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What Are Neutrons? Cold, Thermal, Slow, Intermediate And Fast Neutron Radiation, Space Neutrons, How To Calculate Neutron Radiation Exposure, Shop And Price Compare Neutron Radiation Detectors

WHAT ARE NEUTRONS? 

According to the NRC, "neutrons are high-speed nuclear particles that have an exceptional ability to penetrate other materials. Of the five types of ionizing radiation discussed here, neutrons are the only one that can make objects radioactive. This process, called neutron activation, produces many of the radioactive sources that are used in medical, academic, and industrial applications (including oil exploration).


Because of their exceptional ability to penetrate other materials, neutrons can travel great distances in air and require very thick hydrogen-containing materials (such as concrete or water) to block them. Fortunately, however, neutron radiation primarily occurs inside a nuclear reactor, where many feet of water provide effective shielding.
http://www.nrc.gov/about-nrc/radiation/health-effects/radiation-basics.html#neutron

Wikipedia; "The neutron is a subatomic particle, with no net electric charge and a mass slightly larger than that of a proton. Protons and neutrons, each with mass approximately one atomic mass unit, constitute the nucleus of an atom, and they are collectively referred to as nucleons.[5] Their properties and interactions are described by nuclear physics.

The nucleus consists of Z protons, where Z is called the atomic number, and N neutrons, where N is the neutron number. The atomic number defines the chemical properties of the atom, and the neutron number determines the isotope or nuclide.[6] The terms isotope and nuclide are often used synonymously, but they are chemical and nuclear concepts, respectively. 

The atomic mass number, symbol A, equals Z+N. For example, carbon has atomic number 6, and its abundant carbon-12 isotope has 6 neutrons, whereas its rare carbon-13 isotope has 7 neutrons. Some elements occur in nature with only one stable isotope, such as fluorine. Other elements occur with many stable isotopes, such as tin with ten stable isotopes. Even though it is not a chemical element, the neutron is included in the table of nuclides.[7]

Within the nucleus, protons and neutrons are bound together through the nuclear force, and neutrons are required for the stability of nuclei. Neutrons are produced copiously in nuclear fission and fusion. They are a primary contributor to the nucleosynthesis of chemical elements within stars through fission, fusion, and neutron capture processes.

The neutron is essential to the production of nuclear power. In the decade after the neutron was discovered in 1932,[8] neutrons were used to induce many different types of nuclear transmutations. With the discovery of nuclear fission in 1938,[9] it was quickly realized that, if a fission event produced neutrons, each of these neutrons might cause further fission events, etc., in a cascade known as a nuclear chain reaction.[6] These events and findings led to the first self-sustaining nuclear reactor (Chicago Pile-1, 1942) and the first nuclear weapon (Trinity, 1945).

Free neutrons, or individual neutrons free of the nucleus, are effectively a form of ionizing radiation, and as such, are a biological hazard, depending upon dose.[6] A small natural "neutron background" flux of free neutrons exists on Earth, caused by cosmic ray showers, and by the natural radioactivity of spontaneously fissionable elements in the Earth's crust.[10]

Dedicated neutron sources like neutron generators, research reactors and spallation sources produce free neutrons for use in irradiation and in neutron scattering experiments.

THE HUMAN BODY IS MADE OUT OF 50 PERCENT NEUTRONS, SO WHY DON'T WE EXPLODE LIKE A NEUTRON BOMB?


The Doomsday Explosive! (The Neutronium Bomb)
VIDEO: https://youtu.be/o_EBqZPCZdw 6 min

DETECTING 'NATURAL' NEUTRON RADIATION WITH A NEUTRON RADIATION DETECTOR


Detecting Neutron Radiation in Uranium



Whether the neutrons are 'natural' or man made, they will kill you in sufficiently high doses. Stay away from ionizing radiation emitting substances.

WHAT YOU SEE DEPENDS ON THE SENSITIVITY AND DETECTION CAPABILITY OF THE RADIATION DETECTOR; ALMOST ALL OF THEM ARE VERY INSENSITIVE AND MEASURE ONLY A TEENY TINY FRACTION OF THE TOTAL



Go deeper into various radiation detectors and neutron radiation with AntiProton

Neutron Detection, Answers to Matthew Knight, and Radioactive Material
VIDEO:  https://youtu.be/8iCqVcynoMg16 min

Remember that Geiger counters are VERY inefficient, and only detect a very small percentage of the total amount of ionizing radiation coming out of whatever source; .01 to 5 percent at best. So the real total radiation is a much higher amount than shown on any radiation detector available to consumers. He shows a radiation sample that reads radically different amounts of radiation, all the way up to 150,000 counts per minute CPM (very high) on a very sensitive type radiation detector.

