NUCLEAR PROPERTIES OF URANIUM
•U isotopes all alpha emitters.•Some spontaneous fission (SF).
•Specific activity of U low due to long half-lives …. but …
•Decay through chain of daughter products, ultimately leading to lead or bismuth.
•At secular equilibrium:
–All decay rates are same throughout the chain.
–Daughter product concentration in proportion to half-life.
–~ 95% of specific activity (Bq/kg) is due to daughter products.
•Radon gas most significant.
•HEX is converted into UO2
•UO2 is manufactured into pellets and loaded into pins (or rods)
•The rods are combined into assemblies
1.Nuclear reactivity and control
2.Adequate thermal-hydraulic and heat transfer characteristics (i.e. coolant flow rate, surface area etc.)
3.Containment of radioactive materials under normal and transient conditions (i.e. fission product containment)
4.Minimisation of neutron absorbing impurities
5.Cost competitiveness
a)Long fuel residency (high-burnup)
b)Standardisation of product for economic manufacture
c)Reliability
d)Realistic specifications with good quality control within the acceptable tollerance
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