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Just starting out - more on SL-1 and other topics to come. Brian Rock 03:03, 4 Dec 2003 (UTC)
Just found an entry for SL-1_Reactor_Accident, as I've learned to better navigate. I'll be merging this article into that one. Brian Rock 04:26, 6 Dec 2003 (UTC)
The SL-1_Reactor_Accident article doesn't follow the Wikipedia naming convention, so it's better to merge that description into this one and make it redirect here. Nothing links to it, perhaps because of the name. This one gets several links, probably because it has the most obvious naming. Jamesday 12:05, 8 Dec 2003 (UTC)
What are the names of the three victims? -- Mizchalmers 22:32, 8 Sep 2004 (UTC)
Zdv, Why have you removed my open link to prompt criticality in SL-1? I understand removing a redirect to nothing, but highlighting an obviously non-trivial term is deliberate and done to prompt the writing of a new article with that name. Your actions are not good editorial practice. -- Azazello 02:39, 28 Nov 2004 (UTC)
I think it is now proven fact that the explosion happened due to sabotage (homicide-suicide), because one operator learned that his wife is cheating with the other operator and decided to take the amoroso with him to the afterlife. The third, unconnected operator was just "collateral damage", so to speak.
Human passion is stronger than the atom. —Preceding unsigned comment added by 195.70.32.136 ( talk • contribs) 10:36, 7 December 2005 (UTC)
From the article:
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)
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).
Steven Casey in Set Phasers On Stun reports that the accident took place on January 3, 1961.
— Iain marcuson ( talk) 01:35, 29 October 2008 (UTC)
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)
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)
Parting note: I can't help but comment that the whole thing leaves one wondering as to why they weren't simply employing a mechanical or hydraulic jack of some kind to move the control rod, stuck or otherwise. It just doesn't pass the common sense test to not use one, especially if the rod was sticking...and known to be somewhat heavy...and highly reactive. Whatever...but it seems that a car jack would have done the trick. -- 71.42.142.238 19:22, 5 October 2007 (UTC)
The rod weighed 84 pounds, and the tests done by many men determined it was feasible and had been contemplated by the reactor operators in case the Russians attacked (I kid you not). See the Stacy book, it's free online. I like to saw logs! ( talk) 13:01, 6 March 2011 (UTC)
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/?title=SL-1&oldid=11833643 John Sheu 23:53, 21 October 2007 (UTC)
I've added a {MoreSources} tag to the top of this article as many more citations are needed to support what is being said. Please see WP:When to cite for guidance and some of the WP:GA articles for examples of how this is best done. Johnfos ( talk) 02:24, 19 December 2007 (UTC)
I read about this on the WP:3O page and decided that what's needed for now is a more appropriate tag, namely the {citations} tag; see if you all agree (I have placed it on the article, so read what it says). Hopefully some helpful editors will take the hint and move toward improving the citations. But don't be bashful about adding {citation needed} tags wherever you feel a reference is needed. Dicklyon ( talk) 00:23, 24 December 2007 (UTC)
Why does this page and Three Mile Island's page always mention how these two reactor designs were much better then RBMK? The three had accidents, for chrissake. You don't go on comparing designs when you are talking about malfunctions. The negative void coefficient didn't help to prevent the core at TMI from partially melting, and didn't prevent the explosion in SL-1. What does mentioning Chernobyl here helps to explain? It seems like someone wants to say: "Even though this one exploded, it was still much better then the commie nucular plants." -- NIC1138 ( talk) 16:22, 22 April 2008 (UTC)
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)
"The accident also showed that in a genuine extreme accident both the vaporizing of the core and the water to steam conversion would shut down the nuclear reaction. This demonstrates in a real accident the inherent safety of the water moderated design against the possibility of a nuclear explosion."
I could be wrong, but isn't this balony? if the moderator has a negative co-efficient, then the reaction is shut down and you don't *get* a core which "safely ends the excursion by exploding".
Arguing water moderation is safe because the steam explosion destroys the core (which causes massive local contamination, plus potentially larger scale contamination depending on chance and circumstance), which ends the excursion, seems absolutely duplicious, when a negative co-efficient moderator would end the excursion *without* exploding the core.
