MHI raises nuclear outlook and plans ¥100 billion capacity investment
Mitsubishi Heavy Industries raised its fiscal-2026 nuclear order forecast to ¥600 billion from ¥450 billion and its nuclear revenue forecast to ¥550 billion from ¥400 billion. The company attributes the order revision partly to increased fuel-cycle work and says it currently expects about ¥100 billion of production-capacity investment from fiscal 2027, including renewal of large processing equipment with new nuclear construction in view.
WHY IT MATTERS
The disclosure is a primary-source signal of stronger near-term demand across Japan's nuclear and fuel-cycle supply chain and a concrete commitment to expand heavy-manufacturing capacity for future projects. The ¥100 billion figure is a forward investment plan, not completed spending or evidence that a new reactor project has been approved.
Kyushu files Sendai 1 and 2 ageing-management amendments
Kyushu Electric applied to the NRA to amend the approved long-term facility-management plans for Sendai 1 and 2 after deciding to add a new type of electrical penetration. The operator says its additional evaluation found no soundness problem at the 60-year operating point and no additional maintenance activity required for the new type.
WHY IT MATTERS
The filing updates the regulatory ageing-management basis for two operating 890 MW reactors. It is an application, not an approval: the change remains subject to NRA review and does not alter either unit's current operating classification or establish completion of the regulatory process.
The NRA's 29 October dated page classifies 13 of Japan's 33 existing commercial reactors as operating and 20 as suspended. Compared with the retained 20 October snapshot, Onagawa 2 and Genkai 3 moved from suspended to operating; the other unit classifications are unchanged.
WHY IT MATTERS
The dated regulatory snapshot adds 2,005 MW of unit membership to the NRA operating category and updates the Fleet Pulse and fleet register. It is not presented as a live output feed: current operator observations and OCCTO measured generation remain separately labelled.
54 current records · original Japanese retained · source and collection time shown
Latest discovery cycle: OCCTO, JEPX HJKS and newly available content from accessible NRA/N-ADRES, JAIF, METI/ANRE, TEPCO and Chugoku Electric sources were inspected during the midday cycle on 10 November. OCCTO revalidated 8 November at 298.068 GWh across the full 33-record fleet coverage: 30 complete measured rows and three fully blank non-reporting rows; 9 November was not yet available. The latest complete day contains positive measured generation for 13 units, representing 12.559 GW of nameplate capacity. This is a dated measured snapshot and is not presented as live output. All four rejected dates remain retained, including 9 August outside the rolling 90-day validation window, and no missing day is interpolated. JEPX HJKS recovered from the morning retrieval gap and returned the same 215 mapped nuclear records; no record content changed and no additional disclosure qualified for the feed. TEPCO's 10 November 02:30 operator page reported Kashiwazaki-Kariwa 6 generating at 1,397 MW, while Chugoku Electric's 9 November notice confirmed Shimane 2 continuing commercial operation. These are operator snapshots for individual sites, not national or continuous live coverage, and neither changes the already verified operating classifications. The newest accessible NRA and N-ADRES material established no verified completed reactor milestone. The NRA operating-status page remains dated 29 October at 13 operating and 20 suspended units. JAIF's fleet sheet remains dated 9 October, and accessible METI/ANRE and JAIF content showed no newer primary-source-verifiable completed development. No genuinely new or materially changed development qualified for the feed in the content successfully inspected. Several other operator sources and regional and local-government sources were not successfully inspected in this cycle, so this was not complete coverage of all 37 registered sources and their successful-review times were not advanced.
SUPPLY CHAIN
MHI raises nuclear outlook and plans ¥100 billion capacity investment
Mitsubishi Heavy Industries raised its fiscal-2026 nuclear order forecast to ¥600 billion from ¥450 billion and its nuclear revenue forecast to ¥550 billion from ¥400 billion. The company attributes the order revision partly to increased fuel-cycle work and says it currently expects about ¥100 billion of production-capacity investment from fiscal 2027, including renewal of large processing equipment with new nuclear construction in view.
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WHY IT MATTERS
The disclosure is a primary-source signal of stronger near-term demand across Japan's nuclear and fuel-cycle supply chain and a concrete commitment to expand heavy-manufacturing capacity for future projects. The ¥100 billion figure is a forward investment plan, not completed spending or evidence that a new reactor project has been approved.
ORIGINAL SOURCE RECORD
2026年度第2四半期決算説明資料
Published 06 Nov 2026 · collected 9 Nov 2026, 19:50 JST
Kyushu files Sendai 1 and 2 ageing-management amendments
Kyushu Electric applied to the NRA to amend the approved long-term facility-management plans for Sendai 1 and 2 after deciding to add a new type of electrical penetration. The operator says its additional evaluation found no soundness problem at the 60-year operating point and no additional maintenance activity required for the new type.
