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the navy taught me, in 1979, that SCRAM meant Super-Critical Reactor Axe Man. of course, you can't always believe the navy. — Preceding unsigned comment added by 98.111.199.243 ( talk) 21:17, 26 October 2013 (UTC)
Searching on google show's the term to be Safety Control Rod Axe Man. Also referenced in Control Rod. Amazon also has quite a large number of books on it. Linky. Makes more sense too imo.. (Feel free to change it otherwise if any other sources contradict that..) Nikwong 14:02, 28 October 2007 (UTC)
I've heard the term used as Supercritical Reactor Axe Man.
I've heard US Navy nukes use the above term. Oversoul 01:35, 2 December 2005 (UTC)
After reading the jargon file, I tend to agree with the nukes more than the jargon file. "Safety cut rope axe man" doesn't even make sense. "Supercritical reactor axe man" does. I'll look into this more. Oversoul 01:40, 2 December 2005 (UTC)
I've read that at the Chicago-reactor (1st reactor) there were also a "suicide team" of people standing on a balcony with buckets of "neutron-killer" to poure over the reactor if something happened. Can someone confirm/refute this?
In the Wikipedia entry on Norman Hilberry I notice the following:
On December 2, 1942, he was present for the start up of Chicago Pile-1, the world's first nuclear reactor to achieve criticality. Hilberry stood ready with an axe to cut the scram line, a manila rope connected to control rods that could quickly shut the reactor down. [1] [2]
☺ Dick Kimball ( talk) 13:30, 12 January 2016 (UTC)
I have never in many years of nuclear power operations, both navy and civilian, heard a scram referred to as a "trip." Citation, please? ➥the Epopt 16:49, 25 February 2007 (UTC)
"On a SCRAM, 99.3% of the reaction is almost immediately stopped. The remaining 0.7% continues to generate "decay heat" for some time"
I'm not exactly where this number was pulled from but it is most assuredly wrong and misleading. A scram adds a massive amount of negative reactivity into the core and this obviously makes it highly subcritical. In a couple of minutes the neutron induced fission reactions will be many orders of magnitude below any threshold to measure their heat generation. Saying that 99.3% of the reaction is stopped is misleading at best. This number is probably referencing the heat generation produced by the reactor, but it is wrong as well. If you separate the prompt and delayed parts of a fission reaction apart you will find that 6.5% of the energy is delayed (excluding neutrinos which don't add heat). Thus if you scram the reactor, you will initially have at least 6.5% of the initial power output. I say "at least" because you have to sum up the decay heat from all of the different nuclides in the core at the time of shutdown. This means you have to know the power history. If your core was operating at 100% power for a long time and then shut down, you will have to add in the decay heat from the long-lived radioactive nuclides. And if your core was just started up, pushed to 100% power and then scrammed, you will not have had time to build up a large concentration of long-lived radioactive nuclides. Thus in the first case you will start out above 6.5% and this value will decrease as short-lived nuclides decay and only long-lived nuclides remain. From there it will slowly decrease based on the half-lives and concentrations of all of the different radioactive nuclides in the core. In the second case, you will start out at 6.5% and this value will rapidly drop to almost zero as very little long-lived nuclides exist.-- Burzum 22:06, 19 May 2007 (UTC)
This claim definitely needs a citation. I have heard many different expansions of the SCRAM acronym, but this is a new one to me. It doubly needs the citation because it is in an etymology section. Cheers.-- Burzum 08:11, 14 October 2007 (UTC)
I've heard two though the years. "Safety, Cut the Rope, Axe Man" and "Safety Control Rod, Axe Man". I've never heard of the others. —Preceding unsigned comment added by 66.191.2.195 ( talk) 03:36, 28 August 2008 (UTC)
I attended Navy Nuclear Power School in NTC Orlando and was told the Super-Critical Reactor Ax Man version. Not saying it's true, just that NPS is likely the source of this version. — Preceding unsigned comment added by 2601:602:9201:2C00:5529:ADF8:7EC4:B03C ( talk) 02:11, 15 June 2016 (UTC)
