Board zum Unfall von Fukushima vom physikBlog

Fukushima-Kraftwerksleiter bemühte sich um Besonnenheit:

Die Asahi Shimbun zitiert in ihrem aktuellen Artikel aus dem Bericht der Untersuchungskommission im Bezug auf das Verhalten und die Anordnungen, die Masao Yoshida, der zum Höhepunkt der Krise der Leiter des AKW Fukushima Daiichi war.

Nach dem Tsunami am 11. März habe er in seiner Position im Notfallzentrum um 23:50 Uhr festgestellt, dass die Kühlung nicht arbeitete. Er gibt in dem Bericht an, das Unglück habe alles übertroffen, was er bislang als Bedrohungsszenario für möglich gehalten habe und räumt ein, auch aufgrund der auf ihn einstürzenden unterschiedlichen Informationen im ersten Moment nicht gewusst zu haben, welche Maßnahmen nun zu treffen seien.

Yoshida befahl dann am folgenden Tag, dem 12. März um 12:06 Uhr die Öffnung von Ventilen, um durch die Belüftung den Druck im Reaktor abzubauen – eine gefährliche Aufgabe, da die Strahlung vor Ort hoch war, das er gegenüber den Arbeitern auch einräumte. Nachdem es am 14. März Meldungen über Kühlungsprobleme an Reaktor 2 gab, beschloss der Leiter des Kraftwerks, Arbeiter zu evakuieren.

Einen Tag später, am 15. März, kam es zu einer Explosion an Reaktor 4. Als Yoshida hörte, dass auch am Reaktor 2 heftige Geräuschentwicklung gemeldet wurde, liess er weitere Angestellte evakuieren. Etwa 650 wurden vorübergehend zum Kernkraftwerk Fukushima Daini (AKW Fukushima 2) evakuiert - somit blieben lediglich etwa 50 Arbeiter in der Anlage zurück.

Auch wenn die Asahi Shimbun nicht kommentiert, wie diese Entscheidungen zu beurteilen sind und welche Figur Masao Yoshida, der aufgrund von Speiseröhrenkrebs von seinem Posten zurücktrat, während der Krise machte, so scheint er doch im Rahmen seiner Möglichkeiten durchaus brauchbare Arbeit geleistet zu haben – die Kritik des Berichts an schlechter Kommunikation und eigenmächtigem Handeln von Angestellten vor Ort mildert dies jedoch nicht.

Regierung berichtet über den “Worst Case” der Fukushima-Katastrophe:

Goshi Hosono, Minister für das Krisenmanagement am AKW Fukushima, berichtete heute über das, von der Regierung auf dem Höhepunkt der Krise entworfene Modell des als schlimmstmöglich angenommenen Szenarios. Etwa zwei Wochen nach Beginn der Krise, stellte Shunsuke Kondo, Vorsitzender der japanischen Atomenergiekommission sein Modell vor.

Als denkbar größte Katastrophe ging man von einer Explosion von Reaktor 1, sowie dem austrocknen des Abklingbeckens von Reaktor 4 aus. Allerdings teilte man diese Einschätzung nicht der Öffentlichkeit, da die tatsächliche Entwicklung zu diesem Zeitpunkt nur sehr schwer vorhersehbar gewesen sei und lediglich auf Hypothesen beruht habe. Auf dieser Basis habe man keine unnötige Beunruhigung bei der Bevölkerung wecken wollen., erklärte Hosono der damals im Kabinett des früheren Ministerpräsidenten Naoto Kan als Sonderberater beschäftigt war. Eine tatsächliche Explosion hätte die Radioaktivität in weit größerem Maßstab frei gesetzt, als dies der Fall war. Das berichtet die Nachrichtenagentur Kyodo.

Japan will AKW-Laufzeitbegrenzung auf 40 Jahre:

Die japanische Regierung will die bislang freiwilligen Maßnahmen gegen mögliche schwere Naturkatastrophen künftig zur Bedingungen für die Betreiber von Atomkraftwerken machen - zudem soll die Laufzeit der Anlagen auf vierzig Jahre begrenzt werden. Diese Bestimmungen sind Teil eines neues Gesetzesentwurfs, von dem die Nachrichtenagentur Kyodo berichtet.

Demnach könnten die entsprechenden Pläne auch Teil des Gesetzes zur Regelung von Kernkraftwerken und radioaktivem Brennmaterial werden, dessen Ausarbeitung in Folge der Katastrophe am AKW Fukushima Daiichi begonnen wurde. Mit einer Begrenzung der Laufzeit auf 40 Jahre folgt man nicht nur ähnlichen Vorgaben in den USA, sondern es handelt sich um das erste Mal, dass Japan eine derartige Beschränkung in Angriff nimmt.