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WHY IT MATTERS
The filing updates the regulatory ageing-management basis for two operating 890 MW reactors. It is an application, not an approval: the change remains subject to NRA review and does not alter either unit's current operating classification or establish completion of the regulatory process.
ORIGINAL SOURCE RECORD
川内原子力発電所1、2号機 長期施設管理計画の変更認可申請について
Published 06 Nov 2026 · collected 6 Nov 2026, 13:45 JST
The NRA's 29 October dated page classifies 13 of Japan's 33 existing commercial reactors as operating and 20 as suspended. Compared with the retained 20 October snapshot, Onagawa 2 and Genkai 3 moved from suspended to operating; the other unit classifications are unchanged.
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WHY IT MATTERS
The dated regulatory snapshot adds 2,005 MW of unit membership to the NRA operating category and updates the Fleet Pulse and fleet register. It is not presented as a live output feed: current operator observations and OCCTO measured generation remain separately labelled.
ORIGINAL SOURCE RECORD
発電所の現在の運転状況
Published 29 Oct 2026 · collected 30 Oct 2026, 19:42 JST
Tohoku Electric's 04:40 operator page says Onagawa 2 resumed electricity generation on 29 October after the reactor restart reported on 26 October. The unit was in the process of raising output when the page was inspected.
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WHY IT MATTERS
This is the first primary-source confirmation that the 825 MW unit progressed from reactor startup to electricity generation after its valve inspection outage. It does not establish full output or a completed return to steady commercial operation, which remain separate milestones.
ORIGINAL SOURCE RECORD
女川原子力発電所発電機出力グラフ
Published 29 Oct 2026 · collected 29 Oct 2026, 07:34 JST
Ohi 3 grid reconnection now planned for late January
Kansai Electric says Ohi 3's 22nd periodic inspection, which began on 5 October without a published completion schedule, is now planned to reach grid parallel in late January. The operator will replace the exciter as part of corrective work following the generator and reactor trip on 8 August.
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WHY IT MATTERS
The schedule provides a new primary-source indication of when 1,180 MW could begin returning to the grid and supports maintenance, fuel and wholesale-market planning. Late-January parallel is a plan, not a completed restart or confirmation of full output.
ORIGINAL SOURCE RECORD
大飯発電所3号機の定期検査工程の変更
Published 29 Oct 2026 · collected 29 Oct 2026, 19:35 JST
Kyushu Electric, Kyuden Holdings and Karatsu City signed an amended safety agreement for the Genkai nuclear station following the holding company's creation on 1 October. The agreement adds Kyuden Holdings as a party and states that it must support Kyushu Electric in fulfilling the agreement, while Kyushu Electric remains the nuclear operator.
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WHY IT MATTERS
The amendment clarifies safety-governance responsibilities after the corporate restructuring and preserves a direct local-government accountability framework. It is a governance change, not an operating-status or consent milestone for any reactor.
Onagawa 2 reactor restarted after valve inspection
Tohoku Electric's 03:00 operator page says inspection of the high-pressure feedwater-heater B relief valve was completed and the Onagawa 2 reactor was started on 26 October. The operator says generation will resume once preparations are complete.
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WHY IT MATTERS
This converts the reactor-start milestone from a prospective HJKS signal into a verified operator-reported event for the 825 MW unit. It does not establish grid connection, electricity generation or full commercial operation; those later milestones remain unverified until separately confirmed.
ORIGINAL SOURCE RECORD
女川原子力発電所発電機出力グラフ
Published 27 Oct 2026 · collected 27 Oct 2026, 07:31 JST
Tohoku Electric will reuse Hamaoka clearance metal at Higashidori
Tohoku Electric says reinforcing steel made from clearance metal generated during decommissioning work at Hamaoka 1 and 2 was delivered to Higashidori on 26 October. The material is planned for the foundations of an additional on-site warehouse and will be Tohoku Electric's first use of clearance metal as construction material.
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WHY IT MATTERS
The project is a concrete domestic reuse pathway for very-low-activity metal that has passed the regulatory clearance process, linking decommissioning waste reduction with construction procurement. Delivery is complete, but use in the warehouse foundation remains planned and is not presented as completed construction.
ORIGINAL SOURCE RECORD
東通原子力発電所におけるクリアランス金属の建設資材への再利用について
Published 26 Oct 2026 · collected 26 Oct 2026, 17:34 JST
TEPCO says the sixth ALPS-treated-water discharge of fiscal 2026, and 24th overall, finished at 12:09 JST on 23 October after the transfer from measurement tanks ended on 22 October and residual water in the transfer line was flushed. The completed release ran from 5 to 23 October, discharged 7,852 cubic metres and contained about 1.2 trillion becquerels of tritium.
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WHY IT MATTERS
This converts the previously published start and planned parameters into a verified completed decommissioning operation. TEPCO says daily diluted-water checks remained below 1,500 becquerels per litre and its rapid seawater results remained below investigation and suspension levels; the record does not establish the status of the separately scheduled seventh discharge.
