Talk:Boiling water reactor

message: I feel that much of this article is overly technical for an encyclopedia and focuses too much on details without providing a good overview for people who do not already know a lot about nuclear reactor technology. I have therefore included a brief introductory paragraph and tried to simplify the introductory text while keeping the most relevant parts. I think the later parts of the article would also benefit from cleaning up, and that a lot of the content should be removed, but don't want to make too drastic a change in one go. For example, I don't think that the sections "Start-up", "Reactor Protection System" and "Thermal Margins" really belong in an encyclopedia as they're too detailed and technical and likely to confuse the typical reader. The result that I have in mind would look more like the article on PWRs. Please comment if you have objections.
90.201.125.188 (talk) 00:10, 28 March 2009 (UTC)
replies: text: My thoughts: I understand why you did it, and I agree that the appropriate place for this more technical material might not be this article (perhaps an article like boiling water reactor startup operations or boiling water reactor thermal margins). However, WP is not paper, so we have space, and if the material's notable (it isn't about some local band or a minor character in some obscure anime) and verifiable (it isn't about something which hasn't been written about before in reliable sources), better to keep the material there. It isn't cited, but that doesn't mean that it isn't verifiable - and nobody's claimed that it's incorrect - not great, but not too unusual around here. If you don't object, I'll restore it, within the next day or two, perhaps with a tag to see what the consensus is - whether to split it into its own article at some point down the road. Katana0182 (talk) 03:37, 3 April 2009 (UTC)
replies: text: I'm also in favor of valid material not going away completely. I'd like to see it stay either in this article or another one. --JWB (talk) 06:17, 3 April 2009 (UTC)

text: Agreed, restore the material.  I think a better way to remove unnecessary detail in the article would be to split out the technical detail into other/new articles about them and keep a summary here, with a link to the new articles for further reading.  But if everything is incorporated well, it could stay here.  I'll admit it has been a long time since I read through the article in its entirety though.  Lcolson (talk) 13:12, 3 April 2009 (UTC)

text: The thermal limits portion is not strictly correct. The quantities that must be maintained less than 1 are referred to as thermal margins: MFLCPR (Maximum Fraction of Limiting Critical Power Ratio -- which is a ratio of a ratio), MAPRAT (Maximum Fraction of Limiting APLHGR), FDLRX (Fraction Design Limit Ratio for AREVA fuel), and MFLPD (Maximum Fraction of Limiting Power Density for GE fuel). These are ratios between current values and allowable values (thermal limits). The article doesn't mention PCIOMR (preconditioning heatup rate), which is used to prevent pellet-clad interaction due to the fact that the pellet swells more than the cladding during heatup. Thermal limits are a complex topic and probably should have their own article. 208.46.0.26 (talk) 22:43, 22 April 2009 (UTC)
replies: text: As per your comment, I'm going to tag the Thermal Margins section as potentially being misleading, further, I'm going to post a template to request expert assistance. If you can help fix this, it would be great, as many of us don't know this technical stuff. Thanks for telling us.Katana0182 (talk) 20:01, 16 May 2009 (UTC)
thread_title: Too technical and detail-focused

message: Most other similar lists have a page of their own. It would also help make the BWR page more concise. 213.55.27.154 05:52, 16 February 2007 (UTC)
thread_title: List of BWRs should be a separate article

message: (The title of this section was added by 213.55.27.154 05:52, 16 February 2007 (UTC)
thread_title: Clarification of changes

message: :Dont read too much into the extremely simplified diagram. I doubt that the water/steam is carried by a peice of PVC pipe hung between the two buildings ;) . Post Chernobyl, Hundreds of meticulous engineers will pour over a single reactor design before it is finalized. Hundreds more will do so again during the approval process, not to mention the thousands of peer reviews! In short, even a minutely flawed design would not get approved.
:--distantbody 13:13, 7 December 2005 (UTC)
replies: text: -- 1:05 21st April 2008 (BST)
The above statement is somewhat ludicrous. Do some research on the Chernobyl accident and you'll find that numerous laws and procedures were violated and safety systems disabled to set up the conditions that led to the event. The reactor was less safe than US designs, but not as the previous comment makes it out to be.
208.46.0.26 (talk) 22:24, 22 April 2009 (UTC)
thread_title:  RE: BWR is not safe. 

