数值反应堆堆芯与E级高性能计算的科学内涵

Scientific Connotation of Numerical Reactor Core and Exascale High Performance Computing

反应堆是一复杂的系统过程,是由中子场、温度场、流场、应力场、化学场等多个物理过程相互耦合的装置,这些物理场涉及从微观核反应到宏观能量释放的多尺度作用机理。随着E级(1 000PFLOPS,百亿亿次/每秒)计算机的问世,核能发展的总趋势正从传统工程驱动模式向以高性能数值模拟为主转变。当前四代堆设计立足小型化和精密化,高分辨率数值模拟对提升核装置性能和降低裕量作用突出。为研究解决当前模拟软件与计算机之间存在的浮点效率低、移植周期长、模式通用难和规模扩展难等问题的办法,突破软件和硬件之间存在的编程墙和性能墙,本文通过解读美国NEAMS、CASL和ECP计划,结合团队近年在数值反应堆和高性能计算关键技术突破方面的经验,提出基于并行中间件的集成共性、发展个性的技术路线,探索一条快速提升我国自主CAE软件整体水平的途径,供业内同行探讨,以在国产超级计算机上实现核装置的精细化建模和多物理、多尺度、多过程耦合计算。

Reactor is a complicated system process.It is a device which is coupled by multiple physical processes such as the neutron field,the temperature field,the flow field,the stress field and the chemical field.The physical process involves multi-size reaction mechanism from microcosmic nuclear reaction to macroscopic energy release.With arrival of Exascale(1000PFLOPS)computing era,the total development tendency of nuclear energy is being changed from engineer driving toward to the first place of numerical simulation.At present,the more small size and more precision are approaching in the designs of four general reactors.The numerical simulation of high fidelity is being taken more and more important roles in promotion of nuclear devices property and reduce rich quantity etc.However,the coding wall and property wall exist between hardware and software from beginning to end.On the other hand,the lower efficiency of flops operation,long time of transplanting,poor schema in common use and difficulty extension in scale also exist for a long time.A available method urgently needs to research for above problems.In this paper,our understanding for NEAMS,CASL and ECP from American were given.Then a path of integrating generality and developing individuality based on the research experiment of numerical reactor key technology was recommend.An idea of software development based on the parallel frameworks was also put forwarded.The goal is to realize the detail modeling and coupled computation of multi-physics,multi-dimension and multi-process of numerical reactor in Chinese superpower computers.We think this is a shortcut for improvement of CAE software level of our country.Maybe this suggestion does not mature,it is only for discussion in industry.