次监界聚变嬗变堆高性能双冷包层中子学概念设计研究

基于聚变实验装置近期可达到的堆芯ＤＴ等离子体参数水平,在一维燃耗计算和优化分析的基础上,验证了氚自持、年约处理２９ 个同等热功率压水堆年产的长寿命锕系元素和一定数量裂变产物的次临界聚变嬗变堆带有双冷却系统高性能包层的中子学可行性,并给出了初步的设计方案。     

长寿命放射性废物在聚变-裂变混合堆中燃烧处理的技术可行性研究(英文)

提出了分别用于锕系元素转化(氮化物燃料或合金燃料包层)和裂变产物转化(以Pu作中子倍增剂的包层)的聚变-裂变混合堆的概念设计。为评估系统的性能,进行了中子学和热工水力学计算。结果表明,在现有或近期能达到的等离子体物理实验参数的堆芯条件下,所研究的包层在中子壁负荷为1 MW/m~2,负荷因子为80％时经1年运行可以转化裂变产物~(90)Sr装料的17％或锕系元素装料的23％。因而,此系统能分别燃烧大约40个3GW(t)的压水堆所产生的~(90)Sr废物或65个3GW(t)的压水堆所产生的锕系废物。     

PWR（U）乏燃料中超铀元素在混合堆快裂变包层内嬗变研究

从中子学角度对ＰＷＲ（Ｕ）乏燃料中的超铀元素（２３８Ｐｕ，２３９Ｐｕ，２４１Ｐｕ，２４１Ａｍ，２４３Ａｍ，２３７Ｎｐ，２４４Ｃｍ）在聚变－裂变混合堆快裂变包层内嬗变的可行性进了研究。利用一维中子输运和燃耗计算程序ＢＩＤＥＣＡＹ译不同燃料组分的四个快裂变包层进行分析计算。结果表明，在聚变－裂变混合堆快裂变包层内安全，高效地嬗变ＰＷＲ（Ｕ）乏燃料中的超铀元素是可能的。     

功率展平的压水堆乏燃料发电包层中子学初步研究

聚变裂变混合堆在增殖核燃料、嬗变长寿命核废料及固有安全性等方面具有较大优势,同时,它比纯聚变堆在工程及技术方面要求低,因此较聚变堆更易实现。本工作基于目前国际聚变实验堆（ITER）所能达到的技术水平,提出一种直接利用乏燃料进行发电的聚变裂变混合堆包层概念,利用在不同位置放置不同乏燃料体积分数的方法对燃料增殖区实现了功率展平。计算结果表明：功率展平后的包层功率不均匀系数更小,且包层中燃料区的能量输出要比不展平情况下的能量输出高约21.7%。燃料富集度到运行末期最大可达5.23%。从中子学角度初步论证了该包层的可行性。     

在聚变堆中嬗变~（237）Np的研究

研究了在聚变堆中嬗变长寿命的锕系元素￣（２３７）Ｎｐ，以及转换￣（２３７）Ｎｐ成为可裂变燃料￣（２３９）ｐｕ的物理可行性。探讨了在嬗变包层中￣（２３７）Ｎｐ的浓度、￣（２３９）ｐｕ的中于增殖率、中子壁负载的变化以及嬗变区厚度与￣（２３７）Ｎｐ嬗变率的关系。给出的研究计算结果表明，在１个聚变功率为２００ＭＷ，中子壁负载为１．０ＭＷ／ｍ２的聚变堆包层中，实现年嬗变￣（２３７）Ｎｐ约３．５ｔ，年平均产钚量约２０ｋｇ是可行的。     

聚变-裂变堆中子学的二群扩散理论计算

本文对聚变-裂变堆的中子学问题提出了一个适于解析计算的简化方案:首先用二群扩散理论计算裂变部分的次临界性质,再利用中子数平衡关系计算每个聚变中子可能引起的裂变数。结果表明,聚变-快裂变堆要使用浓缩铀,所需要的核燃料初始投料总量是很大的。     

聚变-裂变混合堆水冷包层中子物理性能研究

研究直接应用国际热核聚变实验堆（ITER）规模的聚变堆作为中子驱动源,采用天然铀为初装核燃料,并采用现有压水堆核电厂成熟的轻水慢化和冷却技术,设计聚变-裂变混合堆裂变及产氚包层的技术可行性。应用MCNP与Origen2相耦合的程序进行计算分析,研究不同核燃料对包层有效增殖系数、氚增殖比、能量放大系数和外中子源效率等中子物理性能的影响。计算分析结果显示,现有核电厂广泛使用的UO₂核燃料以及下一代裂变堆推荐采用的UC、UN和U₉₀Zr₁₀等高性能陶瓷及合金核燃料作为水冷包层的核燃料,都能满足以产能发电为设计目标的新型聚变 裂变混合堆能量放大倍数的设计要求,但只有UC和U₉₀Zr₁₀燃料同时满足聚变燃料氚的生产与消耗自持的要求。研究结果对进一步研发满足未来核能可持续发展的新型聚变-裂变混合堆技术具有潜在参考价值。     

