Semi-Annual Report for Modular Integrated Gas High Temperature Reactor Development during Performance Period April 2022 - September 2022

Abstract

Horizontal Compact High Temperature Gas Reactor (HC-HTGR) is being designed by a multidisciplinary team of nuclear, mechanical, and structural engineers under the support of a DOE-NE Advanced Reactor Demonstration Program's Advanced Reactor Concepts-20 (ARC-20) award. The objective of this ARC-20 project is to deliver a conceptual design for the proposed HC-HTGR in 3 years and support its commercialization as a safe, low-cost HTGR. Argonne National Laboratory (Argonne) is responsible for the design and analysis of the reactor cavity cooling system (RCCS) as a safety system for passive decay heat removal of the reactor concept. Additionally, Argonne is providing analysis of the primary coolant system to ensure temperatures within the core remain below safety margins during steady-state and potential accident scenarios.

Semi-Annual Report for Horizontal Compact High Temperature Gas Reactor (HC-HTGR) Development during Performance Period October 2022-March 2023

“…The three-dimensional water panel was modeled by SAM using the coupled 3D solid-1D fluid technique. As shown in Figure 21 (a), there is only a 0.5 K temperature range across the panel cross section, which is consistent with 3-D CFD results [1]. When this three-dimensional temperature distribution compared to the outer wall temperature in the reduced order model is observed less than 0.5 K difference, thus the axisymmetric model is not expected to introduce a significant error to the core-RCCS coupled model, despite the asymmetric riser panel shape and heat flux.…”

“…This indicates that the system performance evaluated at the reference design condition is primarily limited by the thermal radiation from the RPV. For the ideal case of a cylindrical shell shaped water panel with a smooth surface covering the entire RPV area, radiation heat transfer from the RPV is calculated by equation (1), where e is the emissivity, s is Stephan-Boltzman coefficient, A is the surface area, and D is the diameter [4]. It is estimated 0.95 MWth in the reference design condition with a panel temperature of 65 °C and an emissivity of 0.8, which is close to the target thermal performance.…”

“…For the RCCS design task, efforts made in the FY22 focused on a scoping calculation in estimating HVAC capability for the HC-HTGR reactor building and preliminary performance analyses for the HC-HTGR RCCS design using RELAP5-3D which includes water panel modeling study, development of a reference RELAP5-3D model of the baseline design of the RCCS, and single-phase natural circulation and panel conduction performance analysis. For the primary system analysis task, efforts focused on preliminary work on the development of a full core reduced order model and high resolution 1D-3D assembly level model, which can be found in [1]. This third semi-annual report summarizes the progress made at Argonne on the two tasks during the first half of FY23.…”