The most sensitive radiation detectors are used by the EPA. To see the true radiation exposure, view the EPA total radiation counts, adding together all nine categories of gamma radiation. Alpha and beta and neutron radiation are ignored.

Fukushima Caused US Radioactive Rain, Snow - EPA Relaxed Rules To Allow Massive Radiation In Drinking Water, Downwind Fallout Measurements Information, Global Fallout Measurement, EPA Radiation Monitors, Baby Tooth Survey
http://www.agreenroadjournal.com/2013/01/fukushima-high-radiation-readings-found.html

DETECTING NEUTRON RADIATION ON THE ISS



Radi-N2: Detecting Neutron Radiation on the ISS
VIDEO: https://youtu.be/OMQOkL2zDas

As this astronaut explains, even 'natural' space radiation can harm or kill astronauts and ordinary humans on Earth.. 'Natural' ionizing radiation is a hazard to health and there is no 'safe' dose of it. All ionizing radiation dosage is cumulative.

FUKUSHIMA RELEASED MASSIVE AMOUNTS OF NEUTRON RADIATION, WITH NO WATER SHIELDING AND NOTHING PROTECTING PEOPLE ON SITE


Here is an NRC graph showing the total amount of neutron radiation released by a fission reactor. 

Of course, massive amounts of deadly neutron radiation would be released outside of the reactor, if a nuclear reactor or spent fuel pool blows up, and/or melts out, and/or if the water jacket surrounding the fissioning material is lost/drains away or is steamed out.

 Massive amounts of neutron radiation was present after 3/11 at Fukushima for this reason. 
http://enenews.com/fukushima-released-13000000000-times-neutrons-initially-estimated/

TOTAL NEUTRON RADIATION RELEASED BY FUKUSHIMA DAICHI

Total Fukushima Radiation Released Into Ocean, Air, Groundwater, Storage Tanks
http://agreenroad.blogspot.com/2012/02/total-fukushima-radiation-released-into.html

Since many of the radioactive elements released outside of the reactors also generate neutron radiation, Fukushima is a source of huge amounts of neutron radiation. The initial 'estimates' provided by the nuclear experts turned out to be way to low, by many orders of magnitude. But that is also the norm, for every nuclear accident. 

Fukushima released 13,000,000,000 times more neutrons than initially estimated — “Obvious implication for human health” — Gov’t: “Neutron radiation is the most severe and dangerous radiation” known to mankind; Can travel great distances
http://enenews.com/fukushima-released-13000000000-times-neutrons-initially-estimated/

ACCELERATORS OR ANY SOURCE OF XRAYS SUCH AS FUKUSHIMA, CAN POTENTIALLY GENERATE NEUTRON RADIATION



Since Fukushima building #3 blew out a load of nuclear fuel or spent fuel, that neutron radiation producing fuel is still out there on the ocean bottom and in the soil around Fukushima Daichi, unless of course, TEPCO has spent a lot of time and money gathering up all of those tiny pieces.



Odds are great that most of this blown out MOX fuel will never be collected or properly handled. They cannot even find the lost coriums.


PROMPT NEUTRON RADIATION DOSE CALCULATION FROM ACCIDENTAL CRITICALITY

NRC: PROMPT NEUTRON AND GAMMA DOSES FROM AN ACCIDENTAL CRI1ICALITY
Note that the above calculation is referencing KILOMETERS in terms of doses received from a neutron radiation emitting source. The gate at Fukushima is a long ways away from the neutron source of multiple melting down and out reactors, but the neutron radiation detector easily measured large amounts of neutron radiation washing over it.

Bottom line, the question to ask is, how far out does deadly neutron radiation go from a melting reactor? Is it 10 km, 100 km, or 1,000 km?

What chance is there that if they cannot find multiple 100 ton fissioning and neutron radiation emitting corium blobs at Fukushima, that that can find millions of tiny pieces of radioactive fuel fleas and hot particles that went basically all around the world? 

Fukushima Hot Particle (Fuel Flea) Found 150 Miles Away in Tokyo, Measured At 40 Quintillion Bq/kg
http://agreenroad.blogspot.com/2012/04/hot-particles-from-fukushima-continue.html

SPONTANEOUS FISSION SOURCES OF NEUTRON RADIATION

Neutron radiation comes from 'natural' radionuclides found on Earth, such as uranium, and from man made radionuclides such as plutonium, cerium and californium, which is why you don't want to have this stuff around you, nor live on top of rocks that have deposits of this kind.


