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Kategori: thorium

Publisert Legg igjen en kommentar til TEDxBergen: Nuclear weapons and thorium and stuff

Finally, the video from the TEDxBergen conference is now on-line!

The subject of my talk was Could nuclear weapons save the planet? , and you can watch the entire thing here:
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Since I talked about how to dress as a female scientist in my last blogpost, I just have to show you a close-up of the shoes I wore. These shoes from Nelly ended up as my "statement" for this talk - which I felt that I needed, since the rest of the outfit was quite simple; just tight jeans, a loose shirt, and my hair in a bun (not the tightest, but not very messy either):
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One of the really great thing about this trip to Bergen (almost a month ago already!) - besides being allowed to give my third TEDx talk - was that Anders came and spent the weekend with me <3 There's nothing like sharing experiences like this with the one you love, and having Anders in the audience made me feel so much better and more secure than if I had been there all by myself... He was a great supprt!
perfect evening: I was dead tired after  a long day -  I do get really stressed before I'm giving a talk like this. We were thinking about either go to the after party with the rest of the people from the conference, or maybe go out in Bergen... But instead we stayed in the hotel; we took a looong bath (where we drank two bottles of Prosecco), before we ordered pizza to the room, ate it in bed and watched several episodes of the Big Bang Theory. It was just perfect <3
 

Publisert Legg igjen en kommentar til Pure joy!

Good morning everyone <3 Day two of this California/Berkeley trip has just started, and so far I'm very happy 🙂
Yesterday I "finished" the first part of the uranium analysis (which is to find the nuclear level density of uranium-234) - that I wrote about in my last blog post - and started the second part of the analysis (which is to find the gamma ray strength function of uranium-234). The picture above show the very first result of my gamma ray strength data (the squares - both black and white) plotted together with different data from the big nuclear data bases. When I wrote "plot" and this appeared I actually screamed with excitement and joy, and hugged Cecilie, who was sitting next to me and helping me, because it looks soooo pretty - even before I've started to "tweak" my data to fit with the ones from the data bases (the ones on the right side of the plot - the little triangles). 
The goal of this trip is btw to put these two properties of the nucleus (the nuclear level denisty and the gamma ray strength function) into simulations of different reactors (that uses thorium based fuel) and see if they affect the results of the simulations - when we compare to standard simulations where we don't do anything about these nuclear properties 🙂 *excited*
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Below are a couple of pictures from yesterday and today. The first one, of Anders, is probably more like what you would imagine when I say "pure joy"...;) He has just rented a nice car and is on his way to Palo Alto as we speak - he is also excited. (Actually kind of wish i could go with him, but I'm on my way to the lab now, with Cecilie - and that will of course also be fun...but in a quite different way 😛 )

beautiful morning at Berkeley campus
cutest squirrel at Berkeley campus

Cecilie and Darren discussion something important (I'm guessing 😉 ) at Jupiter, where we had dinner yesterday - and the day before, when we'd just arrived

Jupiter <3

Jupiter <3

Publisert Legg igjen en kommentar til Q-value
Today I've made this table (with my new favourite: this calculator 😀 ):
So this beautiful table shows the different Q-values for the different reactions that go on in my experiments (oh, yes, there's beryllium and there's carbon and there's oxygen there - even though it would've been nice if it was only uranium...).
The Q-value tells how much energy that is released in a certain reaction: for the first reaction, for example, the Q-value is 4620 keV, which means that when a deutron hits a uranium-233 nucleus, and a proton goes out of that reaction, around 4600 keV (energy) is released ;). If that same deutron hits an oxygen-16 nucleus instead of the uranium-233, and a triton (instead of a proton) is released, the reaction absorbs energy instead of releasing energy: 9406 keV to be (almost) exact...
I also, finally, submitted my application about changing my theoretical curriculum for my PhD degree 😀
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It's beautiful at the University these days, btw - don't you agree? Love blossoming cherrytrees:)

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Publisert 3 kommentarer til Foredrag: Thorium Mythbusters

