Energy From Thorium Discussion Forum

It is currently Dec 15, 2017 8:57 am

All times are UTC - 6 hours [ DST ]




Post new topic Reply to topic  [ 40 posts ]  Go to page Previous  1, 2, 3
Author Message
PostPosted: Feb 28, 2015 4:46 pm 
Offline

Joined: Jul 14, 2008 3:12 pm
Posts: 5056
The 10 billion is a DTE estimate, I think. It is mentioned in various places such as here:

https://nuclearstreet.com/nuclear_power ... PI2oC6oOhk

The anti nuclear nonsense websites even claim 20 billion.

In a sane world this project should cost about $1 billion.


Top
 Profile  
 
PostPosted: May 01, 2015 10:22 pm 
Offline

Joined: Jun 19, 2013 11:49 am
Posts: 1494
Apparently the licence for Fermi 3 was issued today.


And my ongoing (currently paused due to uni exams) capacity purchase paper assumed a capital cost of between $3030/kW and $7,570/kW for a series built ESBWR (for my low and high cost cases respectively).


Top
 Profile  
 
PostPosted: May 02, 2015 1:23 am 
Offline

Joined: Sep 02, 2009 10:24 am
Posts: 508
I see the literature quotes:

Quote:
The ESBWR design's core damage frequency at power of 1.7 x 10-8/year is the absolute lowest of any advanced reactor design available in the industry today


I assume a good chunk of the approvals money has gone on establishing this fact.

For a molten salt reactor, what would be the "core damage frequency at power" target? Will regulators insist on a ultra low value as with ESBWR and EPR?


Top
 Profile  
 
PostPosted: May 02, 2015 10:05 am 
Offline

Joined: Jun 19, 2013 11:49 am
Posts: 1494
GE have been trumpetting that for years.

Because core damage = plant lost.
Which is a loss of billions of capital investment.


Top
 Profile  
 
PostPosted: May 02, 2015 6:25 pm 
Offline

Joined: Jul 28, 2008 10:44 pm
Posts: 3070
A core damage quote of 1e-6 or 1e-8 really isn't any different since at this level the important issues are the ones that were not included. I rather doubt that the accident sequences that lead to TMI, Chernobyl, or Fukushima were on anybodies fault tree evaluation of core damage frequency.


Top
 Profile  
 
PostPosted: May 03, 2015 2:26 am 
Offline

Joined: Jul 14, 2008 3:12 pm
Posts: 5056
Lars wrote:
A core damage quote of 1e-6 or 1e-8 really isn't any different since at this level the important issues are the ones that were not included.


This is true, a big issue with any type of PRA/QRA is making sure all the "what can possibly go wrong"s are covered.

In the case of the ESBWR though, seismic, fire and flood PRA was also done. The 1.7 e-8 that is often quoted is just the internal events PRA. This does include TMI type events. In the specific case of TMI though, separate requirements are in order, to design this out. In case of ESBWR it has non-reclosable depressurization and coolant injection valves. That means operators can't decide to close the coolant valves after an accident. To be fair a TMI type accident is pretty much blocked completely from the design requirements now in place for any new reactor design...

Now, fire flood and seismic analysis do have issues. Since the ESBWR has a standard license it used a number of assumptions, so it wasn't a site specific seismic PRA. As for flood only internal floods are considered, for some weird reason. I don't take issue with this for ESBWR because the design can cool its core and containment even with a flooded up basement, and no AC and DC power.

Seismic is potentially more serious. The ESBWR has been designed for a 0.3 g seismic movement. The fragility analysis showed that 0.5 g is still ok but a 1 g earthquake would produce serious damage. I wouldn't build any ESBWR in a subduction area.

Quote:
I rather doubt that the accident sequences that lead to TMI, Chernobyl, or Fukushima were on anybodies fault tree evaluation of core damage frequency.


TMI is in it, Chernobyl not but to be fair isn't relevant with such a different design (positive power coefficient, different safety systems, no containment). Fukushima now that is an interesting case. PRAs do consider station blackout (SBO). And it has been known for decades that BWRs have SBO as the dominant core damage frequency, typically it is more than 70% of the core damage frequency!! Which is why the whole design of the Fukushima Daiichi plants is so bizarre. Had they used PRA to guide the design they would certainly not have put all that critical electrical equpment in the basement. They would have known about the one in a hundred year 10-15 meter tsunamis, that would have degraded the core damage frequency to 10-2.

