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Another access control irregularity at Kashiwazaki-Kariwa Nuclear Power Station: exit gate fails to intercept unauthorized passage

Tokyo Electric Power Company (TEPCO) announced on August 7 that an irregularity related to access control occurred at the Kashiwazaki-Kariwa Nuclear Power Station. An operator improperly used his own ID card to allow a colleague who had left his ID card in the central control room to pass through the gate and exit. TEPCO stated that the access control system failed to display an error message at the time and was unable to prevent this unauthorized passage. According to disclosed information, the incident occurred during the exit process and involves management matters related to nuclear material protection. TEPCO has not yet publicly disclosed the specific date of the incident, the identities of the personnel involved, the detailed reasons why the system failed to trigger an alarm, or subsequent disciplinary actions and preventive measures. Kashiwazaki-Kariwa...

2026-08-08

Rising Seawater Temperatures Prompt New Nuclear Safety Rules: TEPCO Sets Temporary Shutdown Criteria for Kashiwazaki-Kariwa Plant

Tokyo Electric Power Company Holdings announced on August 7 that it has established a set of self-determined criteria for evaluating whether to temporarily halt nuclear reactor operations at the Kashiwazaki-Kariwa Nuclear Power Plant in Niigata Prefecture, in response to rising seawater temperatures in the surrounding area. These criteria are not mandatory requirements directly imposed by external regulatory authorities, but rather proactive measures voluntarily implemented by TEPCO based on safe operational needs. According to the conditions announced by TEPCO, the company will consider temporarily shutting down the relevant nuclear facilities when the 7-day average seawater temperature in the waters surrounding the plant exceeds 31 degrees Celsius, when water temperatures above 34 degrees Celsius are observed, or when water temperatures above 33 degrees Celsius persist for 12 hours. These numerical thresholds indicate that seawater temperature has been incorporated as a key variable in nuclear power plant operational risk management.

2026-08-08

Mutsu City Requests Submission of Revised Plan for 5,000-Ton Transport to Spent Fuel Interim Storage Facility

On August 7, Tomoya Yamamoto, Mayor of Mutsu City, Aomori Prefecture, Japan, met with representatives of Recycle Fuel Storage (RFS) and its co-investors Tokyo Electric Power Company Holdings (TEPCO HD) and Japan Atomic Power Company (JAPC), requesting the three parties to submit a revised mid-to-long-term spent nuclear fuel transport plan, with consideration given to inter-operator cooperation. The plan may involve accepting spent nuclear fuel from other electric power companies. The facility in question, located in Mutsu City, Aomori Prefecture, is currently Japan's only interim spent fuel storage facility situated outside a nuclear power plant site. Under the existing siting agreement, the facility's acceptance scope...

2026-08-08

KEK in Japan Completes World's First "Quantum Multi-Beam Utilization" Synchrotron Radiation Beamlines

On August 6, the High Energy Accelerator Research Organization (KEK) announced that the BL-11A and BL-11B beamlines at its Photon Factory (PF) synchrotron radiation experimental facility have been completed as the world's first quantum multi-beam utilization beamlines, enabling the simultaneous use of hard X-ray and soft X-ray beams. According to reports, BL-11A and BL-11B were constructed in collaboration with the Synchrotron Radiation Academic Infrastructure Network. This network consists of synchrotron radiation facilities operated by university joint-use organizations and joint-use/joint-research centers, positioned as scientific research and educational infrastructure. The main feature of the new beamlines is the ability to simultaneously use hard X-ray and soft X-ray under the same experimental conditions, completing observations that previously required separate measurements...

2026-08-07

First Validation of Novel PRI Technology: Existing PET Tracers Can Image Tissue Microenvironment

August 6, 2026 - A joint research team from the Graduate School of Engineering at the University of Tokyo and the University of York in the UK announced that they have established a novel geometric imaging principle utilizing positron three-photon decay and successfully validated Positronium Ratio Imaging (PRI) technology for the first time. This method can be used in conjunction with existing clinical PET tracers and is expected to provide a new means of observing tissue microenvironments in nuclear medicine imaging. Conceptual diagram of next-generation nuclear medicine imaging utilizing positron-3-photon decay. Current clinical PET scans primarily rely on the positron two-photon annihilation process to visualize the distribution and accumulation of tracers in the body, but they provide limited information on microenvironmental factors such as tissue hypoxia that are associated with disease malignancy...