ALPHA RADIATION EMITTING SOURCES ALSO EMIT NEUTRON RADIATION




MORE ALPHA RADIATION SOURCES THAT ALSO EMIT POTENTIAL NEUTRON RADIATION



DOSE CALCULATION FOR FAST NEUTRON RADIATION EXPOSURE

There would be no reason to calculate a dose, if there is nothing harmful about neutrons. The only very clear and simple Youtube video that provided neutron dose calculations was deleted. 

What follows are some resources that approach this subject. Maybe someone does not want you to know? 

NRC; Neutron sources and neutron radiation exposure calculations



Los Alamos Radiation Monitoring Notebook
http://www.nrrpt.org/documents/la-ur-00-2584.pdf (see pages 14 and 15)

Measurement of dose rate for neutron radiation via neutron radiation detector (very general summary, simple, but with no specifics)

Dose Calculations for neutron radiation exposure
https://ocw.mit.edu/courses/nuclear-engineering/22-55j-principles-of-radiation-interactions-fall-2004/lecture-notes/dos_calculations.pdf


NEUTRON DOSE PER FLUENCE AND WEIGHTING FACTORS FOR USE AT HIGH ENERGY ACCELERATORS
http://lss.fnal.gov/archive/2008/pub/fermilab-pub-08-244-esh.pdf

How to convert counts per second (CPS) Neutron radiation measurement into dose equivalent?
https://hps.org/publicinformation/ate/q8437.html

Principles of Radiation Interactions
https://ocw.mit.edu/courses/nuclear-engineering/22-55j-principles-of-radiation-interactions-fall-2004/lecture-notes/intro_absorb_dos.pdf

Absorbed dose equations: The general solution of the absorbed dose equation and solutions under different kinds of radiation equilibrium
https://www.diva-portal.org/smash/get/diva2:327454/FULLTEXT01.pdf

NEUTRON RADIATION IS THE MOST DEADLY FORM OF IONIZING RADIATION, BUT MOST PEOPLE NEVER HEARD OF IT, AND MANY NUCLEAR EXPERTS CLAIM IT IS HARMLESS


Where and when can a person be exposed to harmful neutron radiation? Well, astronauts are exposed to it.  

Here is an NRC list of neutron radiation emitting sources... 


Neutron radiation is the most deadly form of radiation but very few people have ever heard of it. Even nuclear experts don't know much about, and some claim that it is 'safe' because it goes right through a person with no effect whatsoever.

Among all of those individuals who own a Geiger counter or dosimeter of some kind, a tiny percentage own a neutron radiation detector, so it is not a radiation that is monitored or measured by civilians.

Even in the nuclear industry, neutron radiation is ignored or denied for the most part, because it complicates and increases the costs of radiation safety, radiation protection and monitoring. It is much easier just to deny neutron radiation exists and pretend to measure only small pieces of gamma, beta and alpha radiation.

WHERE IS NEUTRON RADIATION BEING USED? THIS ALSO MEANS POTENTIAL 'LEAKS' AND EXPOSURE FOR PEOPLE USING THESE DEVICES



DANGERS OF NEUTRON RADIATION, HEALTH EFFECTS ON HUMANS


Health hazards and protection
Wikipedia; "In health physics neutron radiation is a type of radiation hazard. Another, sometimes more severe hazard of neutron radiation, is neutron activation, the ability of neutron radiation to induce radioactivity in most substances it encounters, including the body tissues. This occurs through the capture of neutrons by atomic nuclei, which are transformed to another nuclide, frequently a radionuclide. This process accounts for much of the radioactive material released by the detonation of a nuclear weapon. It is also a problem in nuclear fission and nuclear fusion installations as it gradually renders the equipment radioactive such that eventually it must be replaced and disposed of as low-level radioactive waste.

Neutron radiation protection relies on radiation shielding. Due to the high kinetic energy of neutrons, this radiation is considered to be the most severe and dangerous radiation to the whole body when it is exposed to external radiation sources. In comparison to conventional ionizing radiation based on photons or charged particles, neutrons are repeatedly bounced and slowed (absorbed) by light nuclei so hydrogen-rich material is more effective at shielding than iron nuclei. The light atoms serve to slow down the neutrons by elastic scattering so they can then be absorbed by nuclear reactions. However, gamma radiation is often produced in such reactions, so additional shielding has to be provided to absorb it. Care must be taken to avoid using nuclei which undergo fission or neutron capture that results in radioactive decay of nuclei that produce gamma rays.

