et NUCLEAIRES
SEISMES ET ENERGIE NUCLEAIRE
JAPON, le 16 juillet 2007
SUIVI
(seuls les fichiers de moins d'un écran sont directement lisibles, les autres sont en lien)
2009
| TOKYO, 1er février (Xinhua)
-- Une équipe d'experts de l'Agence internationale de l'énergie
atomique (AIEA) a indiqué vendredi que la centrale nucléaire
japonaise de Kashiwazaki-Kariwa de la préfecture de Niigata
n'avait subi aucun dégât grave suite au fort séisme
de juillet dernier.
Après cinq jours de contrôle du complexe, Philippe Jamet, directeur de la Division de l'AIEA pour la sécurité des installations nucléaires et chef de l'équipe d'experts, a dit à la presse dans la journée qu'aucun dégât conséquent n'avait été détecté sur les éléments relatifs à la sécurité. Les 12 experts ont revisité la centrale jeudi et ils se sont entretenus avec des officiels de la centrale et de l'Agence japonaise pour la sécurité industrielle et nucléaire. Ils ont également contrôlé les conditions géologiques du site et l' intérieur des cuves sous pression du réacteur au moyen d'une caméra. |
La centrale, la plus
grande du monde en termes de capacité de production, a dû
être fermée en raison de fuites de matières radioactives
suite au séisme de magnitude 6,8 du 16 juillet 2007 et qui a fait
plus de 10 morts et plus de 2.000 blessés.
En août dernier, une équipe de six membres de l'AIEA avait déjà contrôlé la centrale à l'invitation du gouvernement japonais. Elle avait alors conclu que le séisme avait "considérablement dépassé le niveau d'activité sismique pour lequel la centrale avait été conçue bien que les fuites radioactives se situent bien en dessous de la limite autorisée pour garantir la santé publique et la sécurité de l'environnement".  |
| Une équipe d'experts de
l'Agence internationale de l'énergie atomique (AIEA) a entamé
lundi une inspection de suivi dans la centrale nucléaire de
Kashiwazaki- Kariwa (centre du Japon), fermée en juillet dernier
après avoir été endommagée par un séisme.
La centrale avait déjà fait l'objet d'une inspection de l'agence onusienne en août dernier. La mission, dirigée par Philippe Jamet, directeur de la division sur la sécurité des installations nucléaires de l'AIEA, devra écouter le compte rendu des autorités nuélcaires japonaises et de l'opérateur de cette centrale, numéro un dans le monde sur le plan de la capacité de production, a rapporté l'agence de presse Kyodo News. La centrale, située dans la préfecture de Niigata, a été fermée suite à de légères fuites radioactives après un séisme de 6,8 degrés sur l'échelle de Richeter le 16 juillet, qui avait fait une dizaine de morts et plus de 2.000 blessés. |
Durant cinq jours, les inspecteurs devraient
réexaminer la centrale nucléaire avant de s'entretenir
avec les responsables de l'autorité et de l'entreprise électrique.
En outre, les experts comptent aussi analyser les conditions géologiques souterraines sur le site ainsi que l'intérieur des réacteurs, selon la même source. Pourtant, il est encore trop tôt pour savoir si cette inspection de suivi sera la dernière, et quand la centrale sera rouverte. En août dernier, une équipe de six experts de l'AIEA (avait déjà) procédé à la première inspection dans la centrale endommagée, sur demande du gouvernement nippon. Ils (avaient) jugé que le séisme a dépassé de manière singificative la capacité de résistance conçue de la centrale (mais) que la fuite radioactive bien en dessous des limites autorisées, (posait) peu de danger à la santé du public et à l'environnement. |
| Des centaines de failles "cachées"
risquent de provoquer de violents séimes dans des régions
du Japon considérées jusqu'ici comme sans danger sur les
cartes officielles, a découvert un chercheur en géologie
qui doit présenter son rapport le mois prochain au gouvernement.
Shinji Toda, responsable d'une équipe de recherches sur la tectonique et les séismes, est parvenu à cette conclusion en étudiant les 30 derniers séismes de magnitude 6,5 ou plus survenus au Japon depuis 1923, et dont l'hypocentre était situé à une profondeur maximum de 30 km, ce qui en général provoque des destructions massives. "Sur ces 30 tremblements de terre, seuls 5 ont laissé des traces visibles à la surface de la terre", a-t-il expliqué lors d'une interview à l'Institut national de sciences et de technologie industrielles avancées de Tsukuba (banlieue de Tokyo). Cette étude remet totalement en question les cartes officielles de sismologie du Japon qui étaient basées jusqu'ici sur les traces des précédents séismes provoqués par les grandes failles. Le Japon est au confluent de quatre plaques tectoniques et subit 20% des séismes les plus violents enregistrés dans le monde. "Il y a des 'failles cachées' ou des 'failles immatures' dans beaucoup de régions qui ne sont cependant pas classées comme zones à risques par les cartes officielles. Il y a aussi beaucoup de petites failles qui n'ont pas encore été détectées", a souligné M. Toda. Selon lui, aucune région n'est désormais à l'abri. "On se sait ni quand, ni où un grand séisme peut se produire". Il a cité en exemple le séisme de magnitude 6,8 survenu en juillet à Niigata (centre), une région qui abrite la plus grande centrale nucléaire du monde, et considérée comme une zone à faible risque sur les cartes. La secousse a fait 11 morts et plus de 1.000 blessés. |
"Les géologues savaient que c'était
une région de failles actives", a affirmé M. Toda. Mais
les études faites par le constructeur lui-même, à savoir
la compagnie Tepco (Tokyo Electric Power Co.) dans les années 70
et 80, ont sous-estimé la longueur des failles sous-marines -- 7
ou 8 km au lieu de 20 km -- et ignoré 4 autres failles proches de
la centrale nucléaire.
