Small Nuclear Reactors for the Production of Nuclear Medicine Radioisotopes and for Co-Generation

该研究项目旨在开发两种不同的小型固有安全核反应堆：SNB25区域供热和热电联产反应堆和均匀SLOWPOKE反应堆。用确定性代码WIMS-AECL和概率（蒙特卡罗）代码MCNP 5对两个反应堆进行了模拟，结果吻合良好。SNB25反应堆以TRISO燃料颗粒为基础，浓缩度为20%，通过95℃的水产生25兆瓦的热量，用于加热加拿大在北极的军事基地的各种建筑，例如拟议中的努纳武特的Nanisivik基地。这种能量也可以提供给基于朗肯循环的系统，以16%的效率发电。先前的工作已经证明了该概念的固有安全特性和反应堆12年的最低堆芯寿命，这确实代表了在北极等恶劣天气条件下应用的重要资产。这里提出的工作旨在改进反应堆的计算机建模，并通过改进的朗肯循环设计更有效的热传输系统和电力生产系统。拟议项目中考虑的另一个核反应堆是均匀型SLOWPOKE反应堆，以成功的SLOWPOKE-2研究反应堆为基础。均质SLOWPOKE反应堆有双重使命：在现有的SLOWPOKE-2研究堆的堆芯使用寿命结束时取代它们，继续它们的研究/教学任务，并生产用于包括核医学在内的几个重要应用的放射性同位素。与SLOWPOKE-2反应堆一样，均质反应堆也能产生20千瓦的热量，并且在之前的工作中被证明是安全的。为了遵守《核不扩散条约》，铀燃料的浓缩率最高保持在20%。燃料是硫酸铀酰（UO2SO4）的均匀水溶液，其质量浓度测定为1.46 mol kg-1，用于Zircaloy-2反应堆容器。该池式核反应堆的运行缓速剂-冷却剂温度为40oC，反应堆瞬态模拟工作表明，最坏工况下的峰值温度为83oC，峰值功率为546 kW。该研究项目提出的进一步发展工作包括用三维确定性软件取代二维wwin - aecl模拟代码，开发计算反应堆堆芯内燃料运动的模拟代码（中子和热工水力学代码的耦合），以及模拟反应堆堆芯内饱和裂变产物（如135Xe）的行为。

The research project aims at developing two distinct small inherently safe nuclear reactors: the SNB25 district heating and co-generation reactor and the Homogeneous SLOWPOKE reactor.  Both reactors are simulated with the deterministic code WIMS-AECL and the probabilistic (Monte Carlo) code MCNP 5, with the results of both simulations agreeing very well. The SNB25 reactor is based on the TRISO fuel particles with an enrichment of 20% and produces 25 MW of heat by means of water at 95oC that is sent for heating the various buildings of a Canadian Forces base in the Arctic, such as the proposed base at Nanisivik, Nunavut.  This energy can also be supplied to a Rankine cycle-based system to produce electricity with a 16% efficiency.  Previous work has demonstrated the inherent safety characteristics of the concept and the 12-year minimum core life of the reactor, which indeed represents an important asset for applications in areas with harsh weather conditions such as in the Arctic.  The proposed work here aims at improving the computer modelling of the reactor and at designing a more efficient heat transport system and the electricity production system via an improved Rankine cycle.  The other nuclear reactor considered in the proposed project is the Homogeneous SLOWPOKE reactor, based on the successful SLOWPOKE-2 research reactor.  The Homogeneous SLOWPOKE reactor has a double mission: to replace the existing SLOWPOKE-2 research reactors at the end of their core service life and continue their research/teaching mission, and to produce radioisotopes used in several applications including important ones in nuclear medicine.  Like the SLOWPOKE-2 reactor, the Homogeneous reactor produces 20 kW of heat and has been proven as inherently safe in previous work.  The enrichment of the uranium fuel is kept to a maximum of 20% to comply with the Non Proliferation Treaty.  The fuel is an homogeneous aqueous solution of uranyl sulfate (UO2SO4) with a molality determined as 1.46 mol kg-1 for a Zircaloy-2 reactor vessel.  This pool-type nuclear reactor has an operating moderator-coolant temperature of 40oC and simulation work of the reactor in transient states has shown that the worst scenarios result in peak temperatures and power of 83oC and 546 kW, respectively. Further development work proposed for this research project includes replacing the 2-D WIMS-AECL simulation code with a 3-D deterministic software, developing a simulation code accounting for the movement of the fuel within the reactor core (coupling of neutronics and thermal-hydraulics codes), and modelling the behaviour within the reactor core of saturating fission products such as 135Xe .