A portable shield for a neutron howitzer used for instructional and research purposes

• MCNP5 was used to characterize the neutron dose and the gamma flux from a 1 Ci 239PuBe neutron howitzer.
• A portable neutron and gamma shield with a removable port was designed and built.
• Measured neutron rates for both unshielded and shielded howitzer were compared with simulated rates.

Neutron howitzers are routinely used in universities to activate samples for instructional laboratory experiments on radioactivity. They are also a convenient source of neutrons and gammas for research purposes, but they must be used with caution. This paper describes the modeling, design, construction, and testing of a portable, economical shield for a 1.0 Curie neutron howitzer. The Monte Carlo N Particle Transport Code (MCNP5) has been used to model the 239PuBe source and the howitzer and to design the external neutron and gamma shield.