ORIGINAL SOURCE RECORD
福島第一原子力発電所 2026年度第6回(通算24回)ALPS処理水海洋放出の完了
Published 23 Oct 2026 · collected 24 Oct 2026, 13:33 JST
Kyushu Electric files eighth safety-improvement evaluations for Sendai 1 and 2
Kyushu Electric submitted the eighth statutory safety-improvement evaluations for Sendai 1 and 2 to the NRA. The operator says the reviews confirmed that existing safety activities and previously implemented measures remain effective, and identified further work covering instrumentation-and-control upgrades, equipment changes to reduce severe-accident workload, heat-stress measures in radiological areas, spent-fuel dry storage and enhanced education and training.
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WHY IT MATTERS
The filing provides current primary-source evidence of the operator's next safety-investment priorities for two generating 890 MW units. It is a submitted evaluation and programme of further measures, not evidence that every identified upgrade or the planned dry-storage facility is complete.
Kyushu Electric schedules Genkai 3 generation resumption for 29 October
Kyushu Electric says Genkai 3 has nearly completed the inspections required while shut down for its 19th periodic inspection. The operator plans to start the reactor and reach criticality on 27 October, resume generation on 29 October, then raise output progressively during adjustment operation before a planned return to normal operation on 25 November.
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WHY IT MATTERS
The operator's schedule provides primary-source milestones for the expected return of a 1,180 MW unit and corroborates the prospective HJKS output-reduction window already tracked. Every date remains a plan: reactor startup, criticality, grid generation and normal-operation return must each be verified after they occur and are not presented as completed or live.
ORIGINAL SOURCE RECORD
玄海原子力発電所3号機の発電再開予定をお知らせします
Published 23 Oct 2026 · collected 24 Oct 2026, 07:50 JST
HJKS schedules a Genkai 3 output-reduction window from 29 October
A new official JEPX HJKS disclosure schedules a Genkai 3 output-reduction window from 15:00 JST on 29 October, with restoration indicated for 1 November. The record gives a 556 MW registered reduction and states maximum and minimum reductions of 1,121 MW and 295 MW.
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WHY IT MATTERS
Genkai 3 is currently in periodic inspection, so the disclosure is a forward operational signal relevant to the unit's return pathway. HJKS labels it as a future output-reduction event; it does not establish reactor startup, grid connection, commercial-operation resumption or current generation.
ORIGINAL SOURCE RECORD
玄海原子力発電所3号機 出力低下
Published 22 Oct 2026 · collected 22 Oct 2026, 16:08 JST
HJKS posts an Onagawa 2 startup-curve window beginning 28 October
A new official JEPX HJKS disclosure schedules an Onagawa 2 startup-curve output-reduction window from 18:00 JST on 28 October, with restoration indicated for 31 October. The record gives a 127 MW registered reduction and identifies the cause as output reduction associated with the startup curve.
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WHY IT MATTERS
The disclosure provides the first official forward signal in this feed for Onagawa 2's expected return after its 17 October planned shutdown. It remains a schedule: Tohoku Electric's latest inspected operator page still records the unit stopped, and no restart, grid connection or current generation is claimed until separately verified.
ORIGINAL SOURCE RECORD
女川原子力発電所2号機 出力低下(起動カーブに伴う出力低下)
Published 22 Oct 2026 · collected 22 Oct 2026, 16:08 JST
TEPCO schedules fiscal-2026 seventh ALPS-treated-water discharge for 26 October
TEPCO says its analyses and an external laboratory's results met the release criteria for the fiscal-2026 seventh ALPS-treated-water discharge. It plans to begin on 26 October and finish on 13 November, discharging about 7,800 cubic metres with an estimated total tritium amount of about 1.4 trillion becquerels and an estimated post-dilution concentration of about 240 becquerels per litre.
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WHY IT MATTERS
The primary-source schedule defines the next monitored Fukushima Daiichi discharge window and its planned parameters. The analysis result is verified, but the 26 October start, 13 November completion and planned volumes remain prospective and must not be presented as completed operations.
Kansai Electric strengthens monitoring at Takahama 1 after renewed valve-temperature rise
Kansai Electric says the C pressurizer safety-valve outlet temperature at Takahama 1 began rising again at 15:00 JST on 20 October and reached about 66°C by 14:00 on 21 October, after remaining within its usual range of about 50°C or below since 5 October. The unit remained in constant rated thermal-power operation, other plant parameters were normal and the operator reported no radiological impact.
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WHY IT MATTERS
The renewed increase warrants continued monitoring because it affects a safety-valve train at an operating 826 MW reactor. The operator has not reported a shutdown, power reduction or abnormality in other plant parameters, so this notice is not used to infer any output change.
