Talk:Harry Daghlian

message: How should the name Daghlian be pronounced? Is the gh silent? Winston.PL 19:17, 6 January 2007 (UTC)
replies: text: Not that we know he used any Armenian, but in Armenian it's pronounced  (Հարութիւն Գրիգոր Տաղլեան). As far as English is concerned, the MPHPA say it was pronounced 'dolly-an', make of that what you will. – Quoth (talk) 11:52, 13 April 2010 (UTC)
thread_title:  Pronunciation 

message: Criticality accidents makes it clear that such incidents do not produce enough thermal energy to raise the temperature of the sphere by much more than 100 degC, so how could it have been hot enough to nearly to melt? A reliable source is needed to back up that statement. Dan100 (Talk) 20:45, 4 October 2007 (UTC)
replies: text: It doesn't matter what that article says, but what the truth is. Criticality accidents in assemblies like this will result in phase change to liquid or gas if reactivity is sufficiently high. The exact effective multiplication factor necessary to effect this is geometry and material dependent, but Los Alamos's analysis of the Arzamas-16 accident states that reactivity of greater than 120 cents will cause assembly vaporization. The demon core reached at least 100 cents.VmZH88AZQnCjhT40 (talk) 22:41, 19 February 2015 (UTC)
thread_title:  "Enough to melt the sphere" 

message: The article refers to the core going 'prompt critical' and the reference cited states 'super prompt critical' however the link to prompt critical states that it is a special case  of super criticality occurring over microseconds and resulting in explosive disassembly. This does not seem to have occurred.
Is the term 'prompt critical' incorrect or is the linked definition incorrect?  —Preceding unsigned comment added by 203.31.40.71 (talk) 02:44, 28 January 2008 (UTC)
replies: text: "Prompt critical" means critical on the basis of prompt_neutrons alone.  "Super critical" means more than critical.  Since the total neutron production is formed by prompt neutrons plus delayed neutrons, a prompt critical assembly is by definition super critical when delayed neutrons are added.  The prompt critical link is a bit overstated when it comes to explosive disassembly in microseconds, but the time constant for neutron multiplication is correct.  JohnAspinall (talk) 00:51, 30 April 2008 (UTC)

text: The reference states that the assembly was "superprompt critical." This is a technical term which specifically means that the assembly is supercritical on prompt neutrons alone. Reactivity significantly in excess of prompt criticality is necessary to cause fuel vaporization (~>1.2 times prompt criticality). See LA-13600. Just because a nuclear power reactor would be destroyed by a prompt criticality doesn't mean a bare sphere would. VmZH88AZQnCjhT40 (talk) 22:57, 19 February 2015 (UTC)
thread_title:  prompt critical? 

message: If he was working alone, how is it possible for anyone to describe the accident in detail? "As he was moving the final brick over the assembly, neutron counters alerted Daghlian to the fact that the addition of this brick would render the system supercritical. As he withdrew his hand, he accidentally dropped the brick onto the center of the assembly." Then, we are told that he panicked. Next, we know exactly what he did after he panicked. All of this must be the result of rational inference, but it is not a certain description of the actual events. How could it be?Lestrade (talk) 00:59, 11 December 2009 (UTC)
replies: text: Presumably they got a full debrief report from Daghlian ASAP after the accident. He would have been conscious and (at least for some hours) not even in much pain. Then his hands would have started to swell and hurt, he'd have had nausea, and so on. SBHarris 02:44, 11 December 2009 (UTC)
replies: text: Oh, no, not after a whole body dose of 5 gray. That's barely 50% fatality level (he would probably have survived today). It takes doses of 80 Gy or 16 times that dose to incapacitate soldiers from CNS-swelling effects, in a few hours, as (for example) with a "neutron bomb." Daghlian should have had little more than nausea, diarrhea, and some hand pain for at least several days, and been completely coherent otherwise (if somewhat anxious, knowing he had a good chance of eventually dying from infection and bleeding as his bone marrow failed). SBHarris 02:41, 12 December 2009 (UTC)
thread_title:  Inferences 

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thread_title:  File:Radiation Burn Hand of Daghlian.png Nominated for Deletion 

message: Thanks for the close, BD2412.  The original move (here) had nothing unusual about it, and was several days after the close of the RFC and revision of WP:JR that said no-comma is preferred, so I'm wondering why you added "Whether the move was correct as a matter of process in the first place" to your closing statement.  As far as I know, I did nothing questionable there.  Let me know if you see an issue, otherwise I'll consider it water under the bridge.  Thanks again. Dicklyon (talk) 01:24, 22 April 2016 (UTC)
thread_title: Postscript

message: This may not be the right place but what I'm wondering about is what specifically this early criticality experiment sought to find out.
In a "normal" quantitative science experiment, what you do is keep all parameters constant except one, which you vary in order to obtain different results. These results then make it possible to arrive at formulas or algorithms to describe the interrelations between the different parameters.
For example, a simple experiment about the electrical conductivity of liquid solutions would be to dip two electrodes into a sample solution, apply a current and measure the voltage. In a series of experiments you could then vary the distance between the electrodes, or the concentration of the solution, or the current, or the voltage etc, and even do multiple series for different electrolytes to compare those to each other, and arrive at the specific conductivity of given electrolytes.
Now it is clear that in the criticality experiment, they measured neutron flux. But the variable parameter in the Daghlian experiment seems to have been the "number of reflector blocks" which seems oddly undspecific; the results would seem to be applicable only to his sepcific experimental set-up. Cancun (talk) 12:10, 23 November 2021 (UTC)
thread_title:  Criticality experiment specifics