一般边界条件下球形压力容器钢壁中氚和氦-3的浓度变化规律研究

为了认识储氚高压容器壁材料的力学性能变化及其导致的容器承载能力变化, 必须研究储氚期间, 容器壁中氚和氦-3浓度的空间分布和随时间的变化. 针对容器外表面为一般传质边界条件和容器内部氚为范德瓦尔斯气体的情况, 同时考虑容器腔内和容器壁中氚的衰变和扩散, 建立求解储氚高压容器壁中氚和氦-3浓度的解析理论模型, 导出了氚和氦-3浓度的理论公式. 通过解析计算给出了器壁中氚和氦-3浓度随外表面传质系数的变化曲线和浓度的时空变化曲线, 提出了氦-3浓度的2β ₁ + β ₂ / 2倍定律, 即处于开放空间的储氚球形高压容器, 器壁中氦-3的浓度呈内高外低的分布, 时间越长, 浓度沿径向的梯度越大, 在时间足够长时, 各处浓度逼近时间无限长时的最终值, 也就是各处的最大值, 内表面处的最大值是该处氚初始时刻浓度的2β ₁ + β ₂ / 2倍, 这里β ₁ 和β ₂ 为与氚的范德瓦尔斯常数相关的参数. 研究结果为储氚高压容器的强度安全性评估提供了前提.

Research on tritium and helium-3 content distributions in steel wall of spherical pressure vessel under general boundary condition

In order to understand the changes of mechanical properties of the wall materials and the carrying capacity of vessel which contains high pressure tritium,the spatiotemporal changes of tritium and helium-3 content in the wall should be studied during tritium storage.Talcing into consideration the case that the outer surface of the vessel is with general mass transfer boundary condition and the tritium inside the vessel is van der Waals gas,and also taking into account both decay and permeation of tritium inside the vessel and decay and diffusion of tritium in the wall material,the analytical theoretical models of tritium and helium-3 content in the wall are developed and solved,and relevant theoretical formulas are deduced.Through analytical calculations,the curves of tritium and helium-3 content in the wall versus mass transfer coefficient of the outer surface,storage time and the spatial positions are plotted. Through analysis,a law called 2β₁ +β₂/2 time law of helium-3 content is put forward,whereβ₁ andβ₂ are the coefficients which are related to van der Waals constant of tritium.The law is proposed:helium-3 content in the wall of the spherical high pressure vessel storing tritium which is in an open space rises along the radius from outer to inner,and the content radial gradient increases with storage time.If storage time is long enough,the helium-3 content at any point will approach to its final value,that is,a maximal value at a relevant point.The ratio of the maximum helium-3 content to the related initial tritium content is 2β₁ +β₂/2 at the inner surface.The obtained formulas and understandings can be used as a premise of the safety assessment of tritium stored vessel.