Talk:SL-1

message: Just starting out - more on SL-1 and other topics to come. Brian Rock 03:03, 4 Dec 2003 (UTC)
thread_title: 2003

message: What are the names of the three victims? --Mizchalmers 22:32, 8 Sep 2004 (UTC)
thread_title: 2004

message: From the article:
:The three most common theories proposed for this discrepancy are sabotage or suicide attempt by one of the operators, inadvertent withdrawal of the main control rod, which was known to be "sticky," or an intentional attempt to "exercise" the sticky rod, to make it travel more smoothly within its sheath.
Suicide is right out, since the designers didn't even know you could cause an explosion by withdrawing the control rod too far.
The main control rod was the only control rod that didn't have a history of sticking. Not to say that it didn't stick that night, just that it hadn't before. AEC investigators made extensive trials to reproduce the accident by having men pull on mock-control rods and releasing the rods suddenly. They also tried goosing the men (giving the test lifters an unexpected pinch in the rear, as Legg was suspected of having done), but never were the 100-lb bars lifted more than a few inches.
Similarly, the "exersizing" the operators had been doing previously only consisted of sliding the rod up and down a few inches.
The article's statement remains true, however, that those are the three most common theories. The article needs to also mention that the reactor design was also to blame. The control rods could get stuck, as mentioned. Withdrawing a single center control rod could send the core to critical (which is a reactor flaw unique to the SL-1 design). Boron "poison" meant to quell the excessive radiation when the uranium fuel was new was supposed to be alloyed into the fuel itself. This proved to great a metalurogical challenge for the time, so they just tacked on boron-alluminum allow strips to the fuel. The strips flaked off over time, so the degree of control the operators had over the nuclear reaction was narrowed and partially unknown.
Tafinucane 21:05, 28 December 2005 (UTC)
replies: text: There was an article on this in one of the science magazines in the 1960's. I don't recall which one, could've been Popular Science or Science and Mechanics. It had a few photos, including one of the flaked and swelled boron "poison strips" that frequently caused the control rods to stick. The theory it presented was that the strips caused the main rod to stick and the operator had to pull hard on the rod to reconnect it to its motor drive. The rod popped free and *boom*. IIRC it said that a different crew had been there earlier to service the control rod drives and had left it to the next shift to reconnect them. —Preceding unsigned comment added by Bizzybody (talk • contribs) 04:45, 27 November 2008 (UTC)
thread_title:  Causes ideas 

message: I'm not sure if the SL-1 accident took place on January 3 (1961). I have a Ryszard Szepke's book in which it is written that the event was on January 10.
Please, verify this information. —The preceding unsigned comment was added by Krzy B (talk • contribs) 20:14, 12 April 2007 (UTC)
thread_title:  Problem with date 

message: My edit was intended to fix the link for Roentgen to point to the unit of measurement rather than the disambiguation page. Although it appears as R%C3%B6ntgen in the edit summary, the text appears properly in the rendered page in my browser and the link in my revision points where I intended. Is there a problem in other browsers or is the "rubbish text" just in the edit summary? Langhorner 13:15, 28 August 2007 (UTC)
replies: text: Hi there,I am very sorry, and you are correct, your version does appear correct in the rendered page-to me the edit appeared as rubbish characters-as you described. Next time I'll be a little more careful before I jump on perceived vandalism. your edit does appear to fix the link! i'll revert my own (incorrect) edit.--Read-write-services 22:51, 28 August 2007 (UTC)
thread_title:  Röntgen -- rubbish text? 

message: My recollection from many years ago is that the operator's actions regarding over-withdrawal were established by after-accident analysis to be intentional, though his reasoning for doing so remained unknown. Reasoning: the weight of the control rod was fairly substantial (75 lbs or so?) and precluded an unintentional move of 16 inches or so, including the scenario of the sudden freeing of a stuck rod. Reconstruction via manual tests, including stuck-rod scenarios, confirmed this (again, as best I can recall). However, I'm so-far not able to find a reference for the weight of the rod. At this point, I can only leave this note for future editors' consideration. --71.42.142.238 18:57, 5 October 2007 (UTC)
thread_title:  Weight of "the" control rod 