message: Both the BWR and the PWR are designed to the same safety-related criteria with regard to probability of accidents, requirements for accident mitigating equipment, reliability of accident-mitigating safety systems, and allowable releases of radioactivity during postulated accidents.  The general methods of achieving the required levels of safety are similar for both designs.  Specifically, with regard to a postulated failure of steam piping outside the BWR containment -- all BWRs include primary containment isolation valves both directly inside and directly outside the penetration points; these are not shown on the simplified drawing.  If a pipe break occurs outside the containment, the valves will quickly close to isolate the reactor inside the containment from the broken piping outside the containment.  PWR designs include similar valves in the secondary loop -- so, there is little fundamental difference in BWR and PRW design with regard to this detail.  A statement that BWRs are "not safe" or even "not as safe as PWRs" is simply wrong.  No one with detailed understanding of either system and the underlying design criteria would make such a sweeping generalization.
BoHawk 13:33, 21 December 2005 (UTC)
thread_title:  Short Rebuttal to "BWR is not safe" 

message: This definetely needs a introduction cleanup - please put it in simpler English! 124.168.77.95 11:06, 31 May 2006 (UTC)
thread_title:  Requires cleanup for intro 

message: The image BoilingWaterReactor.gif is over 800kB in size!  Is this necessary? 203.132.67.89 09:23, 20 December 2006 (UTC)
thread_title:  Image Size 

message: Should there be something about the history also: 
I found this post in the "atomic blog" containing an interview with an insider ...
 YordanGeorgiev (talk) 07:11, 27 November 2007 (UTC)
thread_title:  Something about history 

message: I find the "advantages" and "disadvantages" part of this article and the PWR article informative. I was wondering if people feel that perhaps the articles could move towards some conclusions, like about the merits of each design? Is there any literature that's been written about the comparative overall merits of these two light-water reactor systems that could provide answers about this? 
From what I've gathered, from these articles, and elsewhere...
*BWRs are more forgiving of human error and improper maintenance standards than PWRs?
*PWRs are more compact than BWRs?
*BWRs are mechanically simpler than PWRs?
*PWRs operate more efficiently than BWRs?
*BWRs are cheaper than PWRs?
*PWRs are simpler to operate than BWRs, due to the two-phase flow of both water and steam in the core?
*As to which design is safer--I can't even begin to speculate...are there informed opinions either way?
*Human factors--which designs do operators and maintenance personnel tend to prefer? (Or is it like a Ford vs Chevy thing?)
Any conclusions that can be drawn either way on either design?
Katana0182 (talk) 05:42, 28 October 2008 (UTC)
replies: text: Too controversial. - Depends on which model of BWR you compare with its contemporary PWR ? - Rod57 (talk) 11:35, 17 October 2021 (UTC)
thread_title: Overall evaluation of BWR v. PWR?

message: Please, don't use that old DBA definition. You explain it as nowadays no longer used term "Maximal credible accident".
The plant has to be designed (in terms of e.g. redundancy, equipment qualification, etc.) to handle so called enveloping DBAs (so not just one). However there are some very unlikely accidents going beyond DBAs, called Beyond DBAs (BDBAs) or Design Extension Conditions (DECs). These include Severe Accidents (core melt) and Complex Sequences (e.g. containment bypass). And of course new plants have to be designed to cope with such accidents as well. The difference is, the requirements are not so strict (e.g. single failure does not have to apply, radiological impact limits are higher, etc.).  —Preceding unsigned comment added by 89.102.54.239 (talk) 21:10, 21 August 2009 (UTC)
thread_title:  DBA 

message: Many mistakes for the European BWRs:
*Germany: All BWR's are not GE-type, instead fully new invented design by Siemens-KWU! Neither BWR 1-6 nor Mark 1-3!
*Sweden: Same problem, design by Asea, the former ABB! Neither BWR 1-6 nor Mark 1-3 
*Switzerland: In fact GE-type, but wrong details: Mühleberg 355 MW-el., BWR-4, Mark-1 ; Leibstadt: 1150 MW-el., BWR-6, Mark 3 
--62.202.237.115 (talk) 13:49, 8 October 2009 (UTC)
replies: text: Sorry to correct you, but the German BWRs were almost all designed by AEG (which is today more commonly known as manufacturer of washing machines and ovens). AEG had acquired a license from GE in the 1960s and designed a total of nine plants (Gundremmingen, Lingen, Großwelzheim, Würgassen, Brunsbüttel, Tullnerfeld, Isar 1, Philippsburg 1 and Krümmel), the last six of which are commonly known as "Type 69". After the Würgassen accident in 1972 the nuclear branch of AEG was sold to Siemens in 1976, which completed the five half-finished plants and developed an own line of BWRs ("Type 72") of which only two units were built at Gundremmingen B & C. GE later copied the Gundremmingen design and used it to develop the ABWR. --Ironclad G (talk) 18:23, 20 March 2011 (UTC)
thread_title:  List of BWRs  

