Radioactive Materials Analysis and Research Facility Laboratory-1 construction report

Shindo, Ryuji; Ichimura, Takahito; Nozawa, Yoshihiko; Komori, Tsuyoshi; Rachi, Reona; Kitahara, Katsumi*; Nakamura, Tomoki*; Koike, Akihiro*

JAEA-Technology 2026-005, 379 Pages, 2026/08

JAEA-Technology-2026-005.pdf:45.42MB

Laboratory-1 of the Radioactive Material Analysis and Research Facility (Laboratory-1) is a facility for analyzing and testing the properties of low and medium radiation dose debris, logging, incinerator ash, and secondary wastes from the decommissioning of the TEPCO HD Fukushima Daiichi Nuclear Power Station (1F) to obtain technical prospects for treatment and disposal measures and their safety. In addition, the ALPS treated water was analyzed by a third party independent of TEPCO HD prior to its discharge into the sea. Laboratory-1 was constructed by the Japan Atomic Energy Agency from January 2017 to June 2022 as part of the 1F Specific Nuclear Facility. The construction work of Laboratory-1 is classified into "building work" for construction of the building by architectural work, electrical equipment work, and mechanical equipment work, and "interior equipment work" for the maintenance of analysis facilities such as iron cells, glove boxes, hoods, etc. This report is a compilation of construction records related to the "building work" that Okuma Construction Office was in charge of. This report is a compilation of construction records and other information related to "building construction" handled by Okuma Construction Office. This report comprehensively summarizes the experience and knowledge from a technical perspective on construction management related to the construction of nuclear facilities, including quality control and construction status for each type of building work, composite coordination, implementation systems and methods for safety and construction quality management, and permits and approvals (such as changes to implementation plans, building permit applications, and forest land development permits). The report also includes a summary of the specific management details such as radiation control for construction in special environments such as construction on the 1F site and construction in a difficult-to-return zone. In the future, we hope that this report will be used as a reference for the development of nuclear facilities such as Laboratory-1, contributing to the identification of issues and rational facility planning.

Benchmark analyses of criticality calculation on SCALE 6.2.3 code system

Okamoto, Naritoshi; Komeno, Akira; Seya, Atsumasa; Inaba, Hideki*; Terakado, Shinichi*; Higuchi, Masashi*

JAEA-Data/Code 2025-022, 497 Pages, 2026/03

JAEA-Data-Code-2025-022.pdf:18.06MB

The Plutonium Fuel Third Development Laboratory of the Nuclear Fuel Cycle Engineering Laboratories has applied for a change of use permit (hereinafter referred to as "license") for plutonium fuel facilities. For the criticality safety design of gloveboxes and equipment/instruments handling mixed oxide (MOX), various criticality calculation codes are used. The most recent employs the 3D Monte Carlo calculation code KENO-V.a embedded in the SCALE 4.4 code system, along with the 27-group ENDF/B-IV neutron cross-section library. SCALE 4.4 was released by the Oak Ridge National Laboratory (ORNL) in the US in 1998, and has now been in use for 27 years. ORNL has continuously improved its functionality, with SCALE 6.3.2 released in 2024. When designing and constructing new MOX fuel facilities, it is desirable to obtain a license using criticality calculation codes based on the latest knowledge. However, it is necessary to verify that these codes have sufficient reliability. Therefore, in 2018, benchmark calculations were performed using the 252-group ENDF/B-VII.1 neutron cross-section library (v7-252n) for two versions of the criticality calculation sequences KENO-V.a and KENO-VI from SCALE 6.2.3, based on past criticality experimental setups. The estimated critical-limiting multiplication factor was calculated. The results indicate that these codes can be used with sufficient confidence for criticality safety design of MOX fuel facilities.

