Mechanical Engineering ETDs


Lin Zheng

Publication Date



As part of its nuclear nonproliferation mission, the U.S. Department of Energys Global Threat Reduction Initiative (GTRI) is working to develop a sustainable means for producing the critical medical isotope molybdenum-99 (99Mo) without using highly enriched uranium (HEU). 99Mo is the parent product of technetium\xad99m (99mTc), a radioisotope used in approximately 50,000 medical diagnostic tests per day in the U.S. The primary uses of this product include detection of heart disease, cancer, study of organ structure and function, and other applications. 99Mo has a short half-life (66 hours) and cannot be stockpiled. U.S. demand is approximately 50% of the world market. The objective of the domestic 99Mo project is to accelerate existing commercial projects to meet at least 100% of the U.S. demand of 99Mo produced without HEU by the end of 2016. New methods for generating 99Mo are being explored in an effort to eliminate proliferation issues and provide a domestic supply of 99mTc for medical imaging within the United States. For this project, electron accelerating technology is used by sending an electron beam through a series of 100Mo targets. During this process a large amount of heat is created, which directly affects the operating temperature set for the system. The wall temperature along the target section must be maintained between 550 \u2103 and 650 \u2103. This temperature range is dictated by the tensile stress limit of the wall material. To maintain the required temperature range, helium gas is used to server as a cooling agent that flows through narrow channels between the target disks. This thesis investigated the cooling performance on a series of new geometry designs of the cooling channel by using Computational Fluid Dynamics (CFD) software ANSYS FLUENT 14.5. An experiment was also conducted to conclude whether the CFD model is valid and able to predict the right physics of the cooling channels. As a result, a new optimal geometry for the cooling channels will be selected for the purpose of the 99Mo project.'


Molybdenum-99, Diffuser, Circulation, computational fluid dynamics, 3D Modeling, LANL

Degree Name

Mechanical Engineering

Level of Degree


Department Name

Mechanical Engineering

First Committee Member (Chair)

Vorobieff, Peter

Second Committee Member

Poroseva, Svetlana

Third Committee Member

Olivas, Eric


Los Alamos National Laboratory

Document Type