Beslut i morse: "Nu går vi in i reaktorn!"

2011-05-05 08:46  

Iförda gasmasker, syrgastuber och strålningssäkra skyddsdräkter tog sig två kärnkraftstekniker i morse in i den havererade reaktor 1 i Fukushima Daiichi-kraftverket i Japan.

- Det här är det första försöket från våra egna tekniker att ta sig in i reaktorbyggnaden, säger Satoshi Watanabe, talesman för Tokyo Electric Power Co, Tepco till nyhetsbyrån AFP.

Alla sex kärnreaktorer i Fukushima-anläggningen är stängda. Fyra stycken förstördes av jordbävningen och tsunamin medan de övriga två skadades lindrigt.

Tepco planerar att skicka in ytterligare ett tiotal tekniker i reaktorbyggnaden för att installera ett ventilationssystem och minska den radioaktiva strålningen inne i reaktorbyggnaden.

- De kommer att arbeta i grupper om fyra åt gången i tiominutersskift. Det är trångt därinne, sade Tepco på en presskonferens tidigt i morse.

Hittills har radioaktiviteten varit alltför hög för att Tepco skulle våga skicka in sitt folk i byggnaden för att reparera kylsystemet till reaktorn.

Man räknar med att de som nu är inne och arbetar med ventilationssystemet utsätts för 3 millisievert strålning för varje tiominutersskift.

Lagen i Japan tillåter bara 100 millisievert strålning för kärnkraftsanställda under fem år. 

Men när Fukushima-katastrofen inträffade den 11 mars höjde regeringen fyra dagar senare tillfälligt gränsen till 250 millisievert - per år.

Tepco sade på presskonferensen i morse att det kommer att ta resten av 2011 innan man får kontroll över anläggningen.

Detta är läget i Fukushima

Pressmeddelande från Tepco 5 maj 2011:

All 6 units of Fukushima Daiichi Nuclear Power Station have been shut down.

Unit 1 (Shut down)

- Explosive sound and white smoke were confirmed after the big quake

  occurred at 3:36 pm on March 12. It was assumed to be hydrogen explosion.

- At approximately 2:30 am on March 23, seawater injection to the nuclear

  reactor through the feed water system was initiated.

- From 3:37 pm on March 25, we started injecting freshwater and are now

  injecting fresh water by a motor driven pump powered by the off-site

  transmission line. From on April 27, we have increased the amount of

  injecting freshwater from approximately 6 m/h to approximately 14 m/h.

  At 10:14 am on April 29, we put the amount of injecting freshwater back

  to approximately 6 m/h.

- As it is suspected that hydrogen gas is accumulated inside reactor

  containment vessel, we commenced the valve opening operation concerning

  injection of nitrogen gas into the reactor container vessel at 10:30 pm

  April 6th and commenced injection at 1:31am April 7.

Unit 2 (Shut down)

- At approximately 6:00 am on March 15, an abnormal noise began emanating

  from nearby Pressure Suppression Chamber and the pressure within the

  chamber decreased.

- From 10:10 am on March 26, we started injecting freshwater to the

  reactor and are now injecting fresh water by a motor driven pump powered

  by the off-site transmission line.

Unit 3 (Shut down)

- Explosive sound and white smoke were confirmed at approximately 11:01am

  on March 14. It was assumed to be hydrogen explosion.

- From 6:02 pm on March 25, we started injecting fresh water to the

  reactor and are now injecting fresh water by a motor driven pump powered

  by the off-site transmission line.

Unit 4 (Outage due to regular inspection)

- At approximately 6:00 am on March 15, we confirmed the explosive sound

  and the sustained damage around the 5th floor rooftop area of the

  Nuclear Reactor Building.

- At this moment, we do not consider any reactor coolant leakage inside

  the reactor happened.

Unit 5 (Outage due to regular inspection)

- Sufficient level of reactor coolant to ensure safety is maintained.

- At 5:00 am on March 19, we started the Residual Heat Removal System Pump

  (C) in order to cool the spent fuel pool.

- At 2:30 pm on March 20, the reactor achieved reactor cold shutdown.

- At this moment, we do not consider any reactor coolant leakage inside

  the reactor happened.

Unit 6 (Outage due to regular inspection)

- Sufficient level of reactor coolant to ensure safety is maintained.

- At 10:14 pm on March 19, we started the Residual Heat Removal System

  Pump (B) of Unit 6 in order to cool the spent fuel pool.

- At 7:27 pm on March 20, the reactor achieved reactor cold shutdown.

- At this moment, we do not consider any reactor coolant leakage inside

  the reactor happened.

Operation for cooling the spent fuel pools

- We will continuously conduct further water spray depending on the

  conditions of spent fuel pools, if needed.

Others

- Regarding the transfer of high level radioactive wastewater in Unit 2 to

  the Centralized Radiation Waste Treatment Facility, while we temporarily

  suspended transfer due to the inspection of transferring facilities at

  9:16 am on April 29, transfer was restarted at 2:05pm on April 30.

- The transfer of accumulated water in Unit 6 turbine building to a

  temporary tank was conducted from 2:00 pm to 5:00 pm on May 3.

- From March 27, transfer of accumulated water in Unit 5 turbine building

  to a condenser has been conducted, and water with the amount of

  approximately 600m has been transferred from March 27 to May 2.

- From May 2, we have started work relating to the set up of exhausters,

  in order to improve the working environment inside the reactor building

  of Unit 1.

- We will continue to take all measures to ensure the safety and to

  continue monitoring the surrounding environment around the power station.

 

Lars Anders Karlberg

Mer om: Tsunami Fukushima

Kommentarer

Välkommen att säga din mening på Ny Teknik.

Principen för våra regler är enkel: visa respekt för de personer vi skriver om och andra läsare som kommenterar artiklarna. Alla kommentarer modereras efter publiceringen av Ny Teknik eller av oss anlitad personal.

  Kommentarer

Debatt