Glove operation compartment with cuboid cans for efficient handling of size-reduced solid waste generated from plutonium-contaminated glovebox dismantling activities

Iguchi, Satoshi; Yoshida, Masato; Hirano, Hiroshi*; Kitamura, Akihiro

Nuclear Technology, 15 Pages, 2026/00

https://doi.org/10.1080/00295450.2025.2600872

The size reduced materials resulting from the dismantling of the plutonium-contaminated gloveboxes are eventually packed into the containers as radioactive waste. Conventionally, the execution of this task has been entrusted to workers equipped with air-fed suits, a practice that carries inherent risks, including potential suit damage and inhalation hazards. Moreover, in order to mitigate these risks, the size reduced materials are covered with rags or plastic to enhance safety for workers. However, this approach entails the separation of non-flammable waste and flammable waste during the disposal process. To circumvent these issues, we have designed a glove operation compartment that enables waste handling and packing activities through glove operations instead of air-fed suits. This reduces the risks associated with air-fed suit operations and eliminates the need to cover size reduced materials with rags and plastic. The procedure involves packing the size reduced materials into metal cans, weighing the cans, and storing them in the containers. We tested these operations using the compartment's test bed and modified them through mock-up experiments to ensure feasibility. This report presents the features of the glove operation compartment, the assumed handling procedures, and the insights obtained from the test results.

RI production using research reactors; Activities at JRR-3

Kinase, Masami

Radioisotopes, 74(2), p.233 - 238, 2025/07

https://doi.org/10.3769/radioisotopes.740212

no abstracts in English

Renovation and restart of STACY (Static Experiment Critical Facility)

Sono, Hiroki

Robutsuri No Kenkyu (Internet), (78), 12 Pages, 2025/03

https://rpg.jaea.go.jp/else/rpd/annual_report/pdf78/No78-03.pdf

The Static Experiment Critical Facility (STACY) was renovated from a "solution fuel reactor" to a "reactor using fuel rods and light water moderator", and restarted operation on August 2, 2024, after a hiatus of 13 years and 8 months. During that time, it took 8 years and 11 months to obtain its permission and approval, 3 years and 1 month for its construction, and 4 months for pre-operation inspections on the reactor performance. This article reports on the history of STACY from its birth to its restart of operation, as well as its future utilization.

Nuclear fuel storage container opening inspection and metal inner container repacking

Licensing Application Group, Fuels and Materials Department

JAEA-Testing 2024-002, 20 Pages, 2024/08

JAEA-Testing-2024-002.pdf:1.46MB

The contamination accident occurred at Plutonium Fuel Research Facility (PFRF) in Japan Atomic Energy Agency (JAEA) Oarai Research and Development Institute on June 6, 2017. During the work of opening the fuel storage container and checking the properties of the contents, the plastic bag that double-packed the inner container burst. The scattering of the fuels contaminated the work room and exposed the worker. The cause of the plastic bag burst was that the enclosed epoxy resin was decomposed by -rays and the internal pressure increased due to the generated hydrogen gas. The 54 storage containers containing plutonium held at PFRF also at risk of increasing internal pressure. Therefore, an opening inspection was conducted to confirm the contents of the storage container in the hot cell. In addition, the contents of storage containers that may generate gas were stabilized. We are planning to transport the fuel storage containers out to another facility for the decommission of PFRF. The other 9 storage containers include oxide raw material powder: Pu + U in excess of 220 g. In order to decrease to less than 220 g (the limit of transport cask), the metal inner containers in the storage container were taken out and repacked in another storage container. This report describes advance measures such as permit application and the details of about storage container opening inspection and metal inner container repacking.

Replacement of incinerator adopted to Plutonium Waste Treatment Facility

Yamashita, Kiyoto; Maki, Shota; Yokosuka, Kazuhiro; Fukui, Masahiro; Iemura, Keisuke

