of of what's going on everyone, alida here, back with a brand new episode of iran tech and we're picking up where we left off last week where we headed inside uh terron research reactor and got really up close and personal with the core of the react. and talked about how it works, how the fuel of the reactor is procured and how the whole thing works and everything else in between, but this week we're not talking about how it works, but rather how to take advantage of what happens within the core of the reactor, so as the nuclear fision occurs within the core of the reactor and the nuclear bombardment also happens uh the neutron bombardment also happens, what do we do with those neutrons? now specifically for this week's episode we're talking about how we can actually angle these new... rons and get beam out of them to

uh use it for imaging purposes, because while we have imaging systems such as x-ray, which does, which works really well when it comes to denser material such as our phones, this is why we use x-ray for imaging our bone structure, but this is rather complementary imaging system, neutron radiography, it works a lot better when it comes to uh lighter, less dense material such as what? or leaves or the flow of water within a plant, this is where uh neutron radiography complements x-ray imaging uh so uh without any further ado let's head back into the research reactor and see how neutron radiography works within the neutron imaging laboratory.

so we are at tehran research reactor which has been in operation since the year 1967 uh and in fact just few days ago it celebrated its 56th year of operation now into the 57 so this is a research reactor which means that it has to operate a maximum uranium enrichment level of 20%. now there are lower uranium enrichment levels that are used for different purposes for example in nuclear power plants. in boucher which operates uh a uranium enrichment level of 4% to create electricity uh but this one for research purposes the limit is 20% given by the international atomic energy organization uh so these researches also include a medical and industrial use cases so for the medical uh aspect of things we have uh radio isotopes that are being made at the core of the reactor so we have uh lutitium 177 uh we also have uh iodine therapy which the radio

isotope for these radio therapeuticles uh is uh made at the core of the reactor right here at the 7 meter depth of this light water pool, but then there's the industrial side of things, there are different equipmentts such as beam tubes which we're going to be checking out in a little bit uh so with these beam tubes we can actually uh converge or or use the beam of electrons, the beam of neutrons that are created in the core of the reactor to accomplish various tasks and one of which... is neutron radiography uh, so i'm going to be going downstairs a little bit closer to the core of the reactor to talk more about neutron radiography, how it works, but first let's hear a little bit more about these bean tubes and how they work. beam tubes are an integral part of nuclear research reactors. they provide path for the neutrons that are being released from within the core to go to... experimental facilities,

they're also submerged in the pool along with the reactor itself for safety of the operators of the reactor against contamination. number of these beamtubes penetrate the wall of the pool to find their way into the research facilities. these tubes of are either kept as a vacuum tube or filled with inert gases such as helium to suppress activation along the neutron path. each neutron particle released from the core as a result. mult of nuclear efficient of uranium 235 with up to 20% enrichment has a certain amount of energy on release. that amount is roughly two mega electron volts that consistently goes down as the neutrons hit hydrogen atoms in the water and lose part of their energy on each impact. and as the energy level goes down, the speed of neutrons come down with it. so the water acts as what we call moderator. the significance of the

speed of neutrons will make sense in a bit, so now let's talk about what actually happens inside the beamtubes, there's a small aperture within the beamtube at the... the colimeter, the aperture is made up of a combination of lead and bismith which work together to shield the colimator against most the gamma rays that are also emited during nuclear fishing. this will prove important later. so now that the neutrons of a variety of different speeds and energy levels have entered through this tiny aperture go through the boral walls of the colimator. boral is and made from the element borium. there's also cadmium linings in the walls, which combine with borium and lead, act to absorb fast neutrons, which haven't yet lost much speed and energy, and the cold neutrons which have lost too much speed and energy. what they let pass through is thermal neutrons

with an energy level of roughly 25 milli electron volts. just for reference, one electron volt is the equivalent of 1 over 10 to the power of 19. j. another thing that the colimator does is that it turns the tiny opening for the flow of neutrons into a bigger, more operational surface area with a diameter of 25 cm, and that's what beamtubes are and how they work. so we're downstairs now, closer to the core of the reactor, and that is one of the beamtubes that is currently not being used, but is left out for possible future projects that would take advantage of the speam tube for any kind of research purpose uh so there are eight bean tubes in total, two of which are called through tubes, which weirdly enough actually doesn't go through the core of the reactor, the other six, they collude with the core of

the reactor and they're taking the neutrons that are resulted uh by the neutron fision within the core of the reactor, but the the two uh through tubes there... and for uh some specific research purposes and the only difference is that they have lower rate of gamma raised within them, so they have some certain applications that we're not going to get into today uh, but for now let's uh move a little bit to the left where we are actually using one of these beam tubes uh for neutron radiography. the subject of this week's episode of iran tech is behind this 60 centm. meter thick concrete wall inside the neutron imaging laboratory at the atomic energy organization of iran, very close to the core of the reactor. it's a kind of imaging system known as neutron radiography that has some very specific use case scenarios where x-ray imaging just doesn't

