- 9시간 전
카테고리
📚
학습트랜스크립트
00:01Let me continue from this slide.
00:04We skipped a few pages without detailed explanation.
00:11Those slides will come again from now on.
00:17This topic is energy changes during nuclear reaction.
00:21We already know nuclear reaction is much different from regular chemical reaction or physical reaction.
00:29Here, we see the two hydrogen atom have two neutrons and then it becomes helium.
00:43This is not regular chemical equation, right?
00:47In the chemical equation, we measure that enthalpy where those are the level,
00:54but these are atoms, so they are all zero energy part.
00:58So it's very difficult to calculate this kind of the energy related equation.
01:05But here, during this reaction, there might be some mass defect.
01:14Let's take a look at here if they have any mass defect.
01:21As I mentioned before, this arrow means equal and then upper number should be the same as the lower part
01:32number.
01:33Let's take a look at upside first.
01:36So 2 times 1, that's 2.
01:38And 2 times 2, 1 equals 2.
01:41And that generated 4.
01:44So the number is fine.
01:47That's the mass, right?
01:49Actually.
01:49And then the lower part, this is just the proton and 2 proton and zero.
02:03So they added just 2 proton.
02:062.
02:07So the charge and the nucleons, there's no change, right?
02:15But still, we expect some mass defect.
02:20That's the interesting part, right?
02:23So maybe in this topic, this is one of the most important topics in nuclear chemistry.
02:32Mass defect.
02:33Suppose we measure the masses of individual protons and neutrons and then add them together.
02:40That's what we have done here, right?
02:42But we didn't see that much like a change is noticeable, right?
02:48So in the textbook, it says like a surprisingly, the resulting value is greater than the actual mass of the
02:55nucleon state form.
03:02So missing mass.
03:06We don't know much about the missing mass here in this reaction, but there could be, might be, should be
03:14some mass defect.
03:17The missing mass is called a mass defect.
03:22Where did this mass go?
03:25According to the Einstein's famous equation and his words and everything equals mc squared.
03:34That's already we know about.
03:36And the mass and energy are interchangeable.
03:40Okay.
03:41That's nice word, right?
03:43They are interchangeable.
03:45So we know the small amount of mass can be changed to the huge amount of energy.
03:52That could be light or heat.
03:56But anyway, it's kind of wave related, some energy part.
04:01It says the other one, not the other way is also possible interchangeable.
04:06So if we have a lot of light or energy that could be compressed into a small mass.
04:17Can we use this kind of the, the thing for solve this kind of climate changes?
04:29You know, the earth is, the, is getting hotter and hotter, warmer and warmer.
04:34So if we can collect, then concentrate the energy in, in the one spot, and then that can be changed
04:46to the, maybe small piece of just the, the bead or the sand, whatever.
04:57I hope we can manage that kind of energy in the near future to solve all this climate change.
05:04You know, the soul is very hot these days in the summer.
05:09When I was young, it was not that hot.
05:11I was living in Seoul, and the, I don't think I, I experienced like some temperature over 35 or something.
05:2527, 29, those temperatures are already enough to feel, to make us feel like hot.
05:35But these days, much, much higher.
05:40Okay.
05:41And then the, so the, the classical chemistry teaches the law of conservation of mass.
05:50That's what we have learned.
05:52And then physics also teaches the law of conservation of energy.
05:56So nuclear reactions reveal that these two laws are actually just one single principle.
06:06When mass disappears during a nuclear reaction, energy appears.
06:11When energy is absorbed, mass may increase.
06:16We haven't seen that kind of thing before, but it could be possible, right?
06:22We didn't measure that much, the energy changes or mass changes.
06:31So therefore, the, what is conserved is not masses alone or energy alone, but the combined total of mass and
06:43energy.
06:44They are, they are conserved.
06:50So the Einstein, that guy, but there's some, some sense like Einstein's wife was very clever.
07:02And then she taught a lot of this kind of theory in, to Einstein, but I don't know that's true
07:08or not.