Beaucoup d'experts ont reproché au gouvernement d'avoir fait preuve de négligence en autorisant la construction de nouveaux réacteurs sans vérifier les données fournies par Tepco. Le séisme s'est en effet avéré 2,5 fois plus puissant que le maximum prévu par les plans de la centrale. Un transformateur a pris feu et de l'eau légèrement radioactive s'est déversée en mer. Le complexe a depuis été arrêté en attendant que des milliers de vérifications soient effectuées et que la résistance des bâtiments soit renforcée. M. Toda espère que les cartes sismiques vont être modifiées et que les gouvernements locaux vont mettre en place des plans d'urgence en prévision de catastrophes. L'industrie du bâtiment pourrait également se voir imposer des normes de construction antisismiques draconiennes comme celles en vigueur sur la côte du Pacifique, notamment dans la région de Tokyo dévastée par un gigantesque séisme et un tsunami le 1er septembre 1923, qui avait fait près de 143.000 morts ou disparus. Depuis, les Tokyoïtes vivent avec la crainte d'une réédition du "Big One". Mais selon M. Toda, si on se base sur la récurrence de ce grand séisme, il ne devrait pas se reproduire avant une centaine d'années. "Grâce aux documents historiques, on retrouve la trace de tsunamis provoqués par des séismes offshore et le précédent dans la région de Tokyo remonte à 1703, a-t-il expliqué. Il y a donc un certain consensus parmi les experts sur le fait de ne pas trop s'inquiéter pour l'instant d'un séisme de magnitude 7,8 ou 8 dans cette partie du Japon." |
| TOKYO (AFP)
Le violent séisme qui a endommagé le 16 juillet le complexe nucléaire de Kashiwazaki-Kariwa, dans le centre du Japon, était 2,7 fois plus fort que la limite maximale prévue par les constructeurs de la centrale, affirme dimanche le quotidien Mainichi Shimbun. Selon le journal, la compagnie exploitante Tokyo Electric Power (Tepco) a mesuré une accélération de 993 Gals de la roche située sous la centrale au moment du séisme, alors que Kashiwazaki-Kariwa était prévue pour supporter une accélération maximale de 370 Gals. Toujours d'après le Mainichi Shimbun, 8 des 17 centrales nucléaires du Japon ont été édifiées selon la même estimation d'accélération maximale du sol, et les normes de construction devront sans doute être durcies. |
Le Gal, tiré du nom du physicien et
astronome Galilée, est l'unité de mesure de l'accélération.
Un Gal correspond à une accélération de 0,01 mètre
par "seconde carrée" (c'est à dire que la vitesse d'un objet
en chute libre s'accroît d'un centimètre par seconde chaque
seconde).
Le séisme, de magnitude 6,8 sur l'échelle ouverte de Richter, avait fait onze morts et plus de mille blessés. La centrale nucléaire, la plus grande du monde, avait subi un sérieux incendie et de légères fuites radioactives. Elle a été fermée pour une durée indéfinie. A la suite d'une inspection, les inspecteur de l'Agence internationale de l'énergie atomique (AIEA) ont cependant estimé que "la centrale a été arrêtée en toute sécurité et les dommages paraissent moins importants que prévu". |
| La firme
d'électricité japonaise Tokyo Electric Power (Tepco) a activé
mercredi, pour la première fois depuis 17 ans, des mesures d'urgence
afin de prévenir une pénurie imminente de courant due à
la canicule et à la fermeture d'une centrale nucléaire endommagée
par un séisme.
Tepco a activé une clause spéciale de ses contrats qui lui permet d'ordonner à ses gros clients industriels de réduire leur consommation électrique, a indiqué un porte-parole de l'entreprise. Tepco, la plus grande compagnie d'électricité privée du monde, devait également remettre en service d'urgence mercredi après-midi une ancienne centrale hydraulique inutilisée de 900 MW à Shiobara (nord de Tokyo). C'est la première fois depuis 1990 que des mesures de ce type sont prises. Tepco a dû fermer en juillet pour une durée indéfinie sa centrale nucléaire de Kashiwazaki-Kariwa (centre), la plus grande du monde, endommagée par un violent séisme qui a provoqué un incendie et de légères fuites radioactives. |
Cette centrale de 8.212
MW jouait un rôle-clé dans l'approvisionnement en électricité
de la mégalopole de Tokyo.
Dans le même temps, la compagnie doit répondre à une demande d'électricité inhabituellement forte cet été en raison des records de chaleur, qui poussent entreprises et particuliers à faire tourner à fond les climatiseurs. Après une période de répit la semaine dernière, au cours de laquelle de nombreuses entreprises japonaises ont fermé leurs portes pour les traditionnels congés du Bon (fête des morts), la situation est devenue critique depuis lundi avec le retour à une activité normale. Tepco estime qu'elle ne peut plus assurer un approvisionnement normal en électricité si les températures dépassent les 35 degrés pendant une période prolongée. Le mercure a atteint 34,2 degrés à Tokyo mardi, et 37 degrés dans la préfecture voisine de Saitama. |
| Le cas de
la centrale japonaise de Kashiwazaki-Kariwa est en discussion à
Vienne, au siège de l'Agence internationale de l'énergie
atomique (AIEA). La direction de l'agence onusienne a auditionné,
lundi 13 août, l'équipe d'inspecteurs ayant visité
le site touché par le séisme de magnitude 6,8 survenu dans
la préfecture de Niigata le 16 juillet. Menée par Philippe
Jamet, directeur du département de sûreté des installations
au sein de l'AIEA, elle a passé quatre jours dans l'enceinte de
la centrale.