God midtuke alle! Her kommer et lite foredragstips fra meg 😉
Jeg skal nemlig holde tre foredrag fremover - eller, det vil si; jeg skal holde ett foredrag - Thorium Mythbusters - tre ganger i tiden fremover. Dette kan jo kanskje være interessant for noen av de fineste leserne mine, og siden det er åpent for alle så må jeg jo nesten si i fra 😉
Det første foredraget er allerede nå til lørdag, ifbm. NFK (Norske Fysikkstudenters Konferanse), klokken 12:30 i Store Fysiske Auditorium på Fysisk institutt på Blindern.
De to andre er torsdag 9. april på Real Frokost (kl 08:30) på Realistforeningen, og det siste er tirsdag den 12. mai er på arrangementet Frokost hos Kristine (jeg kan selvsagt komme med mer info om de to andre foredragene når det nærmer seg, hvis det er ønskelig?)
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Det jeg skal snakke om blir omtrent som dette <3

Thorium er et naturlig forekommende, lett radioaktivt materiale, som av mange har blitt sett på som redningen for kjernekraftens rykte, og løsningen på klimakrisen.

Å bruke thorium som brensel i kjernekraftverk kan ha flere fordeler, og det som ofte trekkes frem er bla:

  • det fins fire ganger mer thorium enn uran i naturen 
  • man kan produsere mindre radioaktivt avfall
  • sannsynligheten for en reaktor som "løper løpsk" er null
  • man kan gjenvinne avfallet fra thorium-brensel
  • thorium kan ikke brukes til våpenproduksjon

Men stemmer det virkelig at thorium er 200 ganger mer energitett enn uran? Og er thorium-ktaftverk tryggere enn konvensjonelle kjernekraftverk? Går thorium-tilhengerne for langt, og er kanskje thorium blitt vår tids teknologiske kult?

Foredraget tar for seg myter og misforståelser rundt kjernekraft generelt, og throium spesielt.

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Publisert 3 kommentarer til Coffee and (DARK!) chokolate
Good morning!
I forgot it takes forever to get from Charles de Gaulle airport, north of Paris, to the lab in Orsay, south of Paris... Normally I prefer to fly Norwegian to the Orly airport, which is just between the city and the lab, but this time Air France was the only company with reasonable flight times. Anyway, by the time I finally arrived at the lab, I was starving, and had to get something to eat. Then there was catching up to do, and suddenly it was 10:30 PM and I had to go to sleep because I had signed up for the morning/day shift today. I´ve been at the lab since 7 AM, and heavy doses of chocolate and coffee are needed 😉
(Didn´t have time to put on my make up this morning btw., so I look a little...hmmm...don´t really know...:P )

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So I told you yesterday that I was embarrassed, and that I would tell you about it - was planning on doing it last night, but now you know how come that didn´t happen. I will tell you now instead:
Last Friday I was on the radio, and one of the things I was talking about was the amount of radioactivity that was present at earth 3.5 billion years ago (when life started). So I was talking about the half-lives of thorium-232, uranium-238 and uranium-235. 
Thorium-232 has a half-life of 14 billion years, so the amount of thorium here on earth is more or less the same as it was 3.5 billion years ago. The half-life of uranium-238 is 4.5 billion years, so around half of what was here 3.5 years ago is gone.
So far, so good...
But then I talked about uranium-235, which has a half-life of "only" 700 million years. This means that 3.5 billion years is more or less the same as 5 half-lives of uranium-235. Then I did the mistake: I said that since 5 half-lives of this uranium isotope has gone by, there is one fifth of it left - in other words, 3.5 billion years ago there was 5 times as much uranium-235 on earth, as it is today.
WRONG! 5 half-lives doesn´t meen that there was five times more :/ *feeling stupid*
1 half-life of something means that after that time half of it is gone. Two half-lives means that 3 quarters is gone, three half-lives means 7/8 is gone, four half-lives means 15/16 is gone, and five half-lives means 31/32 is gone - 1/32 is left. 1/32 is around the same as 3%, and 3.5 billion years ago there was 32 times more uranium-235 on earth...!
My excuse is that I was really stressed the day before, and something did NOT feel right (e.g. I didn´t get the right percentage of uranium-235 to have fission and a chain reaction going on in nature - and now I know why 😛 ); but this was a "rookie mistake" - and I shouldn´t have done it 🙁