ORIGINAL SOURCE RECORD
高浜発電所1号機 C加圧器安全弁の出口温度上昇に伴う監視強化の状況
Published 21 Oct 2026 · collected 22 Oct 2026, 07:33 JST
NRA updates the national operating-status snapshot
The NRA's 20 October dated page classifies 11 of Japan's 33 existing commercial reactors as operating and 22 as suspended. Compared with the previously retained NRA snapshot, Onagawa 2 and Ohi 3 are now suspended, while Mihama 3 and Shimane 2 are operating. Kashiwazaki-Kariwa 6 remains classified as operating.
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WHY IT MATTERS
The total operating denominator is unchanged, but its unit membership has materially changed. This dated regulatory snapshot updates the Fleet Pulse and fleet register without being presented as a live status feed; current operator observations and OCCTO measured generation remain separately labelled.
ORIGINAL SOURCE RECORD
発電所の現在の運転状況
Published 20 Oct 2026 · collected 21 Oct 2026, 22:14 JST
Onagawa 2 completes planned shutdown for valve inspection
Tohoku Electric says Onagawa 2 stopped generating at 01:00 JST on 17 October and reached cold shutdown at 13:57 JST. The operator will inspect, dismantle and replace parts in the high-pressure feedwater-heater B relief valve after monitoring a small water leak into a controlled drain tank.
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WHY IT MATTERS
This converts the previously announced roughly ten-day stop from a schedule into a verified operational event affecting an 825 MW reactor. OCCTO's complete 17 October national record is consistent with a partial generating day for Onagawa 2, but it is not used to claim a live reactor state. Restart remains prospective until separately confirmed by the operator.
ORIGINAL SOURCE RECORD
女川原子力発電所2号機における原子炉の計画停止について
Published 17 Oct 2026 · collected 19 Oct 2026, 09:05 JST
Tohoku Electric schedules roughly ten-day Onagawa 2 stop
Tohoku Electric says it plans to stop Onagawa 2 around 17 October to dismantle, inspect and replace parts in a relief valve on high-pressure feedwater heater B. The operator has monitored a small water leak into a controlled drain tank since 1 September and says the amount increased slightly. It expects the interval from shutdown to restart to be about ten days.
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WHY IT MATTERS
The planned stop temporarily removes an 825 MW reactor from generation and should be visible in national output after it occurs. The operator says the water is collected and treated, there is no environmental radiological impact and the event is not reportable under national law. The schedule is verified, but the stop and restart remain future actions and are not presented as completed or live.
OCCTO's complete national record for 11 October contains positive 30-minute measured generation for Mihama 3. The validated national total was 254.011 GWh across all 33 nuclear-unit records, with 30 complete measured rows, three fully blank non-reporting rows and 12 units reporting positive generation.
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WHY IT MATTERS
This is official dated evidence that the 826 MW unit generated during 11 October after Kansai Electric's planned reactor-start milestone. It is not a live operating-status claim and does not verify completion of adjustment operation or the planned November commercial-operation milestone. The incomplete 10 October OCCTO record remains rejected, so no day-on-day change is calculated across that gap.
ORIGINAL SOURCE RECORD
発電情報公開システム
Published 12 Oct 2026 · collected 12 Oct 2026, 19:30 JST
KEPCO schedules Mihama 3 reactor start for 10 October
Kansai Electric says repairs and preparations are complete after identifying an external-corrosion hole in piping near the 6A high-pressure feedwater-heater level-control valve. The operator plans to start the Mihama 3 reactor and begin adjustment operation on 10 October, followed by full commercial operation after the integrated load-performance test on 4 November.
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WHY IT MATTERS
The schedule provides a primary-source pathway for the return of an 826 MW reactor that stopped manually on 18 September. Both dates are planned milestones: this record does not verify that reactor start, grid synchronization or commercial-operation resumption has occurred.
JAIF publishes September reactor performance and 9 October fleet sheet
JAIF's September performance report records 7,814,218 MWh of generation across the 33-unit existing commercial fleet, with an aggregate capacity factor of 32.8%. Twelve of the 15 historically restarted reactors generated during the month. Mihama 3 generated for 61 hours before stopping again, while Takahama 3, Ohi 3 and Genkai 3 recorded full-month outages. JAIF's companion 9 October fleet sheet retains 33 existing units and 15 historically restarted units.
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WHY IT MATTERS
The publication provides the freshest comparable monthly unit-level capacity-factor and time-availability evidence and updates the website's reactor-performance table. It is a monthly JAIF compilation of utility data, not a live operating-status feed; values above 100% follow JAIF's rated-output convention.
ORIGINAL SOURCE RECORD
「日本の原子力発電所の運転実績(2026年9月)」等の掲載について
Published 09 Oct 2026 · collected 9 Oct 2026, 13:48 JST
Japan launches execution-focused nuclear workforce consortium
The Japan Atomic Human Resource Consortium (J-AHRC) launched on 7 October as a reorganization of the Nuclear Human Resource Development Network. JAIF says the 84 participating institutions are expected to continue, while 13 founding organizations will operate a standing secretariat and implementation structure. The consortium plans to quantify workforce gaps by occupation and specialty and prepare a roadmap during fiscal 2026.
