Fission product release in high-burn-up UO2 oxidized to U3O8

Volatile fission product behaviour during thermal annealing of irradiated UO2 fuel oxidised up to U3O8

“…trapping in bubbles for fission gases, or creation of intermediate phases for chemically reactive fission products (Cs, Rb, I, Te, Ba, Sr) [1,2]. During postulated severe reactor accidents, characterised by temperatures that significantly exceed the normal operation temperature and by ingress of air and steam, the release behaviour and the vaporisation rate of the fission products from the nuclear fuel depend drastically on the surrounding atmosphere, mainly on the concentration of oxygen defining the oxygen potential [3][4][5].…”

“…Mo, Tc or Te, and eventually makes the formation of complex phases more likely, e.g. (Ba,Sr)MoO 4 , Cs 2 MoO 4 , Cs 2 TeO 4 , Cs 2 UO 4 , (Ba, Sr)UO 3 or (Ba,Sr)UO 4 [13,14]. Most of these oxides and compounds have been studied by Knudsen cell mass spectrometry [13,[15][16][17][18][19], or postulated from re-deposition studies in simulated accident conditions [20][21][22].…”

A mass spectrometry method for quantitative and kinetic analysis of gas release from nuclear materials and its application to helium desorption from UO2and fission gas release from irradiated fuel

“…Light gases like hydrogen and helium are difficult to pump with turbo pumps compared to other heavier gases: their concentration tends to increase and even accumulate in the primary vacuum circuit (16,23) and thus makes it difficult to pump them out of the HP sample chamber (1). To solve this problem, two leak valves are installed, one at the sample gas inlet (11), before the compressing turbo-molecular pump (12), and one on the HP sample chamber turbo-molecular pump (10), in order to be able to rinse the system with argon.…”

“…The Q-GAMES (Quantitative GAs MEasurement System) facility presented in this paper is originally designed to work in combination with two other devices: the first one is a high-temperature Knudsen effusion mass spectrometer (KEMS) [14][15][16] suited for thermodynamic (vapour pressure) [17,18] and kinetic (release behaviour) [4,15,16,[19][20][21] measurements on irradiated nuclear fuel. The second one is a laser heated Knudsen cell mass spectrometer (LKC-MS) [22] which is used to study the thermal release of gas from infused materials.…”

Remote Fabrication of DUPIC Fuel Pellets in a Hot Cell under Quality Assurance Program

“…During this process, UO 2 is oxidized to U 3 O 8 and reduced back to UO 2 , with about a 30% volume change due to a phase transformation between the cubic and orthorhombic. 9,10) This change in volume breaks up the irra- diated fuel pellets into a powder and it produces microcracks in a particle. The OREOX-treated powder was milled by an attrition mill at a speed of 450 rpm for 10 min and 600 rpm for 10 min.…”