Anyone working in the field of radiation protection is well aware of neutrons, neutron radiation and the adverse effects it can have on living things. Neutrons form the basis of an atom, and together with protons, they make up more than 99 percent of the mass of an atom. The chance of neutron ejection is pretty slim and hard to detect, and usually occurs only as a result of nuclear fission and radioactive decay. Depending on the exposure dose, the effects of neutrons on living human body tissues can be deadly. Since the human body carries a large amount of water molecules, which consists of hydrogen, being exposed to neutron radiation can ionize the living tissues, causing substantial and irreparable damages by killing the impacted tissues. Some studies show that without appropriate neutron shielding, neutron radiation increases the incidents of neoplastic cell transformation, mutation, chromosomal aberrations and cancer.

Considering its dangerous effects, for many industries in which radiation— including neutron radiation— constitutes a major work hazard, the government mandates that the use of shielding, particularly neutron shielding is compulsory. With the advance of new technologies, materials and equipment, neutron shielding products have improved tremendously in term of their efficiency, reliability and cost effectiveness in recent years.

Neutron shielding objectives

Neutron shielding equipment is used to provide safety and to protect people and environments that are frequently expose to a level of neutron radiation that is deemed as damaging for living tissues. Companies that operate in the industries that produce radiation also need shielding solutions in accordance with the government’s regulation. Additionally, the shielding product specifications need to meet the regulatory requirements regarding their composition data, thermal properties, material compatibility and so on. Companies that fail to comply face heavy penalties and potential boycotts by their customers and environmentalists.

Neutron shielding materials

In the most basic forms, water, and some types of plastic or concrete can be utilized for shielding against neutron radiation. However, if the energy emitted from a neutron-released reaction is considerable, more sophisticated materials need to be used to absorb it completely. Rich hydrogen content materials can effectively slow fast neutrons and shield it. Iron can also absorb a great deal of fast neutrons and also a few other radiation rays such as gamma rays. Boron fiber is widely used as one of the most valuable neutron shielding materials due to its ability to seize thermal neutrons by oxidizing them. In addition, polyethylene based materials have also gained increasing popularity in recent years due to the fact that they are injection moldable, an efficient production method capable of producing complex shapes at low cost. Due to some health and regulatory concerns, nowadays, we have witnessed an increased demand for nontoxic high density materials when it comes to choosing shielding materials.

Neutron shielding designs

Successful neutron shielding solutions should be designed in a way such that it captures neutrons of all energy ranges (fast, medium and slow). Fast neutrons must first be slowed down and kept under control before any other method can be used to capture them. Similarly, in an incident where neutron radiation occurs, there often exist other radiations as well, including gamma, beta, and alpha rays. Therefore, the shielding equipment should successfully address these toxic radiations as well to effectually ensure safety for users from all types of radiation produced by that specific application.

In essence, neutron radiation is hazardous and poses a danger to human beings and the environment. Neutron shielding equipment is crucial to many industries, and with more scientific understanding about radioactivity and the widespread use of nontoxic high density materials, the equipment and working environments are gradually improved and to create a safer workplace.

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