核废料处置库存储坑布置间距优化数值模拟

Numerical Simulation of the Optimized Storage Pit Spacing in the Nuclear Waste Repository

膨润土作为核废料处置库首选的缓冲/回填材料,在核废料衰变释放大量热量的影响下,长期处于高温运行状态.因此,如何使膨润土的导热性满足处置库安全运行的要求,是急需解决的关键问题之一.借助多场耦合数值计算有限元软件,在处置库巷道内设置6个处置坑,模拟核废料存储库的温度演化过程,计算存储坑间距与巷道间距,得到核废料处置库存储坑最优布置间距,从而提出保证处置库安全运行的合理建议.结果表明,最优存储坑间距为8 m;当处置库内存储坑间距小于8 m时,存储坑之间会形成温度重叠区,导致金属罐温度升高,反之,则不会产生显著影响.以最优存储库间距为计算基础,发现为使处置库温度低于100℃,巷道间距需大于14 m.此外,存储坑周围介质的温度变化与存储坑的位置有关.

As the preferred buffer/backfilling material for nuclear waste disposal repository,bentonite has been running at high temperature for a long time under the influence of a large amount of heat released by nuclear waste decay.Therefore,how to make the thermal conductivity of bentonite meet the requirements of safe operation of the disposal repository is one of the key problems that need to be solved urgently.With the help of the finite element software for multi-field coupling simulation,six disposal pits were set up in the roadway of the disposal warehouse.The temperature evolution process of the nuclear waste repository was simulated and the spacing of storage pits and roadways was calculated.The optimal layout spacing of nuclear waste disposal storage pits was obtained and reasonable suggestions were put forward to ensure the safe operation of the disposal warehouse.The results show that the optimal storage pit spacing is 8 meters.When the storage pit spacing is less than 8 meters,the temperature overlap zone will be formed between the storage pits,which will lead to the increase of metal tank temperature.Otherwise,it will not have a significant effect.Based on the calculation of the optimal repository spacing,it is found that in order to make the disposal temperature lower than 100℃,the roadway spacing should be more than 14 meters.In addition,the change of the temperature of the medium around the storage pit is related to the location of the storage pit.