Why Aren't Nuclear Power Plants Built Underground?

[vemvare]

Perhaps this is a very stupid question, but why aren't nuclear power-plants built underground?

In a subterranean structure I'm thinking any natural disaster would at worst collapse the cavity without spreading radioactivity.

Are subterranean construction really so intrinsically difficult that the costs would skyrocket compared to an "overground" plant?

 

[Schr0d1ng3r]

There are some current designs which feature underground containment. B&W's mPower SMR, for example: http://www.babcock.com/products/modular_nuclear/

 

[Astronuc]

Perhaps this is a very stupid question, but why aren't nuclear power-plants built underground?

In a subterranean structure I'm thinking any natural disaster would at worst collapse the cavity without spreading radioactivity.

Are subterranean construction really so intrinsically difficult that the costs would skyrocket compared to an "overground" plant?

There are increased costs associated with building the structure underground, as well as seismic (coupling with the surrounding ground) and flood considerations.

 

[CFDFEAGURU]

Has B&W sold one of the mPower designs yet?

 

[Hiddencamper]

Has B&W sold one of the mPower designs yet?

I'm not positive if they've "sold" one, but they did win that money from the DoE and are supposedly going to be working with TVA on building a site.

 

[Astronuc]

Has B&W sold one of the mPower designs yet?

mPower has teamed with TVA (utility) and Bechtel (A&E), so there appears to be intent on the part of TVA to purchase a unit. It would be constructed at the Clinch River site, where CRBR was supposed to have been built.

http://www.babcock.com/products/modular_nuclear/generation_mpower.html
http://www.babcock.com/news_and_events/2012/20121120a.html
http://www.generationmpower.com/about/
http://www.dailyfinance.com/2012/11/20/bw-selected-as-winner-of-does-small-modular-reacto/
http://www.world-nuclear-news.org/NN-mPower_empowered_by_SMR_funds_121112a.html

 

[nikkkom]

Perhaps this is a very stupid question, but why aren't nuclear power-plants built underground?

In a subterranean structure I'm thinking any natural disaster would at worst collapse the cavity without spreading radioactivity.

In order to prevent meltdown, you need to cool the reactor. Just burying it won't help that much - it will melt there too, and very hot contaminated steam WILL find a way out.

 

[mheslep]

There may or may no have been some commercial sales/funding for small modular, but there certainly has been no Combined Operating Licence issued in the US. Nor is a small modular COL likely in the next ten years.

 

[mheslep]

In order to prevent meltdown, you need to cool the reactor. Just burying it won't help that much - it will melt there too, and very hot contaminated steam WILL find a way out.

Unless its a fluid fueled reactor, with gas cooling. If a commercial reactor is ever to be buried, I can't imagine it would be a pressure water reactor.

 

[Hiddencamper]

Unless its a fluid fueled reactor, with gas cooling. If a commercial reactor is ever to be buried, I can't imagine it would be a pressure water reactor.

If you bury some other reactor type, the decay heat will eventually heat up the atmosphere and pressurize it even without steam. This ultimately could lead to failure of the structure (if decay heat loads are high enough). It would likely take longer to occur though.

 

[Astronuc]

There may or may no have been some commercial sales/funding for small modular, but there certainly has been no Combined Operating Licence issued in the US. Nor is a small modular COL likely in the next ten years.

Southern Company reports that the NRC commissioners voted to approve the COL for Vogtle 3&4 (twin AP-1000s).

The Nuclear Regulatory Commission (NRC) voted today to approve the issuance of the Combined Construction and Operating License (COL) for Plant Vogtle units 3 and 4, the first such license ever approved for a U.S. nuclear plant. Receipt of the COL signifies that full construction can begin.

Construction is underway - http://www.southerncompany.com/nuclearenergy/presskit/home.aspx

http://www.nrc.gov/reactors/new-reactors/col/vogtle.html#col

Issuance of Combined Licenses And Limited Work Authorizations For Vogtle Electric Generating Plant (VEGP) Units 3 And 4.
Accession Number: ML113540620
Date Released: Friday, February 10, 2012
http://pbadupws.nrc.gov/docs/ML1135/ML113540620.html

February 10, 2012

Mr. Joseph A. “Buzz” Miller
Executive Vice President
Southern Nuclear Operating Company
241 Ralph McGill Blvd.
BIN 10232
Atlanta, GA 30308-3374

SUBJECT: ISSUANCE OF COMBINED LICENSES AND LIMITED WORK
AUTHORIZATIONS FOR VOGTLE ELECTRIC GENERATING PLANT (VEGP)
UNITS 3 AND 4

The U.S. Nuclear Regulatory Commission (NRC) has issued Combined Licenses (COLs)
NPF-91 and NPF-92 to Southern Nuclear Operating Company and its co-applicants Georgia
Power Company, Oglethorpe Power Corporation, Municipal Electric Authority of Georgia and
the City of Dalton, Georgia pursuant to Title 10 of the Code of Federal Regulations (10 CFR)
Section 52.97, “Issuance of combined licenses.” These licenses were issued after receiving the
report of the Advisory Committee on Reactor Safeguards dated January 24, 2011, and as
authorized by the Commission’s hearing decision dated February 9, 2012. In addition, the
NRC has issued Limited Work Authorizations (LWAs) LWA-001 and LWA-002 pursuant to
10 CFR Section 50.10, “Licensed required; Limited Work Authorization.”

http://pbadupws.nrc.gov/docs/ML1133/ML113360395.pdf

The DCD is up to Rev. 19

 

[Tepconium-311]

As Astronuc said, underground nuclear plants are much more expensive to build.

And they aren't much safer.
Crooked Swiss Lucens mountain nuclear plant made groundwater in its vicinity unusable because of high radioactive contamination.
Soviet Union had a number of weapon plutonium reactors built in mountain caverns, but these were not used for electricity generation iirc.

 

[vemvare]

So it was as I feared, it isn't the superior concept it appeared to be at a glance.

Thanks for all help!