message: See : http://www.bbc.co.uk/news/world-12723092 using a graphic similar to :File:Schema reacteur eau bouillante.svg. Teofilo talk 15:27, 12 March 2011 (UTC)
replies: text: Indeed, and they don't even give credit. On German news channel N24 I also briefly saw a diagram that looked suspiciously identical. It's kind of sad the mainstream media are passing off Wikipedia material as their own. --Morn (talk) 17:30, 12 March 2011 (UTC)

text: Our SVG has apparently been specifically created for Wikipedia based on a previous PNG version. Somehow I think it would be a huge coincidence if BBC/N24 came up with their own versions that just happened to have exactly the same shapes, colors, and general layout as ours. --Morn (talk) 17:04, 14 March 2011 (UTC)
replies: text: I have added Commons:Template:published to  with the legal parameter set to "no". -84user (talk) 18:11, 14 March 2011 (UTC)
replies: text: BBC has used the file again today, and this time with proper attribution: Source: RobbyBer/Wikimedia --Morn (talk) 15:38, 16 March 2011 (UTC)
thread_title:  BBC using similar looking file and caption 

message: The article incorrectly states that Russian RBMK reactors are BWR's- they are not.  In fact they are not even Light Water Moderated Reactors (LWR's).  Russain RBMK reactors are graphite moderated reactors and their design is not remotely similar to a BWR or to any LWR.  —Preceding unsigned comment added by 173.30.155.115 (talk) 23:55, 12 March 2011 (UTC)
replies: text: At least it is a single-cycle reactor type which generates steam inside the reactor like BWRs. In older Russian and German publications the RBMK is in fact termed "Pressure-Channel Boiling Water Reactor". --Ironclad G (talk) 18:07, 20 March 2011 (UTC)
thread_title:  Russian RBMK reactors are not BWR's 

message: The live video feed of Fukushima No. 1 reactor building exploding spectacularly probably spells the end of BWR and only PWR will survive renewed scrunity, yet this article lacks an on-going event tag, even though F3 may also blow up according to recent news? 82.131.131.75 (talk) 23:53, 13 March 2011 (UTC)
replies: text: In Germany all NPPs completed before 1981 have been temporarily shut down after the Fukushima accident. This leaves only one BWR still in operation (Gundremmingen). Theoretically they could be start up again in three months after safety inspections, but with a couple of important elections coming and a traditionally very strong anti-nuclear sentiment here, no-one from the plants expects them to ever reconnect to the grid. --Ironclad G (talk) 18:02, 20 March 2011 (UTC)
thread_title:  Fukushima - The end of BWR? 

message: One of the parameters that the article did not state was to what Richter level the reactor was built to withstand. Clearly not an 8.9! Most of the world's BWR reactors are in areas where earthquakes of that magnitude are not experienced. In the Eastern US, the worst was the New Madrid around 1812, the worst of which was estimated at a high of around 8.1. This would have been 1/256 the power of the lowest estimate of the Fukushima earthquake. The designers must have had something in mind. What was it? Student7 (talk) 17:37, 19 March 2011 (UTC)
replies: text: According tho Japanese media after the earthquake in 2007 Japanese NPPs are designed to withstand quakes of 7.75 magnitude. Some time after 2007 the authorities decided that this should be improved to 8.25, but I don't know if any plant was upgraded due to this. --Ironclad G (talk) 17:54, 20 March 2011 (UTC)
replies: text: As it turns out, the explanation is a lot simpler than I thought. The system was built to "withstand" this earthquake (not necessarily "not fail" just not "fail hard"). What caused the problem (as we all know now) is the lack of power to force water through at a critical juncture. The backup power plant was build to withstand a tsunami ("high water mark") of . The water actually rose to , drowning the backup power. The answer, simple on Monday morning, is to raise the backup power higher. Don't know how high in Japan, but most places don't even begin to have this problem. Not a problem away from the ocean, for example. Student7 (talk) 18:55, 20 March 2011 (UTC)

text: One issue with using the Richter scale is it only describes the energy released from the earthquake. It does not give you any information regarding the actual peak-ground-acceleration at the plant's site. For example, a plant could handle a 9.0 from 100 miles away but not from 20 miles away. Instead nuclear plants are rated on peak-ground-acceleration in all three directions. This makes it difficult to correlate to Richter scale, and confuses regular people and the media.  — Preceding unsigned comment added by 198.29.191.149 (talk) 18:01, 9 September 2011 (UTC)
replies: text:  That problem/confusion with using the Richter scale is still in some of the nuclear power articles. Where is the best explanation ? When it says "designed to withstand quakes of 7.75 magnitude" should that include " epicentre within X km of plant" ? - Rod57 (talk) 11:52, 17 October 2021 (UTC)
thread_title: Richter scale - distance from epicentre 

