Investigation on the separation of Sr-90 from high-level liquid waste and the supply of Y-90 for medical application at a Reprocessing Research Facility

Saga, Kaname

JAEA-Review 2025-003, 23 Pages, 2025/05

JAEA-Review-2025-003.pdf:1.08MB

Diagnosis and treatment using radioisotopes (RI) in the medical field contribute to improving people's welfare. However, almost all medical RI distributed in Japan are imported from overseas. As a result, geopolitical influences and natural disasters lead to difficulties for importing them. Based on these backgrounds, in Japan, a specialized subcommittee on the production and utilization of medical radioisotopes was established within the Atomic Energy Commission, and in May 2022, it formulated the "Action Plan for Promotion of Production and Utilization of Medical Radioisotopes." Japan Atomic Energy Agency (JAEA) launched the NXR Development Center in FY2024 to separate and recycle valuable elements contained in high-level liquid waste (HLLW). The advantages of using HLLW are that it contains a wide variety of nuclides and in large quantities. Therefore, this report focused on the RI contained in HLLW and evaluated whether it can be supplied for medical use. Specifically, the target supply amount of Sr-90, the parent nuclide of Y-90 approved as a RI for medical use, and the amount of Sr-90 in HLLW were estimated. Based on the estimation, the feasibility of separating medical RI from HLLW in a reprocessing research facility was evaluated. As a result, the HLLW possibly contains an amount of RI equivalent to the domestic medical demand. Although it depends on the RI concentration in the HLLW, a small volume of HLLW, ranging from a few hundred milliliters to a few liters, could potentially produce an amount of medical RI equivalent to domestic demand. In addition, the equipment already installed in research facilities, such as NUCEF at JAEA, may be sufficient to produce the medical RI. It may be possible to meet domestic medical demand for Sr-90, as a source of Y-90, by processing a few hundred milliliters to a few liters of HLLW using an existing research facility.

Investigation on partitioning and utilization of valuable elements and radio isotopes from spent nuclear fuel

Saga, Kaname

JAEA-Review 2024-038, 9 Pages, 2024/09

JAEA-Review-2024-038.pdf:0.88MB

The purpose of this report is understanding the elements and radio isotopes with highly useful based on the current trends in the industrial field. The survey was conducted from the viewpoint of the abundance of elements and radio isotopes contained and the demand in the industrial field, and the following survey results were obtained. The economic scale of radio isotopes in the industrial field (including radiation use) has been increasing in recent years in the manufacturing, medical, and agricultural sectors. On the other hand, the domestic production of the utilized radio isotope is still small, and some radio isotopes are entirely imported. Radio isotopes such as Sr-90, Mo-100, Cs-137, and Am-241 from spent fuel are suitable for industrial use because of their abundance in spent fuel and half-lives. As for the utilization of elements, the industrial use of platinum group elements and rare earth elements were explored because these elements are high industrial value and low domestic self-sufficiency. The platinum group elements were evaluated to have the potential to be supplied in a certain amount as a new domestic production source based on their abundance in spent fuel. On the other hand, for rare earth elements, which have also low self-sufficiency rate, the ratio of the amount that could be supplied from spent fuel compared to the current annual supply was evaluated to be less than 1%, and therefore, no effect could be expected. The domestic recycling rate of rare earth elements is low, and the provision of numerical simulation technology, which improves the recycling rate, could highly contribute to the industries. This technology makes it possible to calculate the optimal operating conditions for the separation process, such as the number of processing stages and processing speed, in accordance with the elements to be separated and used.

Current status and issues for clearance, 5; Concept of restricted use of contaminated rubbles in the Fukushima Daiichi NPS

Shimada, Taro; Miwa, Kazuji; Takeda, Seiji

Nihon Genshiryoku Gakkai-Shi ATOMO, 61(7), p.531 - 534, 2019/07

Rubbles less than 5 Sv/h of surface dose rate, which are stored outdoor in the Fukushima Daiichi NPS (1F) site, will be recycled and applied in a restricted reuse only within 1F site in the future. However, there is no precedent for establishing the reference values such as dose and/or concentration for reuse or recycling under the existing exposure situation. In this study, we suggested a concept for establishing the reference radioactive concentration of recycling material for the restricted use in the 1F site. In addition, based on the concept, we calculated the reference radiocesium concentrations of the recycling material used for paved roads and the bases of concrete building.

Disposal and recycling; Safer disposal and reassuring recycling

Nishihara, Kenji

ImPACT Fujita Puroguramu Kokai Seika Hokokukai "Kaku Henkan Niyoru Koreberu Hoshasei Haikibutsu No Ohaba Na Teigen, Shigenka" Seika Hokokusho, Shiryoshu, p.28 - 31, 2019/03

In this project, long-lived fission products (LLFP) contained in conventional high-level radioactive wastes are separated and their life is reduced, and elements that can be used as resources are separated. By shortening the life of LLFP, it has been shown that it may be possible to dispose in intermediate depth of several tens of meters, meeting safety requirements, instead of geological disposal. In addition, for reassuring recycling of usable elements, possible exposure pathways were evaluated to estimate the safe concentration level of radioactivity.

