Three weeks after the tsunami – Nuclear Power? Yes Please

Last updated on March 1, 2013

Update 18:00(CET)/16:00(UTC)/01:00(JST)

The new JAIF update is out. Temperature of the core in Reactor one has gone down and pressure gone up slightly. They have added the water level of the radioactive water in the tunnels they are trying to empty. They now write that they suspect the pressure vessels of reactor number 2 and 3 are no longer airtight but they don’t think there are any holes or crack. A cryptic statement and I wish they would release more information on what they mean exactly. Doesn’t seem possible to exclude a small breach in a few control rod guide tubes due to dripping corium(molten core material). At the same time the temperature readings in the lower head of reactor 3 excludes that the entire bottom has gone out due to massive melting through the vessel. In reactor 2 one neither has any temperature reading from bottom head or any pressure reading within the vessel.

Update 11:00(CET)/09:00(UTC)/18:00(JST)

JAIF has released a update (data from 07:30 JST today) and radiation trends and NISA has an update from yesterday(06:00(JST) march 31).

Reactor 1:
Water level in the core: 1.65 (1.65) meters below the top of fuel assemblies
Flow rate of injected water: 133 liter/minute
Core pressure: 583(612) kPa
Containment pressure: 175(210) kPa
Core temperature(feedwater nozzle): 256.2 (251.2) Celsius
Core temperature(bottom head): 128 Celsius
Dose rate within containment: 41.7 Sv/hour

Reactor 2:
Water level in the core: 1.5 (1.5) meters below the top of fuel assemblies
Flow rate of injected water: 150 liter/minute
Core pressure: unknown
Containment pressure: 110 (110) kPa
Core temperature(feedwater nozzle): 181.2 Celsius
Core temperature(bottom head): Unknown
Dose rate within containment: 38.7 Sv/hour
Spent fuel pool temperature: 58 Celsius

Reactor 3:
Water level in the core: 2.25 (2.3) meters below the top of fuel assemblies
Flow rate of injected water: 116 liters/minute
Core pressure: 117 (121) kPa
Containment pressure: 173 (176.4) kPa
Core temperature(feedwater nozzle): 88.5 Celsius (under review)
Core temperature(bottom head): 114.2 Celsius
Dose rate within containment: 25.7 Sv/hour

Pressures and temperatures seems to be quite stable, albeit high in the number 1 reactor. Nothing new really on the status of the 3 reactors. A temporary pump used to pump water into the number 2 spent fuel pool has malfunctioned and we can see a increasing trend in the water temperature.

They are shifting around water in different places to be able to make room somewhere to pump away the junk water in the basements of the turbine buildings. In order to be able to access the coolant pumps needed to restore the proper cooling of the reactors.

The JAIF radiation trends show that there was big emissions during the 15th and 16th and after that a declining trend. There doesn’t seem to be any continuous emissions from the plant and the emission spikes corresponds with the venting of the containments and following explosions and fires in the reactor buildings. Unless a new need to vent the containments arises, then there shouldn’t be any new big emissions. By now the I-131 content of the reactors have decayed down to a quarter of initial amount and for every week(8 days to be precise) they can prevent venting the amount will further be cut in half. I-131 will stop being a problem after about 80 days, by that time the amount will have been reduced to one thousandth of the initial amount. Cs-137 will of course continue to be a problem with a half life of 30 years.

TEPCO has once again measured wrongly activities in water, but it is likely the ground water around the plant is contaminated. Source of the contamination is unknown but TEPCO suspects its been carried by rain after the initial ventings.

Situation is serious, but it doesn’t seem to deteriorate anymore.