2026-08-07

First Observation of Anti-Kaonic Nuclei in Photon Beam Experiments

The LEPS2/Solenoid collaboration, composed of researchers from the Research Center for Nuclear Physics at Osaka University, Kyoto Sangyo University, the Research Center for Advanced Quantum Beam Science at Tohoku University, Korea University, Gifu University, the Institute of Modern Physics of the Chinese Academy of Sciences, RIKEN, Kyoto University, the Institute of Physics at Academia Sinica in Taiwan, and the University of Saskatchewan in Canada, has for the first time observed nuclei containing anti-kaons in a photon beam experiment. This achievement provides new experimental evidence confirming the existence of anti-kaonic nuclei and offers important clues for understanding high-density nuclear matter and the internal structure of neutron stars. The research team conducted the experiment at the LEPS2 laser-electron photon facility at the large synchrotron radiation facility SPring-8 in Hyogo Prefecture, Japan...

2026-08-07

Mutsu City in Japan agrees to study receiving fuel from other companies at interim spent fuel storage facility

On August 7, Mutsu City in Aomori Prefecture, Japan, notified Tokyo Electric Power Company Holdings (TEPCO Holdings) and Japan Atomic Power Company (JAPC) that it agreed to allow the two companies to study a plan to receive spent nuclear fuel from other electric power companies at the local interim spent fuel storage facility. The facility, promoted and constructed by entities related to the two companies, is the only facility in Japan located outside nuclear power plant sites for interim storage of spent nuclear fuel. Under the current arrangement, the facility only accepts spent nuclear fuel from TEPCO Holdings and JAPC, and spent nuclear fuel from other companies is not permitted to be transported in. On the same day, Mutsu City Mayor Tomoya Yamamoto met with senior executives of the two companies at City Hall...

2026-08-07

New Decommissioning Plan for Fukushima Daiichi: Priority on Internal Investigation of Unit 3 Before Fuel Debris Retrieval

The Nuclear Damage Compensation and Decommissioning Facilitation Corporation of Japan released on August 6 an outline of the 2026 edition of the "Decommissioning Strategic Plan," proposing technical approaches for the decommissioning of Tokyo Electric Power Company's Fukushima Daiichi Nuclear Power Station. The plan highlights that, for the large-scale retrieval of melted fuel debris at Unit 3, expected to commence in or after fiscal year 2037, priority should currently be given to internal investigations of the reactor building to provide a more reliable basis for subsequent engineering plans. The plan states that the fuel debris retrieval method being studied by TEPCO still requires further improvement in certainty, with the key prerequisite being an understanding of the actual internal conditions of the reactor. Due to the high radiation levels of the water inside the unit following the accident...

2026-08-07

Radiation detector malfunction at Unit 2 of Japan's Onagawa Nuclear Power Plant causes hundreds of abnormal reading fluctuations

Tohoku Electric Power Company of Japan announced on August 6 that a detection equipment malfunction occurred at Unit 2 of the Onagawa Nuclear Power Plant, located in Onagawa Town and Ishinomaki City, Miyagi Prefecture. The issue involved detectors used to measure radiation levels in the main steam lines, which transport steam generated by the reactor to the turbine. Among the four detectors, one displayed readings in the central control room that surged and dropped sharply, repeating hundreds of times. Based on publicly available information, Tohoku Electric has classified this incident as a detector malfunction rather than an abnormal release of radioactive materials or a sudden change in reactor operating conditions. The company stated that the situation does not constitute a problem under security regulations, meaning that from...

2026-08-07

IAEA Director General to Inspect Kashiwazaki-Kariwa Nuclear Power Plant

Preparations are in the final stages for IAEA Director General Rafael Grossi's first inspection of Tokyo Electric Power Company's Kashiwazaki-Kariwa Nuclear Power Plant, expected to take place on August 18. Grossi has previously stated that there are "no obstacles to a swift restart," signaling a positive attitude toward the plant's reactivation. This inspection suggests that discussions surrounding the restart may accelerate. However, it is worth noting that local residents still harbor concerns, adopting a cautiously optimistic outlook on future developments. This marks Grossi's first visit to the Kashiwazaki-Kariwa plant, making it a significant event. Against the backdrop of growing attention to nuclear safety, the IAEA's...