Neutrons readily pass through most material, but interact enough to cause biological damage. The most effective shielding materials are hydrocarbons, e.g. polyethylene, paraffin wax or water. Concrete (where a considerable amount of water molecules are chemically bound to the cement) and gravel are used as a cheap and effective shielding due to their combined shielding of both gamma rays and neutrons. Boron is also an excellent neutron absorber (and also undergoes some neutron scattering) which decays into carbon or helium and produces virtually no gamma radiation, with boron carbide a commonly used shield where concrete would be cost prohibitive. Commercially, tanks of water or fuel oil, concrete, gravel, and B4C are common shields that surround areas of large amounts of neutron flux, e.g. nuclear reactors. Boron-impregnated silica glass, standard borosilicate glass, high-boron steel, paraffin, and Plexiglas have niche uses.

Because the neutrons that strike the hydrogen nucleus (proton, or deuteron) impart energy to that nucleus, they in turn will break from their chemical bonds and travel a short distance before stopping. Such hydrogen nuclei are high linear energy transfer particles, and are in turn stopped by ionization of the material through which they travel. Consequently, in living tissue, neutrons have a relatively high relative biological effectiveness, and are roughly ten times more effective at causing biological damage compared to gamma or beta radiation of equivalent energy exposure. Neutrons are particularly damaging to soft tissues like the cornea of the eye.

Effects on materials

High-energy neutrons damage and degrade materials over time; bombardment of materials with neutrons creates collision cascades that can produce point defects and dislocations in the material, the creation of which is the primary driver behind microstructural changes occurring over time in materials exposed to radiation. At high neutron fluences this can lead to embrittlement of metals and other materials, and to swelling in some of them. This poses a problem for nuclear reactor vessels and significantly limits their lifetime (which can be somewhat prolonged by controlled annealing of the vessel, reducing the number of the built-up dislocations). Graphite moderator blocks are especially susceptible to this effect, known as Wigner effect, and have to be annealed periodically; the well-known Windscale fire was caused by a mishap during such an annealing operation.

Radiation damage to materials occurs as a result of the interaction of an energetic incident particle (a neutron, or otherwise) with a lattice atom in the material. The collision causes a massive transfer of kinetic energy to the lattice atom, which is displaced from its lattice site, becoming what is known as the primary knock-on atom (PKA). Because the PKA is surrounded by other lattice atoms, its displacement and passage through the lattice results in many subsequent collisions and the creations of additional knock-on atoms, producing what is known as the collision cascade or displacement cascade. The knock-on atoms lose energy with each collision, and terminate as interstitials, effectively creating a series of Frenkel defects in the lattice. Heat is also created as a result of the collisions (from electronic energy loss), as are possibly transmuted atoms. The magnitude of the damage is such that a single 1 MeV neutron creating a PKA in an iron lattice will produce approximately 1100 Frenkel pairs.[1] The entire cascade event occurs over a timescale of 10^-13 seconds, and therefore, can only be 'observed' in computer simulations of the event[2]

The knock-on atoms terminate in non-equilibrium interstitial lattice positions, many of which annihilate themselves by diffusing back into neighboring vacant lattice sites and restore the ordered lattice. Those which do or can not leave vacancies in-place, which results in a local rise in the vacancy concentration far above that of the equilibrium concentration. These vacancies tend to migrate as a result of thermal diffusion towards vacancy sinks (i.e. grain boundaries, dislocations) but exist for significant amounts of time, during which additional high-energy particles bombard the lattice, creating collision cascades and additional vacancies which migrate towards sinks. The main effect of irradiation in a lattice is the significant and persistent flux of defects to sinks in what is known as the defect wind. Vacancies can also annihilate by combining with one another to form dislocation loops and later, lattice voids.[1]

The collision cascade creates many more vacancies and interstitials in the material than equilibrium for a given temperature, and diffusivity in the material is dramatically increased as a result. This leads to an effect called radiation enhanced diffusion which leads to microstructural evolution of the material over time. The mechanisms leading to the evolution of the microstructure are many, may vary with temperature, flux, and fluence, and are a subject of extensive study[3]

