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Messages - atomicpower

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1
I tried to get 1.1 working, but even after updating Windows it never ran.

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I'm pretty sure 1.0 maps are larger.

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whatevahs / Re: Roast the player above.
« on: June 09, 2017, 09:21:50 AM HST »
I would but it's not even kicking him while he's down, that would be somehow better.

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whatevahs / Re: post something
« on: June 09, 2017, 09:13:26 AM HST »
You know, you can say just about any worry you have about nuclear power plants and I can reply with the same thing: "molten salt reactor".

Let's begin:

Molten-salt fueled reactors are types of reactors where the fuel is dissolved in the same chemical that is being used as the coolant. In Weinberg's uranium-233 fueled design (also known as "liquid-fluoride thorium reactor", "Oak Ridge National Laboratories molten-salt design", or "fluid-fuel thorium reactor"), it's a molten fluoride-beryllium-lithium combination. Thorium-232 is fed into either the core directly in a single-fluid type (as in Weinberg's MSR expirement which ran for five years in the late 1960s), or two-fluid, where the breeding and fission occur in separate parts of the reactor.

Spoiler for Dual-fluid vs single-fluid:
The one-fluid design includes a large reactor vessel filled with fluoride salt containing thorium and uranium. Graphite rods immersed in the salt function as a moderator and to guide the flow of salt. In Weinberg's design a reduced amount of graphite near the edge of the reactor core would make the outer region under-moderated, and increased the capture of neutrons there by the thorium. With this arrangement, most of the neutrons were generated at some distance from the reactor boundary, and reduced the neutron leakage to an acceptable level. Still, a single fluid design needs a considerable size to permit breeding.

In a breeder configuration, extensive fuel processing was specified to remove fission products from the fuel salt. In a converter configuration fuel processing requirement was simplified to reduce plant cost. The trade-off was the requirement of periodic uranium refueling.

The MSRE was a core region only prototype reactor. The MSRE provided valuable long-term operating experience. According to estimates of Japanese scientists, a single fluid LFTR program could be achieved through a relatively modest investment of roughly 300-400 million dollars over 5–10 years to fund research to fill minor technical gaps and build a small reactor prototype comparable to the MSRE.

The two-fluid design is mechanically more complicated compared to the "single fluid" reactor design. The "two fluid" reactor has a high-neutron-density core that burns uranium-233 from the thorium fuel cycle. A separate blanket of thorium salt absorbs the neutrons and its thorium is converted to protactinium-233. Protactinium-233 can be left in the blanket region where neutron flux is lower, so that it slowly decays to U-233 fissile fuel, rather than capture neutrons. This bred fissile U-233 can be recovered by simple fluorination, and placed in the core to fission. The core's salt is also purified, first by fluorination to remove uranium, then vacuum distillation to remove and reuse the carrier salts. The still bottoms left after the distillation are the fission products waste of a LFTR.

The advantages of separating the core and blanket fluid include:

1. Simplified fuel processing. Thorium is chemically similar to several fission products, called lanthanides. With thorium in a separate blanket, thorium is kept isolated from the lanthanides. Without thorium in the core fluid, removal of lanthanide fission products is simplified.

2. Low fissile inventory. Because the fissile fuel is concentrated in a small core fluid, the actual reactor core is more compact. There is no fissile material in the outer blanket that contains the fertile fuel for breeding. Because of this, the 1968 ORNL design required just 315 kilograms of fissile materials to start up a 250 MW(e) two fluid MSBR reactor. This reduces the cost of the initial fissile startup charge, and allows more reactors to be started up on any given amount of fissile material.

3. More efficient breeding. The thorium blanket can effectively capture leaked neutrons from the core region. There is nearly zero fission occurring in the blanket, so the blanket itself does not leak significant numbers of neutrons. This results in a high efficiency of neutron use (neutron economy), and a higher breeding ratio, especially with small reactors.

One design weakness of the two-fluid design is the necessity for a barrier wall between the core and the blanket region, a wall that would have to be replaced periodically because of fast neutron damage. Graphite was the material chosen by ORNL because of its low neutron absorption, compatibility with the molten salts, high temperature resistance, and sufficient strength and integrity to separate the fuel and blanket salts. The effect of neutron radiation on graphite is to slowly shrink and then swell the graphite to cause an increase in porosity and a deterioration in physical properties. Graphite pipes would change length, and may crack and leak. ORNL chose not to pursue the two-fluid design, and no examples of the two-fluid reactor were ever constructed.

