TEPCO recently reported that a thermometer in Fukushima Daiichi’s Reactor 1 recorded an unexpected 80°C temperature increase following nitrogen injection into the primary containment vessel (PCV). Initially, this raised concerns about a possible heat source inside the containment vessel .

However, after an internal review, TEPCO concluded that the reading did not reflect an actual temperature increase, attributing it to instrument malfunction. As a result, they downgraded multiple thermometers to “reference use” and removed them from official monitoring .

Contradictions in TEPCO’s Explanation

TEPCO’s official report claims that the 80°C spike was a sensor anomaly, yet the data contradicts this conclusion. The report states:

「いずれの端⼦台にも、変化量に違いはありますが、似た挙動を⽰す温度計が存在します。」
(“In all terminal blocks, there exist thermometers that show similar behavior, although the magnitude of change varies.”)

This raises a critical contradiction:

• If the anomaly were due to a single sensor failure, the readings should have been random and uncorrelated.
• Instead, multiple thermometers showed similar temperature behavior, suggesting a systemic factor rather than individual sensor malfunctions.

Potential Causes TEPCO Has Not Addressed

If multiple thermometers reacted simultaneously, there are several alternative explanations that TEPCO has not fully explored:

1. Localized Heating Effect – The nitrogen injection may have triggered a thermal reaction inside the containment vessel.
2. Pressure-Temperature Interaction – Increased pressure in the PCV could have influenced heat conduction, affecting nearby thermometers.
3. Electromagnetic or Wiring Interference – If multiple thermometers are showing the same fluctuation, an external electrical disturbance could be influencing them.

Unanswered Questions About Reactor 1

Despite these unresolved discrepancies, TEPCO downgraded the affected thermometers, effectively excluding them from official monitoring.
This raises serious concerns:

• Is TEPCO dismissing inconvenient data?
• Could an unknown thermal process be occurring inside Reactor 1?
• What safety implications does this have for long-term monitoring?

So far, TEPCO has not provided a satisfactory alternative explanation for why multiple thermometers showed the same trend.

東電、80°Cの異常温度上昇を「故障」と判断するも、データは矛盾を示す

1号機で80°Cの異常上昇が観測される

東京電力は、福島第一原発1号機の原子炉格納容器（PCV）内で窒素注入後に80°Cの急激な温度上昇が観測されたことを報告しました。当初、格納容器内の未知の熱源の可能性が懸念されました 。

しかし、東電はこの現象について、「実際の温度上昇ではなく、温度計の故障が原因」と判断し、複数の温度計を「参考値扱い」に格下げしました 。

東電の説明に見られる矛盾

東電はこの温度上昇を個別の温度計の故障と説明していますが、報告書のデータはこの説明と矛盾しています。報告書には以下の記述があります。

「いずれの端⼦台にも、変化量に違いはありますが、似た挙動を⽰す温度計が存在します。」
(“すべての端子台において、変動の幅は異なるが、似た挙動を示す温度計が存在する。”)

この記述は、東電の説明と 明らかに矛盾 しています。

• もし個別のセンサー故障が原因であれば、異常値はランダムに発生するはずです。
• しかし、実際には複数の温度計が同じ傾向の温度変化を示しているため、センサー故障では説明できない可能性が高いです。

東電が説明していない可能性

東電は、以下のような他の要因を十分に検討していません。

1. 局所的な発熱現象 – 窒素注入によって格納容器内で何らかの熱反応が発生した可能性。
2. 圧力と温度の関係 – 格納容器内の圧力上昇が、温度の局所的変化に影響を与えた可能性。
3. 電磁波や配線ノイズの干渉 – 複数の温度計が同じ挙動を示していることから、外部の電気的な影響も考えられる。

1号機で何が起きているのか？

東電はこのデータの矛盾を完全に説明しないまま、対象の温度計を「参考用」として格下げしました。
これは以下のような深刻な疑問を引き起こします。

• 東電は不都合なデータを無視しているのか？
• 格納容器内で未知の熱反応が発生している可能性はないのか？
• 今後の長期監視において、安全性に影響を与えるのではないか？

これらの疑問に対し、東電はまだ納得のいく説明をしていません。

Source

Photo: Reactor 3, taken on 5th January 2018 [URL]

TEPCO’s latest report on tritium removal technologies for ALPS-treated water highlights a drastic drop in submitted proposals over time. Since the call for technologies began in May 2021, the number of proposals has plummeted:

• First round (2021): 65 proposals
• Eighth round (2024): 7 proposals
• Ninth round (2025): 2 proposals​

This sharp decline suggests a lack of viable technical solutions or diminishing interest from researchers and industry.