JAEA-Technology 2023-023, 97 Pages, 2024/03

JAEA-Technology-2023-023.pdf:8.21MB

The incinerator adopted to incineration room, Plutonium Waste Treatment Facility had been demonstrated since 2002 for developing technologies to reduce the volume of fire-resistant wastes such as vinyl chloride (represented by Polyvinyl chloride bags) and rubber gloves for Radio Isotope among radioactive solid wastes generated by the production of mixed oxide fuels. The incinerator, cooling tower, and processing pipes were replaced with a suspension period from 2018 to 2022, which fireproof materials on the inner wall of the incinerator was cracked and grown caused by hydrogen chloride generated when disposing of fire-resistant wastes. This facility consists of the waste feed process, the incineration process, the waste gas treatment process, and the ash removal process. We replaced the cooling tower in the waste gas treatment process from March 2020 to March 2021, and the incinerator in the incineration process from January 2021 to February 2022. In addition, samples were collected from the incinerator and the cooling tower during the removing and dismantling of the replaced devices, observed by Scanning Electron Microscope and X-ray microanalyzer, and analyzed by X-ray diffraction to investigate the corrosion and deterioration of them. This report describes the method of setting up the green house, the procedure for replacing them, and the results from analysis in corrosion and deterioration of the cooling tower and incinerator.

Consideration on roles and relationship between observations/measurements and model predictions for environmental consequence assessments for nuclear facilities

Togawa, Orihiko; Okura, Takehisa; Kimura, Masanori

JAEA-Review 2022-049, 76 Pages, 2023/01

JAEA-Review-2022-049.pdf:3.74MB

Before construction and after operation of nuclear facilities, environmental consequence assessments are conducted for normal operation and an emergency. These assessments mainly aim at confirming safety for the public around the facilities and producing relief for them. Environmental consequence assessments are carried out using observations/ measurements by environmental monitoring and/or model predictions by calculation models, sometimes using either of which and at other times using both them, according to the situations and necessities. First, this report investigates methods, roles, merits/demerits and relationship between observations/measurements and model predictions which are used for environmental consequence assessments of nuclear facilities, especially holding up a spent nuclear fuel reprocessing plant at Rokkasho, Aomori as an example. Next, it explains representative examples of utilization of data on observations/measurements and results on model predictions, and considers points of attention at using them. Finally, the report describes future direction, for example, improvements of observations/measurements and model predictions, and fusion of both them.

Experimental and analytical investigations on aerosol washout in a large vessel with high spray coverage ratio simulating PWR containment spray

Sun, Haomin; Leblois, Y.*; Gelain, T.*; Porcheron, E.*

Journal of Nuclear Science and Technology, 59(11), p.1356 - 1369, 2022/11

https://doi.org/10.1080/00223131.2022.2055673

In severe accident scenarios of PWR, containment spray can be employed to washout the aerosol of radioactive materials, retaining them in the containment. Therefore, it is crucial to correctly predict the washout efficiency for safety assessment. For a PWR, a high spray coverage ratio ( 84%-95%) is required. However, experimental studies on the washout with such a high coverage ratio in a large vessel are quite limited. To understand such a washout phenomenon for model development, aerosol washout experiments are performed in a large vessel with not only aerosol measurements but also spray droplet characterizations. The spray coverage ratios are experimentally confirmed to be compatible with a real PWR. The washout features are investigated in detail. The model in MELCOR is examined using the measured aerosol removal rate, showing the removal rate tendency against particle diameters being reproduced. Although a significant underestimation occurs for large particles, a satisfactory agreement is obtained for smaller ones (0.52 m in diameter) corresponding to the minimum removal rate and around.

Continuous improvement activities on nuclear facility maintenance in Nuclear Science Research Institute of Japan Atomic Energy Agency in 2021

Task Force on Maintenance Optimization of Nuclear Facilities

JAEA-Technology 2022-006, 80 Pages, 2022/06

JAEA-Technology-2022-006.pdf:4.24MB

The Task force on maintenance optimization of nuclear facilities was organized in the Nuclear Science Research Institute (NSRI) of Japan Atomic Energy Agency (JAEA) since November 2020, in order to adequately respond to "the New nuclear regulatory inspection system since FY 2020" and to continuously improve the facility maintenance activities. In 2021, the task force has studied (1) optimization of the importance classification on maintenance and inspection of nuclear facilities, and (2) improvement in setting and evaluation of the performance indicators on safety, maintenance and quality management activities, considering "the Graded approach" that is one of the basic methodologies in the new nuclear regulatory inspection system. Each nuclear facility (research reactors, nuclear fuel material usage facilities, others) in the NSRI will steadily improve their respective safety, maintenance and quality management activities, referring the review results suggested by the task force.