Radiation-induced segregation results from the aforementioned flux of vacancies to sinks, implying a flux of lattice atoms away from sinks: but not necessarily in the same proportion to alloy composition in the case of an alloyed material. These fluxes may therefore lead to depletion of alloying elements in the vicinity of sinks. For the flux of interstitials introduced by the cascade, the effect is reversed: the interstitials diffuse toward sinks resulting in alloy enrichment near the sink.[1]

Dislocation loops are formed if vacancies form clusters on a lattice plane. If these vacancy concentration expand in three dimensions, a void will be formed. By definition, voids are under vacuum, but may became gas-filled in the case of alpha-particle radiation (helium) or if the gas is produced as a result of transmutation reactions. The void is then called a bubble, and leads to dimensional instability (swelling) of parts subject to radiation. Swelling presents a major long-term design problem, especially in reactor components made out of stainless steel.[4] 

Alloys with crystallographic isotropy, such as Zircaloys are subject to the creation of dislocation loops, but do not exhibit void formation. Instead, the loops form on particular lattice planes, and can lead to irradiation-induced growth, a phenomenon distinct from swelling, but one which can also produce significant dimensional changes in an alloy.[5]

Irradiation of materials can also induce phase transformations in the material: in the case of a solid solution, the solute enrichment or depletion at sinks radiation-induced segregation can lead to the precipitation of new phases in the material.[6]

The mechanical effects of these mechanisms include irradiation hardening, embrittlement, creep, and environmentally-assisted cracking. The defect clusters, dislocation loops, voids, bubbles, and precipitates produced as a result of radiation in a material all contribute to the strengthening and embrittlement (loss of ductility) in the material[7] 

Embrittlement is of particular concern for the material comprising the reactor pressure vessel, where as a result the energy required to fracture the vessel decreases significantly. It is possible to restore ductility by annealing the defects out, and much of the life-extension of nuclear reactors depends on the ability to safely do so. 

Creep is also greatly accelerated in irradiated materials, though not as a result of the enhanced diffusivities, but rather as a result of the interaction between lattice stress and the developing microstructure. Environmentally-assisted cracking or, more specifically, irradiation assisted stress corrosion cracking (IASCC) is observed especially in alloys subject to neutron radiation and in contact with water, caused by hydrogen absorption at crack tips resulting from radiolysis of the water, leading to a reduction in the required energy to propagate the crack.[1]
https://en.wikipedia.org/wiki/Neutron_radiation

WHAT IS NEUTRON FLUX?

A measure of the intensity of neutron radiation, determined by the rate of flow of neutrons. The neutron flux value is calculated as the neutron density (n) multiplied by neutron velocity (v), where n is the number of neutrons per cubic centimeter (expressed as neutrons/cm3) and v is the distance the neutrons travel in 1 second (expressed in centimeters per second, or cm/sec). Consequently, neutron flux (nv) is measured in neutrons/cm2/sec.

2017 - Alarm at nuclear plant after radioactive leak — “Damaged fuel in reactor” — Workers immediately evacuated from site — Reactor in “a very special condition”… Dangerous neutron flux in core reported (VIDEO)
Mar 3, 2017 (emphasis added): October 25th brought reports that there was a release of radioactive iodine from the Halden Reactor [in Norway]… The iodine emission began when the IFE [Institute for Energy Technology] should have dealt with damaged fuel in the reactor hall. This led to a release of radioactive substances via the ventilation system… The next day, the NRPA conducted an unannounced inspection of the IFE. The situation was still unresolved and radioactive released were still ongoing…

Via HoTaters MARCH 7, 2017 Sounds like the rate of flux, heading toward an uncontrolled reaction is the issue. This explains it better (danger of explosion of reactor core during a "supercriticality"):

Japan Nuclear Engineer: US reactor at risk of ‘supercriticality’ during recent emergency… “That’s something scary” — Damaged nuclear fuel rods and fuel fragments found at plant, conditions reported as “seriously degraded” (VIDEO)

OUT OF CONTROL UNMODERATED NEUTRON FLUX CAN CAUSE FISSION AND ULTIMATELY A CRITICALITY EXPLOSION AT FUKUSHIMA OF MOLTEN 100 TON LAVA CORIUM BLOBS


Fukushima, design, build firms are not being held to account, and are making huge profits off of the mega nuclear disaster. The public pays the damages and absorbs the risks, but huge nuclear companies profit. Tokyo has radiation hot spots and people are moving away due to this. Neutron flux at Fukushima around melted out MOX fuel.. As it melts, it can fission and go critical again and again, basically FOREVER.
VIDEO: http://youtu.be/pR7WIrkPCqQ 7 min.