Ausnahmen von dieser Regelung werde es nur “sehr selten” geben, so Krisenminister Goshi Hosono auf einer Pressekonferenz. Falls ein Kernkraftwerksbetreiber eine Verlängerung beantrage, so würde die Regierung zunächst den Grad der Überalterung feststellen um dann zu prüfen, ob das Unternehmen über die technischen Möglichkeiten verfügt, die veraltete Anlage weiterhin sicher zu betreiben.

Die Überalterung ist in der Tat ein wichtiger Punkt, denn von den insgesamt 54 industriell genutzten Reaktoren Japans sind mindestens drei mindestens 40 Jahre alt. Neben Reaktor 1 des AKW Fukushima Daiichi, gehören auch das Kraftwerk Tsuruga in der Präfektur Fukui, das von Japan Atomic Power betrieben wird, sowie das AKW Mihama, das sich ebenfalls in der Präfektur Fukui befindet, dessen Betreiber jedoch Kansai Electric ist.

The government's moves to overhaul the state's nuclear policy were prompted by serious contradictions discovered in that policy, as a result of the nuclear crisis at the Fukushima No. 1 nuclear power plant.

Although the Law on Compensation for Nuclear Damage stipulates that electric companies have unlimited liability in the case of accidents, the government had no choice but to support Tokyo Electric Power Co.'s efforts to pay compensation for damage caused by the Fukushima crisis. Therefore, the government plans to overhaul the law, including a review of utilities' unlimited liability.

If it does so, however, entrusting utility companies with the operation of cost-efficient nuclear power plants, the companies may just siphon off profits and push the risk of accidents onto the state.

Hence, the government likely will review the current system in which electricity companies possess and operate nuclear power plants. There are various options for overhauling the nation's nuclear policy:

-- Bringing the operation and management of nuclear power plants under state control, completely separating the plants from utility firms.

-- Entrusting only the operation of plants to the state.

-- Managing plants through a public organization funded jointly by the public and private sectors.

A new system of managing nuclear power generation may have a serious impact on the earnings of utility firms such as Kansai Electric Power Co. Nuclear power plants provide a large share of KEPCO's profits.

The separation of nuclear power plants from electricity firms may require passage of a resolution at the companies' general meetings for shareholders. However, it is highly possible such resolutions would have difficulty passing.

Edano: Fair competition needed

The Yomiuri Shimbun

The following is a Yomiuri Shimbun interview with Economy, Trade and Industry Minister Yukio Edano:

The Yomiuri Shimbun: The crisis at the Fukushima No. 1 nuclear power plant has brought to light problems with the government policy of entrusting the management and operation of nuclear power plants to private utility firms.

Yukio Edano: Electric companies have been collecting revenue from nuclear power plants. But after the outbreak of the nuclear crisis, [Tokyo Electric Power Co.] cannot pay for the damage [by itself ] and is using taxpayers' money, which has made it very unclear [where the responsibility lies]. It should be clarified whether they will take all the risks [of operating nuclear plants], or give up the perks they enjoy and ask the government to handle the management.

Concerning who should operate the power plants, we'll hammer out a course of action by summer based on discussions in the Energy and Natural Resources Committee [the economy minister's advisory body] and a decision by electric companies.

Q: The government has proposed four types of reform to force utilities to separate power generation from power transmission and distribution, toward liberalization of the power supply business.

A: It's necessary to set up a system in which [users] can choose electric companies and power rates. The power transmission section [monopolized by electric firms] has become an obstacle to increasing renewable energy sources and the number of new companies entering the business. So we should institute a fair power transmission system.

Japanese utility firms separate the accounting for their power transmission sections, which has hindered [new entrants] from participating in the business for fair competition.

The most likely option is that various enterprises generate power while neutral entities transmit the electricity. Furthermore, it is necessary to greatly strengthen "tie lines" [that connect different electricity systems through which the firms buy and sell electricity]. So, we'd like to intensify public involvement [in the power business.]

Q: What will happen to the temporary state control of TEPCO?

A: Society will not allow that company to rebuild [as a new TEPCO] by casting off its responsibility for such things as compensation for the nuclear crisis and decommissioning the plant. There's a high possibility [the government] will need [to put TEPCO under complete public control] for decommissioning and compensation.

But it is essential for the private sector to shoulder the responsibility to supply electricity. We don't intend [to keep the firm] under state control forever.

Q: What will you do about the management of other electric companies?

A: Other companies' situations are different from that of TEPCO. But the structure--monopolizing local areas' power supply and hindering new entrants--is not socially acceptable. We'd like to create a situation in which winners are determined by the efforts of their management in an environment of fair competition.

