Radiation Shielding A Practical Approach to an Engineering Physics Problem in Engineer 1P03.
Introduction • Geoff Gudgeon • Tony Machado • Aliraza Murji • Evie Sararas
Outline • Problem & Constraints • Background • Lab Results • Material Selection • Proposed Design • Recommendations • Conclusion
Problem & Constraints • Design an object that will shield the gamma rays given off by a radioactive source. • Maximum radiation emitted after shield limited to 50 mSv per year. • Design must be economically and practically feasible.
Background • Types of Radiation Alpha (α) Beta (β) Gamma (γ) Neutron
Background • Nuclear Decay • Atoms with greater than 83 Protons are unstable and will break down (known as Radioactivity). • Gamma Ray Absorption • Photoelectric Absorption • Compton Scattering • Pair Production • Absorbing Powers of Materials • Gamma radiation is attenuated exponentially when passing through a shielding material.
Lab #1 Verify 1/r2 law experimentally using Cesium source. Determine background radiation (0.2 µSv). Lab Results
Lab #2 Experimentally calculate Gamma Attenuation of Plastic, Lead, Aluminum, and Copper. Lab Results
Material Selection (CES) USE LEAD !!!
Three Assumptions: Source emits 1mSv/s. Density of lead is 11,340 kg/m3. Price of lead is $1.50/kg. Proposed Design
Three Unknowns Thickness of lead. Volume of lead. Price of lead. Solution ??? Create C++ Program! Why ??? Allows us to vary parameters to maximize design attenuation and minimize cost! Proposed Design
Proposed Design • Final Design: • Distance from source to inner wall of lead is 5cm. • Thickness of lead is 13.7cm. • Amount of lead used would total 111.055 kg. • Total cost of lead would be $172.58
Recommendation • Design can be easily altered using the C++ program to accommodate changes in input variables. • If not used on bottom floor, a lead plate with equal thickness to radius of dome should be implemented to protect people below. • Cover lead with plastic to prevent handling of toxic lead.
Conclusion • Our design offers the best choice of material to provide highest attenuation. • Low-cost due to small volume of design. • By using a dome, our design becomes geometrically efficient by absorbing radiation evenly. • Health and Safety regulation limiting 50mSv/year of radiation is met.
Conclusion • Thank you for your attention. • At this time, we would invite questions from the audience.