message: "Water exiting the fuel channels at the top guide is about 12 to 15% saturated steam (by mass)" - ??
12% steam *by mass* would mean that more than half of the volume of the water/steam mass exiting the core is steam.
In other words: steam is less dense than water, 12% steam *by mass* has to correspond to much more than 12% steam *by volume*.
Now imagine what would happen if about half of the water by volume turns into steam... that's WAY too energetic boiling!
I suspect that the phrase should read "... about 12 to 15% saturated steam (by volume)".  — Preceding unsigned comment added by 209.132.186.34 (talk) 15:31, 26 May 2011 (UTC)
replies: text: Actually, the steam quality is 12 to 15% which is just a little different than talking about % volume or % mass.  Steam quality exiting the ssteam separator is about 90% and steam that exits the steam dryer is better than 99%.  — Preceding unsigned comment added by 216.99.184.50 (talk) 19:50, 6 December 2011 (UTC)
thread_title:  Error? % steam by mass or volume 

message: There seems to be a lack of anything on waste produced by the reactor, how long it is radioactive, whether it can be reprocessed and what is the rate of waste produced per unit of power produced. This seems a relevant section to be added given the longevity of some radioactive wastes.
dinghy (talk) 12:55, 31 October 2012 (UTC)
thread_title:  Waste 

message: The following is currently a point under the `Disadvantages` section of the article,
"A nuclear power plant requires active cooling for a period of several hours to several days following shutdown, depending on its power history. Full insertion of BWRs control rods safely shuts down the primary nuclear reaction. However, radioactive decay of the fission products in the fuel will continue to actively generate decay heat at a gradually decreasing rate, requiring pumping of cooling water for an initial period to prevent overheating of the fuel. If active cooling fails during this post-shutdown period, the reactor can still overheat to a temperature high enough that zirconium in the fuel cladding will react with water and steam, producing hydrogen gas. In this event there is a high danger of hydrogen explosions, threatening structural damage to the reactor and/or associated safety systems and/or the exposure of highly radioactive spent fuel rods that may be stored in the reactor building (approx 15 tons of fuel is replenished each year to maintain normal BWR operation) as happened with the Fukushima I nuclear accidents."
Firstly, the claim is false.  Reactors do not always require active cooling, and in fact, decay heat is less of a problem for BWRs than for other reactors since BWRs benefit from buoancy-driven flow to a greater extent than other designs. The ultimate example of this is the ESBWR, which requires no active cooling whatsoever.
Secondly, it is really unjustified for a discussion of decay heat (which occurs in every type of reactor) to be listed as a disadvantage, since the advantages/disadvantages section seems to be geared towards comparing the BWR design against other reactor designs, not comparing nuclear vs. non-nuclear power.  If the section were contextualized to compare nuclear vs. non-nuclear power, then it should also include things like cost per kW-hr, average deaths per kW-hr, etc.
So unless there is a rebuttal to my points, I'm going to remove the point regarding decay heat from the disadvantages section. 130.113.78.26 (talk) 16:36, 1 March 2013 (UTC)
replies: text: I agree that decay heat is a function of all power reactors, however decay heat in bwrs, even months after shutdown, needs to be removed. The fuel for bwrs is safe even with no forced flow or after being uncovered for periods of time, but, it is the eventual boil off that causes problems. Regardless it is not a specific BWR disadvantage and should stay removed.  — Preceding unsigned comment added by 50.81.208.229 (talk) 03:27, 14 May 2013 (UTC)
thread_title:  Decay Heat 

message: Going over the article, I think it might be time to remove the technical flag. The very technical information is specifically 'sequestered' in a section called Technical and Background Information. Readers are told what to skip if they do not need a technical understanding of thermal limits.
I've seen articles which are definitely too technical, but this is not one. Readers can quite easily find what suits their needs, whether they are interested in a basic understanding of how PWR works or a more detailed level of knowledge. 
How do you vote/propose to remove the too technical flag?
Roches (talk) 15:53, 26 February 2014 (UTC)
replies: text: Someone has  it. - Rod57 (talk) 11:54, 17 October 2021 (UTC)
thread_title:  Time to remove the too technical flag? 

message: Could say more on  the number of cooling loops - there seem to be 2/3/4 loop designs. Are the turbines and generators all part of a specific cooling loop; no steam cross-feeding ? Could maybe clarify that the diagrams only show a single cooling loop ? - Rod57 (talk) 12:56, 17 October 2021 (UTC)
thread_title:  Could say more on  the number of cooling loops