message: As far as I can tell, Jordan is a company that does manufacture dosimeters and the like. But a "redector" is likely a misspelling of "detector", and in any case, I don't see the point of pointing it out as a Jordan model. I'm going to revert this phrase to the verbiage as of two years ago, at here: http://en.wikipedia.org/w/index.php?title=SL-1&oldid=11833643 John Sheu 23:53, 21 October 2007 (UTC)
thread_title:  "Jordan redector" 

message: In other sources, I find references that contractors' representatives were visiting the site, etc. I can't seem to find the name of the primary contractors on the project. Was it the U.S. Army Corps of Engineers? Westinghouse? Who? If this were an article entirely on the accident, it might not be as relevant. But in an article on the reactor itself, it certainly seems relevant -- "built between June 2040 and January 2041 by Spacely Sprockets," certainly would be a useful fact to include. This article actually starts with a maintenance shutdown, which obviously implies that it had been operational for at least one period previously. --Thatnewguy (talk) 13:48, 22 May 2008 (UTC)
replies: text: I don't have a copy of the references handy but I'm pretty sure the maintenance was handled by the Army itself and the construction was done by military personnel. I think that the design was probably contracted out, but I don't know who made it. IIRC, the reactor was operational for a year or so--long enough to discover that the control rod channel was getting clogged by material rubbing off the walls. Protonk (talk) 20:35, 22 May 2008 (UTC)
thread_title:  Contractors? Construction timeline? 

message: "abandoned its reactor program in 1965" I'm a veteran of the Army Nuclear Power Program, and I served there from March 1968 to March 1971. Best I recall, the program shut down around 1974. Several years ago I had a website on the ANPP (and the Army Air Defense Command Nike missile system), and I had some materials from other ANPP vets who knew the folks killed at the SL-1, personally. I don't know, however, being a newbie, how I can incorporate any of that here, since it would be hearsay and not reference-able. Also, there was a comment above about "poorly trained operators." That, I can from personal experience assure you, is nonsense. The ANPP program was quite rigorous (I was a licensed Control Room Operator, and for a time the Health Physics Supervisor, of the SM-1 at Ft. Belvoir).
Also, I added a link for "health physics" since many readers won't know what that is.
Rb88guy (talk) 02:39, 6 January 2009 (UTC)
thread_title:  At least one wrong date; added a link. 

message: Whoever wrote the section on prompt criticality seems to be confusing two important concepts in reactor control: prompt criticality and fast fission. Prompt criticality is determined by prompted and delayed neutrons. Fast fission is determined by fast or thermal neutrons. "Prompt" and "fast" are not the same thing.
Fast fission occurs when a high-energy (i.e. not thermalized) neutron splits a nucleus, usually U-238, which would simply absorb a thermal neutron. Fast fission happens all the time, and is a minor contributing component of the overall reactivity of the core.
Prompt neutrons are created by the fission of a nucleus. Delayed neutrons are released during the radioactive decay of certain fission products, and they occur up to several seconds after the initial fission. Prompt Criticality occurs when the core achieves criticality using only prompt neutrons (i.e. those produced by fission alone), and the additional "delayed neutrons" released by fission product decay serve to accelerate the chain reaction to a state of supercriticality (i.e. increasing power level). Prompt Criticality has nothing to do with the thermalization time of the neutrons.
The explanation of how the accident occurred seems to confuse these two concepts (unless they're teaching a whole new kind of nuclear engineering now than they were 20 years ago). Would take some effort to disentangle the two.Shirakhan —Preceding undated comment added 19:00, 16 October 2009 (UTC)
replies: text: Shirakhan, your point is noted. I just read through the article and indeed it's my judgment as well that the reactor physics and kinetics discussion in that section were misleading and seemed confused particularly on the issues of delayed neutrons and moderation. I've attempted a quick fix; give it a look. Much more could be done to make this article accurate, documented, and comprehensive. I hope some other people with particular expertise in the subject will kick the can down the road.--Carlwillis (talk) 10:00, 11 November 2009 (UTC)
thread_title:  Prompt Criticality is a function of delayed neutrons, not thermalization 