cut it. turn into this week's episode to see how neutron radiography works. okay, this is literally the closest we can possibly get to the core of the reactor, it's just like a couple meters behind this wall uh. but it's inactive right now so we we should be good uh but when the reactor is activated and when we want to do the imaging this shutter which acts as a shield against the neutron bombardment that is coming out of the beamtube will go up so the beam of neutrons will hit whatever is on this desk our object of interest and then uh however many neutron particles go through it will be picked up by the sintilator and the sensor that is inside this imaging system i can't show the in of this imaging system because it has to be dark inside, but i can show it with some visual aids. let's review what we had behind the shutter at the end of the beamtube first. we have beam of thermal neutrons with a specific

range of energy of around 25 millielectron volts, not much lower and not much higher, because they would result in noise in the final radiography. we've also filtered out gamma rays at the opening of the colimator so as not to damage our image sensors, which are vulnerable to gamma rays. once the shutter goes up, the neutrons will pass through the object that we want to radiograph, and some them will be absorbed while lot of them will pass through it, the same way the x-ray scans work. now we need to map the neutrons we have passed through a film or a sensor. this is where... two distinct imaging processes can be used, the more rudimentary form is using a photosensitive film layer, but of course regular film isn't sensitive to neutron bombardment, so we need it attached to the back of what we call a converter, a converter

layer that releases electrons upon neutron impact. film is sensitive not only to photons (i.e: visible light or x-ray), but they also happen to be sensitive to... electrons, but they must be kept within a tiny dark room of sorts so that room light doesn't interfere with imaging. the converter layer, by the way, is made from the element. elenium, but the method used in this lab is more sophisticated and allows not only for 2d radio graphs, but 3d rendered reconstruction the object as well. the similarity is that again, digital seamos camera sensors are insensitive to neutrons, so the neutron beam passing through the object must be translated to some sort of visible light. instead of gatilium-based converter, we have a sintilator plate, made up of a combination of zinc sulphide and lithium fluoride. the

lithium absorbs the neutrons and releases alpha rays which are absorbed by the zinc sulphide and turned into photons (i.e. visible light). but a very minuscule amount of visible light that only ultra low noise cameras can pick up with very high isos and the tens of thousands. there's a periscopic element here as well so... is not to expose the camera sensor to the small amount of gamma rays that have seeped through the system and inside the beam, and because our sensor is digital and can take multiple photos, it allows us to create 3d images of objects as well, like the example you're seeing on the screen right now, the importance of having only thermal neutrons and nothing faster or slower is that, well put simply at different energy levels they would result. a wider variety of visible light production which negatively affects accuracy, and that's how neutron radiography

works. one of the many applications of nuclear industry is radiography. this can be done with both x and gamma photons or with neutrons. normally we use x and gamma photons in radiography, however there are some limitations. to this method, especially for lighter materials with a low atomic number such as hydrogenated and carbonated materials as well as very heavy materials with a high atomic number such as nuclear fuels like uranium. in addition to that, radioactive imaging can't be done with x-rays and gamma rays. neutron radiography can be used to resolve all these three limitations and can complement industries in this case. neutron radiography has various applications. it is used in archaeology and energy industry as well as in checking the quality of turbine

blades. regarding imaging, we have been able to get quite good results here in research reactor of tehran. in 2019, we started a project here to initiate neutron imaging system. up to now, we have been able to successfully conduct various methods of neutron radiography such as film radiography, digital radiography, radiography as neutron. and also nuclear fuel radiography in this reactor. throughout the world, the are about 50 research reactors capable of conducting neutron radiography, out of which there are almost 10 reactors with high quality imaging that is used in a wide range of applications. in tehran reactor, we have been doing our best to get closer to these top 10 reactors by creating high quality images and utilize this reactor in a wide range of... applications: one of the benefits that come

with having such a research reactor is that countries in the region who wants to study material, they can actually bring their objects in to study it using this neutron radiography system, and also the reactor as a whole, if they want irradiate a substance for whatever usage, maybe a medical usage or industrial usage, they can bring their substance irradiated at. the core of the reactor and take it back and use it where they want to, so it's definitely one of the benefits and one of the plans uh for the making of this research reactor as a whole and uh with that said we've come to the end of this edition, i thank you very much for watching, i'll see you next week.

it seems the israeli occupation will conclude the grand operation in the city of khan unis in southern gaza within days withdrawing thereafter to the newly. establish security zone along the border with gaza, just as it did weeks ago in the city of gaza and its surroundings to the north. does this mean that the next step is to begin the ground operation in rafah? it appears that the... decision regarding the operation is still pending, not only for field related reasons, but lot of regional players prefer the negotiating path to end the zinust aggression against gaza, hence all eyes are now a possible improved prisoner exchange deal both in form and content, compared to the first paris formula reached between qatar, egypt, the united states and the zianist israeli entity last january. gaza talks underway this

week on the media stream. impressive headlines, millions of iranians are heading to polls to elect members of the country's parliament and assembly of experts, leader ofuranza islamic. revolution calls on voters to cast their ballots in the early hours of voting saying, "i turn out will disappoint ill-wishers of the nation." and the un rights chief warns israel's ground invasion of the southern gaza city of rafa will incur potentially massive loss of life on people sheltering there.