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Cooling with Liquid Helium
Published in David A. Cardwell, David C. Larbalestier, Aleksander I. Braginski, Handbook of Superconductivity, 2023
The isotope of helium with two protons and one neutron, 3He exists at a level of 1.4 parts per million in naturally occurring helium gas on the earth. The lighter isotope has a critical point of 3.19 K, remains a liquid under its saturation pressure all the way down to absolute zero, and transitions to a superfluid phase at the very low temperature 1.8 mK. Helium 3 is a useful coolant for very low temperatures, not only because of the lower temperatures associated with its saturation curve compared to helium 4, but also because of the unique features afforded by mixtures of helium 3 and helium 4 in the temperature range below the lambda transition of helium 4. Both types of cooling technologies are well described by Van Sciver [2012] and Pobell [2007] and readers are directed to these two references for a convenient introduction and detailed description respectively. Although the details of such cooling systems are outside the scope of this document, several key features are highlighted here.
Radiochemical Methods
Published in Somenath Mitra, Pradyot Patnaik, Barbara B. Kebbekus, Environmental Chemical Analysis, 2018
Somenath Mitra, Pradyot Patnaik, Barbara B. Kebbekus
Tritium is a radioactive isotope of hydrogen. Its mass number is 3. It is produced naturally by interaction of cosmic rays with hydrogen. It is also detected in the residual fallout from nuclear tests. It is also produced in nuclear reactors (light-water nuclear reactors) to generate electricity. Tritium decays by beta emission to helium-3. Its half-life is 12.26 years. The maximum beta energy of tritium is 0.018 MeV.
Radioactivity
Published in Pradyot Patnaik, Handbook of Environmental Analysis, 2017
Tritium is a radioactive isotope of hydrogen. Its mass number is 3. It is produced naturally by the interaction of cosmic rays with hydrogen. It is also detected in the residual fallout from nuclear tests. It is also produced in nuclear reactors (light-water nuclear reactors) to generate electricity. Tritium decays by beta emission to helium-3. Its half-life is 12.26 years. The maximum beta energy of tritium is 0.018 MeV.
Performance Restoration of a Tritium-Aged LaNi4.25Al0.75 Sample
Published in Fusion Science and Technology, 2020
Gregory C. Staack, David W. James
LANA.75 acts as a hydride by storing hydrogen atoms in interstitial sites within its crystal lattice. Therefore, improved LANA.75 crystallinity suggested that the hydride performance may be at least partially restored. The objective of this testing was to verify whether hydride performance could be restored by heating to higher than normal conditions under vacuum. Performance restoration would likely include a reduction in the amount of unusable tritium trapped in the metal. An additional benefit of regeneration includes recovery of significant quantities of 3He from the tritium-aged LANA.75. Helium-3 is a valuable by-product used predominantly in neutron detectors, ultra-low-temperature cryogenics, and medical imaging.
An Experimental Validation of Spectrally Matched Neutron Detection Systems Using 3He and BF3
Published in Nuclear Technology, 2023
Codey Olson, Jesse Snow, Meng-Jen (Vince) Wang, Glenn Sjoden, Edward Cazalas
Helium-3 gas is widely used in neutron proportional counters, which have uses in nuclear research, commercial/industrial applications, and national defense.[1] This inert gas offers excellent stability, sensitivity, and gamma/neutron discrimination, and is generally considered the gold standard for thermal neutron detection. Helium-3 is a byproduct of tritium (3H) decay, and almost all the world’s production comes from dismantling nuclear weapons, with most of the supply coming from the United States and Russia. Due to this limited production chain, 3He is in very limited supply. No more than 14 kL per year is distributed from the federal supply.[2]
Evaluation of Environmental Tritium Activity Levels and the Impact on the Public Health around the Cernavoda Nuclear Power Plant after 25 Years of Operation
Published in Fusion Science and Technology, 2023
Simona Zaharov, Alexandru E. Nedelcu, Liliana A. Samson
Natural tritium is created in the upper atmosphere from the cosmic interaction of nitrogen with neutrons. Tritium then combines with oxygen to produce tritiated water (HTO) and enters the hydrologic cycle. Tritium decays (T1/2 = 12.3 years) to a rare, stable isotope of helium (3He) by β− emission with a maximum energy of 18.6 keV. Lithogenic tritium is produced by the showering of lithium present in rocks by neutrons produced during the spontaneous fission of uranium and thorium.[1]