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  • #16
    Originally posted by Doozer View Post

    We have? How do you know I have heard of that?
    Unless we are secret lovers and I talk in my sleep?

    -D
    OK but you gotta spoon me.





    The shortest distance between two points is a circle of infinite diameter.

    Bluewater Model Engineering Society at https://sites.google.com/site/bluewatermes/

    Southwestern Ontario. Canada

    Comment


    • #17
      Originally posted by Paul Alciatore View Post
      Yea, cut the rope and stop the reactor from going critical. Reactor time to go critical = micro seconds or less. Reaction time of man with ax plus time needed for the rod to fall = many seconds.

      Guess who/what wins.

      Annnnnnnnd it's Reactor by a million or more!

      and

      Ax man = TOAST!

      There is just no way that the ax man could react fast enough to stop an accident if it got out of control. And he probably knew that.
      I don't believe they had enough material to go boom but used it keep the radiation levels from going to high if things went wrong. Considering this was the very first attempt, at doing something that no one understood very well, it was probably a good if possibly non-effective idea.
      The shortest distance between two points is a circle of infinite diameter.

      Bluewater Model Engineering Society at https://sites.google.com/site/bluewatermes/

      Southwestern Ontario. Canada

      Comment


      • #18
        I never heard this term before, but again, I am also not in the nuclear industry.

        Comment


        • #19
          Originally posted by J Tiers View Post
          That is probably a "backronym"...... created later to cover the situation. ....
          That implies an acronym therefore precedes the terms it represents. Not so - it's simply a pronounceable abbreviation, regardless of whether it's the chicken or the egg.
          Lynn (Huntsville, AL)

          Comment


          • #20
            Originally posted by lynnl View Post

            That implies an acronym therefore precedes the terms it represents. Not so - it's simply a pronounceable abbreviation, regardless of whether it's the chicken or the egg.
            But the word existed........ The WORD (scram) being already present (slang) suggested some mental gymnastics to turn it into an amusing acronym after the fact. Hence "bacronym".

            Besides, the entire legend has been thoroughly de-bunked, so it simply did not happen until way after the event. No "genuine" acronym, just one created later to use existing slang.
            2801 3147 6749 8779 4900 4900 4900

            Keep eye on ball.
            Hashim Khan


            It's just a box of rain, I don't know who put it there.

            Comment


            • #21
              Can you reference that for us.
              The shortest distance between two points is a circle of infinite diameter.

              Bluewater Model Engineering Society at https://sites.google.com/site/bluewatermes/

              Southwestern Ontario. Canada

              Comment


              • #22
                Try Post #10
                2801 3147 6749 8779 4900 4900 4900

                Keep eye on ball.
                Hashim Khan


                It's just a box of rain, I don't know who put it there.

                Comment


                • #23
                  I do not know if they had enough fissionable material to go boom, in light of the small size of some A-bombs, they very well may have. But their reactor was not a bomb. The design, the very geometry of that reactor would have prevented that. What they could have had was a run-away reaction which is precisely what they were worried about because it would have exposed them to a lot of radiation and contaminated the whole area as well as possibly a melt-down.

                  Such a run-away reaction has been witnessed in several reactor accidents around the world, and it usually results in a melt-down. When those reactors had run-away reactions and they did have explosions (of a sort) those explosions were not of a nuclear nature (as in A-bomb). They were the result of extremely hot cooling fluids producing a pressure beyond the ability of the containment structure to hold. Those explosions were more akin to what happened when steam locomotives exploded. Radioactive material was present and was scattered around the general area, but they were not nuclear explosions.

                  It is almost completely impossible for a reactor, modern or even that first one, to produce a nuclear explosion. The requirements for that are simply far too much beyond any reactor's design, even when they fail.

                  PS: That first reactor did not have any kind of containment structure. It only had shielding to keep the amount of radiation that the people present were exposed to. It may have melted down, but it could not have even had the type of high pressure gas explosion that I described above.



                  Originally posted by loose nut View Post

                  I don't believe they had enough material to go boom but used it keep the radiation levels from going to high if things went wrong. Considering this was the very first attempt, at doing something that no one understood very well, it was probably a good if possibly non-effective idea.
                  Paul A.
                  SE Texas

                  And if you look REAL close at an analog signal,
                  You will find that it has discrete steps.

                  Comment


                  • #24
                    It was a primitive version of the Chernobyl reactor, sans containment. That does not necessarily mean it could do the same thing..... because it had no containment.

                    It could run away. Going "boom" requires a lot of speed in getting the critical mass assembled. (Implosion, or gun firing a plug into a ring, for instance) That would not be happening with the reactor they had.
                    2801 3147 6749 8779 4900 4900 4900

                    Keep eye on ball.
                    Hashim Khan


                    It's just a box of rain, I don't know who put it there.

                    Comment


                    • #25
                      Originally posted by Paul Alciatore View Post
                      Yea, cut the rope and stop the reactor from going critical. Reactor time to go critical = micro seconds or less. Reaction time of man with ax plus time needed for the rod to fall = many seconds.

                      Guess who/what wins.

                      Annnnnnnnd it's Reactor by a million or more!

                      and

                      Ax man = TOAST!