Toby Douglass ( talk) 12:28, 2 January 2009 (UTC)
Toby Douglass, Prosfilaes this was intended to address those unfamiliar with nuclear power who are worried about power reactors becoming nuclear explosions. The design was safe against that and one of my goals when describing the incident was to explain to a lay audience what happened and why it couldn't have become a nuclear explosion. Even after it killed or disabled everyone looking after it, with talk that it might have been deliberate, the design still shut itself down to the point of becoming definitively subcritical in this event. That's a success story. Not a good enough one, but it beats the alternative fears that many in the general public have.
It's still grossly unacceptable today and you're completely right that there are more inherently safe designs around. We can do without more successes like this but they still beat failures to protect the general public. Jamesday ( talk) 13:18, 12 February 2010 (UTC)
"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)
Was the operator impaled by "the" control rod, meaning the central control rod or was he impaled by another control rod? The "Idaho Falls" book says that there were several control rods. Was the operator squatting over the top of one while working on the central control rod? Tashiro ( talk) 22:03, 8 October 2009 (UTC)
We were always told in debriefs of the accident at the INEL (late 1980's) that it was the central control rod, which was moved by hand. He was presumably leaning over the reactor moving the rod when the criticality excursion occurred. Shirakhan
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).
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)
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)
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)
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)
See http://en.wikipedia.org/wiki/File:Cs-137-decay.svg I like to saw logs! ( talk) 07:20, 17 September 2012 (UTC)
At that time, I worked at the OMRE (Organic Moderated Reactor Experiment) which was a couple of miles west of the SL-1 reactor. It was clearly visible from where I worked. That night I had worked until 9 PM, which was about the same time as the SL-1 explosion. I drove home, going right in front of the road to that reactor; but emergency vehicles had not arrived yet, because they were stationed further away from the SL-1 than where I worked (they arrived about 5 minutes after I drove by). When I drove by, there was no visible evidence of any problem.
The next day, reports started coming to us regularly. Most of the report here and on YouTube is accurate, but not all. It was stated that the truth could not be told since the Army would give a large cash donation to anyone’s family who was killed by a military accident. But no such donation could be given to anyone’s family if the military person died from their own accident. This was clearly an accident caused by these three men, not a military accident. Here are some unmentioned facts that I was told in the hours and days following that accident.
There had been several alarms from the SL-1 reactor over the past few weeks or months, and the emergency vehicles always went to find the problem, but it was always something wrong with the alarm system, not a reactor or building problem. The alarm that night seem different so they were in a hurry to get there. It was known that the reactor was shut down because the main, central control rod had been sticking and was not moving up and down properly. This made the operation of that reactor very dangerous. There was a requirement that any reactor with fuel in it had to have all the monitoring equipment (electronic data recorders, meters, etc.) always on and operating so that if any strange unexpected event occurred, the data could give a clue if not all the facts as to what happened. It was also required that a control room crew would always be on duty in the control room, even if nothing was going on. So that crew that night would be bored stiff. There would never be an assignment for the control room men to do any attempts to repair the reactor problem, especially at night.
The report was that at first only one man went inside to investigate if there was any real problem. He noted that all of the recording equipment in the control room had been turned off and nobody was in there, a forbidden action. Then he went into the reactor room and saw the two men on the floor by the exploded reactor. He was not wearing any special protective clothing and he realized that he was likely seriously contaminated with radioactive material, so he promptly went outside and was monitored by another person with a radiation meter, which showed a high level of contamination. Therefore he had to strip naked (at minus 17 degrees) and go to an outside shower facility to wash most of the rest of the contamination off of his skin. This was a very difficult task, but he succeeded. He was then taken back to the main building while others started the investigation as described on YouTube.
At first, only the two men on the floor were seen, and the third man was not seen for several hours, probably not until daylight. It was seen that both of these men had their faces impacted with many pieces of glass. When the third man was seen, it was obvious that the reactor's central main control rod had gone into his body and pinned him to the ceiling. This made it perfectly obvious that he had been standing above that control rod when the explosion occurred.