07:10But anyway, you know, there are a lot of people who are very, very, very smart and shows us some
07:18excellences in like science or engineering.
07:26Okay.
07:27So the, the combination of mass and energy must be conserved.
07:31So this is the thing.
07:34And so the, here I mentioned that, right?
07:40Like Euclidean said, the, the iron, Fe, that's the highest binding energy.
07:49Something.
07:51So that's the, what is the most stable, the atom in the world so far.
08:00But that's what the, the textbook says.
08:03I don't know that's real or not.
08:05We have to believe that, but you can suspect some part.
08:11That's your mind.
08:13Okay.
08:14So now nuclear fission and fusion, the relationship between like binding energy and nuclear stability explains two of the most
08:24important nuclear processes, fission and fusion.
08:28Very heavy nuclei, very heavy nuclei can become more stable by splitting into smaller nuclei, right?
08:38So that's what we observe here to the left side.
08:42This process is nuclear fission and very light nuclei in the left side can gain stability and release energy by
08:54fusing that nuclear fusion.
09:01So for nuclear fission, the example includes some like uranium 235 and what is that plutonium 239 or something, right?
09:14So very light nuclei can become more stable.
09:17For example, like hydrogen and helium, that's what we observed in the previous slide, right?
09:26So the, although fission and fusion appear the opposite, both processes release like energy.
09:34That's quite interesting, right?
09:37So the reason is that like both the move nuclei toward the regions of higher binding energy and greater stability.
09:47So it's, it's, you know, in chemistry and physics, we already experienced that kind of teaching, right?
09:55So some, we, something is more stable and that means it went down to lower energy.
10:04The energy, the gap energy should be released, right?
10:07So the, then what should we do to, then what should we do to absorb the energy the other way,
10:28right?
10:28So the iron should be some sort of uranium and then that'll absorb the energy because it's higher energy state.
10:40And then once we make this uranium, then the uranium should go to the space.
10:49Then we can remove some energy from the earth completely, but we have to use this uranium to obtain the
11:00energy, right?
11:02So that will continue.
11:03We will see.
11:06Okay.
11:07Nuclear fission.
11:08We saw, we mentioned that uranium 235 nucleus fragments when struck by a neutron.
11:16Oh, here's some important part.
11:20So neutron is required to hit this.
11:26What else?
11:28But anyway, the neutron can be, like a trigger to, like a, to divide into pieces.
11:41Krypton and the volume.
11:58So we mentioned this neutron hit this uranium, but the, in, in textbook, it says like a, when a neutron
12:07is absorbed by a uranium nucleus.
12:10Is it absorbing or heating, whatever.
12:15The, the expression quite, might be a little bit different.
12:18And then the understanding could be also changeable because like a heating or absorbing is quite different, right?
12:27So when we, uh, when we, uh, think about some mechanism, that might be a completely different one.
12:34But here, the textbook says like a absorbing and, uh, also the, the heating, whatever.
12:44So, uh, nuclear fission, the reaction, we, let's see like a, this is a chain reaction.
12:55So one neutron is absorbed or hit the uranium.
13:00And then see barium and krypton, they, uh, have like a smaller pieces.
13:08And see what we have here.
13:10This is the important.
13:12Three neutron.
13:14Right.
13:16We started from one neutron and that generates a three neutron.
13:20And then those neutron will be available to hit another the uranium around.
13:28Right.
13:29So a self-sustaining reaction whose product initiates a further reaction that will, they will go.
13:42That happens in the uranium set that power generation fraud.
13:54So this is the one, right?
13:58Uh, you may understand what's happening here.
14:03Like, uh, the controlled and uncontrolled chain reaction might occur in this whole chamber.
14:11You see that fuel elements are located here.
14:15That's the control rods.
14:18Then fuel elements and reactor.
14:21And then, you know, the, during this reaction, we saw like a lot of heat is released and participated in
14:33this whole reaction.
14:35And water goes inside and then take the energy and move to this, like, um, uh, what is that?
