Thermal-Hydraulics Study of a 75 kWth Aqueous Homogeneous Reactor for 99Mo Production

Daniel Milian Pérez,Carlos A. Brayner de Oliveira Lira,Jesús Salomón Llanes,Daniel E. Milian Lorenzo,Carlos R. García Hernández,Manuel Cadavid Rodríguez,Lorena P. Rodriguez Garcia

doi:10.1155/2015/268034

Abstract

Tc99m is a very useful radioisotope, which is used in nearly 80% of all nuclear medicine procedures. Tc99m is produced from 99Mo decay. A potentially advantageous alternative to meeting current and future demand for 99Mo is the use of Aqueous Homogeneous Reactors (AHR). In this paper, a thermal-hydraulics study of the core of a 75 kWth AHR conceptual design based on the ARGUS reactor for 99Mo production is presented. As the ARGUS heat removal systems were designed for working at 20 kWth, the main objective of the thermal-hydraulics study was evaluating the heat removal systems in order to show that sufficient cooling capacity exists to prevent fuel solution overheating. The numerical simulations of an AHR model were carried out using the Computational Fluid Dynamic (CFD) code ANSYS CFX 14. Evaluation shows that the ARGUS heat removal systems working at 75 kWth are not able to provide sufficient cooling capacity to prevent fuel solution overheating. To solve this problem, the number of coiled cooling pipes inside the core was increased from one to five. The results of the CFD simulations with this modification in the design show that acceptable temperature distributions can be obtained.

Highlights

99mTc is a very useful radioisotope, which is used in about 30– 40 million procedures worldwide every year [1]
As the Aqueous Homogeneous Reactors (AHR) conceptual design heat removal systems are based on the ARGUS reactor, the first step was evaluating the heat removal systems for the ARGUS designed thermal power (20 kWth)
The primary objective of this paper is contributing to the thermal-hydraulic analysis of one of the most promissory alternatives to produce medical isotopes: the use of Aqueous Homogeneous Reactors

Summary

Introduction

99mTc is a very useful radioisotope, which is used in about 30– 40 million procedures worldwide every year [1]. In AHR, because of the radiolytic decomposition of the fuel solution, bubbles will be produced. The production of these bubbles will play an important role in the reactor behavior because of the diminution of the density of the fuel solution and the expansion of fuel solution volume [8, 9]. The only large scale experiment on the use of an AHR in steady-state operation is the highly enriched uranium (HEU) Russian ARGUS reactor (Figure 1), which operates since 1981 at a maximum power density of 1 kW/L of solution (20 kWth) [6] at the Russian Research Centre “Kurchatov Institute” (RRC KI). After neutron-physical and thermal-hydraulic feasibility calculations for its conversion to low enriched uranium (LEU) fuel during 2010–2012 [10], the ARGUS reactor reached first criticality with LEU fuel in July 2014 [11]

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