2026-08-06

Japanese PET Study Suggests Late-Onset Psychosis May Be Linked to Neurodegenerative Pathology

A nuclear medicine imaging study conducted by a Japanese research team has shown that many adults who experience psychotic symptoms such as hallucinations and delusions for the first time after age 40 have abnormal protein deposits in the brain associated with Alzheimer's disease and other neurodegenerative disorders. The study included 37 patients with late-onset psychosis and 47 age-matched healthy controls. The researchers used the amyloid PET tracer ^11C-PiB and the tau protein PET tracer ^18F-florzolotau to assess the accumulation of β-amyloid and tau proteins in the participants' brains. The results showed that among patients with late-onset psychosis, β-amyloid positivity...

2026-08-06

Japan's Plutonium Stockpile Expected to Remain at 44.4 Tons by End of 2025

Japan's Cabinet Office reported to the Japan Atomic Energy Commission (JAEC) on August 5 that Japan's plutonium stockpile is expected to be 44.4 tons by the end of 2025, unchanged from the end of the previous year. By source, domestically sourced plutonium stockpile is expected to be 9.9 tons, while overseas-sourced plutonium stockpile is 34.5 tons. The overseas-sourced plutonium mainly comes from separated plutonium formed after Japan entrusted its spent fuel reprocessing operations to the United Kingdom and France. The report shows that in 2024, Kansai Electric Power Company (KEPCO) processed 1.3 tons of plutonium stored in France into mixed uranium-plutonium oxide fuel, namely MOX fuel, resulting in a decrease in overseas-sourced plutonium stockpile. Subsequently, this batch of MOX fuel was shipped to the Takahama Nuclear Power...

2026-08-06

Shimane Nuclear Power Station Unit 2 scheduled inspection completion date moved up to September 16

Chugoku Electric Power Co., Inc. announced on August 5 that the schedule for the 18th periodic utility inspection of Shimane Nuclear Power Station Unit 2 has been revised, with the inspection completion date moved up from September 17, 2026 to September 16, and the power generation resumption date moved up from August 19 to August 18. Shimane Nuclear Power Station Unit 2 is a boiling water reactor unit with a rated electrical output of 820 MW. The unit was shut down on February 9, 2026 and entered its 18th periodic utility inspection. The reason for this adjustment is that, during the reactor start-up preparation work, the procurement of the nitrogen gas source used to fill the reactor containment vessel was completed earlier than planned, allowing the related work to be advanced accordingly...

2026-08-05

Japan Nuclear Security System Introduces SmartHR to Advance Centralized HR Data Management

On August 5, SmartHR Inc. announced that Japan Nuclear Security System Co., Ltd. has adopted its back-office system SmartHR for personnel and organizational management, to promote paperless HR operations and centralized employee information management. Japan Nuclear Security System, headquartered in Minato-ku, Tokyo, provides comprehensive security services for nuclear-related facilities, particularly nuclear power plants, through a combination of mechanical security and personnel security. One of the direct reasons for introducing the new system is that the company's existing HR system has ceased support, necessitating the selection of a replacement. Previously, ...

2026-08-05

Mitsubishi Heavy Industries to Fully Develop Small Modular Reactors, Targeting Commercialization in Japan

Against the backdrop of the Japanese government's push to expand nuclear energy utilization, Mitsubishi Heavy Industries has decided to proceed with full-scale development of Small Modular Reactors (SMRs), with the goal of achieving commercial application in Japan. This is seen as a significant step forward by a Japanese private enterprise toward the practical deployment of SMRs. The Basic Energy Plan approved by Japan's Cabinet last year calls for maximizing the use of nuclear energy. At a ministerial meeting held last week, the Japanese government once again confirmed its commitment to advancing the research, development, and deployment of next-generation nuclear reactors. SMRs represent one of the technology pathways for next-generation nuclear reactors. Due to their smaller unit size and higher degree of modularization, the industry generally...

2026-08-05