One additional design weakness of the two-fluid design was its complex plumbing. ORNL thought it necessary to use complex interleaving of the core and blanket piping in order to get a high reactor power level with acceptably low power density. More recent research has put into question the need for complex interleaving graphite tubing, suggesting a simple elongated tube-in-shell reactor would allow high total reactor power without complex tubing.
Spoiler for Long, long, long list of benefits:
Thorium-fueled molten salt reactors offer many potential advantages compared to conventional solid uranium fueled light water reactors:

Safety

    Inherent safety. LFTR designs use a strong negative temperature coefficient of reactivity to achieve passive inherent safety against excursions of reactivity. The temperature dependence comes from 3 sources. The first is that thorium absorbs more neutrons if it overheats, the so-called Doppler effect. This leaves fewer neutrons to continue the chain reaction, reducing power. The second part is heating the graphite moderator, that usually causes a positive contribution to the temperature coefficient. The third effect has to do with thermal expansion of the fuel. If the fuel overheats, it expands considerably, which, due to the liquid nature of the fuel, will push fuel out of the active core region. In a small (e.g. the MSRE test reactor) or well moderated core this reduces the reactivity. However, in a large, under-moderated core (e.g. the ORNL MSBR design), less fuel salt means better moderation and thus more reactivity and an undesirable positive temperature coefficient.

    Stable coolant. Molten fluorides are chemically stable and impervious to radiation. The salts do not burn, explode, or decompose, even under high temperature and radiation. There are no rapid violent reactions with water and air that sodium coolant has. There is no combustible hydrogen production that water coolants have. However the salt is not stable to radiation at low (less than 100 C) temperatures due to radiolysis.

    Low pressure operation. Because the coolant salts remain liquid at high temperatures, LFTR cores are designed to operate at low pressures, like 0.6 MPa (comparable to the pressure in the drinking water system) from the pump and hydrostatic pressure. Even if the core fails, there is little increase in volume. Thus the containment building cannot blow up. LFTR coolant salts are chosen to have very high boiling points. Even a several hundred degree heatup during a transient or accident does not cause a meaningful pressure increase. There is no water or hydrogen in the reactor that can cause a large pressure rise or explosion as happened during the Fukushima Daiichi nuclear accident.

    No pressure buildup from fission. LFTRs are not subject to pressure buildup of gaseous and volatile fission products. The liquid fuel allows for online removal of gaseous fission products, such as xenon, for processing, thus these decay products would not be spread in a disaster. Further, fission products are chemically bonded to the fluoride-salt, including iodine, cesium, and strontium, capturing the radiation and preventing the spread of radioactive material to the environment.

    Easier to control. A molten fuel reactor has the advantage of easy removal of xenon-135. Xenon-135, an important neutron absorber, makes solid fueled reactors difficult to control. In a molten fueled reactor, xenon-135 can be removed. In solid-fuel reactors, xenon-135 remains in the fuel and interferes with reactor control.

    Slow heatup. Coolant and fuel are inseparable, so any leak or movement of fuel will be intrinsically accompanied by a large amount of coolant. Molten fluorides have high volumetric heat capacity, some such as FLiBe, even higher than water. This allows them to absorb large amounts of heat during transients or accidents.

    Passive decay heat cooling. Many reactor designs (such as that of the Molten-Salt Reactor Experiment) allow the fuel/coolant mixture to escape to a drain tank, when the reactor is not running (see "Fail safe core" below). This tank is planned to have some kind (details are still open) of passive decay heat removal, thus relying on physical properties (rather than controls) to operate.

    Fail safe core. LFTRs can include a freeze plug at the bottom that has to be actively cooled, usually by a small electric fan. If the cooling fails, say because of a power failure, the fan stops, the plug melts, and the fuel drains to a subcritical passively cooled storage facility. This not only stops the reactor, also the storage tank can more easily shed the decay heat from the short-lived radioactive decay of irradiated nuclear fuels. Even in the event of a major leak from the core such as a pipe breaking, the salt will spill onto the kitchen-sink-shaped room the reactor is in, which will drain the fuel salt by gravity into the passively cooled dump tank.

