Abstract

This paper reports the results of subchannel thermal-hydraulic studies (using the ASSERT-PV code) of the effects of variations and uncertainties in operating/boundary conditions and geometry on the predictions of pressure drop, dryout power, and dryout location for two types of advanced, nonconventional fuels in a pressure tube heavy water reactor (PT-HWR) fuel channel with 12 fuel bundles. The fuel bundles tested include a 37-element fuel bundle made with SEUO₂ (1.2 wt% ²³⁵U/U), with a central fuel element made of ThO₂, and 35-element fuel bundle made with (LEU,Th)O₂, using 5 wt% ²³⁵U/U low-enriched uranium (LEU), 50 wt% LEUO₂, and 50 wt% ThO₂. Results indicate that for a range of flow conditions, the dryout power for the thorium-based 35-element fuel bundle is 10% to 26% higher than that for the uranium-based 37-element fuel bundle. Variation/uncertainty in the pressure tube diameter has the most significant impact on the pressure drop, dryout power, and dryout location. Results from these studies may have implications for the operations of PT-HWRs with advanced fuels, and further modifications may be desirable to further enhance thermal-hydraulic margins.

摘要

本文报告了子通道热工液压研究（使用ASSERT-PV代码）的结果，这些结果对两种类型的压降，变干功率和变干位置的预测中操作/边界条件和几何形状的变化和不确定性的影响带有12个燃料束的压力管重水反应堆（PT-HWR）燃料通道中的高级非常规燃料。测试的燃料束包括由SEUO ₂（1.2 wt％²³⁵ U / U）制成的37个元素的燃料束，由ThO ₂制成的中央燃料元件，以及由（LEU，Th）O ₂制成的35个元素的燃料束。，使用5 wt％的²³⁵ U / U低浓铀（LEU），50 wt％的LEUO ₂和50 wt％的ThO ₂。结果表明，在一定范围的流动条件下，35基35元素燃料束的干燥能力比铀基37元素燃料束高10％至26％。压力管直径的变化/不确定性对压降，变干能力和变干位置有最大的影响。这些研究的结果可能对使用先进燃料的PT-HWR的运行产生影响，可能需要进一步修改以进一步提高热工水力裕度。