There seems to be a goodly amount of confusion when it comes to radiation from nuclear actions: what is "safe" ... and what isn't ... and when or where or how often, how much or what? Radiation seems to be this invisible and unpredictable monster that's "not well understood" and can be very bad, even good or indifferent.
I will, therefore, attempt to clarify some points on radiation.
Radiation of light ... ranges from from high-energy, short-wavelength, invisible-to-the-eye GAMMA radiation/X-rays, ... all the way through to longer wavelength ultra-violet, and then to visible violet ... through to red and then invisible infrared and down to microwave and radio waves and finally ... even to the invisible electromagnetic field surrounding power lines. They are ALL radiations.
In a nuclear chain reaction there are a variety of radiations being emitted and ONLY the gamma radiation truly falls into the category of electromagnetic emanation. I will list these radiation types and attempt to offer an explanation for each one.
1) Alpha radiation.
Alpha radiation is the emission of a "clump" of nucleus particles consisting of 2 protons and 2 neutrons sort of joined together. Since this is the makings of a Helium atom nucleus, helium gas is what actually results from alpha radiation.
These particles are pretty big and dense and have been likened to bowling balls being thrown across a lumpy lawn. They don't go far but they inflict quite a blow to whatever they strike.
A piece of paper will stop alpha radiation but there are lighter membranes which allow alpha radiation to pass through. You might say that if you wrapped a piece of depleted uranium metal with saran wrap and then wrapped waxed paper over the saran wrap ... you would get helium gas developing between the two wraps from the emission of alpha radiation.
Alpha radiation is harmless to one's body as long as it stays on the outside. If it's inhaled though, the constant alpha radiation inside of the lungs can cause damage to the ionic fluids inside of the body and eventually result in cancer. (It can remove hydrogen electrons from ionized liquids passing by, to create helium ... and this is highly disruptive to the electrolytic functioning of the body. It can also damage DNA, leading to eventual cancer.)
Alpha radiation travels only a few inches through the air but it has an ionizing effect on the air it travels through. This is the type of radiation used in smoke detectors. Two charged electrodes are separated by a small space, with air between them, and radiated by a small piece of alpha radioactive nuclear material. When smoke or steam comes between the electrodes, the alpha radiation ionizes them -(knocks off electrons from the smoke/steam particles)- creating a chain of charged particles which then acts as a conductor between the electrodes, making a current flow through the gap. This sets off the smoke detector.
Natural U238 and plutonium BOTH emit alpha radiation. U235, on the other hand, through its "occasional" spontaneous fissioning ... produces high energy gamma radiation (X-rays).
2) Beta radiation.
Beta radiation is more powerful than alpha radiation and travels through air up to 16 feet. It can be stopped by a thin piece of aluminum (tinfoil?). Beta radiation is classified as "electron emission" but it's really not quite that. Electrons have a negative charge but beta radiation comes from the nucleus, where there ARE supposedly no electrons. Yet, the nucleus is supposed to be filled ONLY with positively charged protons! Beta radiation is negatively charged particles coming out of the nucleus with a weight or mass of something like a proton. So they call the particle a "positron", (go figger).
Electrons have no appreciable mass but protons do. Electrons have a negative charge and protons have a positive charge. Yet, beta radiation is negatively charge particles with a mass like protons ... which come out of the nucleus of certain types of radioactive atoms like Strontium-90
Beta radiation is somewhat more destructive than alpha radiation and has ionizing and dna-mutating qualities much like alpha particles ... but penetrate more tissue. Strontium 90, for instance ... gets stuck into the bones because it resembles calcium and will radiate for a life time with only half of it decayed in 29 years.
3) Gamma radiation.
Gamma radiation is the one most feared because it's also the most powerful. It can radiate for indefinite distances, just like light. However, because the intensity decreases inversely to the square of the distance (just like light) ... the amount of it quickly becomes less, the farther away it is. Hiroshima victims suffered radiation burns from several miles away, resulting in sickness and death only weeks later.
