摘要:
Provided are a method of controlling the compositional gradient and solubility of doped-additives at grain boundaries during sintering of a uranium-based oxide green pellet including the additives, and a method of manufacturing a sintered nuclear fuel pellet having a large grain size using the same. The grain boundary solubility of the doped-additives is maintained at a certain level by stepwise varying of an oxygen partial pressure during isothermal sintering of a uranium-based oxide green pellet including the additives. The method of manufacturing a sintered nuclear fuel pellet having a large grain size includes preparing additive mixed uranium oxide powder, forming an additive mixed uranium oxide green pellet using the mixed powder, heating the green pellet to a sintering temperature in a gas atmosphere having a low oxygen partial pressure, and sintering while a sintering gas atmosphere is changed to stepwise increase an oxygen partial pressure at the isothermal sintering temperature.
摘要:
A method for fabricating a sintered annular nuclear fuel pellet includes molding nuclear fuel powder or granule, an oxide of a fissile element (M), to fabricate an annular nuclear fuel green body. A rod-like shaped structure is inserted into the annular nuclear fuel green body and sintered in a slight oxidizing gas atmosphere such that the oxide of the fissile element has a balanced O/M ratio higher than a desired O/M ratio (oxygen/fissile element) of a final sintered annular nuclear fuel pellet, while being maintained in a cubic phase. The sintered annular nuclear fuel pellet is then reduced in a reductive gas atmosphere so as to have the desired O/M ratio in the state that the rod-like shaped structure is inserted.
摘要:
A method for fabricating a sintered annular nuclear fuel pellet includes molding nuclear fuel powder or granule, an oxide of a fissile element (M), to fabricate an annular nuclear fuel green body. A rod-like shaped structure is inserted into the annular nuclear fuel green body and sintered in a slight oxidizing gas atmosphere such that the oxide of the fissile element has a balanced O/M ratio higher than a desired O/M ratio (oxygen/fissile element) of a final sintered annular nuclear fuel pellet, while being maintained in a cubic phase. The sintered annular nuclear fuel pellet is then reduced in a reductive gas atmosphere so as to have the desired O/M ratio in the state that the rod-like shaped structure is inserted.
摘要:
Provided are a method of controlling the compositional gradient and solubility of doped-additives at grain boundaries during sintering of a uranium-based oxide green pellet including the additives, and a method of manufacturing a sintered nuclear fuel pellet having a large grain size using the same. The grain boundary solubility of the doped-additives is maintained at a certain level by stepwise varying of an oxygen partial pressure during isothermal sintering of a uranium-based oxide green pellet including the additives. The method of manufacturing a sintered nuclear fuel pellet having a large grain size includes preparing additive mixed uranium oxide powder, forming an additive mixed uranium oxide green pellet using the mixed powder, heating the green pellet to a sintering temperature in a gas atmosphere having a low oxygen partial pressure, and sintering while a sintering gas atmosphere is changed to stepwise increase an oxygen partial pressure at the isothermal sintering temperature.
摘要:
A method for fabricating a sintered annular nuclear fuel pellet includes: molding nuclear fuel powder or granules to fabricate an annular nuclear fuel green body; inserting a rod-like shaped structure into the annular nuclear fuel green body; sintering the rod-like shaped structure-inserted annular nuclear fuel green body in a reductive gas atmosphere; and separating the sintered annular nuclear fuel pellet from the rod-like shaped structure.
摘要:
A method for fabricating a sintered annular nuclear fuel pellet includes: molding nuclear fuel powder or granules to fabricate an annular nuclear fuel green body; inserting a rod-like shaped structure into the annular nuclear fuel green body; sintering the rod-like shaped structure-inserted annular nuclear fuel green body in a reductive gas atmosphere; and separating the sintered annular nuclear fuel pellet from the rod-like shaped structure.
摘要:
Disclosed is a method of manufacturing large-grained uranium dioxide pellets through the use of U3O8 single crystals. The method consists of two main steps; producing U3O8 single crystals and manufacturing large-grained UO2 pellets. The U3O8 single crystals are produced by annealing U3O8 powder to make U3O8 polycrystalline aggregates having a large crystal size, and by dividing the U3O8 polycrystalline aggregate into its constituent U3O8 single crystals. Large-grained UO2 pellets are produced by forming a mixture comprising UO2 powder and the U3O8 single crystals, making granules of the mixture, pressing the granules into green pellets, and sintering the green pellets above 1600° C. for more than one hour in a reducing gas. The U3O8 powder is produced preferably by heating defective UO2 pellets in air to oxidize UO2 to U3O8. The invention provides a method of manufacturing a large-grained UO2 pellet with defective pellets reused.
摘要翻译:公开了通过使用U3O8单晶制造大粒径二氧化铀颗粒的方法。 该方法由两个主要步骤组成: 生产U3O8单晶并制造大粒度UO2颗粒。 U3O8单晶通过退火U3O8粉末制成具有大晶体尺寸的U3O8多晶聚集体,并将U3O8多晶聚集体分成其组成的U3O8单晶。 通过形成包含UO 2粉末和U 3 O 8单晶的混合物来制备大粒度的UO2颗粒,制备混合物的颗粒,将颗粒压成生球团矿,并将生坯颗粒在1600℃以上烧结超过1小时 减少气体。 U3O8粉末优选通过在空气中加热有缺陷的UO 2颗粒而氧化U 2 O至U 3 O 8。 本发明提供一种制造具有有缺陷的颗粒的大颗粒UO2颗粒的方法。
摘要:
A method is disclosed in which fuel scrap of UO.sub.2 alone or UO.sub.2 containing an oxide of plutonium, gadolinium or erbium is recycled into the manufacture of nuclear fuel pellets. The fuel scrap consisting of defective fuel pellets is comminuted through oxidation to fuel particles of U.sub.3 O.sub.8 alone or U.sub.3 O.sub.8 containing an oxide of plutonium, gadolinium or erbium, and a sintering aid containing an element selected from the group consisting of aluminum, magnesium, niobium, titanium, vanadium, chromium, lithium, silicon, tin and mixtures thereof is added in a quantity of about 0.02% to about 2% by weight to the sintering powder which consists of said recycled fuel particles and fresh fuel powder having a composition of UO.sub.2 alone or UO.sub.2 in a mixture of PuO.sub.2, Gd.sub.2 O.sub.3 or Er.sub.2 O.sub.3. The sintering powder is then mixed uniformly, in which the amount of the recycled fuel particles is in the range of about 10% to about 100% by weight. Green pellets are made by pressing the sintering powder and then sintered at about 1500.degree. C. to about 1800.degree. C. in a reducing atmosphere to produce new fuel pellets.
摘要:
The present invention relates to a method for measuring the content of Lanthanides dissolved in uranium oxide, wherein the Lanthanides content in the nuclear fuel pellet is measured using the thermo gravimetric analysis which measures the weight variation caused by the oxidation and heat treatment of the nuclear fuel pellet. This method provides an advantage in that the Lanthanide content can be measured using relatively simple equipments such as an electric furnace and a balance.
摘要:
A method of manufacturing new UO2-based fuel pellets by recycling irradiated UO2-based fuel pellets. Irradiated UO2-based fuel pellets are oxidized so as to make U3O8-based powder, and then the U3O8 -based powder is mixed with an additive which contains at least one oxide of an element selected from the group consisting of niobium, titanium, vanadium, aluminum, magnesium, chromium, silicon and lithium. Green pellets are formed from the mixed powder, and then sintered, preferably at 1500° C. or higher, in a reducing gas atmosphere to produce UO2-based fuel pellets with high densities.