Au terme de l'inspection, le 10 août, M. Jamet a déclaré que le redémarrage de la centrale, d'une puissance supérieure à huit gigawatts, ne pourrait pas intervenir avant "plusieurs mois, voire une année". Reconnaissant que l'équipe s'était sentie "libre d'enquêter sur tout", l'expert français a insisté sur la nécessité d'"élaborer une méthodologie" avant de remettre en service les sept réacteurs de la centrale. Après l'avoir refusée, le Japon a finalement accepté, fin juillet, la venue des experts de l'AIEA à Kashiwazaki-Kariwa. Le gouvernement a cédé aux pressions des autorités locales et des habitants de la région. L'inquiétude de la population a été alimentée par le comportement de Tepco, la compagnie d'électricité de Tokyo, propriétaire de la centrale. |
Le séisme a provoqué
plusieurs dizaines d'incidents, dont des fuites radioactives. Tepco, déjà
reconnue coupable dans le passé d'avoir dissimulé maints
problèmes, parfois critiques, a cette fois encore tardé à
les reconnaître. Elle a fini par admettre que la centrale de Kashiwazaki-Kariwa
n'avait pas été conçue pour résister à
un séisme d'une telle violence.
Désireux de rassurer une opinion publique plutôt hostile au nucléaire, le gouvernement a établi, en septembre 2006, de nouvelles normes antisismiques pour la construction des centrales. Le 10 août, il a, dans un rapport sur le nucléaire, signalé que "la sécurité devait être une priorité absolue". Dans une tribune publiée le lendemain par le quotidien Asahi, Katsuhiko Ishibashi, expert en sûreté urbaine à l'université de Kobe, soulignait l'insuffisance des nouvelles normes qui exigent une capacité de résistance à des accélérations de 450 gal (1 gal = 1 cm/s²) maximum. Pour lui, une centrale devrait pouvoir "résister à une accélération générée par un séisme de magnitude de 7,3, soit potentiellement 1.000 gal". Celle causée par le tremblement de terre de juillet a atteint 993 gal. Philippe Mesmer
|
| The shaking
measured at one building at an earthquake-damaged Japanese nuclear power
plant may have been the strongest ever experienced at any nuclear power
station in the world, a spokesman for the plant operator said Tuesday.
The Kashiwazaki-Kariwa nuclear plant — the world's largest in terms of capacity — was severely damaged July 16 by a magnitude 6.8 earthquake in northwestern Japan that killed 11 and injured more than 1,000. Officials at the Kashiwazaki plant have acknowledged they had not foreseen such a powerful quake hitting the facility, which suffered a range of leaks and malfunctions that have raised public concerns about safety at the nation's nuclear power stations. Until last year, Japan had required plants to be built to withstand a 6.5 magnitude quake. In September, the government began implementing tougher guidelines, though they have not set a fresh magnitude level. Plant operator Tokyo Electric Power Co., or TEPCO, has determined that shaking in the turbine building of the facility's N°3 reactor reached 2,058 gals during the quake, more than 2 1/2 times stronger than the amount it was anticipated could hit the structure, TEPCO spokesman Jun Oshima said. A gal is a unit that measures how quickly an object's speed increases on a horizontal plane. |
That figure was the
highest ever measured at a TEPCO plant during an earthquake, Oshima said,
who added that it may also have been the strongest ever experienced at
any nuclear plant in the world.
The quake triggered a fire that charred a transformer located outside the N°3 reactor's turbine building. TEPCO was criticized for a bungled response to the blaze. Plant officials said they had no chemical fire vehicle at the plant, and local fire officials took 90 minutes to respond to their call. Shaking at the turbine building of the plant's N°1 reactor was nearly seven times stronger than the amount anticipated, he added, while the turbine building at the N°6 reactor experienced shaking 1 1/2 times stronger than imagined. TEPCO is still reviewing the data and plans to conduct a more detailed analysis as it continues its assessment of damage at the plant, Oshima said. The quake caused a range of problems at the plant that included radioactive water sloshing out of a tank and into the sea and radioactive material venting into the air. TEPCO and nuclear regulators have stressed the amounts of radioactivity leaked were extremely low and posed no threat to the environment or local residents, but the plant's seven reactors have been shuttered indefinitely until its safety can be confirmed. |
| A team of
inspectors from the U.N. nuclear watchdog agency will begin work next week
to collect information at a nuclear power plant severely damaged in a quake
last month, an official said Thursday.
The magnitude 6.8 quake on July 16 killed 11 people and injured more than 1,000. It also caused a range of malfunctions and leaks at the plant — the world's largest in terms of capacity — that have raised concerns for safety at the country's nuclear power stations. The International Atomic Energy Agency's team will examine the plant beginning Monday for five days, according to Masahiro Yagi, an official of the Nuclear and Industrial Safety Agency. Japanese officials, already at the plant for investigations, will cooperate with the IAEA team of six officials but the IAEA's probe would be independent, Yagi said. |
The visit came as the
plant's operator Tokyo Electric Power Co., or TEPCO, was under fire in
the wake of the powerful quake, which triggered a small fire at the plant
in Niigata prefecture (state). It took two hours to put out the fire because
plant officials had trouble notifying fire officials.