Most people assume that just because something has never happened before, that it can never happen. Even good scientists and engineers get caught in this 'bubble' of assumptions and logic traps. The Challenger disaster is a good example of how even good engineers, safety experts and management all thought that foam breaking off of a fuel tank would pose no danger to the space shuttle, because it had never posed a hazard before. 

Even after the disaster happened and the space shuttle was destroyed along with everyone on board, the engineers, safety experts and management still did not believe that a little bit of foam could destroy a spacecraft, because it never had done that before. They actually had to set up an experiment that duplicated what happened after launch on that fateful day. They watched in horror as the supposedly weak and harmless foam punched a huge hole into the Challenger wing mock up. 

In the same way, neutron radiation is 'weak' and supposedly cannot do anything to anyone, so it is ignored, denied, suppressed and not taken into account during nuclear reactor operations, nuclear accidents and spills of radioactive materials or liquids that emit neutron radiation. Just like the Challenger disaster, the assumption by the scientific world, is that neutrons are not worth worrying about and cannot cause harm. After all, neutrons are 'neutral'. How can something neutral cause harm?

There is a great and unmet need to do much more research on the dangers of all types of neutron radiation. There is a great and unmet need for measuring neutron radiation not just around nuclear facilities, but also in communities, workplaces and homes. 

NEUTRON RADIATION DISTRIBUTION, THERE ARE MANY TYPES OF NEUTRONS

There is not just one type of neutron radiation, there are many. Just like alpha, beta and gamma radiation, so there is a huge variety and types of neutron radiation, but all of them are deadly. The 'hotter' the neutron, the more energy it has and the more dangerous it is. Thus, a fissioning reactor or corium lava blob outside of a reactor releases the 'hottest' neutron radiation, compared to any other source.

Wikipedia; "The neutron detection temperature, also called the neutron energy, indicates a free neutron's kinetic energy, usually given in electron volts. The term temperature is used, since hot, thermal and cold neutrons are moderated in a medium with a certain temperature. The neutron energy distribution is then adopted to the Maxwellian distribution known for thermal motion. Qualitatively, the higher the temperature, the higher the kinetic energy is of the free neutron. Kinetic energy, speed and wavelength of the neutron are related through the De Broglie relation.

Neutron energy distribution ranges


Neutron energy       range names[1]
Neutron energyEnergy range
0.0–0.025 eVCold neutrons
0.025 eVThermal neutrons
0.025–0.4 eVEpithermal neutrons
0.4–0.6 eVCadmium neutrons
0.6–1 eVEpiCadmium neutrons
1–10 eVSlow neutrons
10–300 eVResonance neutrons
300 eV–1 MeVIntermediate neutrons
1–20 MeVFast neutrons
20 MeVRelativistic neutrons

But different ranges with different names are observed in other sources. For example,

Thermal
  • Neutrons in thermal equilibrium with their surroundings
  • Most probable energy at 20 degrees (C) - 0.025 eV; Maxwellian distribution of 20 degrees(C)extends to about 0.2 eV.
Epithermal
  • Neutrons of energy greater than thermal
  • Greater than 0.2 eV
Cadmium
  • Neutrons which are strongly absorbed by cadmium
  • Less than 0.4 eV
Epicadmium
  • Neutrons which are not strongly absorbed by cadmium
  • Greater than 0.6 eV
Slow
  • Neutrons of energy slightly greater than thermal
  • Less than 1 to 10 eV (sometimes up to 1 keV)
Resonance
  • In pile neutron physics, usually refers to neutrons which are strongly captured in the resonance of U-238, and of a few commonly used detectors (e.g., Indium, Gold, etc.)
  • 1 eV to 300 eV
Intermediate
  • Neutrons that are between slow and fast
  • Few hundred eV to 0.5 MeV
Fast
  • Greater than 0.5 MeV
Ultrafast
  • Relativistic
  • Greater than 20 MeV
Pile
  • Neutrons of all energies present in nuclear reactors
  • 0.001 eV to 15 MeV
Fission
  • Neutrons formed during fission
  • 100 keV to 15 MeV (Most probable: 0.8 MeV; Average: 2.0 MeV)


Epithermal neutrons have energies between 1 eV and 10 keV and smaller nuclear cross sections than thermal neutrons.
—H. Tomita, C. Shoda, J. Kawarabayashi, T. Matsumoto, J. Hori, S. Uno, M. Shoji, T. Uchida, N. Fukumotoa and T. Iguchia, "Development of epithermal neutron camera based on resonance-energy-filtered imaging with GEM" (2012)


Cold neutron source providing neutrons at about the temperature of liquid hydrogen

Ultracold neutrons (UCN)
A chart displaying the speed probability density functions of the speeds of a few noble gases at a temperature of 298.15 K (25 C). An explanation of the vertical axis label appears on the image page (click to see). Similar speed distributions are obtained for neutrons upon moderation.