This section of the article is wrong (there really isn't a better word to describe its condition right now). I'll try writing an article on reactivity that will more clearly describe how prompt neutrons and delayed neutrons work in a nuclear reactor and how they affect the effective neutron lifetime which will be important to understanding how a massive insertion of negative reactivity will affect the core of a nuclear reactor. The fact that we don't have a decent article covering reactor kinetics is probably causing too much confusion among people who have little experience in nuclear engineering. Until then this section will need to be toned down. For anybody that is confused about what I'm talking about Volume 2 of the DOE Fundamentals Handbooks on Nuclear Physics and Reactor Theory describes how a scram works in more detail. If you understand how reactor kinetics, the failures of this section will be obvious but difficult to explain without another article on reactor kinetics. Cheers.-- Burzum ( talk) 14:51, 31 January 2008 (UTC)
This ORNL page describes an account by Wally Koehler, who was actually standing on top of the pile when it went critical. He describes the "SCRAM" as the FIRST line of defense, with him and two others standing by with "vessels" (buckets) of cadmium sulfate in case that proved insufficient. So, not superfluous. Since that's a first-hand account, and it's on the ORNL site, I think maybe we should consider it authoritative? Graft | talk 03:39, 19 December 2008 (UTC)
A few years ago, while working at Hanford, I had the pleasure of talking with a retiree. He was one of the other two men, standing on top of the pile, along with Wally Koehler. His story of SCRAM was essentially the same as Wally's. Now we've got two of the three men with buckets to dump saying the same thing. They were backups (Defense in Depth) in case the control rod stuck, after the axe man cut the rope. Of course, if they had to have dumped their buckets, the only next step would have been to tear the pile apart and clean up everything, then rebuild it. —Preceding unsigned comment added by 68.186.74.80 ( talk) 15:47, 25 October 2009 (UTC)
The oldest reference that I have found citing the origin of the word SCRAM is: Raymond L. Murray, "The Etymology of 'Scram,'" Nuclear News, 31, August 1988, pp 105-107; "Letters," Nuclear News, 31, December 1988, pp 17-18. Now this is referenced in a document titled "Glossary of Nuclear Criticality Terms LA-1 1627-MS UC-714 Issued: October 1989". This 2nd document may be found here. However I can find no online copies of the original document. SunSw0rd ( talk) 23:46, 13 October 2010 (UTC)
Move etymology to top to be congruent with other articles? 79.160.41.207 ( talk) 03:00, 5 April 2011 (UTC)
Right now, the article name is 'Scram', but the term it is about is either 'scram' or 'SCRAM'. It seems to me that the title should be changed to 'SCRAM'. —Preceding unsigned comment added by 75.171.255.25 ( talk) 02:08, 13 May 2011 (UTC)
I have made a minor edit to the etymology section referencing a recent NRC article that disputes the tradition history of the term. Hopefully others will be able to rework the section in the light of this. Sidefall ( talk) 12:35, 24 May 2011 (UTC)
I've added Iodine pit to "see also", but it'd be better to include a line or two about it in the "reactor response" section. The basic issue is that, for some reactor designs, the reactor cannot be restarted for tens of hours after a rapid shutdown from full power. Perhaps someone who is better versed on this topic could add a brief explanation. Will Beback talk 22:48, 28 May 2011 (UTC)
I have changed this to read "under the spectator seating" as the term "bleachers" is not generally understood outside North America. 94.247.241.90 ( talk) 21:03, 10 May 2014 (UTC)
I believe the title, as it is an acronym, should be changed to SCRAM. Also, both "SCRAM" and "Scram" are used several times throughout the article. I think these should be changed for consistency to SCRAM, but they should also match the title of the page. Fhutch21 ( talk) 22:12, 5 May 2016 (UTC)
Means what and this is on someones ankle for a home monitor. ???? Explained definition! 2601:845:8100:350:4114:82B:A2EF:A3F2 ( talk) 23:42, 9 April 2024 (UTC)