In another incident, radioactive water had sloshed out of a tank and was flushed out to sea although the amount of radioactive material was extremely small. Plant officials said they had not foreseen such a powerful quake hitting the facility, and repeatedly underreported its impact afterward. The inspectors plan to compile a report after the inspection, according to Yagi. |
| News reports
continue to shed light on the damage inflicted on Tokyo Electric Power
Co.'s Kashiwazaki-Kariwa nuclear power plant by the magnitude-6.8 earthquake
that struck Niigata and Nagano prefectures July 16. Most worrying is a
report that the tremors were more than double the quake-design benchmark
of the world's largest nuclear-power-generation complex.
What happened at the Kashiwazaki-Kariwa plant has raised doubts about the safety of the nation's 55 power-generation reactors. Power companies must review the capability of their nuclear power plants to withstand seismic tremors under the tougher design guidelines revised by the Nuclear Safety Commission in September. In addition, the government and the commission should not hesitate to further revise plant-design guidelines after taking into consideration the damage wrought by the July 16 earthquake. The focus of the earthquake was about 9 km northeast of the nuclear power plant and about 17 km below the Sea of Japan. Worryingly, the Meteorological Agency analyzed the distribution of aftershocks and ascertained the possibility that the fault that caused the main quake runs directly beneath the nuclear plant at a depth of 20 km. The approximately 15-km-wide aftershock zone extends some 30 km southeast of the quake's focus. The nuclear power plant lies within this zone. The government's earthquake study group is scheduled to carry out a large-scale study to pinpoint the fault that caused the earthquake. Hopefully the study will confirm whether the fault runs beneath the nuclear power plant. A study by a group of experts also indicates that TEPCO may have underestimated the size of a fault whose existence was confirmed by the power company around 1980 — before it expanded the plant. Documents filed by TEPCO for plant expansion identified the fault as located beneath the Sea of Japan, about 20 km west of the plant. TEPCO estimated its length at 7 to 8 km and concluded that there was no need to consider the fault in plant design since evidence suggested that the fault had long been inactive. The group of experts, however, says the fault extends about 30 km in a north-south direction and that it may have caused the July 16 quake. |
Construction of nuclear
power plants is approved on the condition that active faults do not lie
beneath the proposed sites. If an unknown fault does exist beneath a planned
nuclear power plant, it is assumed that such a fault would cause a maximum
magnitude-6.5 quake.
Confirmation that the fault responsible for the July 16 quake runs below the Kashiwazaki-Kariwa plant would undermine the basic assumptions on which the plant was designed. Unlike older design guidelines that applied uniform assumptions about the effects of possible earthquakes to all nuclear power plants, the September 2006 guidelines call for examining geological features and the history of past quakes, and determining whether faults exist or not near planned nuclear power plants. They do not specify the maximum magnitude of an anticipated earthquake, but magnitude 6.8 is accepted as a rough yardstick. However, even a magnitude increase of just 0.2 means a roughly twofold increase in the energy released by a quake. In fact, the July 16 earthquake registered magnitude 6.8, and it was strong enough to cause the ground around a diesel-oil storage tank at the Kashiwazaki-Kariwa plant to fracture and sink 1.6 meters. It is said that under the September 2006 design guidelines, the earthquake resistance of nuclear power plants will increase by 20 to 30%. Given the damage suffered by the Kashiwazaki-Kariwa plant, however, the government and the Nuclear Safety Commission should review the guidelines. The quake highlighted the extent to which nuclear power plants are vulnerable to major earthquakes. A 310-ton ceiling crane above the pressurized chamber of the N°6 reactor at the plant was damaged although the building housing the reactor and crane was supposed to be quake-resistant. Water overflowed from a pool storing spent nuclear fuel, some of which leaked into the sea. A ventilator at the N°7 reactor continued to operate for two days after the quake, spewing radioactive materials into the atmosphere. Oil leaked from the transformers for four reactors, one of which caught fire. And it was found that no power companies have in-house firefighters on duty around the clock. Both the power industry and the government must make enormous efforts if they are to restore people's trust in the safety of nuclear power plants. |
| The damage
at the Kashiwazaki-Kariwa Nuclear Power Plant in Niigata Prefecture, which
was directly hit by the July 16 earthquake, was more serious than initially
thought. A crane on the ceiling of the building that houses the N°6
nuclear reactor at the plant was found broken.
The No. 6 reactor was undergoing periodic inspections when the quake hit. Had it been running at the time, the damage could have occurred just above the reactor where a nuclear reaction takes place. According to Tokyo Electric Power Co. (TEPCO), the operator of the plant, the damage was limited to a part that moves the crane. TEPCO said the breakage would not cause the crane, weighing more than 300 tons, to fall. Even so, the damage should not be taken lightly. The damage underscores the intensity of the quake near the ceiling of the reactor building. Cracks and distortions may not be detected in visual checks of the crane itself or the surrounding area. And there may be similar damage to cranes of other reactor buildings as well. In terms of earthquake-resistance design, structures in nuclear power plants are categorized into classes ranging from A to C according to their degree of importance. Ceiling cranes are class B. However, in huge facilities such as nuclear power plants, damage to peripheral equipment could eventually lead to problems at the heart of the system. Parts classified as relatively low in importance for quake-resistance also need to be thoroughly examined. Nuclear power plant operators should consider how damage to these parts could have led to further problems in a worst-case scenario. |
What was immediately
clear after the earthquake was that a fire broke out in a transformer at
the plant. Later, more than 60 cases of damage became known, including
a leak of radioactive water into the Sea of Japan.