Dose estimation in recycling of decontamination soil resulting from the Fukushima NPS accident for road embankments

Takai, Shizuka; Sawaguchi, Takuma; Takeda, Seiji

Health Physics, 115(4), p.439 - 447, 2018/10

https://doi.org/10.1097/HP.0000000000000904

After the Fukushima Nuclear Power Station accident, large quantities of radiocesium-contaminated soil generated from decontamination activities have been stored in the Fukushima Prefecture. To reduce the disposal volume, the Ministry of the Environment of Japan has presented a policy to recycle low-radioactive decontamination soil limited to civil engineering structures. However, there has been no practical instance or safety assessment of decontamination soil recycling. In this study, the way of ensuring the safety for decontamination soil recycling for road embankments was discussed. First, based on Japanese construction standards, additional doses to workers and the public in construction and service scenarios were evaluated. From the result, the radioactive cesium concentration level of recycled materials, where all additional doses meet the radiation criterion of 1 mSv y, was derived to be 6,000 Bq kg. To confine additional doses to the public in a service scenario below 0.01 mSv y, soil slope protection of 40 cm or more was needed. Finally, additional doses in a disaster scenario were confirmed to be below 1 mSv y.

Estimation of doses from radioactively contaminated disaster wastes reused for pavements

Sawaguchi, Takuma; Takeda, Seiji; Kimura, Hideo; Tanaka, Tadao

Hoken Butsuri, 50(1), p.36 - 49, 2015/03

It is desirable that the disaster wastes contaminated by radioactive cesium after the severe accident at the Fukushima Nuclear Plant are reused as much as possible in order to minimize the quantity to be disposed of. Ministry of the Environment showed the policy that the wastes containing cesium of higher concentration than the clearance level (100 Bq/kg) were reusable as materials of construction such as subbase course materials of pavements under controlled condition with measures to lower exposure doses. In this study, in order to provide technical information for making a guideline on the use of contaminated concrete materials recycled from disaster wastes as pavement, doses for workers and the public were estimated, and the reusable concentration of radioactive cesium in the wastes was evaluated. It was shown that the external exposure of the public (children) residing near the completed pavement gave the minimum radiocesium concentration in order to comply with the dose criteria. The recycled concrete materials whose average concentration of cesium lower than 2,700 Bq/kg can be used as the subbase course materials of pavements.

Environment purification technology using ionizing radiation

Kojima, Takuji

Hoshasen, 29(2), p.77 - 85, 2003/04

http://ci.nii.ac.jp/naid/10011475414

The radiation technologies for environment conservation are useful for purification of pollutants contained in flue gas or wastewater at very low concentration which is difficult to perform by conventional methods: removal using fine filter or charcoals and decomposition using catalysis at high temperature, etc. This paper reviews some examples of radiation application to removal of SO and NO from coal-combustion flue gases, decomposition of dioxin in gas emitted through the incinerator, decomposition of gaseous toxic volatile organic compounds in off gas, reuse of agricultural wastes.

Derivation of clearance levels for solid materials in Japan

Sakai, Akihiro; Okoshi, Minoru

Radiation Risk Assessment Workshop Proceedings, p.175 - 186, 2003/00

To establish the clearance levels, the Nuclear Safety Commission (NSC) has been discussing the clearance levels since May 1997. The NSC derived the unconditional clearance levels for the solid materials, namely concrete and metal, arising from the operation and dismantling of nuclear reactors and post irradiation examination (PIE) facilities. Two destinations of the cleared materials, namely disposal and recycle/reuse, were considered. Deterministic calculation models were established to assess individual doses resulting from 73 exposure pathways, and realistic parameter values were selected considering the Japanese natural and social conditions. The clearance levels for 21 radionuclides of nuclear reactors and for 49 of PIE facilities were derived as radioactivity concentration equivalent to the individual doses of 10 Sv/y. Most of calculated clearance levels were nearly the same as those shown in IAEA-TECDOC-855. Some, however, were different. It is considered that the major reasons depend on differences of fixed scenarios and of selected values of parameters.

Study on measurement of spatial dose rates from simulated products made from recycled metal below clearance levels arising from dismantling of nuclear facilities (Contract research)

Okamoto, Akiko; Kitami, Yasuo*; Ando, Yoshiaki*; Nakamura, Hisashi; Saito, Kimiaki; Nakashima, Mikio

JAERI-Tech 2002-051, 40 Pages, 2002/06

JAERI-Tech-2002-051.pdf:3.63MB

In order to contribute to safety assessment of recycling products made from dismantling metal wastes, metal ingots containing Co were produced and spatial dose rates from the ingots were evaluated by gamma-ray measurement and calculation. Stripping operations were made using detector response functions calculated by Monte Carlo program to derive spatial dose rates from measured gamma-ray spectra. In the computer simulation, Monte Carlo and point kernel calculation codes were used. Agreement between measured and calculated values was satisfactory in spite of an extremely low concentration of Co in the ingots and a complicated geometric condition between detector and samples.

Derivation methods for clearance levels and safety assessments for very low-level radioactive waste disposal

Okoshi, Minoru

KURRI-KR-56, p.39 - 57, 2001/03

no abstracts in English