Summary

• Objects (1 modified, 1 added, 0 removed)
  • Caselist.RoundClass[18]
  • Caselist.CitesClass[19]

Details

Caselist.RoundClass[18]

EntryDate

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1		-2016-11-14 05:19:11.698
	1	+2016-11-14 05:19:11.0

Caselist.CitesClass[19]

Cites

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	1	+Text: Countries should prohibit nuclear power except for LFTR reactors AND invest heavily in LFTRs.
	2	+Competition:
	3	+ A Textual: the CPs prohibits less than the aff
	4	+ B Functional: aff bans LFTRs but the CP invests in them
	5	+LFTRs are way better than current PWRs.
	6	+Follows 14 (8 May 2014. Mike, the Royal Society of Chemistry. Cut by Nueva AK. http://www.rsc.org/eic/2014/05/liquid-fluoride-thorium-nuclear-reactor)
	7	+The thorium fuel used by LFTRs is easier to come by than the uranium-235 used in PWRs. Thorium is present in the Earth’s crust at about four times the amount of uranium and is more easily extracted. Additionally, U-235 has a natural abundance of only 0.7, and requires expensive enrichment to 2.5 before it can be used in a PWR. A person observing many yellow waste barrels Radioactive waste from PWR reactors is stored underground for thousands of years © Thomas Imo / Alamy The LFTRs also do not waste any of their nuclear fuel, unlike PWRs. The solid uranium oxide used in PWRs is a poor thermal conductor and so the fuel rods become stressed by internal temperature differences and damaged by radiation. Fission products are also trapped within the fuel rods, acting as ‘poisons’ and compromising a sustained chain reaction by absorbing neutrons. This means that fuel rods need to be replaced when less than 5 of the available energy has been used, and the plant must be shut down every 18 months to allow one third of the rods to be removed and the remainder shuffled. This ‘spent’ fuel is intensely radioactive and is waste that needs to be managed. In contrast, all of the U-233 dissolved in the molten salt of the LFTR undergoes fission. This is because the U-233 atoms are circulating freely in solution so that every nucleus is equally available to absorb a neutron. Also, unlike solid fuel, liquid fluoride salts are impervious to radiation damage and not subject to structural stress. Poisons bubble out of solution in LFTRs or can be chemically removed. LFTRs work at atmospheric pressure, in contrast to the 150 to 160 times atmospheric pressures needed by PWRs. In PWRs, water is the coolant and there are two cooling stages or loops. In the primary loop, water is pumped under high pressure to the reactor core where it is heated by the energy generated by the fission process. This loop is kept under high pressure to allow the water to warm to up to 330°C. Heat from the primary coolant loop is then conducted through heat exchangers to the secondary loop where steam is generated to spin an electric generator. High pressure in a PWR increases efficiency but expensive piping and pressure vessels are required and, because steam occupies 1000 times the volume of liquid water, massive containment buildings are also needed. The salt in the core of the LFTR acts as its own coolant but is passed through a heat exchanger to maintain the temperature of the salt at 800°C and to transfer heat to an inert gas like carbon dioxide or helium. The thermal expansion of this gas drives a turbine to generate electricity In safe hands
	8	+LFTRs solve terrorism, waste, and meltdowns.
	9	+Follows 14 (8 May 2014. Mike, the Royal Society of Chemistry. Cut by Nueva AK. http://www.rsc.org/eic/2014/05/liquid-fluoride-thorium-nuclear-reactor)
	10	+While the LFTR initially lost out to the PWR because it does not generate as much plutonium waste product, today that is viewed as an advantage. Six more neutron absorptions are required to reach Pu-239 when starting from Th-232, compared to the U-238 which makes up 97.5 of the uranium in a PWR. This prevents fretting about whether Pu-239 is being diverted into a nuclear weapons programme. It also reduces the headache of waste management, as after 300 years the waste from thorium-fuelled reactors is about 10,000 times less toxic than that from uranium-fuelled reactors. The relatively small amount of radioactive waste produced in LFTRs requires a few hundred years of isolated storage versus the few hundred thousand years for the waste generated by PWRs. People in white overalls, gas masks and helmets Touring the damaged Fukushima Daiichi nuclear plant © ZUMA Press, Inc. / Alamy The 2011 meltdown of the Fukushima Daiichi nuclear power plant in Japan was caused by a tsunami disabling the PWR’s cooling system. LFTRs cannot suffer meltdowns because their fuel is already molten. PWRs contain control rods that are designed to absorb neutrons. They are inserted into, and removed from, the core of the nuclear reactor as required to control the rate of fission. They are usually made of boron or cadmium and are suspended from the ceiling by electromagnets. If power failure occurs the control rods fall under gravity into their slots in the reactor core below. However, like applying brakes in a car, the reactor has thermal inertia and cannot stop producing thermal energy instantaneously. The core remains hot and fission continues among the daughter nuclei, which means that meltdown is unavoidable if the coolant stops circulating. In stark contrast, the LFTR needs power to prevent shutdown of the reactor. It has a ‘freeze plug’ at the bottom of the core – a plug of salt, cooled by a fan, to keep it below the freezing point of the salt. If the power turns off, the fan stops. This causes the plug to melt and the liquid fuel to flow, under gravity, into a catch basin below.

EntryDate

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	1	+2016-11-14 05:19:13.546

Judge

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	1	+x

Opponent

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	1	+x

ParentRound

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	1	+18

Round

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	1	+1

Team

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	1	+Sunset bhat Neg

Title

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	1	+SO - LFTR PIC

Tournament

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	1	+x