Extending the maximum operation time of the MNSR reactor

Area of Science:

• Nuclear Engineering
• Reactor Physics

Background:

• The Miniature Neutron Source Reactor (MNSR) has limitations in its maximum operation time, hindering its full utilization.
• Enhancing MNSR operational capacity is crucial for applications like Neutron Activation Analysis (NAA) and radioisotope production.

Purpose of the Study:

• To investigate an effective modification to extend the maximum operation time of the MNSR.
• To enhance the overall utilization of the MNSR reactor.

Main Methods:

• A 3-D neutronic model of the MNSR was developed using MCNP4C code.
• Modifications included inserting polyethylene containers filled with water into irradiation tubes and replacing the cadmium absorber with Boron-10.
• Neutronic parameters of the original and modified cores were compared.

Main Results:

• The modified core showed an increase in excess reactivity from 3.954 mk to 6.241 mk.
• Maximum reactor operation time increased by 139%, from 428 minutes to 1025 minutes.
• Safety reactivity factors remained within acceptable limits (1.654 for old core, 1.595 for modified core).

Conclusions:

• The tested modification effectively extends the MNSR's maximum operation time.
• This enhancement significantly improves the reactor's utility for long-term irradiations and radioisotope production.
• The modified MNSR design offers a more efficient platform for NAA and other applications.