message: Not right at SL1 and post-accident. But at the site. It is an eerie place. It really resembles something you would expect in Nevada or the like. The climate is a true dessert (less than 10 inches per year rain), more arid than most of the arid Southwest. Nobody lives near the site. Everyone drives or more usually is bussed in (this is a lot like the Nevada test site, I've also been there and it is eerie too.) You could LITERARALLY blow up a big atom bomb at the site and people in nearby towns would be OK. I'm not saying a reactor is a bomb...but it seems like they were super cautious when siting this stuff at the beninging of the atomic age. There are all kinds of little tiny antelope (well really small) that run around. They have the use of the site since there is no hunting there. It's really an amazing place... —Preceding unsigned comment added by 69.250.46.136 (talk) 17:49, 1 November 2010 (UTC)
thread_title:  I worked out there a little 

message: The article repeatedly says that the core and its components vaporized. That's usually a term for liquids... or for magic. Which is it? The fuel plates made of aluminum probably did not turn into a vapor. The article makes this assertion SIX times (as a verb form) for the core, whereas it mentions the water vapor as a (noun) ONE time. I think we need a revision here unless someone has some temperatures to corroborate this. I like to saw logs! (talk) 12:55, 6 March 2011 (UTC)
replies: text: Okay, to answer my own question, the fuel in the core apparently did vaporize. Although a prompt critical reactor can be shown to avoid a core meltdown and vaporization, the huge amount of positive reactivity (well over $3, with one dollar being prompt critical) caused the fuel to literally fly apart before the water boiled to steam and appreciably cooling it. I would imagine the Maxwell–Boltzmann distribution of the atoms made the fuel quite erratic to pin down what phase it was in! This is reported in IDO-19313 Additional Analysis of the SL-1 Excursion, Final Report of Progress July through October 1962, November 1962. I like to saw logs! (talk) 07:33, 15 March 2011 (UTC)
thread_title:  The reactor core "vaporized"? 

message: I personally know Bob Archer (Rupert Idaho) one of the first responder firefighters. I asked him for the names of those firefighters on duty who responded to the incident. He named Ken Dearolon Asst Chief, Mel Hess Lt., Bob Archer, Carl Johnson, Egon Lamprecht, & Vern Conlon. I have added their names to the page. According to Bob, he and Egon are the only ones still alive. As a side note Bob has never had cancer! --Tomhung357 (talk) 15:32, 8 April 2011 (UTC)
thread_title:  Firefighters 

message: In the fourth paragraph "Results from the surveys indicated that cesium-137 and its progeny (decay product) are the primary surface-soil contaminants." I do not believe that the product of Cs-137 decay, stable Ba-137 possibly as the carbonate, would be a significant source of contamination. Darian2 (talk) 03:17, 16 September 2012 (UTC)
replies: text: Well if cesium-137 decays to barium, isn't its poisonous nature enough to be a "contaminant"? The sentence doesn't define what sort of contamination it is speaking of. In any case, 137m1Ba can be detectable in the debris with instrumentation that can find the characteristic 661 KeV gamma rays. 95% of the cesium will therefore emit this gamma on top of the already significant contamination beta of 512 KeV. The beta is indicative of contamination. Since its progeny emits the gamma a few minutes later, I would call this a contaminant. And if the cesium/barium (meta state) are indeed so plentiful after 50 years, they would surely top the list of any other contaminants as far as abundance and radioactivity goes. Strontium-90 might be a distant third here, especially since no one is crawling around the Idaho desert where SL-1 blew up and it is unlikely to get mobile in the environment there.
See http://en.wikipedia.org/wiki/File:Cs-137-decay.svg
I like to saw logs! (talk) 07:20, 17 September 2012 (UTC)
thread_title:  Cleanup 

message: The T and cross shaped control/fuel rods, are these vertical in the reactor core? It is hard to visualise from the description. Why are they this shape Vs just straight control rods? Tttonyyy (talk) 11:51, 12 January 2020 (UTC)
thread_title:  Reactor configuration 

message: This core did not melt down. Using the term "meltdown" is completely erroneous, since it was destroyed by mechanical explosion. i.e. "catastrophic disassembly." I have kept a single incidence of the erroneous term at the top of the article, primarily due to its use as a non-technical description of a nuclear reactor that overheats and is destroyed from its own heat. It probably should have scare quotes, as it is a so-called "meltdown." As the article states, corium was not found in it. I like to saw logs! (talk) 18:32, 14 April 2024 (UTC)
thread_title:  Not a meltdown 

message: Can abnormally large reactivity worth be made to sound better. The worth seems especially strange here. Gah4 (talk) 22:46, 15 April 2024 (UTC)
thread_title:  ''abnormally large reactivity worth''