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High-temperature plumbing and advanced reactors
The use of nuclear fission power and its role in impacting climate change is hotly debated. Fission advocates argue that short-term solutions would involve the rapid deployment of Gen III+ nuclear reactors, like Vogtle-3 and -4, while long-term climate change impact would rely on the creation and implementation of Gen IV reactors, “inherently safe” reactors that use passive laws of physics and chemistry rather than active controls such as valves and pumps to operate safely. While Gen IV reactors vary in many ways, one thing unites nearly all of them: the use of exotic, high-temperature coolants. These fluids, like molten salts and liquid metals, can enable reactor engineers to design much safer nuclear reactors—ultimately because the boiling point of each fluid is extremely high. Fluids that remain liquid over large temperature ranges can provide good heat transfer through many demanding conditions, all with minimal pressurization. Although the most apparent use for these fluids is advanced fission power, they have the potential to be applied to other power generation sources such as fusion, thermal storage, solar, or high-temperature process heat.1–3
Bin Liu, Juan Fu, Xuefeng Lyu, Wenqiang Li, Jinsheng Han
Nuclear Science and Engineering | Volume 192 | Number 3 | December 2018 | Pages 298-310
Technical Paper | doi.org/10.1080/00295639.2018.1509570
Articles are hosted by Taylor and Francis Online.
Using the MCNP code, we explore three different 99Tc loading patterns in pressurized water reactor (PWR) burnable poison rods (BPRs). We also calculate the effects on the PWR keff and boric acid concentration readjusted amount after loading 99Tc transmutation material into PWR BPRs. Finally, we carry out the transmutation rate and depletion calculation.
After the 99Tc transmutation material is mixed homogeneously with burnable poison (BP) in the BPRs, keff slightly increases. As the amount of 99Tc coating on the BPRs increases, keff decreases gradually and slightly; this result is similar to the tendency of keff to decrease after applying a thin-layer coating of minor actinide in the BPRs. Our calculation results show that as the coating thickness of 99Tc in the water gap of BPRs increases, keff decreases correspondingly. The more BPR water gaps are filled in with 99Tc transmutation material, the sharper is the decrease of keff. If 99Tc fills in the water gaps of 12 BPRs of each fuel assembly, the coating thickness is 0.02 cm, and the corresponding total 99Tc coating amount is 206.76 kg. This is the annual 99Tc yield of more than three PWRs.
Our calculations also indicate that the more 99Tc is loaded into the PWR, the more boric acid concentration needs to be reduced in the coolant. For instance, if the 99Tc coating thickness in the water gaps is 0.02 cm, when 99Tc fills in 12 BPR water gaps of each fuel assembly, a boric acid concentration of 75 parts per million must be reduced from the PWR primary coolant to allow the PWR return to criticality. The transmutation rate and burnup calculation results indicate that 99Tc mixed homogeneously with BP may be a satisfactory 99Tc loading pattern in 99Tc transmutation in PWRs.