Ultracold neutrons are free neutrons which can be stored in traps made from certain materials.

Thermal neutrons


A thermal neutron is a free neutron with a kinetic energy of about 0.025eV (about 4.0×10−21 J or 2.4 MJ/kg, hence a speed of 2.2 km/s), which is the energy corresponding to the most probable velocity at a temperature of 290 K (17 °C or 62 °F), the mode of the Maxwell–Boltzmann distribution for this temperature.

After a number of collisions with nuclei (scattering) in a medium (neutron moderator) at this temperature, neutrons arrive at about this energy level, provided that they are not absorbed.

Thermal neutrons have a different and often much larger effective neutron absorption cross-section for a given nuclide than fast neutrons, and can therefore often be absorbed more easily by an atomic nucleus, creating a heavier, often unstable isotope of the chemical element as a result (neutron activation).

Fast neutrons


A fast neutron is a free neutron with a kinetic energy level close to 1MeV (100 TJ/kg), hence a speed of 14,000 km/s, or higher. They are named fast neutrons to distinguish them from lower-energy thermal neutrons, and high-energy neutrons produced in cosmic showers or accelerators.

Fast neutrons are produced by nuclear processes:
nuclear fission produces neutrons with a mean energy of 2 MeV (200 TJ/kg, i.e. 20,000 km/s), which qualifies as "fast". However the range of neutrons from fission follows a Maxwell–Boltzmann distributionfrom 0 to about 14 MeV in the center of momentum frame of the disintegration, and the mode of the energy is only 0.75 MeV, meaning that fewer than half of fission neutrons qualify as "fast" even by the 1 MeV criterion.[2]
nuclear fusion: deuteriumtritium fusion produces neutrons of 14.1 MeV (1400 TJ/kg, i.e. 52,000 km/s, 17.3% of the speed of light) that can easily fission uranium-238 and other non-fissile actinides.

Fast neutrons can be made into thermal neutrons via a process called moderation. This is done with a neutron moderator. In reactors, typically heavy water, light water, or graphite are used to moderate neutrons.

Fast reactor and thermal reactor compared


Most fission reactors are thermal reactors that use a neutron moderator to slow down ("thermalize") the neutrons produced by nuclear fission. Moderation substantially increases the fission cross section for fissile nuclei such as uranium-235 or plutonium-239. In addition, uranium-238 has a much lower capture cross section for thermal neutrons, allowing more neutrons to cause fission of fissile nuclei and propagate the chain reaction, rather than being captured by 238U. The combination of these effects allows light water reactors to use low-enriched uranium. Heavy water reactors and graphite-moderated reactors can even use natural uranium as these moderators have much lower neutron capture cross sections than light water.[3]

An increase in fuel temperature also raises U-238's thermal neutron absorption by Doppler broadening, providing negative feedbackto help control the reactor. Also, when the moderator is also a circulating coolant (light water or heavy water), boiling of the coolant will reduce the moderator density and provide negative feedback (a negative void coefficient).

Intermediate-energy neutrons have poorer fission/capture ratios than either fast or thermal neutrons for most fuels. An exception is theuranium-233 of the thorium cycle, which has a good fission/capture ratio at all neutron energies.

Fast reactors use unmoderated fast neutrons to sustain the reaction and require the fuel to contain a higher concentration of fissile material relative to fertile material U-238. However, fast neutrons have a better fission/capture ratio for many nuclides, and each fast fission releases a larger number of neutrons, so a fast breeder reactor can potentially "breed" more fissile fuel than it consumes."
http://en.wikipedia.org/wiki/Neutron_temperature