    Less long-lived waste. LFTRs can dramatically reduce the long-term radiotoxicity of their reactor wastes. Light water reactors with uranium fuel have fuel that is more than 95% U-238. These reactors normally transmute part of the U-238 to Pu-239, a long-lived isotope. Almost all of the fuel is therefore only one step away from becoming a transuranic long-lived element. Plutonium-239 has a half life of 24,000 years, and is the most common transuranic in spent nuclear fuel from light water reactors. Transuranics like Pu-239 cause the perception that reactor wastes are an eternal problem. In contrast, the LFTR uses the thorium fuel cycle, which transmutes thorium to U-233. Because thorium is a lighter element, more neutron captures are required to produce the transuranic elements. U-233 has two chances to fission in a LFTR. First as U-233 (90% will fission) and then the remaining 10% has another chance as it transmutes to U-235 (80% will fission). The fraction of fuel reaching neptunium-237, the most likely transuranic element, is therefore only 2%, about 15 kg per GWe-year. This is a transuranic production 20x smaller than light water reactors, which produce 300 kg of transuranics per GWe-year. Importantly, because of this much smaller transuranic production, it is much easier to recycle the transuranics. That is, they are sent back to the core to eventually fission. Reactors operating on the U238-plutonium fuel cycle produce far more transuranics, making full recycle difficult on both reactor neutronics and the recycling system. In the LFTR, only a fraction of a percent, as reprocessing losses, goes to the final waste. When these two benefits of lower transuranic production, and recycling, are combined, a thorium fuel cycle reduces the production of transuranic wastes by more than a thousand-fold compared to a conventional once-through uranium-fueled light water reactor. The only significant long-lived waste is the uranium fuel itself, but this can be used indefinitely by recycling, always generating electricity.

    If the thorium stage ever has to be shut down, part of the reactors can be shut down and their uranium fuel inventory burned out in the remaining reactors, allowing a burndown of even this final waste to as small a level as society demands. The LFTR does still produce radioactive fission products in its waste, but they don't last very long - the radiotoxicity of these fission products is dominated by cesium-137 and strontium-90. The longer half-life is cesium: 30.17 years. So, after 30.17 years, decay reduces the radioactivity by a half. Ten half-lives will reduce the radioactivity by two raised to a power of ten, a factor of 1,024. Fission products at that point, in about 300 years, are less radioactive than natural uranium. What's more, the liquid state of the fuel material allows separation of the fission products not only from the fuel, but from each other as well, which enables them to be sorted by the length of each fission product's half-life, so that the ones with shorter half-lives can be brought out of storage sooner than those with longer half-lives.

    Proliferation resistance. In 2016, Nobel Laureate physicist Dr Carlo Rubbia, former Director General of CERN, claimed a primary reason for the United States cutting thorium reactor research in the 1970s is what makes it so attractive today: thorium is difficult to turn into a nuclear weapon.

    The LFTR resists diversion of its fuel to nuclear weapons in four ways: first, the thorium-232 breeds by converting first to protactinium-233, which then decays to uranium-233. If the protactinium remains in the reactor, small amounts of U-232 are also produced. U-232 has a decay chain product (thallium-208) that emits powerful, dangerous gamma rays. These are not a problem inside a reactor, but in a bomb, they complicate bomb manufacture, harm electronics and reveal the bomb's location. The second proliferation resistant feature comes from the fact that LFTRs produce very little plutonium, around 15 kg per gigawatt-year of electricity (this is the output of a single large reactor over a year). This plutonium is also mostly Pu-238, which makes it unsuitable for fission bomb building, due to the high heat and spontaneous neutrons emitted. The third track, a LFTR doesn't make much spare fuel. It produces at most 9% more fuel than it burns each year, and it's even easier to design a reactor that makes only 1% more fuel. With this kind of reactor, building bombs quickly will take power plants out of operation, and this is an easy indication of national intentions. And finally, use of thorium can reduce and eventually eliminate the need to enrich uranium. Uranium enrichment is one of the two primary methods by which states have obtained bomb making materials.

