1063/1.442134

no abstracts in English

The Influence of Coolant Flow on Fuel Behavior under Reactivity Initiated Accident Conditions,1; Test Results under Ambient Pressure and Temperature Conditions

; ; ; ; *

JAERI-M 9104, 44 Pages, 1980/10

JAERI-M-9104.pdf:1.7MB

no abstracts in English

An Effective nuclear charge model for the prekiction of valence force constants in polyatomic molecules,1

Journal of Chemical Physics, 72(1), p.1 - 6, 1980/00

https://doi.org/10.1063/1.438876

no abstracts in English