Putting these known facts together made it obvious what had happened. The top of the reactor cover had a few glass windows so that a person could look inside the reactor when needed. But it was not allowed just for curiosity. These men decided that they wanted to go and see the beautiful blue-purple colors of a nuclear reactor in water. I have seen such more than once, and it is just indescribable in its beauty. No doubt these men had heard of such a sight, so they decided to shut off the monitoring equipment to prevent their experiment from being recorded (all but an outside air monitor which really recorded very little).
Whether or not this was the first experiment, it is obvious that the one on top was pulling the control rod up while the other two were watching to see the reaction. So the control rod must have jammed just below the critical elevation. Then that person on top pulled with all his might to get it to move again. When he pulled hard enough, he raised it several inches too far! That caused an immediate nuclear reaction (much heat), not like an atomic bomb, just an extreme amount of heat in a very short time, a few thousandths of a second. That heat boiled the water making a very high powered steam explosion which blew the glass out of the viewing windows into the faces of the two men looking inside, and it ejected the control rod with such velocity that it sent the man holding it to the ceiling and pinned him there. Of course, as the control rod went out, the reactor power went much higher, causing an increase in the steam explosion's power.
The rest of the report is quite accurate. I remember watching the big rigs that went inside the reactor casing to remove the man on top and do the other work as described. — Preceding unsigned comment added by 66.31.196.155 ( talk) 02:45, 9 April 2013 (UTC)
There appears to be a document titled "SL-1 Accident Investigations Report," of which I know of a few pictures appearing elsewhere. I am not sure if this is available by a FOIA, but here is the link to some of it: http://www.mooj.com/rxdept_page28.htm see http://www.mooj.com/images/rx-041204-SL1.jpg I like to saw logs! ( talk) 17:13, 5 November 2013 (UTC)
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)
The article says: Without sufficient moderator, cores such as SL-1 would be unable to sustain a nuclear chain reaction. Note that this has over 93% enrichment, which can easily sustain a reaction without moderator. But yes, at low enrichment moderators are needed. Gah4 ( talk) 09:15, 26 May 2023 (UTC)
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)
Can abnormally large reactivity worth be made to sound better. The worth seems especially strange here. Gah4 ( talk) 22:46, 15 April 2024 (UTC)
This is the
talk page for discussing improvements to the
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Just starting out - more on SL-1 and other topics to come. Brian Rock 03:03, 4 Dec 2003 (UTC)
Just found an entry for SL-1_Reactor_Accident, as I've learned to better navigate. I'll be merging this article into that one. Brian Rock 04:26, 6 Dec 2003 (UTC)
The SL-1_Reactor_Accident article doesn't follow the Wikipedia naming convention, so it's better to merge that description into this one and make it redirect here. Nothing links to it, perhaps because of the name. This one gets several links, probably because it has the most obvious naming. Jamesday 12:05, 8 Dec 2003 (UTC)
What are the names of the three victims? -- Mizchalmers 22:32, 8 Sep 2004 (UTC)
Zdv, Why have you removed my open link to prompt criticality in SL-1? I understand removing a redirect to nothing, but highlighting an obviously non-trivial term is deliberate and done to prompt the writing of a new article with that name. Your actions are not good editorial practice. -- Azazello 02:39, 28 Nov 2004 (UTC)
I think it is now proven fact that the explosion happened due to sabotage (homicide-suicide), because one operator learned that his wife is cheating with the other operator and decided to take the amoroso with him to the afterlife. The third, unconnected operator was just "collateral damage", so to speak.
Human passion is stronger than the atom. —Preceding unsigned comment added by 195.70.32.136 ( talk • contribs) 10:36, 7 December 2005 (UTC)
From the article:
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)
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).
Steven Casey in Set Phasers On Stun reports that the accident took place on January 3, 1961.