Tim said:

> Japan to Stop Using SPEEDI to Decide Whether to Instruct Residents to Take Potassium Iodide Pills

The government recommendation that people voluntarily evacuate from places in the 20-30 km range from the Fukushima Daiichi plant came after the Nuclear Safety Commission watchdog released forecasts based on SPEEDI measurements. It was found that radiation levels differed significantly based on geography and wind direction, and it was suggested that because of this, the way evacuation areas were being designated should be changed and become more detailed. The Yomiuri Shinbun calculated radiation doses based on data from the Fukushima prefectural government and found they corresponded with the forecasts.

On the evening of March 15, Mr. Kan called Mr. Soramoto, who used to design nuclear plants for Toshiba, to ask for his help in managing the escalating crisis. Mr. Soramoto formed an impromptu advisory group, which included his former professor at the University of Tokyo, Toshiso Kosako, a top Japanese expert on radiation measurement. Mr. Kosako, who studied the Soviet response to the Chernobyl crisis, said he was stunned at how little the leaders in the prime minister’s office knew about the resources available to them. He quickly advised the chief cabinet secretary, Yukio Edano, to use Speedi, which used measurements of radioactive releases, as well as weather and topographical data, to predict where radioactive materials could travel after being released into the atmosphere.

The NHK checked the progress of the reinforcement measures listed by the NISA in February, by asking each nuclear plant operator about the 12 points considered "important points", among a list of 30.

All plant operators have installed redundant power supplies, including air-cooled generators and power generating trucks. The installations of watertight building doors are completed or under work. The dispersion of the main power distribution panels, meant to lower the risk of a blackout, is difficult to undertake immediately, as finding a suitable location and construction work take time. The installation of batteries able to supply power to instrumentation for a long time is "under study" at all nuclear power plants.

Pr. Kazuhiko Kudo of Kyushu university says the government must say clearly which items must be completed before the restart of the plants and which items are allowed to be done later.

The 30 points are probably those mentioned in "Technical knowledge on the Tokyo Electric Fukushima Daiichi NPP accident (interim compilation)" (16 February 2012) as "Matters being considered which should be reflected in future regulations".

[Countermeasures for external power]
1 Improvement of reliability of external power lines
2 Improvement of earthquake resistance of transformer equipments
3 Improvement of earthquake resistance of switching stations
4 Quick recovery of external power equipments

[Countermeasures for internal electric power equipments]
5 Dispersion of internal electric equipments into different locations
6 Reinforcement of inundation countermeasures
7 Reinforcement of redundancy and diversification of emergency AC power supplies
8 Reinforcement of emergency DC power supplies
9 Installation of separate power supplies for exclusive use
10 Simplification of electric supply from outside
11 Storage of spare items in relation with electric equipments

[Countermeasures for cooling and water injection]
12 Improvement of judgement capacity during an accident
13 Securing inundation resistance and dispersion into different locations of cooling equipments
14 Reinforcement of final heat sink after an accident
15 Improvement of operational reliability of isolation valves and safety relief valves
16 Reinforcement of alternative water injection function
17 Improvement of reliability of cooling and water supplying function of spent fuel pools

[Countermeasures for primary containtment vessel]
18 Diversification of PCV heat removal function
19 Countermeasures to prevent PCV top head flange damage by excess of heat
20 Secured transition to low pressure alternative water injection
21 Improvement of venting reliability and operability
22 Reduction of the environmental impact of venting
23 Secure independance of venting pipes
24 Prevention of hydrogen explosions (concentration management and appropriate release)

[Countermeasures for management and measurement equipments]
25 Equip and secure the command post used during accidents
26 Secure the communication function
27 Secure the reliability of instrumentation during accidents
28 Reinforcement of plant status surveillance function
29 Reinforcement of monitoring function during accidents
30 Building of emergency response system and performance of drills

Underlined items are for boiling water reactors only.

Der Risikoforscher Ortwin Renn beschreibt Politikberatung in Krisenzeiten

Quake faults at TEPCO's Niigata nuclear power plant may be active

TOKYO, Jan. 24, Kyodo

Some faults under Tokyo Electric Power Co.'s Kashiwazaki-Kariwa nuclear plant, the world's biggest on Japan's northwest coast, could be regarded as active based on new safety standards, Kyodo News found Wednesday through documents that the utility has made public and other materials.

If the faults are judged as likely active by the Nuclear Regulation Authority, established in the wake of the 2011 Fukushima Daiichi complex disaster, the utility will face difficulties in reactivating the plant in Niigata Prefecture.

Under Japanese government criteria, active faults are defined as those that have moved in the last 120,000 to 130,000 years. But the NRA plans to move the benchmark to 400,000 years ago in the new safety standards, which are expected to come into force in July.