Universität zu Köln

Shabani, Doruntin ORCID: 0009-0001-7617-5347 (2026). 99Mo Production at a High-Current Accelerator-based Neutron Source. PhD thesis, Universität zu Köln.

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Abstract

Molybdenum-99 (99Mo) is the parent radionuclide of technetium-99m, which is extensively used in diagnostic nuclear medicine. Since the large-scale production depends on a limited number of research reactors, alternative and complementary production methods are of growing interest. This thesis investigates the feasibility of producing 99Mo by neutron capture on natural molybdenum through the 98Mo(n,γ) 99Mo reaction at a high-current accelerator-based neutron source. It examines how neutron moderation, reflection, irradiation geometry, and self-shielding influence the achievable activity and specific activity. The study combines PHITS neutron transport simulations, activation calculations, and experimental neutron activation benchmarks using bare and cadmium-covered foils. A three-group flux analysis method and an energy-dependent flux folding method were assessed. The benchmarks supported the use of the simulation framework for design studies, while highlighting the sensitivity of epithermal activation to resonance effects. A systematic parameter study varied moderator and reflector materials, reflector thicknesses, and Mo plate geometry. Results indicate that epithermal neutron flux and self-shielding largely determine the 99Mo yield. A water moderator with a magnesium oxide reflector offered the most practical compromise between neutronic performance and engineering constraints. An optimized configuration with a 3 cm axial molybdenum plate and three lateral plates was estimated to produce approximately 2400 Ci of 99Mo after six days of irradiation. Overall, the thesis shows that accelerator-driven neutron capture can provide a technically plausible route for low-specific-activity 99Mo production, provided that neutron spectrum shaping, target geometry, and self-shielding are carefully treated. Further experimental work on thick molybdenum targets will be important for refining the model and moving toward an engineering design.

Item Type:	Thesis (PhD thesis)
Creators:	Creators Email ORCID ORCID Put Code Shabani, Doruntin doruntinshabani@gmail.com https://orcid.org/0009-0001-7617-5347 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-814076
Date:	2026
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Physics > Institute for Nuclear Physics > Professur für Experimentalphysik 5 (Kernphysik)
Subjects:	Physics
Uncontrolled Keywords:	Keywords Language Molybdenum-99 English
Date of oral exam:	28 September 2026
Referee:	Name Academic Title Mücher, Dennis Prof. Dr. Wimmer, Kathrin Prof. Dr. Langer, Christoph Prof. Dr.
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/81407