SPACE NEUTRON RADIATION


Via Angela_R January 17, 2015 "Our Dec. 8th flight to the stratosphere to test a neutron sensor was a success. We successfully detected neutrons in the stratosphere. Peak rates reached 240 neutrons per minute, compared to ~0 neutrons per minute at ground level. Neutrons are important because they provide much of the biologically effective radiation dose at altitudes of interest to aviation and space tourism. Low-energy neutrons also cause single-event upsets in aircraft avionics, especially devices that contain Boron 10. Adding a neutron sensor to our Space Weather Buoy allows the students of Earth to Sky to monitor this important form of radiation at altitudes ranging from ground level to 120,000 feet."

and this from the spaceweather link above:

"The halobacteria were hit by ionizing radiation 28 times stronger than at ground level, similar to what they might experience on the planet Mars. It might seem counterintuitive that the radiation peak did not occur at the apex of the flight. Instead, the extremophiles absorbed their greatest dose about half way up"

"Cosmogenic neutrons, neutrons produced from cosmic radiation in the Earth's atmosphere or surface, and those produced in particle accelerators can be significantly higher energy than those encountered in reactors. Most of them activate a nucleus before reaching the ground; a few react with nuclei in the air. The reactions with nitrogen-14 lead to the formation of carbon-14, widely used in radiocarbon dating."

There are reports of astronauts 'seeing' radiation hitting their brains, as 'light'. It takes some pretty intense radiation hitting the brain in order for it to be interpreted as a light.

RELATED ARTICLES

Could J Parc Neutron Beam Have Caused Fukushima Daichi Mega Nuclear Disaster on 3/11? US Drill For Earthquake And Tsunami Scheduled For Same Day
http://agreenroad.blogspot.com/2014/05/could-j-parc-neutron-beam-have-caused.html

Neutrons; Cold, Thermal, Slow, Intermediate And Fast Neutron Radiation, Space Neutrons, How To Calculate Neutron Radiation Exposure
http://agreenroad.blogspot.com/2015/01/neutrons-cold-thermal-slow-intermediate.html

Fukushima Fast Neutron/Neutrino AntiNeutron Emissions, Gamma Rays Emitted From Nuclear Power Plant, Mines, Recycling Facilities, Neutron Radiation Effect On Human Health And Climate
http://agreenroad.blogspot.com/2013/07/excessive-neutronneutrino-emissions.html

Sam Cohen - Inventor Of the Neutron Bomb; via @AGreenRoad
http://agreenroad.blogspot.com/2013/07/sam-cohen-inventor-of-neutron-bomb.html

13 Neutron Beams Came Out Of Fukushima; Direct Evidence Of Holes In Reactors And Multiple Melt Throughs And Melt Outs
http://agreenroad.blogspot.com/2013/07/13-neutron-beams-came-out-of-fukushima.html

ECAT Low Energy Nuclear Reactors (LENR); Is Cold Fusion Or Cold Fission The Next New Free Energy Source?
http://agreenroad.blogspot.com/2014/10/low-energy-nuclear-reactors-is-cold.html

 Stacey Nuclear Reactor Physics - PDF File  - WILEY 2001 (large file, takes quite a while to download)

How To Spot A Sociopath Or Psychopath - 10 red flags that could save you from being swept under the influence of a charismatic nut job; via A Green Road
http://agreenroad.blogspot.com/2012/12/how-to-spot-sociopath-10-red-flags-that.html

Sacrifice Zones, Nuclear Power and the Sacrificial Victims System Is Spreading Globally As Part Of Predatory Capitalism
http://agreenroad.blogspot.com/2014/09/sacrifice-zones-nuclear-power-and.html

The Nemesis Factor; How It Applies To Nuclear Bombs And Nuclear Power Industry
http://agreenroad.blogspot.com/2014/10/the-nemesis-factor-how-it-applies-to.html

SHOP AND PRICE COMPARE FOR A NEUTRON RADIATION DETECTOR


Neutron detectors are available, but they cost more than standard Geiger Counters

Price compare and shop for a neutron detector at A Green Road Store - Scientific And Industrial Section

FAST NEUTRON SONG


I came in like a fast neutron song
VIDEO: http://youtu.be/pfCubYuWJSU 4 min.

SUMMARY

Bottom line, all ionizing radiation exposure is dangerous and has negative consequences, including neutron radiation, but artificial man made heavy metal radioactive poisons are especially toxic and deadly.


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End

What Are Neutrons? Cold, Thermal, Slow, Intermediate And Fast Neutron Radiation, Space Neutrons, How To Calculate Neutron Radiation Exposure, Shop And Price Compare Neutron Radiation Detectors
http://www.agreenroadjournal.com/2015/01/neutrons-cold-thermal-slow-intermediate.html

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