Unlike thermal power plants and factories, nuclear power plants handle dangerous radioactive materials. Therefore, it takes much longer to inspect them. The damage to the crane was also noticed by experts after removing radioactive contamination from the site. TEPCO will open the lids of pressure containers, which can be likened to furnaces of nuclear reactors, to check for damage inside. Since inspections inside the containers involve a high risk of radiation exposure, the company will use remote-controlled cameras and other equipment for the checks. However, the cranes should first be properly checked and repaired as necessary. At least several months will likely be needed before all seven reactors at the plant are checked and confirmed safe. Local government approval is also needed before the plant resumes operations. Based on fire laws, Kashiwazaki Mayor Hiroshi Aida ordered an emergency shutdown of fuel tanks and other facilities handling hazardous materials at the plant. The earthquake showed that even seemingly minor damage that does not lead to a major accident in the reactors themselves can force nuclear power plants to be shut down for a long time. But spending time to check and repair minor damage can stop fatal disasters from occurring. We should view the suspension of operations as the cost for ensuring safety. |
| ( ... )
As for when Tepco may be able to restart its Kashiwazaki-Kariwa nuclear power complex, the world's largest, Haruki Madarame, head of the expert panel and a University of Tokyo professor specializing in nuclear engineering, said Wednesday night, "At least one year is needed for operations to resume." The government launched the 20-member panel chaired by Madarame on Thursday in a bid to strengthen quake safety measures at nuclear power plants, with its first meeting slated for Tuesday. Panel members include academics, crisis-management experts, journalists and top officials of the city of Kashiwazaki and the village of Kariwa, where the nuclear plant is located. Tepco said Wednesday the utility has yet to work out detailed plans to conduct inspections and confirm safety, and such work could be delayed substantially following its earlier finding that the ceiling crane in the N°6 reactor building was damaged by the quake. On Thursday, Tepco said it will equip each of its three nuclear power stations with chemical fire engines, and also have 24-hour firefighting systems in place at its Kashiwazaki-Kariwa plant and its two other nuclear power stations, in Fukushima Prefecture, including the six-reactor N°1 station, and the four-reactor N°4. |
The system involves
teams of four to five firefighters, with each team taking an eight-hour
shift. Currently, the utility does not require firefighting staff to be
posted at its nuclear plants around the clock, hence the delay in fighting
the fire at the Kashiwazaki-Kariwa plant triggered by the quake.
The measures are part of antiquake steps that Tepco presented the same day to the government's Nuclear and Industrial Safety Agency to ensure safety at its nuclear plants. Along with Tokyo Electric, 10 other nuclear-related companies submitted similar business improvement plans to the agency based on an order issued last week by Economy, Trade and Industry Minister Akira Amari. The fire at the Kashiwazaki-Kariwa plant rekindled public concern about the safety of nuclear facilities in Japan. The quake, which hit Niigata Prefecture and its vicinity, also caused a leak of water containing low-level radioactive material at the plant, as well as other reportedly minor radiation leaks. |
| Published: July 26 2007
The price of uranium, the fuel of the nuclear industry, has suffered its first fall in more than four years – after rising more than 10-fold. A radioactive leak at Japan’s Kashiwazaki-Kariwa nuclear plant following an earthquake this month has contributed to negative sentiment, with fears that it could spark new public opposition to nuclear power. The announcement by the US Department of Energy of a uranium sale from its stockpile also weighed on a market suffering from weak summer demand. The DoE is selling the nuclear fuel to help pay for a clean-up of "contaminated uranium inventories". Prices fell from a record high of $136 a pound in mid-July to $120 a pound this week, the first price drop since June 2003, when uranium prices moved from $11 to $10.90 a pound. However, analysts said prices would continue to trade higher than in the past and most said the price drop was a correction in an upward trend. |
Uranium prices have
jumped by 185% in the past 12 months on the back of rising demand from
new nuclear reactors, the life extension of current plants and supply bottlenecks.
UBS forecast that higher demand and slow supply increases would push prices
to almost $200 a pound in 2008.
Mined uranium satisfies just 55%of global consumption, with the rest coming from dismantled Soviet-era nuclear warheads, government stockpiles and reprocessing. Demand is expected to increase sharply in the next decade as new nuclear power plants come on line in addition to the current 437 reactors. There are 74 reactors under construction and a further 182 planned, according to the World Nuclear Association, the industry body. China, with 23 plants under construction and a further 54 planned, accounts for the bulk of the increase. Supply fears were highlighted after Cameco, the world’s largest uranium supplier, this week said it had suspended production at its Port Hope, Ontario, nuclear fuel conversion plant. |
| Published: July 26 2007
The price of uranium, the fuel of the nuclear industry, has suffered its first fall in more than four years – after rising more than 10-fold. A radioactive leak at Japan’s Kashiwazaki-Kariwa nuclear plant following an earthquake this month has contributed to negative sentiment, with fears that it could spark new public opposition to nuclear power. The announcement by the US Department of Energy of a uranium sale from its stockpile also weighed on a market suffering from weak summer demand. The DoE is selling the nuclear fuel to help pay for a clean-up of "contaminated uranium inventories". Prices fell from a record high of $136 a pound in mid-July to $120 a pound this week, the first price drop since June 2003, when uranium prices moved from $11 to $10.90 a pound. However, analysts said prices would continue to trade higher than in the past and most said the price drop was a correction in an upward trend. |
Uranium prices have
jumped by 185% in the past 12 months on the back of rising demand from
new nuclear reactors, the life extension of current plants and supply bottlenecks.