聚变裂变混合堆钍基增殖锕系元素嬗变包层中子学初步研究

聚变裂变混合堆比纯聚变堆在工程及技术方面要求低,且在产生核燃料、嬗变长寿命核废料以及固有安全性方面具有一定优势,因此,越来越受到人们的重视。增殖包层是混合堆系统的关键部件,已有的包层研究基本上是基于较成熟的铀-钚燃料循环技术。针对我国铀资源相对较少而钍资源较丰富的现状,本文就一种新型的钍基燃料增殖锕系元素嬗变包层进行了初步的中子学研究,利用一维离散纵标法燃耗程序BISONC以及Monte-Carlo粒子输运程序MCNP,对包层的关键核参数,诸如氚增殖比、少量锕系元素的嬗变质量、233U产量以及热功率等,进行了较详细的计算分析。计算结果表明,生成的核燃料233U的富集度可达到3.65%,从而满足压水堆燃料富集度要求。分析结果为下一步的包层优化设计提供了依据。     

激光惯性约束聚变裂变混合能源包层中子学数值模拟

对三维输运与燃耗耦合程序MCORGS进行了适应性改造,并对利弗莫尔实验室提出的激光惯性约束聚变裂变混合能源(LIFE)概念进行了分析和改进。输运计算采用MCNP程序,燃耗计算采用ORIGENS程序,增加氚控制模块和功率控制模块。建立了与LIFE等价的以贫化铀为燃料、Be为中子增殖剂的包层方案,通过数值模拟验证了MCORGS程序的可靠性。针对Be资源短缺及冷却复杂问题,设计了以贫化铀为燃料、Pb为中子增殖剂的包层方案,包层能量放大了4倍,可在55a内稳定输出2 000 MWt功率。     

MCORGS及次临界能源堆包层概念研究进展

次临界能源堆是以能源供应为目的的一种聚变裂变混合堆,以聚变驱动,天然铀为裂变燃料,轻水为冷却剂。本文针对该混合堆开发了基于MCNP与ORIGENS的三维中子输运燃耗耦合程序MCORGS,分析了包层三维中子学模型。提出简化干法后处理,设想利用衰变热将乏燃料加热到2 100K,将沸点低于该温度的裂变产物挥发去除。计算了包层各区材料每年发生的原子移位数,建议采用10a左右的换料周期,乏燃料经后处理后可多次复用。第1个寿期内氚增殖比TBR平均约1.15,包层能量放大倍数M平均约12;第2~9个寿期内TBR平均约1.35,M平均约18。利用流体动力学程序完成了包层CAD模型建立、网格划分及稳态传热计算分析,各区材料的最高温度均低于许用温度并有较大裕量。     

The fusion breeder

The fusion breeder is a fusion reactor designed with special blankets to maximize the transmutation by 14 MeV neutrons of uranium-238 to plutonium or thorium to uranium-233 for use as a fuel for fission reactors. Breeding fissile fuels has not been a goal of the U.S. fusion energy program. This paper suggests it is time for a policy change to make the fusion breeder a goal of the U.S. fusion program and the U.S. nuclear energy program. There is wide agreement that many approaches will work and will produce fuel for five equal-sized LWRs, and some approach as many as 20 LWRs at electricity costs within 20% of those at today's price of uranium ($30/lb of U₃O₈). The blankets designed to suppress fissioning, called symbiotes, fusion fuel factories, or just fusion breeders, will have safety characteristics more like pure fusion reactors and will support as many as 15 equal power LWRs. The blankets designed to maximize fast fission of fertile material will have safety characteristics more like fission reactors and will support 5 LWRs. This author strongly recommends development of the fission suppressed blanket type, a point of view not agreed upon by everyone. There is, however, wide agreement that, to meet the market price for uranium which would result in LWR electricity within 20% of today's cost with either blanket type, fusion components can cost severalfold more than would be allowed for pure fusion to meet the goal of making electricity alone at 20% over today's fission costs. Also widely agreed is that the critical-path-item for the fusion breeder is fusion development itself; however, development of fusion breeder specific items (blankets, fuel cycle) should be started now in order to have the fusion breeder by the time the rise in uranium prices forces other more costly choices.     

On the safety of conceptual fusion-fission hybrid reactors

A preliminary examination of some potential safety questions for conceptual fusion-fission hybrid reactors is presented in this paper. The study and subsequent analysis was largely based upon one design, a conceptual mirror fusion-fission reactor, operating on the deuterium-tritium plasma fusion fuel cycle and the uranium-plutonium fission fuel cycle. The major potential hazards were found to be: (a) fission products, (b) actinide elements, (c) induced radioactivity, and (d) tritium.As a result of these studies, it appears that highly reliable and even redundant decay heat removal must be provided. Loss of the ability to remove decay heat results in melting of fuel, with ultimate release of fission products and actinides to the containment. In addition, the studies indicate that blankets can be designed which will remain subcritical under extensive changes in both composition and geometry. Magnet safety and the effects of magnetic fields on thermal parameters were also considered.     