                      There is just no way that the ax man could react fast enough to stop an accident if it got out of control. And he probably knew that.
                      You seem to have a misunderstanding of how the Chicago pile was designed and operated and what it means to go critical. It took them hours to reach criticality and they toasted with champagne when it finally did go critical. That was the whole point of the experiment... Indeed, commercial reactors operate at criticality. It just means the reaction is producing enough neutrons to sustain itself, a bit like kindling a fire. At some point you can take away the torch / match / ignition source and the fire feeds itself.

                      Just like a fire, nuclear reactions can get "out of control" (which, as you point out, is a melt-down or thermal explosion - never a nuclear explosion due to the quantity and geometry of the fuel) but the time for it to get out of control is highly dependent on a number of factors. Indeed, it usually takes a long time and many poor decisions or many failed pieces of equipment to put a reactor in the position of getting out of control. The time from "dire situation" to "massive steam explosion" (a'la Chernobyl) can indeed be on the order of microseconds, but the runup to that situation is slow, often hours or more.

                      The axe man and bucket man at the Chicago pile were part of the safety mechanisms designed to prevent that slow runup to a dire situation. Although, to be fair, it is doubtful there was enough fuel there to cause a fire, let alone an explosion of any kind. A single control rod was more than sufficient to kill the reaction entirely. The Chicago Pile, despite it's size and weight, operated at about 1/2 watt of power. Even if that was converted with 100% efficiency to electrical power, you'd be hard pressed to light up a flashlight bulb with it. It was a science experiment to demonstrate the feasibility of a controlled, sustained nuclear reaction.

                      But, yeah, SCRAM is not an acronym. Consensus seems to be that it was coined by Bill Wilson, one of the physicists who designed the control rod circuitry.


                      A few other notes:

                      1) I should point out that, even in commercial reactors, due to the use of a moderator to sustain the reaction, there is a window on the order of minutes, NOT microseconds, within which to make adjustments / changes to the reactor. The control circuitry and safety circuitry used in the reactors works on the order of seconds, looking at second-by-second data and making changes. The feedback loops don't need to operate at the microsecond level. So, although things can go from "not exploded" to "exploded" in microseconds, the reaction time of the people / machines controlling the system doesn't need to be nearly that good.

                      2) CP-1 had NO intentional radiation shielding or cooling water. IIRC, the maximum theoretical thermal output of the configuration was maybe 200-300 watts but they never ran it much above 0.5 watt for any length of time because of the lack of shielding. Even at 500 or 1000 watts, there was no real concern of fire or thermal explosion since graphite is a good conductor of heat. CP-2, built in the Argonne woods (later home of Argonne National Lab where I did some of my undergrad research), did have shielding (but no cooling water) and operated for long periods of time at hundreds of watts, maybe even up to 1000 watts but I don't know the details.
                      Last edited by Fasttrack; 01-23-2021, 09:44 PM.

                      Comment


                      • #26
                        If I am not n=mistaken, as I mentioned, speed of assembling a critical mass is essential in a bomb from which you want a blast. If you ust want a dirty bomb, then you can be slower, it will do a much lesser "whuff", but probably spread radioactive gunk all over the area and downwind.

                        Of course, for that, you just need nuclear waste around a bunch of dynamite. No need to get complicated.
                        2801 3147 6749 8779 4900 4900 4900

                        Keep eye on ball.
                        Hashim Khan


                        It's just a box of rain, I don't know who put it there.

                        Comment


                        • #27
                          Originally posted by Ian B View Post
                          I like the term "backronym"!

                          Only one I know is from the oilfield; I've had people tell me that the word PIG (the thing we pump through lines to clean them etc) stands for Pipeline Inspection Gauge. Er, no, it's called a pig because it's sort of pig-shaped. Maybe also because they can be a pig to remove when they get stuck. The backronym came later.

                          Ian
                          What sucks is we lost Red to a water drill job. They do 10,000 ft lines some times.

                          Red and all the rest came from Oildale or whatever its called. Most of them folks are dead now. All Oil Drill Men. JR

                          My old yahoo group. Bridgeport Mill Group

                          https://groups.yahoo.com/neo/groups/...port_mill/info

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                          • #28
                            Red ????????????????????
                            The shortest distance between two points is a circle of infinite diameter.

                            Bluewater Model Engineering Society at https://sites.google.com/site/bluewatermes/

                            Southwestern Ontario. Canada

                            Comment


                            • #29
                              Originally posted by loose nut View Post
                              Red ????????????????????
                              Red Adair ????
                              .
                              "People will occasionally stumble over the truth, but most of the time they will pick themselves up and carry on" : Winston Churchill

                              Comment


                              • #30
                                Originally posted by JRouche View Post

                                What sucks is we lost Red to a water drill job. They do 10,000 ft lines some times.

                                Red and all the rest came from Oildale or whatever its called. Most of them folks are dead now. All Oil Drill Men. JR
                                Really? Where do you come up with this crap? Are you now hinting that you had some job in the oilfield as well?

                                https://en.wikipedia.org/wiki/Oildale,_California
                                He wasn't born in Oildale.
                                https://en.wikipedia.org/wiki/Red_Adair
                                He wasn't a driller either.

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