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Radio-isotopes for medical use

The production of molybdenum 99 (99Mo), and its decay product, technetium 99m (99mTc), the most widely used medical radioisotope for diagnostic purposes, is important for public health. As a matter of fact, disruptions in the supply chain of these medical isotopes, which have half lives of 66 hours for 99Mo and 6 hours for 99mTc, can lead to cancellations or delays in Department of Nuclear Medicine where this isotope is used as Single Photon Emission Computed Tomography (SPECT) tracer. Unfortunately, supply reliability has declined over the past decade, due to unexpected or extended shutdowns at the few ageing 99Mo producing research reactors and processing facilities. These shutdowns have created global supply shortage. As an answer to minimize this risk for the next decades, the Jules Horowitz Reactor took into account as a new major challenge, the production of radioisotopes.

Figure 1: 99mTc utilization in myocardial perfusion imaging with Single Photon Emission Computed Tomography (SPECT)

Moly Project

The objectives of the MOLY project are to be able to produce an annual volume of 25% of European needs on an average basis and up to 50% of European needs in peak production. The new facility will accommodate Low Enriched Uranium (LEU) targets. The objectives of the MOLY project became one of the major challenges at the beginning of JHR. For the business point of view, the project should set up long term agreements with industry. Then, our activities will strengthen the Mo-99 supply and the production of other RI within European network.

To answer to the industrial challenge, we decided to build an industrial project since 2011. An engineering team was structured. It was important to integrate different skills in the team to deal with numerous interfaces with the JHR construction and the development of the MOLY activities. The team is now consistent with the following tasks in different fields :

  • Nuclear conception: physical studies, nuclear safety, technological studies and I&C systems. In this field, the iterative approach and the interfaces between skills are useful in order to converge into a final design ready to manufacture.
  • Nuclear manufacturing : manufacturing until factory acceptance as well as assembly on site
  • Nuclear operating with tests, commissioning and normal operations;
  • Project management;
  • Business approach.


In 2010, feasibility studies have been carried out. Since 2011 design studies were conducted in order to adapt to new objectives assigned and, from 2012, to the conversion of Uranium targets from High Enriched Uranium (HEU) to Low Enriched Uranium (LEU). In the design area, iterations might be required for take into account new input data. This process which can be long has to be formalized by important milestones.

In late 2013, we organized a review process on the detailed design studies and to valid the industrial policy for the manufacturing of the specified MOLY equipments.

Physical Studies

The MOLY irradiation devices will be located in the JHR beryllium reflector. In order to increase the JHR means of radioisotopes production, without decreasing the global experimental capacity, the design of the JHR reflector was slightly modified. Consequently, the irradiation devices will be placed on movable systems in order to achieve the loading and unloading operations out of the neutron flux and to reduce interactions with the vessel. Four locations are devoted to the 99Mo production. The movable systems should be well interfaced with reactor structures. They should be very robust. The irradiation devices are connected by hoses to a dedicated cooling circuit.

Numerous physical calculations were performed. The main objective of neutronic calculations was to define the 99Mo production performance of the uranium target in the environment of the reflector of the JHR. We have to take into account many input data :

  • Target: enrichment in 235U, shape, size, density …
  • MOLY irradiation devices: material, shape, location…
  • Interfaces with others equipments of the Jules Horowitz Reactor

As main result, we have shown that JHR will be able to produce 99Mo with high level yield, so even with a JHR medium thermal power.

The thermo-hydraulics calculations are also an important issue of these studies. Calculations have been realized for both operational and nuclear safety purposes. They allowed us to check the heat removal from U targets and to define the main cooling circuit. The safety circuit was also defined in order to deal with accidental situations. The results of these calculations are also used for I&C system's definition.
We also performed thermo-mechanicals calculations on equipments.

Nuclear Safety Studies

Nuclear Safety Studies are very important in the conception phase of the MOLY facility. They were done in an iterative manner with the technical conception. Safety documents are produced :

  • Safety options file and updates;
  • Nuclear safety analysis of irradiation conditions;
  • Nuclear safety analysis of operation conditions (without neutrons).

MOLY safety documents will be integrated in the general JHR licensing documentation (Safety Analysis Report, General Operating Rules…).

MOLY Circuits Architecture

As known, the Jules Horowitz Reactor is designed to provide the largest experimental capacity possible with the largest flexibility. The MOLY production is an industrial process. Since both objectives should be compatible, the equipments were defined and located in order to minimize the interfaces with those of the reactor and of the experiments. It was decided to use the so called “REP cubicle” for the main part of the cooling system, located near the reactor pool. The figure 1 presents the schematic diagram of the MOLY circuits.

We have defined the mains components for the electric power supplies (normal and rescued). The main principles for the MOLY command control are determined. Finally, the location of electrical cabinets is defined.

Fig 1: schematic diagram of the MOLY circuits © CEA

Technological Studies

In support to the physical studies, numerous technological studies have been carried out. For example, figure 2 presents the detailed design for the MOLY in pile part.

Fig 2: Detailed designs for the MOLY in pile part © CEA

Other more specific studies have been carried out on other equipments (irradiation devices, movable systems, pumps, hoses, test materials, tools…).

Industrial policy for the device manufacturing

In late 2013, a review process has validated the industrial policy for the MOLY device manufacturing. This industrial policy will be axed on 3 different contracts :

  • One for the in pile part of the devices, include the movable system, the Moly system, the hoses until the cubicle and the safety system.
  • One for the out of part of the device, include the cooling circuit in the cubicle, the I&C systems out of the cubicle and all the electric part.
  • One for a support for following the achievements of the manufacturing contracts and for dealing with the interfaces between Moly contracts and those from the JHR.

All the documents to launch the manufacturing of the specified MOLY equipments will be done for the third quarter 2014. Thus, the contracting process may take place early 2015.

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Revision : 2014-02
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