Zero Cases Passed Initial Evaluation in Recent Rounds

• In early recruitment phases (2021-2022), 15 proposals passed the initial evaluation and moved on to secondary feasibility studies.
• However, in the fourth, fifth, seventh, eighth, and ninth rounds, not a single proposal passed the initial evaluation.
• In the most recent ninth round (July – December 2024), only two proposals were submitted, and both failed to meet TEPCO’s evaluation criteria​.

Why Are No Proposals Passing?

TEPCO’s report states that the submitted proposals failed due to:

• Lack of technical justification for tritium separation methods
• Inability to meet TEPCO’s separation criteria
• Insufficient data to verify feasibility​.

The complete lack of successful proposals raises questions about whether a viable tritium removal solution exists at all. For now, it appears that controlled dilution and ocean discharge remain the only “practical approach”—despite ongoing concerns and criticism.

トリチウム除去技術の公募が低迷、成功例ゼロに

トリチウム除去技術の提案数が激減

東京電力の最新報告によると、ALPS処理水のトリチウム除去技術の公募に対する提案数が大幅に減少していることが明らかになりました。
2021年5月に公募が開始されて以来、提案数は以下のように推移しています：

• 第1回募集（2021年）： 65件
• 第8回募集（2024年）： 7件
• 第9回募集（2025年）： 2件​

この急激な減少は、技術的な課題の難しさや、研究機関や企業の関心の低下を示している可能性があります。

直近の募集では初期評価通過例がゼロ

• 2021年～2022年の初期段階では、15件の提案が一次評価を通過し、二次評価（フィージビリティスタディ）に進みました。
• しかし、第4回・第5回・第7回・第8回・第9回募集では、一件も一次評価を通過せず、成功例が完全に消滅しました。
• 最新の第9回募集（2024年7月～12月）では、わずか2件の提案しか提出されず、両方とも基準を満たさず不合格となりました​。

なぜ成功例がゼロなのか？

東京電力の報告によると、提案が不採択となった主な理由は以下の通りです：

• トリチウム分離技術の技術的正当性が不足
• 求められる分離基準を満たせない
• 実用化の検証に必要なデータが不十分​。

完全に成功例が消えた事実は、「トリチウム除去の実現可能性」に大きな疑問を投げかけています。現時点では、批判が続く中でも希釈・海洋放出しか対応策のない状況が変わっていません。

Source

Following the trial retrieval of fuel debris from Reactor 2, detailed non-destructive analysis has confirmed the presence of melted nuclear fuel components, including europium (Eu-154) and americium (Am-241). These elements indicate that the sample contains remnants of uranium fuel that underwent nuclear fission before the meltdown​.

The total weight of the retrieved debris is now confirmed to be 0.693g, slightly lower than previous estimates. The debris is a heterogeneous mixture of materials, primarily reddish-brown, with black and metallic-looking areas​.

X-ray CT and Radiation Analysis Provide Further Insight

Advanced X-ray CT imaging revealed that the debris has an irregular structure, with voids dispersed throughout the sample. Gamma-ray spectrometry confirmed the presence of fission products such as Cs-137 (cesium), Co-60 (cobalt), and Eu-154 (europium), as well as actinides like Am-241 (americium), which originates from neutron capture in U-238​.

Implications for Future Debris Removal

These results will help refine debris removal strategies, providing insight into fuel characteristics, criticality risks, and material hardness. Further analysis, including solid-state and chemical analysis, will continue over the next 6 to 12 months to aid in safer debris extraction and storage planning​.

