In a demonstrational fusion power plant (DEMO), divertor is supposed to protect vacuum vessel and superconducting magnets against neutron flux in the bottom region of the vessel. The vessel is subject to a strict design limit in irradiation damage dose and the magnets in nuclear heating power, respectively. Thus, the DEMO divertor must have the capability to protect sufficiently the vessel and the magnets against neutron flux being substantially stronger than in ITER.

In this paper, a first systematic neutronics study for the European DEMO divertor is reported. Results of the extensive assessment of key nuclear loading features (nuclear heating, irradiation damage & helium production) are presented for two optional concepts, namely, dome and shielding liner including minor geometrical variants. The shielding performance of the two competing design options is discussed together with the case of a bare cassette (no shielding), particularly in terms of damage dose compared with the design limits specified for the European DEMO.

It was found that both the dome and shielding liner were able to significantly reduce the nuclear loads in the cassette body and the vessel. The maximum damage dose at the end of the lifetime remained subcritical for the cassette body for both cases whereas it exceeded the limit for the vessel under the dome, but only locally on the surface underneath the pumping duct. But, the damage could be reduced below the limit for the vessel by increasing the size of the dome or by deploying the shielding liner. The most critical feature was the excessive damage occurring in the own body of the shielding components where the maximum damage dose in the steel heat sink of the dome and the shielding liner far exceeded the design limit at the end of the lifetime.

在示范聚变电站（DEMO）中，偏滤器被认为可以保护真空容器和超导磁体免受容器底部区域中子通量的影响。该容器分别受到辐射损伤剂量和核加热功率磁体的严格设计限制。因此，DEMO分流器必须具有足够的能力来保护容器和磁体免受中子通量的侵害，而中子通量要比ITER强得多。

本文报道了对欧洲DEMO偏滤器的首次系统中子学研究。提出了对两个关键概念（核加热，辐照损伤和氦气产生）的关键核负荷特征进行广泛评估的结果，这两个概念是圆顶和包括较小几何形状变化的屏蔽衬里。讨论了两个竞争设计方案的屏蔽性能，以及裸盒（无屏蔽）的情况，尤其是与欧洲DEMO规定的设计极限相比，在损坏剂量方面。

已经发现，圆顶和屏蔽衬套都能够显着降低盒体和容器中的核负荷。在两种情况下，使用寿命对盒式磁带盒而言，最大损坏剂量仍处于亚临界状态，而超过了圆顶下容器的极限，但仅局部位于泵送管道下方的表面上。但是，可以通过增加圆顶的大小或部署屏蔽衬套来将损坏降低到容器极限以下。最关键的特征是在屏蔽组件本身中发生的过度损坏，在球型罩和屏蔽衬垫的钢制散热器中，最大损坏剂量在使用寿命结束时就远远超过了设计极限。