14:43Like steam generating the column.
14:46That should be very big.
14:47No, this, this is the, just a picture.
14:51And then the whole size is huge.
14:54Right.
14:55Like a regular, um, the big building.
15:00Um, it's in our university, maybe much, much bigger than, um, regular, the research building, whatever.
15:17And then that's very hot.
15:20Or, uh, no, no, I'm sorry.
15:21I'm sorry.
15:22I'm sorry.
15:22This could be water or sometimes, uh, it's very hot.
15:26Uh, the, the mercury or non-mercury, mercury is not used, but, uh, people trying to use like germanium or
15:35some other metal.
15:36Uh, metal.
15:38So, they do not have any, the chemical reaction.
15:42So, here it says like a water and then water goes in and then when go, it goes out, it's
15:47very hot.
15:48So, the, this, this will be like a boiling and then that steam will go through this, this, this, go
16:03through this like a rod or pipe and then, uh, run the steam turbine and generates the electrical output.
16:15This steam must be condensed to be reused here.
16:22To condense this, the steam, they, uh, they take like a cold, the sea water, that's 27 degree Celsius.
16:32And then after the, doing this kind of mission, they release a 38 degree Celsius temperature water to the outside.
16:45So, um, you know, in the world, you know, how many, like the, uh, this kind of a power generator
16:53is located along the seashore.
16:55And then they all release the energy by taking this low temperature water and then release this high temperature water,
17:10sea water.
17:11They are doing 24 hours a day and seven days a week and 335 days a year.
17:20And then all the country and how many reactor they have.
17:25So, all the time.
17:29That's why sea is getting hotter and hotter.
17:33Don't you think?
17:35So, if we consider the whole amount of the sea water, the, this temperature change might be very negligible.
17:44But the most of the water will stay inside without the changing, the mixing that much.
17:52So if we consider the surface water, this temperature changes a lot.
18:01I know like this is also very, uh, it shows a quite important mission to grow some, the fish.
18:14And also we can utilize this kind of the warm temperature for some other kind of purpose.
18:24But also, it also has some sort of, some, the bad factors for our, uh, lives.
18:37See, uh, you know, the nuclear reactors, uh, can you guess how many nuclear, uh, the kind of bomb is
18:55located around some, some sort of Fukushima, some accidents too.
19:01And, uh, the United States, they have a lot of this nuclear, nuclear reactor.
19:08French is number two country and Japan is number three.
19:14Russia and Germany, South Korea, Ukraine, Ukraine, Canada.
19:22And, uh, but this is quite old data, but I think they have like, uh, the, uh, they might have
19:33still the same order of the country ranking, I guess.
19:43Okay, nuclear fission and fusion.
19:46And, uh, we, we observed like some nuclear fission part.
19:51Now we take a look at like a nuclear fusion part.
19:55So fusion is the opposite of fission.
19:57So the, they are adding two things and then we see one electron out or just a thing, but it
20:09could be some mass changes too inside.
20:12So hydrogen, the, the nuclei gradually combine through a sequence of fusion reactions and ultimately producing helium.
20:22And during these reactions, a small amount of mass is converted into a tremendous amount of energy.
20:30That's what we observed in the previous, the reaction shows too.
20:37So, so, um, the, without nuclear fission, life on earth would not exist because the sun could not provide the
20:48light and heat necessary for life.
20:54That's what the textbook says.
20:57And fusion is therefore one of the most important energy producing processes in, in the universe.
21:06Okay, so, uh, what's the advantages and challenges of fusion?
21:15You know, in the sun that hydrogen atom is added to each other and then helium can be generated.
21:24That's what we see, but that's what, I'm sorry, that's not what we see.
21:28That's what we believe.
21:30And, uh, that's what we are told.
21:35So nuclear fusion offers the, uh, several significant advantages here.
21:41Relatively cheap fuel sources because the, the hydrogen atom, just a few atom is enough to generate that much of
21:50energy.
21:51And products are non-toxic helium or something.