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WHY IT MATTERS
This creates a more execution-oriented industry, government and academic mechanism for a constraint that affects reactor operation, maintenance, decommissioning and potential replacement construction. The launch is verified through JAIF, a founding organization; future workforce numbers and the roadmap remain planned outputs, not completed findings.
ORIGINAL SOURCE RECORD
原子力人材確保へ新コンソーシアム発足 課題解決に向けた実行体制へ機能強化
Published 08 Oct 2026 · collected 9 Oct 2026, 07:45 JST
Genkai 4 planned-outage restoration moves to 18 January
JEPX HJKS updated Kyushu Electric's Genkai 4 planned-outage disclosure. The outage remains scheduled to begin at 09:00 JST on 12 November 2026, while the expected restoration date moved one day earlier, from 19 January to 18 January 2027.
monitor⌄
WHY IT MATTERS
The revision modestly shortens the disclosed maintenance window for a 1,180 MW operating reactor and refines winter supply planning. It is a future operator schedule disclosure, not evidence that Genkai 4 is currently offline or that the restoration date is guaranteed.
ORIGINAL SOURCE RECORD
玄海原子力発電所 4号機・計画停止・停止/定期検査等
Published 05 Oct 2026 · collected 5 Oct 2026, 19:38 JST
TEPCO says it began the fiscal-2026 sixth—and 24th overall—ALPS-treated-water discharge at 11:21 JST on 5 October. The operator reported that external and internal analyses met the applicable release criteria. It plans to discharge about 7,800 cubic metres through 23 October, with an estimated total tritium amount of about 1.2 trillion becquerels and an expected post-dilution concentration of about 200 becquerels per litre.
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WHY IT MATTERS
This converts a previously announced schedule into a verified operational decommissioning event and starts the latest monitored discharge window. The source verifies the start and planned parameters; it does not verify completion, and monitoring results during the discharge remain relevant.
ORIGINAL SOURCE RECORD
福島第一原子力発電所 2026年度第6回(通算24回)ALPS処理水海洋放出の開始
Published 05 Oct 2026 · collected 7 Oct 2026, 14:10 JST
Following the 1 October establishment of Kyuden Holdings, Kagoshima Prefecture, Satsumasendai City, Kyushu Electric Power and the new holding company signed an amended safety agreement and exchanged an updated memorandum concerning the Sendai nuclear power station. Kyushu Electric says it remains the entity responsible for the nuclear business.
monitor⌄
WHY IT MATTERS
The four-party arrangement clarifies local-government oversight and corporate accountability after the group reorganization. It does not change Sendai 1 or 2's verified generating status, reactor licensing or output.
ORIGINAL SOURCE RECORD
キューデンホールディングス株式会社設立に伴い川内原子力発電所に関する安全協定を締結しました
Published 05 Oct 2026 · collected 6 Oct 2026, 19:45 JST
TEPCO schedules Fukushima Daiichi 2 robotic-arm work from 2 October
TEPCO's 1 October roadmap material says work using the Fukushima Daiichi Unit 2 robotic arm was scheduled to start on 2 October with construction of an access route into the primary containment vessel. TEPCO says the overall sequence—access-route construction, three-dimensional mapping, debris sampling and other data collection—is expected to involve about six months of remote operations.
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WHY IT MATTERS
The plan moves a larger robotic system toward detailed internal investigation and trial fuel-debris retrieval, a technically important step in Fukushima Daiichi decommissioning. The primary source states a scheduled start: it does not verify that work began, that the arm reached the target area or that debris was retrieved.
ORIGINAL SOURCE RECORD
2号機 PCV内部調査・試験的取り出し作業の状況
Published 01 Oct 2026 · collected 2 Oct 2026, 19:45 JST
Hitachiomiya accepts literature survey for final-disposal siting
Hitachiomiya Mayor Sadayuki Suzuki announced that the city will accept the economy minister's request for a literature survey concerning geological disposal of high-level radioactive waste. The mayor said the decision followed discussions with the national government and framed the survey as an initial evidence-gathering step.
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WHY IT MATTERS
The decision adds a new municipality to Japan's first-stage final-disposal siting process and broadens the geographic pipeline for resolving a national fuel-cycle constraint. Acceptance does not mean a repository has been selected, that field investigation has begun or that later-stage local consent has been granted.
ORIGINAL SOURCE RECORD
文献調査受け入れに係る市長発言(令和8年9月30日記者会見)
Published 30 Sept 2026 · collected 2 Oct 2026, 13:40 JST
Onagawa 2 dry-storage operation shifts to December 2028
Tohoku Electric moved the planned start of construction for Onagawa 2's first spent-fuel dry-storage building from September to December 2026 and its planned start of operation from March to December 2028. The operator cited additional time required for regulatory review and authorization, and submitted a related construction-plan change notice to the NRA.
