Talk:Nuclear chain reaction

message: In the section "Effective neutron multiplication factor", there is a link to "Reactivity_(nuclear)" which is the same page as "Nuclear chain reaction".
165.91.10.150 (talk) 21:55, 2 December 2012 (UTC)
thread_title: Cyclical Link

message: Caesium is NOT archaic - but the standard UK spelling. Linuxlad
: You are Right see Caesium  
Scott 22:49, 13 September 2005 (UTC)
thread_title: Spelling

message: Hi,
is it really a good idea to define a nuclear chain reaction (in the introductory sentence) as always having an increasing reaction rate? In a fission reactor at normal operation, the reaction rate is controlled to be constant (k = 1), but it is still a chain reaction. 217.190.37.72 15:16, 30 May 2006 (UTC)
thread_title:  Exponential increase 

message: I don't get it. Could someone rewrite it? --Gbleem 03:14, 13 June 2006 (UTC)
thread_title:  effective neutron multiplication factor k 

message: Why was Semyonov not mentioned in this article? He was the one who developed the theory of nuclear chain reaction fully. I added passage on his work.99.231.50.118 (talk) 04:33, 31 October 2008 (UTC)
thread_title:  Semyonov 

message: This article doesn't really explain, how is criticality maintained exactly without risking an exponential run-away? Cesiumfrog (talk) 02:35, 25 March 2011 (UTC)
thread_title:  stability 

message: Every section seems to be plagued by some mention of why a nuclear reactor will not explode. I suggest either a section be created on this, or that these statements be deleted. I'm not saying these statements are wrong but they seem random and sometimes irrelevant. Here is an just such an example:
"Furthermore, all power plants licensed in the United States require a negative void coefficient of reactivity, which completely eliminates the possibility of the accident that occurred at Chernobyl (which was due to a positive void coefficient)".-if you go back and see what the original section was about you'll see how these sort of statements seem a little out-of-place. Themanofthewiki (talk) 17:40, 7 August 2011 (UTC)
replies: text: I agree that they are out of place. Also wrong. A negative void coefficient mostly refers to whether or not the moderator is water or graphite, so that bubbles make it a worse moderator, or not. In Chernobyl, what made coolant voids BETTER moderators (as rods were being inserted) was that control rods actually had graphite tips so that they increased moderation in the leading-rod area during a (slow) SCRAM while the tip was in the "wrong" place for a moment. In retrospect, a bad idea, but not an essential feature of a graphite reactor. A carbon-moderated reactor could be built to rapid SCAM and with no graphite in the control rods (indeed they could be tipped with a neutron poison, in order to avoid the Chernobyl effect).  A negative void coefficient, of course, also doesn't guarantee no explosion, since explosions can happen by other mechanisms. An explosion can happen after the reactor has already been shut down (scrammed). The explosian even at Chernobyl was a steam explosion from a power excursion from this carbon tip, slightly before SCRAM. During the Fukushima Daiichi nuclear disaster it was a hydrogen bubble caused by overheating from decay heat due to loss of coolant flow (due to loss of power for the pumps), long after the reactors had been SCRAMed. But still devastating, as fuel rod material was still exposed to the atmosphere. SBHarris 18:03, 7 August 2011 (UTC)
thread_title:  topic intrusion 

message: I feel this definition is incomplete:
"A nuclear chain reaction occurs when one nuclear reaction causes an average of one or more nuclear reactions, thus leading to a self-propagating series of these reactions. "
It should state that this must happen with low enough variance for the chain reaction not to stop: the average is not necessarily enough.  I don't know what the precise physical requirements are, however.
This is a nuanced critique that would mainly concern a VERY short period of time during which the (above, imprecise) definition for a chain reaction could be met and unmet several times, before finally it is met with 'n' high enough that the average is never wiped out by the variance, and it does not stop.
Given the nature of the article, I feel the definition should be precise.  --80.99.254.208 (talk) 18:39, 14 May 2012 (UTC)
replies: text: If you know avogadros number (and typical rates of spontaneous decay in a realistic lump of fuel) then I think the onus is on you to first demonstrate that the variance is ever actually relevant. Have you tried calculating how short that time period of concern is yet? Do you have a fuel in mind for which the variance really would be significant? (If so then maybe that could be interesting to eventually note+explain+cite in the article somewhere, but the lead should still stick to the simplified core idea IMO.) Cesiumfrog (talk) 23:08, 14 May 2012 (UTC)
replies: text:  In my opinion, it doesn't matter if it's ever actually relevant.  It's that the definition of a 'chain reactin' should never be met and then unmet and then met again - however briefly - before a chain reaction actually occurs.  Otherwise, what good is a definition? --80.99.254.208 (talk) 08:34, 15 May 2012 (UTC)
thread_title:  I feel the definition is incomplete. 

message: "The article says a few neutrons (the exact number depends on uncontrollable and unmeasurable factors." What are these factors? Is there a citation? TheDrD1ng3r (talk) 01:43, 23 June 2021 (UTC)
thread_title:  Uncontrollable 

message: "A laser is then used to enrich the hexafluoride compound." What is this supposed to mean? The gas is enriched my the centrifuge. I don't think it involves a laser TheDrD1ng3r (talk) 01:51, 23 June 2021 (UTC)
thread_title:  Enriched by laser 

message: The External Links don't appear to link to what they represent. Suggest complete removal
* Nuclear Chain Reaction Animation
* Annotated bibliography on nuclear chain reactions from the Alsos Digital Library
* Stochastic Java simulation of nuclear chain reaction Archived 2011-06-11 at the Wayback Machine by Wolfgang Bauer
MoonProjections (talk) 17:26, 11 September 2023 (UTC)
thread_title:  External Links are Broken or Non-functioning