21:56We need a helium, right?
21:58These advantages, the temperature of 40 million Kelvin is needed to initiate the process.
22:06Ooh, that's huge.
22:09I can't imagine how high that 40 million Kelvin could be.
22:15You know, the 1000 Kelvin K is already high enough to be scared.
22:2640 million Kelvin.
22:32I can't imagine.
22:34I can't imagine.
22:35Should we imagine?
22:39But we will see.
22:42If somebody can show us how high this temperature could be.
22:53The biographic imaging or some other, the shocking method, picture, whatever.
23:05That might be very helpful to understand this kind of thing.
23:09You know, the, the person who was working for this kind of, the, the part.
23:20And, uh, we, the, I don't see that many people for this kind of research.
23:33But we need them.
23:35Uh, and also, still, I don't know, this could be, um, done in the near future or not.
23:44We will see.
23:47And, uh, also, nucleotransmutation, mutation.
23:53It's changing, right?
23:55So, uranium and helium can be, uh, added.
24:00And then, that generates some plutonium and then neutron.
24:07Then plutonium 241 decays into americium.
24:13You know, americium, that means it's not, like, stable.
24:16It doesn't look like, uh, originally it is located in, in the periodic table.
24:23Right?
24:24So, that's the one, like, uh, the production, mutation.
24:38So, uh, historically, the idea of changing one element into another fascinated, uh, the ancient
24:47alchemist.
24:48Right?
24:49So, uh, I have been doing some alchemist product in Korea.
24:53And that's for the, the transparent solar cells.
24:57And, uh, this year I'm, I'm wrapping it up.
25:02Then I have done for seven years work.
25:05And, um, the, we achieved the, the world highest record for the transparent solar cell.
25:13And then we will continue work on to keep that kind of record.
25:18The, you know, this is the, also one of the alchemist part.
25:23They try to make some, the diamond, gold, a lot of, like, very, the, uh, high cost, the metal,
25:34from just a regular cheap one.
25:38So, um, you know, the scientists routinely perform transmutation using the, the particle accelerators
25:47and nuclear reactors.
25:51So, if that nuclear reactor is quite cheap, then we can, like, generate a lot of gold from
25:58some, some other things.
26:01So, this transmutation is also, like, a very future bright, the topic many people would like
26:11to work on.
26:12Um, but the device, that reactor is quite huge.
26:17And also it has many, the, the high, the, the energy participation.
26:25That might be a scary part for this nuclear energy, the reaction part.
26:34And also some, the cobalt one.
26:39The, this slide is for, like, a preparation of cobalt-60.
26:45So, cobalt-60 is used in radiation therapy for cancer patients.
26:51So, here, in, in, in, in Korea, we have some Carrie, I don't remember exact the, what this represents.
27:05Like, this is Korea, and this is the atom, because, uh, the atom.
27:13Atomic or Energy Research Institute, maybe.
27:17So, I had been there for a short time.
27:21And then they have, like, a huge reactor.
27:25It's called, like, Hanaro.
27:29Hanaro.
27:30They are making this kind of, like, Hanaro is huge.
27:38And then, uh, they are, like, making this kind of the cobalt-60 or new, uh, the isotope or some,
27:51the highly active, the, this compound.
27:56Because they can use, be used for cancer therapy.
28:04It will, it will decay very soon, though.
28:08So, um, uh, if you are interested, then it, this emits, like, the high energy gamma rays that can be
28:20directed toward, like, cancerous tumors.
28:25By carefully targeting tumors, like, physicians can destroy cancer cells while minimizing damage to surrounding, uh, healthy tissue.
28:38So, these radioisotopes are produced through transmutation.
28:46And, uh, this is also used for industrial inspection and food, food sterilization.
28:54Food sterilization is, uh, also very, uh, the, the, very, what is that, like, a broad, the commercial, the part,
29:06which is very, the, important for the, what is that, like, a commercial, the part, which is very important for
29:13the, what is that, like, a commercial.
29:16비즈니스의이지만
29:18They take a lot of money.
