In a subcritical reactor, each neutron produces only $k_{\mathrm{eff}}<1$ neutrons per generation (asymptotically and on average), and thus, the neutron population decreases exponentially in the absence of an external source. The chain reaction is thus easy to stop, making such reactors inherently stable. Interestingly, and contrary to common wisdom, there is no relation between $k_{\mathrm{eff}}$, the external source intensity, and the output power of the reactor. Here, various possible strategies to exploit this fact are presented, and they are applied to the design of a rudimentary multilayer system that allows an arbitrarily large number of fissions per source neutron to be reached, while keeping $k_{\mathrm{eff}}<1$ fixed (here, $k_{\mathrm{eff}}=0.97$). The behavior of the amplifier is verified with simple Monte-Carlo transport simulations. The proposal admittedly brings complications and subtleties that need to be studied further, but, if developed, could allow subcritical reactors to be driven with faint neutron sources, e.g., radioisotope based.

中文翻译：

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亚临界核反应堆中任意大的中子放大

在亚临界反应堆中，每个中子只产生 ${克}_{\mathrm{效果}}<1$每代中子数（渐近和平均），因此，在没有外部源的情况下，中子数量呈指数下降。因此，链式反应很容易停止，使这种反应器本质上是稳定的。有趣的是，与常识相反，两者之间没有关系${克}_{\mathrm{效果}}$、外源强度和反应堆的输出功率。在这里，提出了利用这一事实的各种可能策略，并将它们应用于基本多层系统的设计，该系统允许达到每个源中子的任意大量裂变，同时保持${克}_{\mathrm{效果}}<1$ 固定（这里， ${克}_{\mathrm{效果}}=0.97$）。放大器的行为通过简单的蒙特卡洛传输模拟得到验证。诚然，该提议带来了需要进一步研究的复杂性和微妙之处，但是，如果开发出来，可以允许用微弱的中子源（例如基于放射性同位素）驱动亚临界反应堆。