福島第一原発2号機の燃料デブリ分析—溶融核燃料成分を確認

重量0.7g未満のデブリからウラン・核分裂生成物を検出

福島第一原発2号機から試験的に取り出された燃料デブリの詳細分析が進み、燃料デブリには、核燃料由来の成分であるユーロピウム（Eu-154）やアメリシウム（Am-241）が含まれていることが確認されました。これらは、デブリに核燃料の溶融物が含まれていることを示しています​。

また、デブリの総重量は0.693gと確定されました。サンプルは不均一な組成を持ち、全体的に赤褐色で、一部に黒色や金属光沢を帯びた部分が見られました​。

X線CTと放射線分析が詳細なデータを提供

X線CT撮影により、デブリ内部には多くの空隙が存在することが判明しました。また、γ線スペクトロメトリの分析では、Cs-137（セシウム）、Co-60（コバルト）、Eu-154（ユーロピウム）といった核分裂生成物に加え、U-238の中性子捕獲によって生成されたAm-241（アメリシウム）も検出されました​。

今後の燃料デブリ取り出しに向けた影響

今回の分析結果は、今後の燃料デブリ取り出し計画に重要な知見を提供します。特に、燃料の特性、臨界リスク、硬度などの要素が、安全なデブリ取り出し方法の選定に役立つと期待されています。さらに、固体・溶液分析を含む詳細解析が今後6ヶ月から1年かけて実施される予定です​。

Source

Photo ; Nuclear debris collected from the reactor 2

Recent reports reveal that the fuel debris sample retrieved from Fukushima Daiichi’s Reactor 2 weighed 0.7 grams, significantly less than the initially estimated 3 grams. This marks the first successful removal of core material from the reactor since the 2011 disaster. Analysis confirmed the presence of europium, a component derived from melted nuclear fuel, indicating that the debris includes portions of the reactor’s original fuel​​.

Transportation for Detailed Analysis

The retrieved debris was transported to the Japan Atomic Energy Agency’s (JAEA) Oarai Research Institute on November 12. Over the coming months, this material will undergo thorough analysis to guide future debris removal strategies, safety measures, and storage protocols​.

A Daunting Task Ahead

The total amount of radioactive fuel debris at Fukushima Daiichi is estimated to exceed 880 tons across reactors 1, 2, and 3. This latest step represents a small yet significant milestone in the decommissioning process. However, it underscores the enormity of the task ahead.

福島第一原発2号機デブリ採取 – 回収量はわずか0.7g

想定を下回る回収量

最新の報告によると、福島第一原発2号機から試験的に採取された燃料デブリは、当初見込まれていた3グラムよりも少ない0.7グラムであることが判明しました。これは2011年の事故以来、初めて原子炉内のコアデブリが取り出されたものです。分析の結果、デブリには溶融核燃料に由来する成分であるユーロピウムが含まれていることが確認されました​​。

構外分析施設への輸送完了

採取されたデブリは、11月12日に日本原子力研究開発機構(JAEA)の大洗研究所へ輸送されました。今後数か月から1年程度かけて詳細な分析が行われ、今後予定されているデブリ取り出し工法や安全対策、保管方法の検討に活用される予定です​。

果てしない廃炉への道のり

福島第一原発には、1号機から3号機までに推定880トン以上の放射性燃料デブリが残されています。今回の作業は、廃炉に向けた小さな一歩ですが、課題の大きさを改めて浮き彫りにしました。

Source 1 2

Photo ; Collected nuclear fuel debris from reactor2

Tsunehisa Katsumata, former chairman of Tokyo Electric Power Company (TEPCO), passed away at age 84 on October 21. Known as the “Emperor” within TEPCO due to his powerful influence, Katsumata led the company through significant periods, including the 2011 Fukushima Daiichi nuclear disaster. However, despite his long-standing authority, he left without resolving key decommissioning issues at Fukushima​.

Awareness of Tsunami Risk Without Action

In February 2009, a critical internal meeting—later known as the “Gozen Kaigi” (御前会議) —highlighted the risk of a tsunami exceeding the plant’s protective barriers. Despite this, Katsumata refrained from directing immediate countermeasures, even as the potential threat to Fukushima loomed.