UBS forecast that higher demand and slow supply increases would push prices
to almost $200 a pound in 2008.
Mined uranium satisfies just 55% of global consumption, with the rest coming from dismantled Soviet-era nuclear warheads, government stockpiles and reprocessing. Demand is expected to increase sharply in the next decade as new nuclear power plants come on line in addition to the current 437 reactors. There are 74 reactors under construction and a further 182 planned, according to the World Nuclear Association, the industry body. China, with 23 plants under construction and a further 54 planned, accounts for the bulk of the increase. Supply fears were highlighted after Cameco, the world’s largest uranium supplier, this week said it had suspended production at its Port Hope, Ontario, nuclear fuel conversion plant. |
| BY HIDEYUKI MIURA, THE ASAHI SHIMBUN
KASHIWAZAKI, Niigata Prefecture Up to 2,000 tons of water from an outdoor pipe broken in the July 16 earthquake inundated the basement of a nuclear reactor building here, Tokyo Electric Power Co. (TEPCO) said. The basement at the TEPCO-run Kashiwazaki-Kariwa Nuclear Power Plant is a "radiation-controlled area" containing radioactive materials. It must be completely shut off from the outside environment. However, the earthquake showed that the area can be linked to the outside environment. According to TEPCO officials, the ground around the building that accommodates the No. 1 reactor sank by about 20 to 30 centimeters during the earthquake. Underground electric cables leading from the first basement floor of the building to the outside were pulled down by the ground subsidence, creating a large space on the outer wall. An underground water pipe for fire extinguishing near the cables ruptured in the quake, allowing water to flow into the basement areas through the space. "It was beyond our imagination that a space could be made in the hole on the outer wall for the electric cables," a TEPCO official said. |
However, he stressed:
"As the air pressure in the radiation-controlled area was reduced, no
air leaked from the area to the outside environment. No radioactive materials
leaked to the outside."
TEPCO officials said the building itself did not subside because it had been built on solid ground. But the ground around the building sank because it consists of layers of sand. The water that entered the building flowed down a drainpipe to the fifth basement floor, a radiation-controlled area. The water entered a waste water tank, which soon overflowed, inundating the floor with water to a height of 48 centimeters. An estimated 2,000 tons of water spilled on the floor, equivalent to the volume in five 25-meter-long swimming pools. The flooding also apparently damaged motors that send waste water containing radioactive materials to filtering devices, the officials said. But they added that the radioactive-contamination level of the water that flowed onto the floor was low. "We have already closed the space (of the hole on the outer wall). We never imagined that such a situation could take place," one of the officials said. According to the officials, TEPCO is now considering measures to discharge the water from the building.(IHT/Asahi: July 25,2007) |
| Radioactive
water that leaked into the sea from a quake-hit nuclear power plant likely
flowed along electric cables protruding from a damaged floor before reaching
drainage ditches, the plant's operator said Monday.
The July 16 earthquake rocked a storage pool containing about 2,300 kiloliters of water and spent nuclear fuel on the fourth floor of the N°6 reactor building of the Kashiwazaki-Kariwa Nuclear Power Plant in Niigata Prefecture, according to Tokyo Electric Power Co. (TEPCO). The spilled radioactive water reached a hole about 8 centimeters in diameter where the electric cables run through for equipment used to transport spent fuel, TEPCO said. Under normal circumstances, packing material fills the spaces between the sides of the hole and cables. But the packing material apparently came loose in the magnitude 6.8 earthquake, allowing the water to flow along the cables and then into an air-conditioning duct before pouring into drainage ditches that lead to the Sea of Japan, TEPCO said. The water traveled down three floors of the building. |
The floor where the
storage pool is located is in a radiation-controlled area. But the floors
into which the water flowed are outside the restricted zone, the utility
said.
Water drops were found on the surface of the cables, inside the air-conditioning duct and elsewhere, TEPCO said. An estimated 1.2 cubic meters of radioactive water flowed into the sea, but the company said it is still not certain about the total amount of water that flowed from the pool. A "considerably large amount of water" must have spilled out, a TEPCO official said. "We never assumed that water could flow out of the pool," an official said. "We'd like to come up with countermeasures." The distance between the surface of the water and the top of the pool is more than 1 meter. The temblor also caused the spent fuel pools at the plant's six other reactor buildings to overflow. But no radioactive water leaked into the uncontrolled areas in these cases, according to TEPCO. TEPCO said the radioactive water that reached the Sea of Japan posed no threat to humans or the environment. |
| Radioactive
water that leaked into the sea from a quake-hit nuclear power plant likely
flowed along electric cables protruding from a damaged floor before reaching
drainage ditches, the plant's operator said Monday.
The July 16 earthquake rocked a storage pool containing about 2,300 kiloliters of water and spent nuclear fuel on the fourth floor of the N°6 reactor building of the Kashiwazaki-Kariwa Nuclear Power Plant in Niigata Prefecture, according to Tokyo Electric Power Co. (TEPCO). The spilled radioactive water reached a hole about 8 centimeters in diameter where the electric cables run through for equipment used to transport spent fuel, TEPCO said. Under normal circumstances, packing material fills the spaces between the sides of the hole and cables. But the packing material apparently came loose in the magnitude 6.8 earthquake, allowing the water to flow along the cables and then into an air-conditioning duct before pouring into drainage ditches that lead to the Sea of Japan, TEPCO said. The water traveled down three floors of the building. |
The floor where the
storage pool is located is in a radiation-controlled area. But the floors
into which the water flowed are outside the restricted zone, the utility
said.