Even in modern PRAs though there are some weird things. The PRA typically assumes that in 24 or 72 hours, recovery will take place. But this didn't happen in Fukushima. One of the reactors had cooling for more than 72 hours, and then melted down anyway. There's many more of these arbitrary assumptions in the PRAs. Some are quite shocking, considering how much they have paid for the PRAs. Literally millions USD. For a web of assumptions! Oh yes... let's assume the nasty accident goes away after 3 days, magic!

For me it isn't the low core damage frequency of the ESBWR but the deterministic design features. Isolation condensers with actuation valves that fail in service rather than failing closed, containment cooling with no valves, inerted containment designed for 100% hydrogen generation from zircalloy clad steam reaction, passive hydrogen recombiner beds to further limit pressure buildup from hydrogen... a very robust design this.

The biggest risk actually is when the plant is shut down for refuelling. Because BWRs have to refuel with open reactor vessel and open containment. So, no reactor vessel barrier, no containment barrier, and no passive containment cooling heat sink (as this requires pressure in the containment to function), no spinning turbine to generate power... just the grid and diesels. Loss of power wouldn't be a short term problem because of all the water in the vessel plus the GDCS water supply (needs only DC power to actuate). But, long term there must be manual makeup. If there's any pipe break at the bottom of the vessel like the drain line, then it gets more serious. It is a very unlikely accident but without a containment it directly leads to a large release of fission products to the air if the operators fail to close the lower drywell hatches.

I do believe in PRA, it is theoretically a great tool for estimating risk, and with that investment and planning decisions. As well, it is a great tool to guide the design. The ESBWR for example decided to use diverse valves for the isolation condenser system, after PRA showed a great improvement from this change. Of course you could argue that you don't need PRA and can just use common sense, and that'd be a good point.

Unfortunately I'm not very confident in the actual PRAs that have been done. I take comfort in stead in the deterministic design features of these new LWRs. It is much more convincing to have a fail-safe cooling system that doesn't need power to operate.


Top
 Profile  
 
PostPosted: Jul 01, 2016 10:37 pm 
Offline
User avatar

Joined: Nov 30, 2006 3:30 pm
Posts: 3351
Location: Alabama
Toshiba withdraws ABWR certification application

Quote:
Toshiba said, "As it has become increasingly clear that energy price declines in the US prevent Toshiba from expecting additional opportunities for ABWR construction projects there, Toshiba has determined that it is no longer necessary to continue the [design certification] renewal process. Toshiba has accordingly withdrawn the application." The decision would have no impact on Toshiba's overall nuclear power business, it added.


Top
 Profile  
 
PostPosted: Jul 02, 2016 5:10 am 
Offline

Joined: Sep 02, 2009 10:24 am
Posts: 508
Is this is a reflection on the future of nuclear power in the USA? With gas prices so low, and the occasional release of zero marginal cost solar onto the market, building a nuclear plant will be difficult. Not worth the risk of spending several hundred million dollars on NRA approval.

Wouldn't it be easier to get approval in Canada and Mexico, and pipe the electricity in?


Top
 Profile  
 
PostPosted: Jul 02, 2016 6:13 pm 
Offline
User avatar

Joined: Nov 30, 2006 9:18 pm
Posts: 1954
Location: Montreal
I thought this thread was about "Status on the ESBWR licensing".


Top
 Profile  
 
PostPosted: Jul 03, 2016 6:58 pm 
Offline

Joined: Jun 05, 2011 6:59 pm
Posts: 1335
Location: NoOPWA
It is not "gas prices" per-se but the combination of large subsidies and priority placement for the unREliables backed up with low gas prices that is hammering nuclear power. If the first two factors were out if the picture, no utility with a sapient leadership would replace nuclear with gas given its propensity to be so variable in price and availability.

_________________
DRJ : Engineer - NAVSEA : (Retired)


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 40 posts ]  Go to page Previous  1, 2, 3

All times are UTC - 6 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
cron
Powered by phpBB® Forum Software © phpBB Group