Re: Terremoto in giappone e problemi al reattore

From: Alessandro <IO_at_NOSPAM.IT>
Date: Thu, 19 Jul 2007 12:38:09 +0200

"Carlini Alessio" <alessioc71_at_gmail.com> ha scritto nel messaggio
news:1184830663.060660.13680_at_x40g2000prg.googlegroups.com...
> Grazie per la risposta, spero saprai dare qualche conferma in piu
> Alessio


Le uniche notizie ufficiali dell'azienda in questione che ho letto sono
quelle che ho gi� riportato
http://www.world-nuclear-news.org/regulationSafety/Kashiwazaki_Kariwa_nuclear_units_shutdown_on_earthquake_160707.shtml


" The earthquake, centred about 250 km northwest of Tokyo, hit at around
10.13 am, injuring more than 1000 people while destroying 300 buildings.
Many roads were cracked, a temple roof collapsed and 35,000 people lost
their water supply. Nine were killed.

At the Kashiwazaki Kariwa nuclear power plant, three of seven reactors -
units 3, 4 and 7 - were in operation. Those reactors shut down safely as
tremors began. Unit 2 was in the process of starting operation, and all
systems shut down automatically as well.

Units 1, 5 and 6 were not operating as periodic inspections were being
carried out. The tremors caused 1.2 cubic meters of water to spill from the
used nuclear fuel cooling pond of unit 6. Plant owners Tokyo Electric Power
Company (Tepco) said the water would contain 90 kBq of radioactivity, and
had drained from the plant building to the sea in accordance with
environmental regulations. The cooling pond itself was undamaged.
There was also a fire in the transformer of unit 3 following the earthquake.
Tepco said this had been safely extinguished by 12.10 pm.

Transformers are used in all types of power station. As part of the system
connecting the power unit's generator to the transmission grid, they step up
the voltage of the electricity generated by the plant for transmission of
energy over great distances without high losses. They are large oil-cooled
components which deal with very high energy loads. As such they are located
in designated and separated area of the plant and provided with ad-hoc
monitoring systems, back-up units and fire protection.
In addition, Tepco said hundreds of drums of solid low-level radioactive
waste (LLW) in the plant's solid waste storage facility fell from position.
The lids of dozens of these were found open. LLW is typically composed of
paper, filters, lightly-contaminated clothing and tools. Shigenori Makino of
Tepco told World Nuclear News that the LLW drums in the facility contained
either ash resulting from the incineration of flammable LLW items, the
flammable items prior to incineration, or inflammable items as-is.
Tepco is currently inspecting all seven nuclear power units at the plant to
assess what damage, if any, the earthquake may have caused and the exact
reason for the transformer failure.

The earthquake was the biggest to affect the region since one of magnitude
6.8 in 2004. At that time no damage was recorded to the Kashiwazaki Kariwa
plant."


Quindi in definitiva dei 7 reattori presenti nell'impianto solo 4 erano in
funzione o stavano per esserlo. Tutti i danni sono stati causati al
reattore 6. In particolare ci sono stati danni ai trasformatori che hanno
causato l'incendio nella parte elettrica dell'impianto, la fuoriuscit� di
acqua radioattiva dalla piscina di raffreddamento in quantit� non
apprezzabili e lo scoperchiamento di centinaia di fusti che contengono
rifiuti solidi di basso livello, compresi quelli inceneriti : in
quest'ultimo caso si tratta per� solo di rifiuti allo stato solido e a basso
livello di radioattivit�, tipicamente materiali "usa e getta" usati nella
gestione degli impianti nucleari, non certo combustibile irraggiato od
esaurito che si trovava nelle piscine o al pi� ancora nei reattori che erano
in operazione e che non sono risultati danneggaiti
Received on Thu Jul 19 2007 - 12:38:09 CEST

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