One long-lasting gamma emitting element is Cesium. Cesium is totally man-made and yet ... tests done on any material, anywhere on earth today ... can determine whether something existed in a sealed container without being opened from before 1940! Anything and everything open to the air in the entire world ... has traces of Cesium in it from man made nuclear reactions or explosions.
4) Neutron radiation.
Neutron radiation is simply the emission of high speed neutrons coming from the nuclei of splitting atoms. Was it neutron radiation or gamma radiation which killed people quickly after being exposed to high doses of nuclear radiation in bombs or lab accidents? I don't really know but it makes sense that neutron bombardment would do more tissue damage than gamma radiation. It's like the difference of being shot with quite a lot of tiny needles (gamma) vs. being hit by far fewer .44 bullets (neutrons). Which type of bombardment would make you sicker or kill you faster? Which type would give you a metallic taste in the mouth and then make you throw up minutes later ... leaving your vital organs to rot with gangrene in the following days and weeks? I'm not sure. I'd like to hear other dissertations on it.
Those are the four types of radiation produced by nuclear decay, chain reaction and fission. I think that pretty much covers the radiation spectrum of nuclear reaction ... although there are other types of emissions which occur simultaneously since the process is almost as complex as a car pileup on a highway: how do you describe the collision process using pure physics terms?
There's also another type of radiation which isn't particularly nuclear in nature but which has found its way into the Fukishima reactor rhetoric ... and that is, "ion beam".
Allegedly, there's a hole in the side of one reactor containment which is throwing some kind of beam out sideways ... to a distance of about a mile. At first it was called a "neutron beam" but then the next day it was called an "ion beam" by the same radio person
! So what is it REALLY and why did the fellow confuse himself?
A neutron beam would make sense ... sort of. Since there are so many millions of neutrons being emitted (even AFTER the chain reaction was halted) by the decay or breakdown of secondary elements into lower elements, and all of THOSE emit neutrons too ... I can well believe that a neutron "storm" could still be occurring. The "beam" part would simply be the aperture or HOLE in the wall that lets these neutrons go flying out in that single direction -much like an opened door from a lit house will cast a "beam" of light out from the doorway into the darkness.
The "problem" with this being a neutron beam is that neutrons have no electrical charge. They're neutral and that's why they're called neutrons. Only an electrically charged particle or electron can ionize air molecules and only ionization causes visible light to be emitted by the gas through which an ionizing beam is passing. So theoretically, this visible bluish beam seen at Fukishima could NOT be caused by neutron emission.
On the other hand, ionizing beams from alpha and beta radiation travel only a few inches and 16 feet respectively, through air. So this visible beam, going out for over a mile could not be alpha or beta radiation.
The CORRECT terminology (from this radio guy) should be "an IONIZING beam
" and not an "ion beam." Let me explain the difference ...
An ion is actually a WHOLE ATOM of an element -electrons and nucleus- which has be been "excited" by the addition or removal of an electron from its outer shell. In other words, it's not an electron or a charged particle but rather, a charged ATOM.
An ion beam then, consists of charged atoms
flying towards a target. While this DOES happen on a very small scale in various applications, it would take a staggering amount of difference voltage between source and end point to generate an ion beam through air for over a mile!! On the other hand, an ionizing beam would simply knock electrons off of atoms along its path, making those atoms glow in the pathway of the ionizing beam.
To visualize the difference, let me give a few examples of ionizing "beams" versus real ion beams.
Lightning jumps a large gap in the sky, ionizing the air ... through which electrons then pass very rapidly. We see that as a bluish white light expanding into a very wide explosion of expanding air around the lightning bolt. In the case of lightning, the ionization is created by electrons moving from a high voltage difference to the other side of the voltage difference.
Neon lights are also the result of a very high voltage difference between two points ... an electron breakthrough (like lightning) and/but then a RESTRICTION of electron flow through the ionized gas, utilizing a high value resistor. (Once a gas has become ionized, it loses its natural electrical insulation value and becomes a low resistance conductor.) This makes the neon gas give off a red glow. So the pathway or the "beam" in both of the above cases is an IONIZING beam of ELECTRONS. Not an ion beam but an ionizing beam.