Hope you can forgive me <3 <3 <3

Tomorrow is an important nuclear anniversary - anyone that can guess what it is? I will tell you tomorrow 🙂

Publisert Legg igjen en kommentar til Number 15
Only 8ish days ´til Christmas now...and in todays calendar is another cross-section graph - this time it´s the cross-section/probability of neutron capture on uranium-233:

On the y-axis is the value of the cross-section (the higher the number, the higher the probability of a neutron being captured by the nucleus when hitting it), and on the x-axis is the energy of the neutron.
But there are several graphs here...and they all show different values for this cross-section - the truth is that we don´t exactly know what it is (my research is into this...) :/ The blue, turqoise and red lines are the "official numbers" (evaluated nuclear data), the different dots are actual measurements (some with HUGE error bars), and the green line is calculated with the default input parameters about the nucleus.
It´s quite an important cross-section for the thorium fuel cycle, since it tells us about the probability of a neutron being captured by uranium-233 instead of making it fission (which is what we want it to do) - so it would be nice to know it better 😉

Publisert Legg igjen en kommentar til 13 + 14
So, yesterday I didn´t get the chance to share a graph, so today you´ll get a double dose 😀
Also, I got a complaint that the last graphs didnt´have any christmas decorations on them - so I´ve tried to do better this time...;)
Today you get two versions of ALPHA! 
ALPHA is the "capture to fission ratio" - it tells us how often a neutron is captured/absorbed, rather than causing a nucleus to fission. We want ALPHA to be as low as possible - since a low ALPHA means that little waste is produced 😀
First there is ALPHA for neutrons with low energy:
The red line is for uranium-233, and the blue is for plutonium-239. For low-energy neutrons, ALPHA is lower for uranium-233 than plutonium-239, and this means that there is a smaller waste production from thorium-fuels than uranium...IF the neutrons have a low energy/are thermal (this can´t be said often enough 😉 )!
Then there is ALPHA for neutrons with high energy - and here it changes (as it also did with ETA):
For neutrons with high energy the waste production is smaller for uranium-fuels than with thorium...

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Publisert 2 kommentarer til The 12th of December
Today is December the 12th, and in the calendar is the rest of what I gave you yesterday - it´s ETA again, but this time it´s ETA for neutrons with high energy (fast neutrons). The graph is very important for the neutron economy of a nuclear reactor...
ETA tells us about how many neutrons you get out for each neutron going in (to a nucleus) on average ("neutrons emitted/neutrons absorbed"). As you can see you get, on average, more neutrons from fission of plutonium-239 (blue line) than you get from uranium-233 (red line) - if the neutron going in has high energy/is a fast neutron. In other words: it´s exact opposite of what was in the calendar yesterday...!
So, since plutonium-239 is a better fissile material than uranium-233 (when hit by high-energy neutrons), you can produce more new fissile material from uranium, than you can from thorium 😀 Or, to sort of conclude: for thermal neutrons, thorium seems to be the way to do it, bur for fast neutrons, uranium/plutonium seems to be the way to do it <3<3<3

Publisert Legg igjen en kommentar til Number 11
In the calendar today is a graph that is very important for the thorium fuel cycle... 
Today I give you ETA!
ETA tells us about how many neutrons you get out for each neutron going in (to a nucleus) on average ("neutrons emitted/neutrons absorbed"). As you can see you get, on average, more neutrons from fission of uranium-233 (red line) than you get from plutonium-239 (blue line) - if the neutron going in has low energy/is a thermal neutron.
So, since uranium-233 is a better fissile material than plutonium-239 (when hit by low-energy neutrons), you can produce more new fissile material from thorium, than you can from uranium 😀 We like that <3<3<3

Publisert Legg igjen en kommentar til Thorium (fuel cycle)
I dag har jeg brukt ganske mye tid på å fundere på om The thorium fuel cycle burde være et eget kapittel i avhandlingen min, eller om det bør være et underkapittel. Foreløpig står det som et underkapittel til Introduksjons-kapittelet, men jeg har vel kanskje litt på følelsen av at det blir et eget kapittel... Det kommer vel litt an på hvor langt og omfattende det blir. 
Tror jeg.
bilde fra masteroppgaven min 🙂