Massive Quake Hits NE Japan

[Docfeelgood]

How old are you?

[Wezil]

Old enough to know better than that.

[Docfeelgood]

Old enough to know better than that.

Very good, well thought out, adult answer.

[BlackCat]

NYE -

Because you can't count on the nuke for power as it is being shut down?

I'm curious about why the diesels were so susceptible to the tsunami. Isn't a tsunami a very good possibility for an island nation after an earthquake? If these things are to prevent a meltdown, why weren't they better protected?

They were placed int the basement. Not the smartest site.

[Asher]

The assumption was the seawall would prevent the tsunami from damaging the plant.

[Wezil]

If that is the assumption then why bother with the diesel at all? If it is the to allow a safe shutdown of a compromised plant the presumption should be that something Very Bad has happened.

[Asher]

You always need the backup cooling incase your main cooling system fails, for whatever reason. Even Chernobyl had one. Ironically, the reason Chernobyl had its accident was an experiment to try to improve how quickly the backup cooling could come online.

[Wezil]

I get that. I'm saying the backup is needed in times of dire need so why isn't it built as near impervious to outage as possible? If the backup fails you have recent news events...

[Asher]

Yeah, it's an obvious oversight in retrospect.

[Wezil]

Hindsight is always helpful.

I originally had doubts about the wisdom of nuke plants in areas prone to seismic instability but I must confess the fact these 40 year old plants are still standing at all after that shake impresses me. I presume newer plants are built to higher standards...

[Dinner]

The Diablo Canyon nuclear plant is arguably one of the worst situated in the country wrt earthquake and tsunami threats but it seems better prepared then the Japanese plant having the problem. For instance DC has it's diesel supplies underground so if a tsunami hits they can't be washed away unless the whole surface of the earth erodes away also the cooling water can be gravity fed so even if everything goes wrong you will still get water running as long as we still have gravity.

[Thorn]

does anyone know what the radiation level is now in RADS?

[Ogie Oglethorpe]

There is a lot of hindsight applied and this ends up being the basis of new regulatory requirements. Basically the NRC in the US looks at operating experience near miss incidents and holds the utilities to ever strengthening regulatory requirements.

A couple of points the diesels did activate immediately following the quake and tsunami but failed an hour later. The fuel supply was contaminated with sea water and failed due to contaminated fuel supply. The design ofnthe diesels and all associated systems withstood the impacts. The point is these safety systems are designed to withstand a design basis event. In the case of seismic forces the basis depends on the seismic surveys of the site and surrounding region. Likewise the meteorological design basis flooding etc. These are the assumptions of the design. The tsunami was far greater in magnitude then ever anticipated in the design basis. No doubt the industry will require reevaluation of design bases going forward and undoubtedly require even more conservative bases going forward.

[germanos]

I must confess the fact these 40 year old plants are still standing

Ehrrr, three blew up.

[Asher]

The Diablo Canyon nuclear plant is arguably one of the worst situated in the country wrt earthquake and tsunami threats but it seems better prepared then the Japanese plant having the problem. For instance DC has it's diesel supplies underground so if a tsunami hits they can't be washed away unless the whole surface of the earth erodes away also the cooling water can be gravity fed so even if everything goes wrong you will still get water running as long as we still have gravity.

It's also 20 years newer and has to throttle down in storms such that kelp doesn't get in the system.