Being the Vacuum Vessel Pressure Suppression System (VVPSS) one of the most important passive safety systems to be foreseen in DEMO plant, design and integration challenges have to be faced to ensure that best performance within safety requirements are always achieved. In this framework, parametric safety analyses have been performed to support VVPSS design activities; in particular to determine the minimum flow area required by the suppression system pipework to limit the vacuum vessel pressure below the limit imposed as a requirement by design.

The selected Postulated Initiating Event (PIE) is a double-ended guillotine break in the Primary Heat Transfer System (PHTS) feeding pipe of the Breeding Zone (BZ) during plasma activity. Coolant is discharged inside the VV upper port volume and an unmitigated disruption occurs, causing further breaks in the first wall (FW) cooling channels. Considering that limiters could be introduced in the future design of the EU DEMO reactor to prevent damages to plasma-facing components, the same parametric study has been performed considering limiters accident mitigation effects.

Because discharge flow area toward the suppression pool could also affect the source terms mobilization, the transport of radioactive products (e.g. tritium, tungsten dust and activated corrosion products) has been simulated with the fusion version of the MELCOR code (ver. 1.8.6).

作为真空容器压力抑制系统（VVPSS），是DEMO工厂中最重要的被动安全系统之一，必须面对设计和集成方面的挑战，以确保始终达到安全要求内的最佳性能。在此框架中，已经执行了参数安全分析以支持VVPSS设计活动。特别是确定抑制系统管路所需的最小流通面积，以将真空容器的压力限制在设计要求的限制以下。

选定的假定启动事件（PIE）是等离子活动期间繁殖区（BZ）的一次传热系统（PHTS）进料管中的双头断头台断裂。冷却剂被排放到VV上端口容积内，并且发生了不可缓解的破坏，导致第一壁（FW）冷却通道中的进一步破裂。考虑到可以在EU DEMO反应堆的未来设计中引入限制器，以防止损坏面向等离子体的组件，因此考虑限制器事故缓解效果，已经进行了相同的参数研究。

由于流向抑制池的流量区域也可能影响源术语的动员，因此已使用MELCOR编码（版本1.8.6）的融合版本模拟了放射性产物（例如tri，钨尘和活性腐蚀产物）的运输。 。