Oroville Dam: Feds and state officials ignored warnings 12 years ago • Hacker News Board

Re: Oroville Dam: Feds and state officials ignored warnings 12 years ago

#61

Post by tristanj » Mon, Feb 13, 2017, 8:03 PM UTC

rurban wrote: post #52

tristanj wrote: post #49

Earlier quoted context omitted.

For nuclear incidents, I'm worried the next one will be in China, not in the states. China is building dozens of nuclear power plants, too quickly for the amount of trained technicians, critics say. There is also a disregard for nuclear safety standards. Last year there were 16 publicly reported incidents at Chinese nuclear power stations. According to RadioFreeAsia [1], > Six [of the 16] incidents involved staff mem…

But nobody else would be so reckless to build nuclear power plants on the ring of fire, or in major hurricane areas. Only Japan and the USA do. (Diablo, Fukushima, South Texas - even a crazy experimental one with overlarge vessels)

It's clear China has the exact issues you described. About half their nuclear power plants are in major typhoon areas; and plants in fujian and sichuan (totaling a half-dozen) are subject to major earthquakes.

Re: Oroville Dam: Feds and state officials ignored warnings 12 years ago

#62

Post by Animats » Mon, Feb 13, 2017, 8:33 PM UTC

jnsaff2 wrote: post #9

Animats wrote: post #7

As of midnight, the reservoir level was at 899.77 feet, and flow over the emergency spillway has stopped. If the level is above about 900 feet, the excess goes over the emergency spillway. Peak was around 902 feet. Data feed from dam sensors here: [1] Google Maps view of emergency spillway under normal conditions here: [2] Compare with drone footage from yesterday.[3] Main spillway (which has gates) is back in use. T…

The outflow hasn't changed so I'm not convinced that the flow over the lip has stopped. #armchairanalysis

It's good to see the lake level coming down. 896 feet now, four feet below overflow at the emergency spillway.

Don't take the outflow rate number too seriously. The emergency spillway is just a concrete lip with no flow metering. Here's the actual data source information.[1]

[1] https://cdec.water.ca.gov/cgi-progs/stationInfo?station_id=O...

Re: Oroville Dam: Feds and state officials ignored warnings 12 years ago

#63

Post by Someone » Mon, Feb 13, 2017, 11:20 PM UTC

the_cap_theorem wrote: post #56

rhizome wrote: post #50

Earlier quoted context omitted.

You can't just pave a lake, engineers have to be calculating the dirt spillways as ablative. Water is powerful stuff.

what does ablative mean in this context?

http://www.geography.learnontheinternet.co.uk/topics/river_e...:

"Rivers erode in four ways:

Abrasion or corrasion - This is when large pieces of bedload material wear away the river banks and bed.

Attrition - This is when the bed load itself is eroded when sediment particles knock against the bed or each other and break, becoming more rounded and smaller.

Hydraulic Action - This is when the force of water erodes softer rock.

Solution or corrosion - This is when acidic water erodes rock."

So, there will be larger pieces of rock intake water that hit the bank of the spillway, slowly destroying it.

When engineering the spillway, you have to take that into account.

That means we have to accept that it will need repairs after use, just as a fire extinguisher needs it after use.

Re: Oroville Dam: Feds and state officials ignored warnings 12 years ago

#64

Post by xenophonf » Tue, Feb 14, 2017, 3:22 AM UTC

coldtea wrote: post #55

xenophonf wrote: post #54

Earlier quoted context omitted.

I'll take that bet.

Well, it's always "different this time", because "newer designs". Meanwhile countless tones of toxic waster from said reactors are also transported through regular highways and roads en route to disposal and/or are dumped in the sea by governments and "cheapest offer" subcontractors (including the mafia [3]). [1] http://www.independent.co.uk/news/ministers-admit-nuclear-wa... [2] https://www.wsj.com/articles/SB100014…

As I understand it, coal-fired power plants emit more radiation than nuclear power plants:

https://www.scientificamerican.com/article/coal-ash-is-more-...

Until sufficient solar and wind power generation comes online, I would rather we use nuclear and gas-fired power plants, and in that order. I think that on the balance nuclear power is cleaner. The sooner we get off fossil fuels, the better.