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WHY IT MATTERS
The nine-month shift delays additional spent-fuel management capacity at an operating reactor and may affect future fuel-pool and outage logistics. It is an operator schedule revision, not regulatory approval, construction completion or an operating-status change.
ORIGINAL SOURCE RECORD
女川原子力発電所2号機における使用済燃料乾式貯蔵施設第1棟目の着工および運用開始時期見直しについて
Published 29 Sept 2026 · collected 1 Oct 2026, 19:40 JST
Onagawa 2 third DC power-system completion moves to August 2028
Tohoku Electric revised the planned completion of Onagawa 2's third permanent on-site DC power system from March to August 2028 after reassessing the large-scale work required inside the reactor building. The operator submitted revised operating-plan and construction-plan notices to the NRA; the applicable transitional deadline is December 2029.
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WHY IT MATTERS
The change updates the delivery schedule for a required resilience system but remains inside the stated regulatory transition period. It does not establish a shutdown, loss of compliance, regulatory approval or current output change.
Mihama 3 begins manual shutdown after water drip is found
During power-ascension checks at Mihama 3, Kansai Electric found water dripping at about three drops per second from insulation around an air-vent valve on the outlet piping of the No. 6A high-pressure feedwater heater's normal water-level control valve. The operator decided at 17:45 JST on 17 September to stop the reactor for inspection and began reducing load at 20:30. JEPX HJKS subsequently recorded a planned outage entry beginning at 01:30 on 18 September, with the cause under investigation and no restoration outlook stated.
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WHY IT MATTERS
The 826 MW unit had positive measured output in the latest complete OCCTO national record, so the shutdown can materially reduce subsequent national nuclear generation. The 16 September Fleet Pulse remains a dated measured snapshot and is not rewritten as live output; the next complete OCCTO day will determine the measured national effect.
NRA receives withdrawals of Hamaoka 3/4 restart-review applications
The NRA received Chubu Electric's withdrawal of the Hamaoka 3 and 4 reactor-installation-change applications and Unit 4's construction-plan and operational-safety-rule applications on 25 September. This completes the filing step announced in the operator's 14 September board decision.
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WHY IT MATTERS
Neither unit now has an active new-regulation conformity application, so both move from active NRA review to the no-active-application segment of the restart pipeline. Any future restart case depends on new, credible applications and supporting evidence. The withdrawals do not remove the units from the 33-unit existing fleet and are not decommissioning decisions.
The NRA received TEPCO's report that a water leak in the cylinder head of Unit 6 emergency diesel generator B made the generator unavailable. That also made the Unit 6-to-7 inter-unit emergency power-transfer function unavailable, leading to operating-limit deviation declarations for Units 6 and 7.
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WHY IT MATTERS
The event temporarily reduces credited backup-power availability across the two-unit safety arrangement and requires prompt corrective action under the operating rules. The NRA notice does not establish a reactor shutdown or generation loss, and this item does not treat the deviation as either.
Shimane 3 advances its risk and severe-accident review
At the NRA's 10 September review meeting, Chugoku Electric submitted responses on Shimane 3's accident-sequence selection, probabilistic risk assessment, portable severe-accident equipment locations and access routes, together with an updated review-explanation schedule.
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WHY IT MATTERS
The submissions move a 1,373 MW reactor under construction through a substantial block of the new-regulatory-standard review. The meeting and documents do not establish NRA approval, construction completion, fuel loading or a confirmed operating date.
JNFL proposes live-solution verification before Rokkasho completion
In material submitted to the NRA, Japan Nuclear Fuel proposed moving verification runs using process solutions and high-level liquid waste to before completion of the Rokkasho reprocessing plant. The runs are intended to confirm long-idled equipment and vitrification-system performance.
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WHY IT MATTERS
The proposal changes the planned commissioning sequence for a central constraint in Japan's nuclear fuel cycle and could improve evidence available before completion. It remains an operator proposal under regulatory review: the NRA record does not establish approval, completion, commercial operation or a revised completion date.
NRA opens consultation on reactor operating-maintenance rules
The NRA opened public consultation on a draft amendment to the review standard for commercial-reactor operational safety regulations. The comment period runs from 3 September through 2 October 2026.
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WHY IT MATTERS
The proposal could change the regulatory framework utilities use for maintenance while reactors are operating, affecting outage planning and plant work management. It remains a draft under consultation and is not an enacted rule or a reactor-level operating-status change.
Tohoku Electric confirmed that it submitted an installation-change permit application to the NRA for replacing Onagawa 2's containment hydrogen concentration monitors, one day after initiating prior consultation with Miyagi Prefecture, Onagawa Town and Ishinomaki City.
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WHY IT MATTERS
The filing converts a planned regulatory step into a verified application and opens the NRA review path for the equipment change. It is not an approval, installation completion or operating-status change; Tohoku says it will respond to the forthcoming review.