Economy and efficiency
Comparison of annual fuel requirements and waste products of a 1 GW uranium-fueled LWR and 1 GW thorium-fueled LFTR power plant.

    Thorium abundance. A LFTR breeds thorium into uranium-233 fuel. The Earth's crust contains about three to four times as much thorium as U-238 (thorium is about as abundant as lead). It is a byproduct of rare-earth mining, normally discarded as waste. Using LFTRs, there is enough affordable thorium to satisfy the global energy needs for hundreds of thousands of years. Thorium is more common in the earth’s crust than tin, mercury, or silver. A cubic meter of average crust yields the equivalent of about four sugar cubes of thorium, enough to supply the energy needs of one person for more than ten years if completely fissioned. Lemhi Pass on the Montana-Idaho border is estimated to contain 1,800,000 tons of high-grade thorium ore. Five hundred tons could supply all U.S. energy needs for one year. Due to lack of current demand, the U.S. government has returned about 3,200 metric tons of refined thorium nitrate to the crust, burying it in the Nevada desert.

    No shortage of natural resources. Sufficient other natural resources such as beryllium, lithium, nickel and molybdenum are available to build thousands of LFTRs.

    Reactor efficiency. Conventional reactors consume less than one percent of the mined uranium, leaving the rest as waste. With perfectly working reprocessing LFTR may consume up to about 99% of its thorium fuel. The improved fuel efficiency means that 1 ton of natural thorium in a LFTR produces as much energy as 35 t of enriched uranium in conventional reactors (requiring 250 t of natural uranium), or 4,166,000 tons of black coal in a coal power plant.

    Thermodynamic efficiency. LFTRs operating with modern supercritical steam turbines would operate at 45% thermal to electrical efficiency. With future closed gas Brayton cycles, which could be used in a LFTR power plant due to its high temperature operation, the efficiency could be up to 54%. This is 20 to 40% higher than today's light water reactors (33%), resulting in the same 20 to 40% reduction in fissile and fertile fuel consumption, fission products produced, waste heat rejection for cooling, and reactor thermal power.

    No enrichment and fuel element fabrication. Since 100% of natural thorium can be used as a fuel, and the fuel is in the form of a molten salt instead of solid fuel rods, expensive fuel enrichment and solid fuel rods' validation procedures and fabricating processes are not needed. This greatly decreases LFTR fuel costs. Even if the LFTR is started up on enriched uranium, it only needs this enrichment once just to get started. After startup, no further enrichment is required.

    Lower fuel cost. The salts are fairly inexpensive compared to solid fuel production. For example, while beryllium is quite expensive per kg, the amount of beryllium required for a large 1 GWe reactor is quite small. ORNL's MSBR required 5.1 tons of beryllium metal, as 26 tons of BeF2. At a price of $147/kg BeF2, this inventory would cost less than $4 million, a modest cost for a multibillion-dollar power plant. Consequently, a beryllium price increase over the level assumed here has little effect in the total cost of the power plant. The cost of enriched lithium-7 is less certain, at $120–800/kg LiF. and an inventory (again based on the MSBR system) of 17.9 tons lithium-7 as 66.5 tons LiF makes between $8 million and $53 million for the LiF. Adding the 99.1 tons of thorium at $30/kg adds only $3 million. Fissile material is more expensive, especially if expensively reprocessed plutonium is used, at a cost of $100 per gram fissile plutonium. With a startup fissile charge of only 1.5 tons, made possible through the soft neutron spectrum this makes $150 million. Adding everything up brings the total cost of the one time fuel charge at $165 to $210 million. This is similar to the cost of a first core for a light water reactor. Depending on the details of reprocessing the salt inventory once can last for decades, whereas the LWR needs a completely new core every 4 to 6 years (1/3 is replaced every 12 to 24 months). ORNL's own estimate for the total salt cost of even the more expensive 3 loop system was around $30 million, which is less than $100 million in today's money.

    LFTRs are cleaner: as a fully recycling system, the discharge wastes from a LFTR are predominantly fission products, most of which (83%) have relatively short half lives in hours or days compared to longer-lived actinide wastes of conventional nuclear power plants. This results in a significant reduction in the needed waste containment period in a geologic repository. The remaining 17% of waste products require only 300 years until reaching background levels. The radiotoxicity of the thorium fuel cycle waste is 10,000 times less than that of the uranium/plutonium fuel lifecycle.