Now what about true ion beams; where do we encounter those?
Well, there was an interesting (though little publicly known) case of ion beams being generated in old television B+W picture tubes in days of yore. (Actually ALL picture tubes have the same problem -even modern ones- but they found a solution to that problem back in the B&W days already ... and simply carried the solution forward.)
In a television picture tube, there's a negative electrode, called a "cathode" at the back of the neck and another electrode which is positive -the anode- at the front of the picture tube. The voltage between these two electrodes ranges from about 10,000/15,000 volts for B&W tubes .... to about 25,000 volts for color picture tubes.
Electrons are emitted at the back -the cathode- and fly toward the front -the anode- at a very high speed, through vacuum. When electrons hit the front of the screen, they strike phosphor dots, making those phosphors glow from being struck. By shaping the electron flow into a very narrow beam with the use of electrostatic lenses ... and deflecting the beam across the screen with large electromagnets and modulating the strength of the beam (to make lighter/darker glow of the phosphor dots) ... the moving picture illusion is created on the phosphor surface of the CRT picture tube.
The PROBLEM though, as it turned out ... is that tiny particles of the cathode would tear off and -because these particles had a high negative charge in comparison to the anode- they would fly at high speed toward the anode, smash into the phosphor and gradually destroy it over time. This created a brown spot in the middle of the screen which gradually deadened completely. Since these charged particles -ions- had a lot of mass in their nucleus, they couldn't be so easily deflected as electrons can and so they always crashed into a pretty small area of maybe a few inches in diameter, in the middle of the picture tube. This was the true definition of an ion beam: charged atoms flying at high speed, striking a target of opposite polarity and doing damage. The solution to the problem turned out to be quite simple: put a little magnet on the side of the neck of the picture tube in a strategic spot and bend everything over in one direction ... then bend the electron beam back again! The electrons would respond easily to deflection; the ions would not ... and so the ions simply ended up skidding down the neck of the tube, off to one side, piling up in a small mound of "dust" there ... I guess ... without doing any harm to the front phosphors.
And another -very commonly known- application of ion beaming occurs in DC electric welding. First, the welder has to "strike" an arc by touching his stinger rod or wire to the surface he's going to weld. As soon as he starts the current flowing, he pulls back his electrode and ionization
creates a low resistance path between electrode and surface ... and creates the bright light between his stick/electrode and the surface he's welding. Why is there an ion "beam" between the two electrical surfaces? Well, the metal melts from his stick or wire and BECAUSE it's charged negatively ... the metal goes flying into the positive surface being welded! So the stinger has to be negative and the welded surface has to be positive in order to make the liquid charged metal go "penetrating" into the surface being welded. A reverse polarity would cause metal to fly out in the opposite direction. An AC welder (where current direction changes continually) does a pretty poor job all around insofar as striking and holding an arc ... and penetrates poorly too.
Getting back to that Fukishima beam for a bit ...
It seems most likely to me, that it would be a neutron beam because only neutrons would have the energy to fly that far from the source through air. (Gamma is invisible). Yet, neutrons should -theoretically- cause no ionization because they're not charged positively or negatively.
This is rather interesting to me because ... during the Manhattan project during the 1940's, when the A bomb was being developed, a couple of fellows accidentally "nuked" themselves at two different times ... with the very same two pieces of plutonium they were testing
... and in both cases, the victims and witnesses reported seeing a very blue light fill the room. These reports have been dismissed as illusory, with the explanation that flying neutrons striking the optic nerve PROBABLY creates the illusion of a blue light.
Well then, how does one explain the Fukishima beam? If it can be observed externally as a beam, there are no neutrons flying OUTSIDE of that beam and therefore, no neutrons could be striking the observers' optic nerves.
It seems to me therefore ... that neutrons DO create ionization through some mechanism "not yet well understood."~
NEXT: TYPES of EXPLOSIONS