Legal Challenges and Unpaid Compensation

Following the Fukushima disaster, Katsumata and other former executives faced multiple lawsuits, including a landmark shareholder derivative suit that ordered him and three other former executives to pay over 13 trillion yen (around 100 billion USD). Despite this ruling, compensation had yet to be paid by the time of his passing.

In July 2022, a civil court held TEPCO executives accountable for negligence regarding tsunami countermeasures, noting that if measures had been implemented, the disaster’s impact could have been significantly reduced. This marked the first time former management was deemed financially responsible on such a large scale.

Mixed Reactions to His Death

The news of Katsumata’s death has triggered complex responses, especially among Fukushima survivors. Many feel unresolved anger, recalling his persistent denial of responsibility during trial testimonies, where he often claimed ignorance on technical matters. Katsumata’s departure symbolizes the long-standing challenges of achieving justice and closure for the victims of Fukushima.

福島第一原発事故を巡る責任：元東電会長、勝俣恒久氏の死去

「東電の天皇」と呼ばれた勝俣氏の遺産

東京電力の元会長、勝俣恒久氏が10月21日に84歳で亡くなりました。東電社内で「天皇」として知られ、長期間にわたり会社の実権を握っていた勝俣氏は、2011年の福島第一原発事故を経験しましたが、福島の廃炉問題を解決することなく生涯を終えました​。

津波のリスクを認識しながらも対策指示せず

2009年2月、東電内で開かれた「御前会議」において、福島の敷地高を超える津波のリスクが指摘されましたが、勝俣氏は即座に対策を指示することなく、リスクを放置しました​。

法的課題と未払いの賠償金

福島事故後、勝俣氏や他の旧経営陣は株主代表訴訟に直面し、13兆円以上の賠償を命じられましたが、死去するまで賠償金の支払いは行われませんでした​。

2022年7月、裁判所は東電元幹部に津波対策の怠慢があったと認定し、管理責任を追及。適切な対策を講じていれば、事故の深刻度は大幅に軽減されていた可能性があると判断されました。

彼の死に対する福島の被災者の反応

勝俣氏の死去に対して、福島の被災者からは複雑な反応が寄せられています。多くの人が、裁判中に繰り返された責任の否定や、「技術的なことは分からない」といった証言に対して、怒りと失望を抱いています。勝俣氏の死去は、被災者が長年抱える正義と救済の難しさを象徴しています。

Source

Resuming Debris Retrieval Amid Setbacks

After over a month’s delay, TEPCO has resumed trial fuel debris retrieval from Reactor 2. The process, intended to begin in August, faced repeated delays due to operational issues and high radiation levels. On October 28, TEPCO successfully reactivated its telescopic retrieval device following previous camera malfunctions that paused work in September.

Less Than 3 Grams Recovered Out of 880 Tons

The recent retrieval extracted under 3 grams of radioactive material—just a fraction of the estimated 880 tons of fuel debris across reactors. This preliminary collection will be analyzed at a specialized lab to inform full-scale removal strategies. TEPCO maintains that safety remains the highest priority, with worker exposure capped at 24 mSv/hr.

Challenges Ahead

The retrieval device, operated through remote controls, encounters substantial difficulties in navigating radiation-dense zones within the primary containment vessel (PCV). This third attempt at debris extraction reflects TEPCO’s persistence but underscores the immense challenge of handling irradiated material nearly 13 years after the disaster.

Source 1 , 2

Despite ongoing efforts, Fukushima Daiichi’s Reactor 2 remains largely inaccessible due to severe radiation and equipment malfunctions. The trial fuel debris retrieval has encountered numerous setbacks, further highlighting the complexity of the decommissioning process.

Core Removal Delayed by 3 Years

Originally planned for 2021, the fuel debris extraction from Reactor 2 has faced multiple delays. The remote-operated telescopic arm used to retrieve fuel debris from the primary containment vessel (PCV) encountered operational issues. Radiation levels near the reactor pressure vessel (RPV) and inside the PCV remain high, complicating every step of the process.

Recent Camera Malfunctions Hinder Progress

On September 17, 2024, two crucial cameras—the end-tool monitoring camera and arm-tip camera—malfunctioned, cutting off critical visual data needed for the operation. Preliminary investigations suggest that the failure was due to radiation-induced electrostatic charging, which may have disrupted camera signals transmitted via optical fiber cables​.