Water drops were found on the surface of the cables, inside the air-conditioning duct and elsewhere, TEPCO said. An estimated 1.2 cubic meters of radioactive water flowed into the sea, but the company said it is still not certain about the total amount of water that flowed from the pool. A "considerably large amount of water" must have spilled out, a TEPCO official said. "We never assumed that water could flow out of the pool," an official said. "We'd like to come up with countermeasures." The distance between the surface of the water and the top of the pool is more than 1 meter. The temblor also caused the spent fuel pools at the plant's six other reactor buildings to overflow. But no radioactive water leaked into the uncontrolled areas in these cases, according to TEPCO. TEPCO said the radioactive water that reached the Sea of Japan posed no threat to humans or the environment. |
| Le tremblement
de terre qui a frappé le Japon le 16 juillet pourrait coûter
cher à Tokyo Electric Power (Tepco), la compagnie d'électricité
qui exploite la centrale nucléaire de Kashiwasaki-Kariwa, fermée
depuis la catastrophe. Si Tepco se refuse à avancer le moindre chiffre
avant la fin du mois de juillet, le quotidien japonais Nikkei évoquait,
dimanche 22 juillet, un coût total d'au moins 200 milliards de yens
(1,2 milliard €).
En cause, la difficulté pour la centrale de reprendre son activité avant mars 2008, le temps de renforcer ses capacités antisismiques. Et de faire l'objet d'une inspection de la part de l'Agence internationale de l'énergie atomique (AIEA). Le gouvernement de Tokyo a en effet accepté dimanche la demande de l'AIEA, en vertu d'un principe de transparence, et pour rassurer la population sur d'éventuelles fuites radioactives. |
La centrale, la plus
grande du monde, produit à elle seule la moitié de la production
nucléaire du pays et fournit presque exclusivement l'alimentation
de Tokyo, dont les besoins grimpent avec les températures d'été.
Pour compenser cette perte, le président de Tepco, Tsunehisa Katsumata, a déjà annoncé la mise en place de plusieurs mesures: l'augmentation de la production d'autres centrales, l'utilisation d'énergies alternatives (charbon et gaz) et le rachat d'électricité à d'autres entreprises. Les Japonais devraient aussi être appelés à réduire leur consommation. Ces mesures d'urgence seront-elles à même de rassurer les marchés nippons: pas sûr. Car Tepco, qui avait déjà vu sa valeur boursière chuter de 13% la semaine dernière, se trouve également fragilisée par la hausse du prix du pétrole. La compagnie pourrait ainsi voir ses profits réduits de 60 milliards de yens cette année, si le prix du baril ne descend pas. Audrey Steeves
|
| Tokyo Electric
Power Co. announced Saturday that water containing radioactive substances
spilled from a spent fuel pool at five of the seven nuclear reactors of
the Kashiwazaki-Kariwa nuclear power plant in the Niigata Prefecture Chuetsu
Earthquake in October 2004.
According to TEPCO, the surface of the pools at the N°2, 3, 4, 5 and 7 reactors was greatly disturbed by the shock of the 2004 quake. The water in the pools was similarly disturbed in the latest Niigata Prefecture Chuetsu Offshore Earthquake. However, the water did not leak beyond areas designated for handling radioactive substances at any of the reactors. |
The largest quantity
of water, 200 liters, was spilled at the N°4 reactor. At all five of
the reactors, the spilled water made puddles near the spent fuel pools.
Asked why it had not publicized the incident, TEPCO said it did not regard it as a problem at the time because the quantity of spilled water was insignificant and did not leak outside the reactor buildings. In the latest quake, water spilled from the spent fuel pool at all seven of the reactors and water was found to have leaked beyond the area for handling radioactive material at the N°6 reactor. (Jul. 22, 2007) |
| Tokyo Electric Power Company's seven reactor Kashiwazaki-Kariwa atomic power plant, the largest in the world in terms of electricity output, suffered 50 cases of "malfunctioning and trouble" after a 6.7 tremor struck nearby two days ago. Radioactively contaminated water, at first estimated to be around 315 gallons but later raised by 50%, leaked into the Pacific Ocean. Barrels containing radioactive waste tipped over, and 10% of their lids fell off; the number of barrels was first estimated at 100, but later increased to 400. Hazardous radioactive isotopes cobalt-60 and chromium-51 were emitted into the atmosphere from an exhaust stack. The first sign of trouble was not an alert issued by the company, but rather a column of black smoke pouring off a transformer fire that took two hours to bring under control. | The quake, epi-centered on a previously unknown fault line just over five miles from the nuclear plant, created forces 2.5 times stronger than the plant was designed to withstand. Based upon data from the quake's aftershocks, Japanese authorities now fear an extension of the fault line may pass very near to, or even directly under, the atomic complex itself. The twelve hour delay before the company announced the radioactive leak into the ocean, the day-long delay in discovering the tipped over barrels, and the increasing magnitude of the spills and other problems has caused consternation among environmental groups, local residents and politicians, even with the Japanese Prime Minister himself. |
| TOKYO (AFP) Jul 19, 2007
Survivors of the world's only atomic attacks called Thursday on Japan to review the safety of nuclear plants after a powerful earthquake caused radioactive leakage. "Even if the leakage was very small, this is not permissible after an earthquake," said Gensuikin, a group representing victims of the nuclear attacks on Hiroshima and Nagasaki. "It clearly shows how the current safety calculations were based on over-optimistic thinking," it said in a statement, saying that the standards "should be overhauled completely." Japan has been sensitive about nuclear issues due to the US atomic attacks at the end of World War II, which killed more than 210,000 people instantly. Tens of thousands later died from radiation and horrific burns. |
But Japan's government
has embraced atomic energy. Despite being one of the most earthquake-prone
nations, the world's second largest economy has virtually no oil or gas
resources.