用自射线照相技术研究放射性核素在岩石和矿物上的吸附

应用自射线照相和岩相照相技术联合图象法研究了锕系元素和长寿命裂变产物在岩石和矿物上的吸附行为，直接观察到不同矿物和化学成份对核素的吸附。应用这个方法，研究了＾２３９Ｐｕ、＾２４１Ａｍ在花岗岩上的吸附，＾９０Ｔｃ在辉锑矿、锑赭石和脆硫锑铅矿上的吸附以及＾１２５Ｉ在灰硒汞矿上的吸附，得到了一些有价值的结果。     

An Alternate Development Path for Magnetic Fusion

Mid-century requirements for carbon free energy are daunting. Perhaps fusion could play a vital role. One of rather few possible solutions for sustainable development might be the fission fusion hybrid coupled with transmutation of the long lived actinide wastes. This paper suggests such an alternate development path for fusion, one that could lead to the production of multi-terawatts of carbon free power by 2050.     

Fission-suppressed blankets for fissile fuel breeding fusion reactors

Two blanket concepts for deuterium-tritium (DT) fusion reactors are presented which maximize fissile fuel production while at the same time suppress fission reactions. By suppressing fission reactions, the reactor will be less hazardous, and therefore easier to design, develop, and license. A fusion breeder operating a given nuclear power level can produce much more fissile fuel by suppressing fission reactions. The two blankets described use beryllium for neutron multiplication. One blanket uses two separate circulating molten salts: one salt for tritium breeding and the other salt for U-233 breeding. The other uses separate solid forms of lithium and thorium for breeding and helium for cooling.Nuclear power is the sum of fusion (D + T 14 MeV neutron+ 3.5 MeV alpha) power plus additional power from neutron-induced reactions in the blanket.     

The implication of high-flux fusion neutron source for the self-consistency in multi-component nuclear energy system

Among fission products (FP) discharged from a fission reactor, long-lived fission products are considered as of primary concern. Their transmutation has been of high priority to reduce the long-term consequences of nuclear energy generation. A self-consistent nuclear energy system (SCNES) in which we center fast breeder reactor may not have enough degree of excess neutron sources to transmute the fission products that potentially would poses environmental hazards in long-term period if they are buried in geologic disposal. Here we propose a so-called multi-component SCNES in which fission reactor systems can be combined with fusion reactor systems mainly for compensating the loss of enough capability for the transmutation. Amongst long-lived fission products, major concern has been paid for iodine and technetium and little attention was given to radioactive ⁹³Zr, although its hazard appears to be rather substantial. The importance of ⁹³Zr transmutation is emphasized and the transmutation capability was examined with fusion neutron sources by incorporating adequate moderation structures. As a result, we have demonstrated that the fusion neutron sources with high-flux blanket can be applied to transmute ⁹³Zr sufficiently and resolve the problem of its accumulation within the time period of several decades.     

加速器驱动次临界堆堆芯物理概念研究

分析了加速器驱动次临界堆芯的裂变核素增殖和平衡条件,主要长寿命放射性废物的积累,裂变产物毒性的影响及次临界堆的运行周期,输出功率和能量增益等主要性质,并对次临界热堆和次临界快堆的物理性质进行了比较。     

Regulatory aspects of fusion power-lessons from fission plants

Experience from fission reactors has shown the regulatory process for licensing a nuclear facility to be legalistic, lengthy, unpredictable, and costly. This experience also indicates that much of the regulatory debate is focused on safety margins, that is, the smaller the safety margins the bigger the regulatory debate and the greater the amount of proof required to satisfy the regulator. Such experience suggests that caution and prudence guide the development of a regulatory regime for fusion reactors. Fusion has intrinsic safety and environmental advantages over fission, which should alleviate significantly, or even eliminate, the regulatory problems associated with fission. The absence of a criticality concern and the absence of fission products preclude a Chernobyl type accident from occurring in a fusion reactor. Although in a fusion reactor there are large inventories of radioactive products that can be mobilized, the total quantity is orders of magnitude smaller than in fission power reactors. The bulk of the radioactivity in a fusion reactor is either activation products in steel structures, or tritium fuel supplies safely stored in the form of a metal tritide in storage beds. The quantity of tritium that can be mobilized under accident conditions is much less than ten million curies. This compares very favorably with a fission product inventory greater than ten billion curies in a fission power reactor. Furthermore, in a fission reactor, all of the reactivity is contained in a steel vessel that is pressurized to about 150 atmospheres, whereas in a fusion reactor, the inventory of radioactive material is dispersed in different areas of the plant, such that it is improbable that a single event could give rise to the release of the entire inventory to the environment. These intrinsic features give fusion a significant safety and environmental advantage over fission. With such significant intrinsic safety advantages there is noa priori need to make fusion requirements/regulations more demanding and more stringent than fission. To do so could have the effect of making the licensing process more difficult, more costly, and less certain. The result could be a delay in the advent of a safer and more environmentally benign energy system.