29:23Okay, so let's see ionizing radiation part.
29:29So a molecule can be ionized by radiation.
29:34And then the radiation that knocks an electron from a molecule, thereby ionizing it.
29:41So this kind of radiation measuring, are you interested, are you familiar with this kind of thing?
29:50Radian or Curie, Gray, some Becquerel.
30:00So the Ram, Sievert.
30:09So yeah, I saw many of these units and things, but I'm not familiar with these scales.
30:24You know, alpha particle and beta particle.
30:27We mentioned many different kinds of radioactive material.
30:34And then when they move the TV news or the in the science report.
30:45And when you have a big disaster, they mentioned some sort of this kind of unit in the news.
30:51But I don't know much about it.
30:58Maybe I don't think many people are familiar with this kind of units.
31:04But sometimes we might have to know about those.
31:09But that's for a short time.
31:11And then we just forget it again.
31:15So this Geiger counter is used to detect the previous unit.
31:21And if you take a look at the textbook, like physics book and other things,
31:27many textbook is handling this Geiger counter.
31:31And if you take a look at the detector, most part is also some sort of silicon and silicon solar
31:41cell grade sensor.
31:45So this is just one of the most famous radiation detection instrument.
31:51So the Geiger counter contains a gas field, the tube maintained at high voltage.
32:00And when ionizing radiation, the enters the tube.
32:05It ionizes gas molecule inside, right?
32:09The resulting, the charged particle trigger an electrical pulse.
32:15Because they are approaching this one.
32:19Then they feel like some current changes, right?
32:23So each pulse can be detected electronically and counted.
32:28So counting way is much different from this simple picture.
32:34So in some textbook, they are focusing on that multiplication and then how they can,
32:41what is that, how they can emphasize to show us the actual level value.
33:01And this is more friendly to us, for the scientists.
33:09So I have a particle beta and the gamma or the X-ray.
33:16And they have some energy level here.
33:19So mega electron volt.
33:21Do you remember that electron volt?
33:23One electron is applied to one volt.
33:26That's one electron volt, right?
33:29So one mega electron volt means one electron is applied to one megavolt.
33:38So mega volt?
33:39So mega volt?
33:40So mega volt?
33:40Like not, you, we already, you know, the, we, I had an experience.
33:48I accidentally touched that 220 volt, but that's 200.
33:55And if just one electron is participated, then that's one, 202, 220 electron volt.
34:08This is already enough to make us feel bad or sometimes going to bed or like sometimes dying, right?
34:21And in that case, we may have like much higher value of the electron, number of electron, but
34:31thousand or almost mega electron or many electron.
34:41That's huge amount of energy part.
34:44So that's the energy.
34:47And then the penetrating depth or distance.
34:51This is also important as a scientist.
34:53I want you to get familiar with this kind of number.
34:58So I have a particle, the helium particle, that's pretty quite serious one.
35:03And then they can reach only this millimeter thick.
35:09That's very thin, right?
35:10So alpha particle can be protected by just a regular paper or your clothes.
35:18That's enough to protect this alpha particle.
35:21So as long as we do not take it, take this into your mouth.
35:28So if it goes to our mouth, that's a complete different story because they can be absorbed to the skin.
35:41And then the energy will be transferred to the skin a lot.
35:45And then that tissue or protein, whatever, they can be mutated and then change some other cancer tissue or some
35:59other things.
36:01There are that electron a little bit thicker.
36:07And then the X-ray or some gamma ray.
36:12That's huge, right?
36:14So 20 centimeter.
36:16That's quite.
36:17So to protect this gamma ray, people are using like red.
36:24Red brick, right?
36:27So that's the thing.
36:32Biological effect of radiation.
36:34Here, those are some.
36:36Here they show some.
36:37There might be many different kinds of units, but they hear RAM.
36:42They use RAM.
36:430 to 25.
36:45No detectable effects.
36:47That's what we feel like normal life.
36:50And 25 to 100.