Tokyo Electric Power Co (TEPCO), operator of the world's largest nuclear plant, has acknowledged it had not prepared for an earthquake as forceful as Monday's, which killed 10 people and destroyed hundreds of buildings. The company said that radioactive material leaked from the massive facility northwest of Tokyo but that the amount was far too small to pose any health risks. Japan relies on nuclear energy for about one-third of its needs, the highest level among Group of Eight industrial nations except for France. |
| Une nouvelle
petite fuite radioactive a été détectée mercredi
dans la centrale nucléaire de Kashiwazaki-Kariwa, la plus grande
du monde, endommagée lundi par le violent séisme qui a frappé
le centre du Japon, selon l'agence de presse locale Jiji.
La fuite a été localisée dans un filtre de l'un des sept réacteurs de la centrale, a précisé Jiji, en précisant qu'il n'y avait pas de risque pour la santé humaine ou l'environnement. La centrale de Kashiwazaki-Kariwa se trouve à seulement neuf kilomètres de l'épicentre du séisme de magnitude 6,8 sur l'échelle de Richter qui a fait dix morts, plus de mille blessés et détruit ou endommagé plus de 2.000 bâtiments. |
La secousse a provoqué
un incendie dans un transformateur et a fait se déverser 1,2 mètre
cube d'eau légèrement radioactive dans la Mer du Japon.
Un total de 438 fûts d'acier hermétiques destinés à recueillir les gants et autres vêtements potentiellement irradiés se sont renversés lors de la secousse. La centrale nucléaire, qui n'était pas conçue pour résister à un séisme aussi puissant, a été fermée pour une période indéfinie par les autorités. |
| Les images
d'une épaisse fumée noire se dégageant de la centrale
nucléaire japonaise de Kashiwazaki-Kariwa, après le tremblement
de terre de lundi, ont ranimé la crainte d'une industrie pas comme
les autres. Est-ce vraiment prudent d'installer des centrales nucléaires
dans un pays souvent secoué par des séismes ? La question
est d'autant plus brûlante au Japon que le pays est le troisième
producteur mondial d'électricité nucléaire, derrière
les Etats-Unis et la France.
«Le tremblement de terre dans la mer du Japon démontre à nouveau la vulnérabilité des centrales nucléaires quand la nature déchaîne sa furie», affirme l'«Asahi Shimbun» dans son éditorial de mercredi. S'il était spectaculaire, l'incendie était moins grave que l'écoulement d'eau contaminée dans la mer du Japon - une première. Le grand quotidien de Tokyo s'inquiète: «Le séisme a dépassé l'intensité maximale pour laquelle la sécurité des réacteurs nucléaires a été conçue.» D'après un article figurant dans la même édition du quotidien, le choc a été deux fois plus intense que le maximum prévu! |
La polémique pourrait grandir sur la région d'implantation de la centrale. Avant de construire des réacteurs, à la fin des années 1980, la compagnie d'électricité privée Tepco avait bien signalé l'existence de quatre failles, distantes de 19 à 39 kilomètres du site. Mais «elle avait conclu que les quatre failles pouvaient être considérées comme inactives». En mars, un tremblement de terre nippon avait montré qu'un rival de la Tepco avait sous-estimé le risque dû à une autre faille. L'«Asahi Shimbun» tire la sonnette d'alarme: «Certains soutiennent l'énergie nucléaire, affirmant que les centrales nucléaires, produisant une énergie propre, sont utiles pour éviter le réchauffement climatique, contrairement aux centrales thermiques qui émettent de grandes quantités de CO2. Mais (...) ce qui s'est passé lundi à Kashiwazaki-Kariwa doit être pris comme un avertissement contre toute décision hâtive nous menant vers une dépendance accrue à l'égard de l'énergie nucléaire.» |
| Il semblerait (information à vérifier) que les autorités ont procédé au dégazage de la centrale nucléaire accidentée. Sachons que dans une centrale nucléaire 30% de la radioactivité présente est constituée sous forme de gaz radioactif ce qui représente 30% de 10 milliards de curies. C'est une énorme quantité de radioactivité. | Il semblerait que les nuages radioactifs de dégazage se déplaceraient maintenant vers la ville de Tokyo, et que personne n'ait encore reçu l'invitation de prendre les pilules d'iode afin de parer à l'accumulation d'iode 131 (radioactif) dans la thyroïde.. Si cela est vrai alors les mesures de protection seraient défectueuses. Maurice ANDRE, président de l'AIPRI (association internationale pour la protection contre les rayons ionisants). Phone ++32 4 374 24 62. |
| ( ... )
Nuclear reactors at power plants were shut down automatically, but the quake caused a small fire at an electrical transformer at a nuclear plant in Kashiwazaki, a coastal town close to the quake's epicenter. Japanese television stations showed flames and black smoke billowing from the facility, which is operated by Tokyo Electric and is the world's largest nuclear plant. |
Tokyo Electric initially said that there was
no radiation leak at the plant. But later in the evening, it said in a
statement that 1.5 liters (a bit less than three pints) of water containing
low levels of radioactive material leaked into the Sea of Japan from two
locations at its N°6 reactor.
The leaks occurred at about 12:50 p.m., but the company was not certain five and a half hours later that the water was radioactive, the statement said. ( ... ) |