— Iain marcuson ( talk) 01:35, 29 October 2008 (UTC)
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)
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)
Parting note: I can't help but comment that the whole thing leaves one wondering as to why they weren't simply employing a mechanical or hydraulic jack of some kind to move the control rod, stuck or otherwise. It just doesn't pass the common sense test to not use one, especially if the rod was sticking...and known to be somewhat heavy...and highly reactive. Whatever...but it seems that a car jack would have done the trick. -- 71.42.142.238 19:22, 5 October 2007 (UTC)
The rod weighed 84 pounds, and the tests done by many men determined it was feasible and had been contemplated by the reactor operators in case the Russians attacked (I kid you not). See the Stacy book, it's free online. I like to saw logs! ( talk) 13:01, 6 March 2011 (UTC)
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/?title=SL-1&oldid=11833643 John Sheu 23:53, 21 October 2007 (UTC)
I've added a {MoreSources} tag to the top of this article as many more citations are needed to support what is being said. Please see WP:When to cite for guidance and some of the WP:GA articles for examples of how this is best done. Johnfos ( talk) 02:24, 19 December 2007 (UTC)
I read about this on the WP:3O page and decided that what's needed for now is a more appropriate tag, namely the {citations} tag; see if you all agree (I have placed it on the article, so read what it says). Hopefully some helpful editors will take the hint and move toward improving the citations. But don't be bashful about adding {citation needed} tags wherever you feel a reference is needed. Dicklyon ( talk) 00:23, 24 December 2007 (UTC)
Why does this page and Three Mile Island's page always mention how these two reactor designs were much better then RBMK? The three had accidents, for chrissake. You don't go on comparing designs when you are talking about malfunctions. The negative void coefficient didn't help to prevent the core at TMI from partially melting, and didn't prevent the explosion in SL-1. What does mentioning Chernobyl here helps to explain? It seems like someone wants to say: "Even though this one exploded, it was still much better then the commie nucular plants." -- NIC1138 ( talk) 16:22, 22 April 2008 (UTC)
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)
"The accident also showed that in a genuine extreme accident both the vaporizing of the core and the water to steam conversion would shut down the nuclear reaction. This demonstrates in a real accident the inherent safety of the water moderated design against the possibility of a nuclear explosion."
I could be wrong, but isn't this balony? if the moderator has a negative co-efficient, then the reaction is shut down and you don't *get* a core which "safely ends the excursion by exploding".
Arguing water moderation is safe because the steam explosion destroys the core (which causes massive local contamination, plus potentially larger scale contamination depending on chance and circumstance), which ends the excursion, seems absolutely duplicious, when a negative co-efficient moderator would end the excursion *without* exploding the core.
Toby Douglass ( talk) 12:28, 2 January 2009 (UTC)
Toby Douglass, Prosfilaes this was intended to address those unfamiliar with nuclear power who are worried about power reactors becoming nuclear explosions. The design was safe against that and one of my goals when describing the incident was to explain to a lay audience what happened and why it couldn't have become a nuclear explosion. Even after it killed or disabled everyone looking after it, with talk that it might have been deliberate, the design still shut itself down to the point of becoming definitively subcritical in this event. That's a success story. Not a good enough one, but it beats the alternative fears that many in the general public have.
It's still grossly unacceptable today and you're completely right that there are more inherently safe designs around. We can do without more successes like this but they still beat failures to protect the general public. Jamesday ( talk) 13:18, 12 February 2010 (UTC)
"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)
Was the operator impaled by "the" control rod, meaning the central control rod or was he impaled by another control rod? The "Idaho Falls" book says that there were several control rods. Was the operator squatting over the top of one while working on the central control rod? Tashiro ( talk) 22:03, 8 October 2009 (UTC)
We were always told in debriefs of the accident at the INEL (late 1980's) that it was the central control rod, which was moved by hand. He was presumably leaning over the reactor moving the rod when the criticality excursion occurred. Shirakhan
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).
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)
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)
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)
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)
See http://en.wikipedia.org/wiki/File:Cs-137-decay.svg I like to saw logs! ( talk) 07:20, 17 September 2012 (UTC)
At that time, I worked at the OMRE (Organic Moderated Reactor Experiment) which was a couple of miles west of the SL-1 reactor. It was clearly visible from where I worked. That night I had worked until 9 PM, which was about the same time as the SL-1 explosion. I drove home, going right in front of the road to that reactor; but emergency vehicles had not arrived yet, because they were stationed further away from the SL-1 than where I worked (they arrived about 5 minutes after I drove by). When I drove by, there was no visible evidence of any problem.