36:52Temporary decreases in white blood cell count.
36:59And 120.
37:02Dosea.
37:04Vomiting.
37:07You know those words, right?
37:09Diarrhea.
37:10But yeah, those are just the common words, I guess.
37:19So eventual death in nearly all cases.
37:22Woohoo.
37:23In all cases, no exceptions.
37:30So application.
37:31Where do we apply this kind of things?
37:36That's quite important, right?
37:38So dating.
37:42Dating.
37:43Dating with radioisotopes.
37:46So nitrogen changes to, what is that?
37:52Carbon-14.
37:53Radioactive carbon-14 is constantly being generated in the upper atmosphere by neutron bombardment.
38:01Bombardment.
38:02Yeah, that's the word.
38:04Yeah, that's the word.
38:04So it's heating instead of absorbing bombardment.
38:09Carbon-14 eventually enters the food chain via the formation of carbon dioxide.
38:19And it's uptake by plants via photosynthesis.
38:22Eating this plant distributes carbon-14 throughout all living organisms.
38:30That's what it says.
38:31And this high energy particle from space generate neutrons, which react with the nitrogen-14.
38:46Where does this one come from?
38:49That's what I said.
38:51And so as a result, all the living organisms contain small amount of carbon-14, right?
39:05While the organism remains alive, the carbon-14 concentration remains approximately constant because carbon is continually exchanged with the environment.
39:26This process forms the basis of radio carbon dating.
39:39And so when an organism dies, it no longer exchanges carbon with the environment, right?
39:50So it stops there.
39:52The amount of carbon-14 within the organism begins to decrease through radioactive decay.
40:01So the half-life of this decay is 5730 years.
40:12That's huge.
40:14So it's the carbon-14 decays into nitrogen-14 by beta emission going back.
40:25So if we take a look at the number, this carbon-14 has a half-life of this one.
40:35So if it decreased the half by half to compare with regular things, that means it has been this long
40:49year.
40:51Since it's dead, right?
40:55Or whatever.
41:00So scientists can determine the age of a sample by measuring the ratio of carbon-14 to carbon-12 remaining
41:10in the material.
41:11Right?
41:13So once it stopped with the exchanging with the environment, that ratio is fixed.
41:21But carbon-14 is changing, it's decaying to nitrogen compound.
41:27So we can guess how long it has been there as it was.
41:37So geological, the things, age can be determined by analysis of potassium-40 the same way.
41:48But we will see how they can see.
41:53This potassium, what's the half-life?
42:02It doesn't say that here.
42:07Potassium-40 is like a naturally occurring radioactive isotope with a very long half-life approximately.
42:16Where is it?
42:18It should be somewhere.
42:24I don't remember the exact value, but some sort of a million years or a billion years.
42:32Do you think we saw that in the previous slide here, potassium?
42:41Oh, here, potassium.
42:45A thousand, million, billion.
42:48It's billion years.
42:51That's huge.
42:53Can you imagine the billion years?
43:02So the same way, but the higher value, billion years.
43:10Over time, potassium-40 decays into argon-40 throughout radioactive processes.
43:20So when rocks solidify, the argon becomes trapped within the mineral structure inside.
43:29So comparing the amount of potassium-40 remaining to the amount of argon-40 produced, scientists can estimate the age
43:39of geological samples.
43:41So next time, we might become some geologist to see how we can expect the age of that.
44:02Okay, and then also medical uses of radioactivity.
44:06In vivo, it's inside the body.
44:10In vitro means outside the body.
44:13So in the inside, determination of whole blood volume using red blood cell labeled with like chromium-51.
44:22So they do that way.
44:24And therapeutic procedure, irradiation of tumors.
44:27That's what we mentioned in the previous slides, cobalt-60.
44:31And beta emission of iodine-131 to treat thyroid disease.
44:38Some, it's thyroid, you know, some sort of, what was it?
44:45Thyroid, it's some, whatever, right?
44:53So the imaging procedure.
44:56So one of my friends in NIH, he's doing a lot of work using this one.