Kyushu Electric confirmed receipt of 24 new fuel assemblies for Sendai 1 and 28 for Sendai 2 after a combined land-and-sea shipment from Nuclear Fuel Industries conducted from 30 August through 2 September.
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WHY IT MATTERS
The completed delivery is a verified fuel-supply and outage-planning milestone for two operating reactors and a concrete demand signal for Japan's domestic PWR fuel chain. It does not establish that the fuel has been loaded or change either unit's operating status.
Tohoku seeks local consultation on Onagawa 2 hydrogen-monitor upgrade
Tohoku Electric initiated local prior consultation for replacing Onagawa 2's containment hydrogen concentration monitors with a detector design it says has better operability and maintainability. The change follows detector faults in May and June 2025; monitoring currently continues with quality-improved detectors.
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WHY IT MATTERS
The proposal addresses a known reliability and maintenance burden in post-accident hydrogen monitoring. Tohoku says it plans an NRA installation-change application and implementation during the 13th periodic inspection, but neither regulatory approval nor installation is complete and no operating-status change is inferred.
Kyushu Electric confirmed that 72 new fuel assemblies for Genkai 4 were transported from Mitsubishi Nuclear Fuel and received after a combined land-and-sea shipment conducted from 27 August through 1 September.
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WHY IT MATTERS
The completed delivery is a verified fuel-supply and outage-planning milestone for an operating reactor and a concrete order-flow signal for Japan's domestic PWR fuel chain. It does not indicate that the assemblies have been loaded or change Genkai 4's current operating status.
Fukui grants prior consent for dry storage at Mihama and Takahama
Fukui Prefecture announced prior consent for Kansai Electric's spent-fuel dry-storage plans at Mihama and for the first phase at Takahama. Kansai Electric separately states that the consent covers those two plans; the company still needs the applicable detailed regulatory approvals before construction can proceed.
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WHY IT MATTERS
The decision clears a material local-consent gate for additional on-site spent-fuel management capacity at two operating stations. It supports fuel-pool management and future transport logistics, but it does not mean either facility is built, licensed for use or operating, and it does not cover the still-pending Ohi plan.
ORIGINAL SOURCE RECORD
関西電力の乾式貯蔵施設設置計画の事前了解について
Published 28 Aug 2026 · collected 1 Sept 2026, 07:44 JST
Ikata 3 returned to compliance after a protection-channel signal
The NRA received Shikoku Electric's report that one of four overtemperature delta-T protection channels produced an unreliable signal at Ikata 3. After confirming the other three channels remained operable, the affected channel was bypassed and the unit returned to compliance with its operating limits.
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WHY IT MATTERS
The notice records a verified temporary reduction in protection-channel redundancy and its recovery. It does not establish a reactor shutdown, generation loss or continuing non-compliance, so no operating-status or output change is inferred from it.
ORIGINAL SOURCE RECORD
四国電力(株)から伊方発電所3号機における運転上の制限からの逸脱及び復帰に係る報告を受理
Published 27 Aug 2026 · collected 1 Sept 2026, 13:44 JST
Government adopts the Power GX energy-resilience package
The Cabinet Secretariat says the government compiled the Power GX package following the 17th GX Implementation Council on 26 August. The package calls for maximum use of nuclear power alongside renewables as part of strengthening Japan's energy-supply structure; it is a policy direction, not approval or a restart decision for any reactor.
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WHY IT MATTERS
The package raises the policy priority attached to nuclear utilization and may affect future restart support, investment frameworks and supply-chain demand. Reactor-level timing still depends on NRA review, operator readiness and local processes, so no fleet-status change is inferred from the package.
ORIGINAL SOURCE RECORD
エネルギー需給構造強靭化総合パッケージ(パワーGX)
Published 26 Aug 2026 · collected 31 Aug 2026, 09:41 JST
BWR operators target early 2029 applications for 10×10 fuel
Denki Shimbun reports that Japan's BWR operators plan to apply to the NRA in early 2029 for installation changes needed to introduce 10×10 fuel assemblies, which use more fuel rods than conventional 9×9 fuel. The NRA confirms that one 10×10 product received type certification in late June; the 2029 timetable remains attributed to Denki Shimbun.
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WHY IT MATTERS
This provides the first identified operator timetable for moving the new fuel from generic design approval toward plant-specific deployment. Adoption could improve safety performance and fuel utilization, while creating a multi-year regulatory and procurement pathway for BWR utilities and fuel suppliers. No plant-specific application or installation date has yet been announced.
ORIGINAL SOURCE RECORD
BWR新燃料、29年許可申請へ/安全性向上見込む(1面)
Published 14 Aug 2026 · collected 14 Aug 2026, 07:52 JST
Reported · Denki Shimbun · primary records corroborate background
Ohi 3 remains stopped after an automatic reactor trip
The NRA received a legally reportable event notice after Ohi 3 automatically shut down from rated thermal-power operation on 9 August. NRA inspectors confirmed no environmental impact. KEPCO lists the unit as stopped and published an investigation update on 19 August; the cause investigation remains ongoing.