TEPCO replaced the cameras on October 18 after a detailed investigation of the cable connections, video converters, and insulation resistance measurements. Despite this, the initial malfunction’s root cause has not been fully identified​. Further tests on the telescopic device and a nitrogen purge to stabilize the work environment are planned before resuming fuel debris retrieval​.

High Radiation Poses Continuous Threat

Radiation levels in Reactor 2 remain a significant barrier, with workers limited to remote operations using robotic arms and radiation shielding. While TEPCO has attempted various measures to reduce worker exposure, including heavy protective equipment and improved remote controls, high radiation complicates both routine checks and complex operations like debris retrieval​.

Uncertain Future of Reactor 2 Decommissioning

The prolonged setbacks are a sobering reminder of the magnitude of the task. With an estimated 880 tons of fuel debris to retrieve across three reactors, the path to full decommissioning remains uncertain. TEPCO aims to continue improving remote systems and shielding to finally begin substantial fuel debris removal from Reactor 2.

Source (including the photo) https://www.tepco.co.jp/decommission/information/newsrelease/

On the bottom of the inside of the base, debris was observed to be accumulating with up to 1m thickness, which is assumed to be the mixture of molten fuel and internal structures of the reactor container vessel. Some parts of the control rod facility were also seen lying on the layered debris, however the rest of the control rod facility is still unstably hanging in the vessel. Even though most parts of the base still can have a half thickness, based on Tepco’s estimate, the concrete is “broken though” at a 60 degree angle around the open door of the base with only iron bars supporting the whole base. In case another major quake hits Fukushima, there’s a risk that the entire base collapses. Tepco admitted this possibility, yet stated it wouldn’t sink more than 30cm due to the exterior structure. However, if the large part of the control rod facility hanging in the vessel falls onto the molten debris, it may crack the debris into small pieces and trigger a recriticality accident according to Tepco. The Nuclear Regulation Authority of Japan demanded Tepco to draft countermeasures but Tepco states the probability of such an accident is significantly low.

Source: https://www.nra.go.jp/data/000426855.pdf

This is 180 times much as the current food safety standard (100 Bq/Kg). 

Moreover, the detected 18,000 Bq/Kg of radioactive cesium consists of Cs-134 and Cs-137.

The half-life of Cs-134 is up to 2 years, nevertheless this black rockfish contained 380 Bq/Kg of Cs-134. Tepco has not publicly made an announcement regarding the detection of Cs-134.

Source ; https://www.tepco.co.jp/decommission/data/analysis/pdf_csv/2023/2q/fish01_230605-j.pdf

Since October of 2022, Tepco has been implementing the breeding experiment of marine life in normal seawater and the water contaminated with tritium, which is planned to be discharged to the Pacific. Currently, flounder and abalone are monitored.

According to Tepco’s record, 2.6 times more abalone died in the tank with the tritium water.
From the 3rd of October, 2022 to the 20th of January, 2023, 29 abalones have been reportedly confirmed to be dead in the contaminated seawater, which include 1,500 Bq/L of tritium. On the contrary, as few as 11 abalones died in the same period of time in the normal seawater.

Tepco announced the significant difference of abalones’ survival rates is due to the density in each tank. At the moment of the 14th of December, 2022, 308 abalones were living in the tank with the normal seawater, while 384 abalones were living in the tank with tritium-contaminated water. However, the sizes of the tanks are not disclosed. Also, it is unclear why Tepco did not set every tank in the same conditions as the control group and treatment group.
Approximately 1,150 Bq/L of tritium was detected from abalone by the time when 24 hours had passed since it was moved into the tritium-contaminated water. The tritium density in abalone slowly increased up to 144 hours after the relocation, nevertheless Tepco interrupted the tritium density measurement to conclude the biological concentration wasn’t observed.

https://www.tepco.co.jp/decommission/information/newsrelease/breedingtest/pdf/2022/202212.pdf

https://www.tepco.co.jp/decommission/information/newsrelease/breedingtest/pdf/2023/20230123.pdf