The Atomic Show #057 – Boiling Water Reactors
Shane and Rod discuss boiling water reactors, one of the two types of established light water reactors.
There are two main types of light water reactors, pressurized water reactors (PWR) and boiling water reactors (BWR). They share some characteristics, but also have a number of differences.
There are plenty of sources of information on the web about the tradeoffs between the two technologies. You can seek them out, or you can listen to Shane and I muddle our way through an audio explanation on this show. We think that you might find the show entertaining and educational enough to spur additional interest. Enjoy.
Here are some sources of additional information:
- ESBWR fact sheet from Energetics.com
- Large view (1.16 MB) of ESBWR from GE. Shane and I are impressed by the details and clarity of this drawing. It looks best on a large screen.
- Natural circulation in ESBWR fact sheet
- Hitachi’s ABWR Key Features and an Update
- Video of the opening of the first private Atomic Power Plant at Vallecitos, CA
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# The steam generator on a PWR is essentially the same shape as heat exchanger in any coal or gas fired thermal plant. The tubes are u-shaped as Rod incideated and the flow is ALWAYS counter to the incoming steam. There is a divider inserted inisde the ‘crease’ where the tubes are bent to come back 180 degrees. This divider allows steam on the outsdie to flow around the *entire* length of the tubes and in the opposite direction.
# Since I work in a steam plant I know a little ‘bit about this. The ‘void above the reactor’ mentiond about the BWR functions as the same as a steam drum does in the above mentioned non-nuclear plants setups. It ‘collects’ the steam in a ‘pack’ which is bled off (full flow, actually) to the high-pressure section of the turbine. In inside a conventional steam drum there are also nifty little items call “cyclone seperators” which are various sized ‘studs’ in the shape of an inverted tornado which forces steam up through it, spinning the drops of water against the metal and displacing the steam into the drum.
Some drums also have baffles which accomplishs the same thing.
David Walters
Below are a couple of web links which may be of interest. The first from ANS is an article which describes how the passive safety features work in the ESBWR. Diagrams are included that show the different flow paths.
http://www.ans.org/pubs/magazines/nn/docs/2006-1-3.pdf
If you liked the 3-D view of the ESBWR from GE, you might enjoy the following YouTube video of the Areva EPR. It is a computer-generated animation sequence with narration describing the major EPR design features. Of course, the EPR is a PWR.
http://www.youtube.com/watch?v=mPi2kT_RbCI
The Areva website has this video and a few others with more information.
The EPR also has a core-catcher to contain molten fuel in case of the worst-case accident. The EPR core catcher seems to be larger than the ESBWR BiMAC core catcher, which doesn’t appear to be much larger in diameter than the reactor vessel. According to the design information on the NRC website, BiMAC stands for Basemat- Internal Melt Arrest Coolability.
Rod and Shane,
Excellent show! A couple of comments on the ESBWR vs. the ABWR: the ESBWR has fewer components overall, and far fewer ACTIVE components which should equate to (1) a lower capitol investment, and (2) lower operating costs because there will be fewer periodic test to run and fewer pumps, valves, and instruments to maintain. Fewer components means fewer failure scenarios, and that means a safer plant (lower core damage frequency for you PRA gurus).
While not finalized, an ESBWR is proposed for the second unit at the Grand Gulf site in Mississippi.
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