    Less fissile fuel needed. Because LFTRs are thermal spectrum reactors, they need much less fissile fuel to get started. Only 1-2 tons of fissile are required to start up a single fluid LFTR, and potentially as low as 0.4 ton for a two fluid design. In comparison, solid fueled fast breeder reactors need at least 8 tons of fissile fuel to start the reactor. While fast reactors can theoretically start up very well on the transuranic waste, their high fissile fuel startup makes this very expensive.

    No downtime for refueling. LFTRs have liquid fuels, and therefore there is no need to shut down and take apart the reactor just to refuel it. LFTRs can thus refuel without causing a power outage (online refueling).

    Load following. As the LFTR does not have xenon poisoning, there is no problem reducing the power in times of low demand for electricity and turn back on at any time.

    No high pressure vessel. Since the core is not pressurized, it does not need the most expensive item in a light water reactor, a high-pressure reactor vessel for the core. Instead, there is a low-pressure vessel and pipes (for molten salt) constructed of relatively thin materials. Although the metal is an exotic nickel alloy that resists heat and corrosion, Hastelloy-N, the amount needed is relatively small.

    Excellent heat transfer. Liquid fluoride salts, especially LiF based salts, have good heat transfer properties. Fuel salt such as LiF-ThF4 has a volumetric heat capacity that is around 22% higher than water, FLiBe has around 12% higher heat capacity than water. In addition, the LiF based salts have a thermal conductivity around twice that of the hot pressurized water in a pressurized water reactor. This results in efficient heat transfer and a compact primary loop. Compared to helium, a competing high temperature reactor coolant, the difference is even bigger. The fuel salt has over 200 times higher volumetric heat capacity as hot pressurized helium and over 3 times the thermal conductivity. A molten salt loop will use piping of 1/5 the diameter, and pumps 1/20 the power, of those required for high-pressure helium, while staying at atmospheric pressure

    Smaller, low pressure containment. By using liquid salt as the coolant instead of pressurized water, a containment structure only slightly bigger than the reactor vessel can be used. Light water reactors use pressurized water, which flashes to steam and expands a thousandfold in the case of a leak, necessitating a containment building a thousandfold bigger in volume than the reactor vessel. The LFTR containment can not only be smaller in physical size, its containment is also inherently low pressure. There are no sources of stored energy that could cause a rapid pressure rise (such as Hydrogen or steam) in the containment. This gives the LFTR a substantial theoretical advantage not only in terms of inherent safety, but also in terms of smaller size, lower materials use, and lower construction cost.

    Air cooling. A high temperature power cycle can be air-cooled at little loss in efficiency, which is critical for use in many regions where water is scarce. No need for large water cooling towers used in conventional steam-powered systems would also decrease power plant construction costs.

    From waste to resource. There are suggestions that it might be possible to extract some of the fission products so that they have separate commercial value. However, compared to the produced energy, the value of the fission products is low, and chemical purification is expensive.

    Efficient mining. The extraction process of thorium from the earth's crust is a much safer and efficient mining method than that of uranium. Thorium’s ore, monazite, generally contains higher concentrations of thorium than the percentage of uranium found in its respective ore. This makes thorium a more cost efficient and less environmentally damaging fuel source. Thorium mining is also easier and less dangerous than uranium mining, as the mine is an open pit, which doesn't require ventilation such as the underground uranium mines, where radon levels are potentially harmful.

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I feel like my initial thought of "Ramadan Bombathon" would have gone down poorly. The closest holiday I could see most people being around to participate in would be Halloween. It would probably be a good idea to make a new thread for it, though.

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It would be best to do it on some holiday, when the most people are out of work or school.

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I think it sounds like a good idea.

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All I can say is  :-\

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Ace of Spades Classic / Re: a client thing
« on: May 24, 2017, 08:56:12 PM HST »
issues is that barely anyone can run openspades and they were too merciful for the smg, making it more OP.

by "barely anyone" do you mean all the german and br children who are gaming on handheld calculators?

Being an American child gaming on a handheld calculator I take offence to that.

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