U-TARGET IRRADIATION AT FRM II - AIMING THE PRODUCTION OF MO-99 - A FEASIBILITY STUDY

Sep 4, 2026

Uploaded by Kyle

A cooperative feasibility study between Technische Universität München and the Belgian Institut National des Radioéléments evaluates whether the FRM II research reactor can serve as a production facility for Mo-99, the parent isotope of Tc-99m. The work identifies a suitable irradiation channel and uses neutronic calculations to show sufficiently high neutron flux densities. Thermohydraulic calculations support the design and integration of an additional cooling circuit into FRM II’s existing heat removal systems. Required uranium-target in-house processes are defined, upgrades are identified, investment cost is estimated, and a potential time schedule is proposed.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages5

Reading Time13 min

AccessFree to download

Introduction

Nuclear medicine supply background (Mo-99/Tc-99m)

Cooperation and study scope

General Boundary Conditions

FRM II reactor overview and irradiation facilities

Target design assumptions

Design of the Future Irradiation Facility

Irradiation channels

Neutronic calculations

U-TARGET IRRADIATION AT FRM II AIMING THE PRODUCTION OF MO-99 – A FEASIBILITY STUDY H. GERSTENBERG, C. MÜLLER, I. NEUHAUS, A. RÖHRMOSER Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM II) Lichtenbergstrasse 1; D-85748 Garching-Germany ABSTRACT Following the shortage in radioisotope availability the Technische Unversität München and the Belgian Institut National des Radioéléments conducted a common study on the suitability of the FRM II reactor for the generation of Mo-99 as a fission product. A suitable irradiation channel was determined and neutronic calculations resulted in sufficiently high neutron flux densities to make FRM II a promising candidate for Mo-99 production. In addition the feasibility study provides thermohydraulic calculations as input for the design and integration of the additional cooling circuit into the existing heat removal systems of FRM II. The required in-house processes for a regular uranium target irradiation programme have been defined and necessary upgrades identified. Finally the required investment cost was estimated and a possible time schedule was given. 1. Introduction Tc-99m is by far the most widely used radioisotope in nuclear medicine. Its low gamma energy and its short half life of only 6 h make it an ideal probe for diagnostic imaging of many human organs. The most common way for the production of Tc-99m requires the irradiation of uranium targets leading to the generation of Mo-99 the mother isotope of Tc-99m which itself has a relatively short half life of 66 h too. Consequently neither Mo-99 nor Tc-99m can be stockpiled for weeks or longer. On the other hand at present only three European research reactors are equipped with facilities allowing the irradiation of uranium targets for the production of the medical isotopes mentioned above. In addition, all of these reactors are in operation since several decades and turned out to become vulnerable against malfunction. This situation led to a serious shortage for medical isotopes in 2008 and consequently a growing public awareness for the reliability of their supply [1] . Already before the shortfall of Mo-99/Tc-99m the Belgian Institut National des Radioéléments (IRE) and the Technische Universität München (TUM) agreed to cooperate on a feasibility study dealing with the possible use of TUM´s research reactor FRM II for the irradiation of IRE’s uranium targets. The study was completed in mid 2009 and provided promising results. 2. General Boundary Conditions The Forschungsneutronenquelle Heinz-Maier-Leibnitz (FRM II) is a 20 MW heavy water moderated, light water cooled research reactor being operated since 2005 by the TUM on its campus in Garching close to Munich. The basic design feature of FRM II is the single cylindrical compact fuel assembly forming the entire reactor core. Typically FRM II is run in cycles of 60 operational days in a row and for up to four cycles per year. Although FRM II has by its design clearly been optimised for basic research by means of beam tube experiments it claims to be a multi purpose reactor offering already presently several irradiation facilities [2, 3] . All of their irradiation channels are located within the heavy water moderator tank but hermetically separated from the heavy water itself by means of a watertight flange. In addition they are all accessible from the working area around the reactor pool for loading and unloading during reactor operation. These features had been transferred asan imperative condition for the target irradiation facility under investigation. The feasibility study was a cooperative effort between TUM and IRE. Consequently the study was a based exclusively on IRE’s target design, i.e. tubular targets containing 4.0 g of highly enriched uranium (HEU ≤ 92.2% in U-235) with a total height of 160 mm and an outer diameter of 22 mm. 3. Design of the Future Irradiation Facility 3.1 Irradiation Channels In the first step after the launch of the

FAQs

Why does the study focus on Mo-99 and Tc-99m production reliability?

Tc-99m is widely used in nuclear medicine, but its production depends on Mo-99 from uranium target irradiation. Since neither Mo-99 nor Tc-99m can be stockpiled for long, reactor facility reliability affects medical isotope supply.

What feasibility results were obtained for FRM II as a candidate for Mo-99 production?

A suitable irradiation channel for uranium targets was identified, and neutronic calculations produced sufficiently high neutron flux densities to make FRM II a promising Mo-99 production option.

How does the study address engineering integration beyond neutron performance?

Thermohydraulic calculations are provided to support design and integration of an additional cooling circuit into FRM II’s existing heat removal systems, and required in-house target irradiation processes and upgrades are specified.

Sep 4, 2026

Uploaded by Kyle