45:01I visited his lab and they had a pretty, like a big chamber and then some nuclear reactor inside that
45:10chamber.
45:10And then the whole experimental lab was surrounded by the lead bricks.
45:17And also it takes forever to enter that lab.
45:22They have to do a lot of the steps before they enter the lab.
45:28And they cannot stay there for a long time because it's, it's, it, it is considered as a, like a
45:38dangerous lab.
45:40Okay.
45:41Sorry.
45:46And this is the, almost the, the, the last part of this whole talk, like a beta voltaic.
45:53So we saw like many, the different kinds of releasing.
46:00So alpha particle can be released or beta particle can be released or gamma particle can be released.
46:07Here we, we take something which emits beta particle.
46:15That's electron, right?
46:16Electricity.
46:17So if we control this electron flow, that's electricity flowing.
46:25So in this time, a huge voltage is developed.
46:28So, you know, like a power equal the, what is that voltage times, I'm sorry, work called voltage times the
46:41current, right?
46:44So then huge voltage, huge voltage is developed.
46:49That means it can work with high value, right?
46:54So the source of radio isotopes used in this technique are strontium-90, krypton-85, and also some tritium.
47:05This type is called like a beta, beta voltage.
47:09So, you know, like a, the solar cell is also called, called like a photovoltaic.
47:16Instead of photovoltaic, they are saying like a betavoltaic.
47:23Actually, you know, in Korea, I don't think we can do this kind of experiment anywhere because the, it's not
47:35allowed to import this kind of thing, even for the research purpose.
47:41Maybe the, the, the Korean, some, they mentioned like a carry, they might do some sort of this kind of
47:49research work in somewhere, but the, I was told it's very difficult to have this kind of a source.
48:03So this cell have a specific power of 24 watts per kilogram.
48:08That's very small amount, you know, 24 watts.
48:11What do we do?
48:13So normally the microwave needs like a 7 watt or 100 watt microwave.
48:23And also the, what else?
48:27The heater.
48:29The heater.
48:30In the winter, the heater needs 1 kilowatt.
48:34That's 1,000 watt per hour, at least.
48:38Even higher value, like two or three.
48:41Three kilowatt per hour.
48:43That's what that heater is using, consuming.
48:48But per kilogram, it's only 24 watts.
48:53That's a small amount.
48:55But you know, like it can operate with a full loading over 10 years operating, sorry, calm.
49:01Even longer than that.
49:03So maybe it needs like a huge size and then also high mass.
49:09But for 10 years, it's generating that power continuously.
49:17So it says the heater efficiency is 25%.
49:21That's huge efficiency, I guess.
49:25So that this is one of the way people are trying to make.
49:38use.
49:40So here, let's take a little power density, milliwatt.
49:45Right?
49:46That's the one we saw.
49:49So half-life, 100 years.
49:52That's 12 years.
49:55Half-life, this is half-life.
49:57So 12 hours, and then another 12 hours, maybe 20 years, something.
50:04It could be used for 20 years.
50:08Because if we have 100, in 12 years, we have 50.
50:16Another 12 years, we have 25 still.
50:21And here, the half-life is 100.
50:24So once we have this kind of big cell inside or under the ground, it generates power for 100 years
50:35or 200 years.
50:37That's a lot, right?
50:38So that's the beta-voltaic can be useful for regular apartment.
50:48They don't have to take some electricity from the outside.
50:55So each line might have one or two, this kind of a big chamber under the ground.
51:04So they generate the energy all the time.
51:11Basic concept, the same thing as like the photovoltaic.
51:15And then the electron has this high electron volt.
51:23And then this could be used to simulate decal 63 source.
51:38So we can use this kind of thing to simulate something.
51:45But that's very, the, not, what is that?
51:50It's not comparable to regular things.
51:56Okay, this is the end.
51:59So I want you to be prepared for our mission next week.
52:07Then we will do something which is shown in this class.
52:15Okay, I will see you in the class.
52:19Bye.