Non-electrical Applications of Nuclear Energy Flashcards
What are the key non-electricity uses of nuclear energy?
Water desalination Hydrogen generation Neutron Activation Analysis Production of radioisotopes for medical uses Propulsion
What methods are currently used to desalinate water?
Reverse osmosis- Pushing water through a membrane
Multi-Stage Flash- Boiling water at pressure to create a distillate and a brine. Temperature and pressure decrease through stages
Why is waste heat from nuclear reactors suitable for water desalination plants
Water desalination plants can be built on or near to a nuclear power plant site
Use of waste heat reduces energy costs by 50-60%
What are the benefits of hydrogen fuel for transport?
Clean burning (produces only water)
Has the potential to be produced cleanly
Flexible- could be used to manufacture synthetic hydrocarbons
What are the possible methods for producing hydrogen?
Thermal decomposition of water (very high temperatures required for significant dissociation, hence is not industrially feasible)
Steam reformation of methane (more commonly used but creates carbon products)
Electrolysis (requires large amounts of electricity and has a low efficiency)
Thermo-chemical cycles (such as Sulphur-Iodine, ideal method, however, huge materials issue has very high temperature strong acids are required)
Outline the process of steam reformation of methane
CH4 + H20 -> CO + 3 H2 (T= 700-1100c)
CO + H20 -> CO2 + H2 (T = 130c)
Outline the Sulphur-Iodine process
Consists of two cycles where water is the only reactant required to be added. The reaction of iodine with sulphur dioxide and water creates hydrogen iodide and sulphuric acid. HI goes on to decompose to H2 and I2 at 450c and the I2 is recycled
Sulphuric acid thermally decomposes to water, sulphur dioxide and oxygen, where SO2 is recycled. This occurs at very high temperatures, which introduces a huge materials challenge
What is Neutron Activation Analysis?
A method for identifying the accurate composition of a material. Neutrons make the material atoms unstable and radioactive, thus causing them to decay, emitting gamma rays of characteristic energies.
What are the uses of radioisotopes in medicine?
Imaging: CT scans, PET scans, SPECT (uses 99mTc)
Radiotherapy
Brachytherapy
Boron Neutron Capture Therapy
How does a Radioisotope Thermoelectric Generator work?
Uses a p-type and n-type semiconductor which are electrically connected. A temperature gradient across the semiconductors cause charge carriers (e in n type and h in p type) to move from hot to cold region, inducing a current.
What does the potential difference across an RTG depend on?
V = a dT - IR V= voltage across load a = Seebeck coefficient dT = Temperature difference across semiconductors I = induced current R = generator resistance
What properties should radioisotopes have which would make them suitable to be used in RTG’s?
Appropriate lifetime (10s of years)
Maximum power per unit mass (alpha emitters > beta/gamma emitters)
RI’s which produce little gamma, x-ray or neutron flux (limit damage to electronics)
When might a nuclear fission reactor be an appropriate energy source for space propulsion?
For power requirements of greater than 100kWe
What are the fuel, moderator and coolant used in nuclear fission reactors used for space propulsion?
Fuel: Uranium fuel
Moderator: Zirconium Hydride
Coolant: Sodium-potassium alloy