The next day, reports started coming to us regularly. Most of the report here and on YouTube is accurate, but not all. It was stated that the truth could not be told since the Army would give a large cash donation to anyone’s family who was killed by a military accident. But no such donation could be given to anyone’s family if the military person died from their own accident. This was clearly an accident caused by these three men, not a military accident. Here are some unmentioned facts that I was told in the hours and days following that accident.
There had been several alarms from the SL-1 reactor over the past few weeks or months, and the emergency vehicles always went to find the problem, but it was always something wrong with the alarm system, not a reactor or building problem. The alarm that night seem different so they were in a hurry to get there. It was known that the reactor was shut down because the main, central control rod had been sticking and was not moving up and down properly. This made the operation of that reactor very dangerous. There was a requirement that any reactor with fuel in it had to have all the monitoring equipment (electronic data recorders, meters, etc.) always on and operating so that if any strange unexpected event occurred, the data could give a clue if not all the facts as to what happened. It was also required that a control room crew would always be on duty in the control room, even if nothing was going on. So that crew that night would be bored stiff. There would never be an assignment for the control room men to do any attempts to repair the reactor problem, especially at night.
The report was that at first only one man went inside to investigate if there was any real problem. He noted that all of the recording equipment in the control room had been turned off and nobody was in there, a forbidden action. Then he went into the reactor room and saw the two men on the floor by the exploded reactor. He was not wearing any special protective clothing and he realized that he was likely seriously contaminated with radioactive material, so he promptly went outside and was monitored by another person with a radiation meter, which showed a high level of contamination. Therefore he had to strip naked (at minus 17 degrees) and go to an outside shower facility to wash most of the rest of the contamination off of his skin. This was a very difficult task, but he succeeded. He was then taken back to the main building while others started the investigation as described on YouTube.
At first, only the two men on the floor were seen, and the third man was not seen for several hours, probably not until daylight. It was seen that both of these men had their faces impacted with many pieces of glass. When the third man was seen, it was obvious that the reactor's central main control rod had gone into his body and pinned him to the ceiling. This made it perfectly obvious that he had been standing above that control rod when the explosion occurred.
Putting these known facts together made it obvious what had happened. The top of the reactor cover had a few glass windows so that a person could look inside the reactor when needed. But it was not allowed just for curiosity. These men decided that they wanted to go and see the beautiful blue-purple colors of a nuclear reactor in water. I have seen such more than once, and it is just indescribable in its beauty. No doubt these men had heard of such a sight, so they decided to shut off the monitoring equipment to prevent their experiment from being recorded (all but an outside air monitor which really recorded very little).
Whether or not this was the first experiment, it is obvious that the one on top was pulling the control rod up while the other two were watching to see the reaction. So the control rod must have jammed just below the critical elevation. Then that person on top pulled with all his might to get it to move again. When he pulled hard enough, he raised it several inches too far! That caused an immediate nuclear reaction (much heat), not like an atomic bomb, just an extreme amount of heat in a very short time, a few thousandths of a second. That heat boiled the water making a very high powered steam explosion which blew the glass out of the viewing windows into the faces of the two men looking inside, and it ejected the control rod with such velocity that it sent the man holding it to the ceiling and pinned him there. Of course, as the control rod went out, the reactor power went much higher, causing an increase in the steam explosion's power.
The rest of the report is quite accurate. I remember watching the big rigs that went inside the reactor casing to remove the man on top and do the other work as described. — Preceding unsigned comment added by 66.31.196.155 ( talk) 02:45, 9 April 2013 (UTC)
There appears to be a document titled "SL-1 Accident Investigations Report," of which I know of a few pictures appearing elsewhere. I am not sure if this is available by a FOIA, but here is the link to some of it: http://www.mooj.com/rxdept_page28.htm see http://www.mooj.com/images/rx-041204-SL1.jpg I like to saw logs! ( talk) 17:13, 5 November 2013 (UTC)
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)
The article says: Without sufficient moderator, cores such as SL-1 would be unable to sustain a nuclear chain reaction. Note that this has over 93% enrichment, which can easily sustain a reaction without moderator. But yes, at low enrichment moderators are needed. Gah4 ( talk) 09:15, 26 May 2023 (UTC)
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)
Can abnormally large reactivity worth be made to sound better. The worth seems especially strange here. Gah4 ( talk) 22:46, 15 April 2024 (UTC)