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WHY IT MATTERS
This is a verified operating-status change for one of the historically restarted reactors and explains why Ohi 3 cannot be counted as currently generating. It also explains the missing-unit validation failures in OCCTO's national daily records from 9 August onward; no restart timing should be inferred until KEPCO confirms it.
ORIGINAL SOURCE RECORD
関西電力(株)から大飯発電所3号機における原子炉の自動停止について報告を受理
Published 10 Aug 2026 · collected 21 Aug 2026, 19:46 JST
JAIF published July reactor operating results and fleet tables
JAIF published its monthly July operating-results tables, including unit, reactor-type and utility capacity factors plus updated operating, construction, planned and closed-down reactor tables.
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WHY IT MATTERS
The publication provides a dated monthly fleet and performance cross-check. It is not a live operating-status source and does not by itself change the 33-reactor existing-fleet denominator.
ORIGINAL SOURCE RECORD
「日本の原子力発電所の運転実績(2026年7月)」等の掲載について
Published 07 Aug 2026 · collected 10 Aug 2026, 13:41 JST
NRA held a closed review meeting for Kashiwazaki-Kariwa 6 and 7
The NRA convened a non-public review concerning specified severe-accident response facilities at Kashiwazaki-Kariwa Units 6 and 7. No decision or substantive meeting material was published with the notice.
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WHY IT MATTERS
The meeting is evidence of regulatory activity, not evidence of approval or restart progress. Its closed status means no milestone should be inferred until the NRA publishes an outcome.
Kyushu reports no Genkai or Sendai abnormalities after Kumamoto earthquakes
Kyushu Electric reported that no abnormalities had been identified at the Genkai and Sendai nuclear stations following recurring earthquakes in Kumamoto from 28 July.
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WHY IT MATTERS
This closes the immediate plant-condition question raised by the earthquakes. It is an operator condition report, not a new numeric output reading.
Onagawa 2 dry-storage construction start moved to September
Tohoku Electric filed a change notice moving the planned construction start for Onagawa 2's first spent-fuel dry-storage building from July to September 2026 while design-and-construction approval review continues. The planned March 2028 start of operation is unchanged.
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WHY IT MATTERS
The two-month construction shift is a concrete fuel-cycle schedule change and signals continued regulatory-review timing risk, without changing the stated 2028 commissioning target or the reactor's operating status.
JNFL secured local prior consent for more depleted-uranium storage at Rokkasho
Japan Nuclear Fuel Limited said Aomori Prefecture and Rokkasho Village gave prior consent to its plan to increase the uranium-enrichment plant's maximum depleted-uranium storage capacity. The supporting plan identifies a July 2026 amendment application and a September 2028 target for use of the changed facilities.
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WHY IT MATTERS
The consent clears a local procedural gate for fuel-cycle infrastructure needed as enrichment operations expand. It is not an NRA approval and does not establish that the additional capacity is already available.
ORIGINAL SOURCE RECORD
六ヶ所ウラン濃縮工場に係る新増設等計画書に関する事前了解について
Published 24 Jul 2026 · collected 13 Aug 2026, 11:10 JST
Ikata 3 reported a secondary-water chemistry instrument fault
Shikoku Electric published a notice concerning an instrument used for secondary-system water chemistry at steam generator 3A.
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WHY IT MATTERS
The notice is operationally relevant, but it is not treated as evidence of a reactor shutdown or a live-output change without a separate operator confirmation.
Kansai Electric lists Takahama 2 as having resumed full commercial operation on 16 July after its periodic inspection.
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WHY IT MATTERS
This is a verified operating-status change and is reflected in the dated operating-capacity snapshot. It does not change the 33-reactor existing-fleet denominator.
Shikoku Electric submitted the fifth safety-improvement assessment for Ikata 3, as required after operation under the post-Fukushima regulatory framework.
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WHY IT MATTERS
The filing adds a new regulatory record for the operating unit; it is not presented as a new operating permit or restart approval.
JSW plans to double nuclear-component capacity by FY2028
Japan Steel Works' updated medium-term plan calls for nuclear-product production capacity in the year ending March 2029 to reach twice the year-ending March 2026 level, amid anticipated large-reactor and SMR demand overseas.
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WHY IT MATTERS
This is a concrete Japanese nuclear-supply-chain expansion signal with potential implications for forgings and other long-lead components. It is a capacity plan, not evidence of secured reactor orders or completed expansion.
ORIGINAL SOURCE RECORD
中期経営計画「JGP2028」アップデートの策定に関するお知らせ
Published 13 Jul 2026 · collected 13 Aug 2026, 11:10 JST
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