Radiochemistry

Question 1

What are the two mechanisms of fission product releases to the RCS?

Answer 1

• Tramp Uranium - uranium oxide imbedded in fule cladding.
• Cladding Defect - a defect in the fuel cladding (pin hole, cracks) through which fuel generated fission products can leave the fuel and enter the RCS. (A sharp increase in activity without large reactor power fluctuations may indicate cladding failure.)

Question 2

Describe two methods for monitoring fuel cladding integrity durring power operations?

Answer 2

• Gross activity - a sample is taken, degassed and counted at exactly 20min agter sampling. this eliminates contribution of variance caused by short half life isotopes.
• Iodine 131/133 ratio - Because of the difference in half life between iodine 131 and 133 a “normal” ration will develop. If iodine 133 increases with respect to iodine 131 it is likely that a “fresh” fuel leaker exists.

Question 3

List the SIX steps in the CRUD cycle.

Answer 3

1. Corrosion - of out of core surfaces.
2. Release - of some portion of the corrosion.
3. Deposition - the corrosion products enter the core.
4. Activation - the corrrosion particals become activated in the core.
5. Release - the activated corrrosion products leave the core.
6. Deposition - the activated corrosion products deposit on surfaces outside the core.

Question 4

What are the three major classifications of activation products?

Answer 4

1. Activation of corrosion products: Co⁶⁰, Ag^110M
2. Activation of Water / Water impurities: N¹⁶, Na²⁴
3. Activation resulting in tritum production: Deuterium, Lithium, Boron.

Question 5

What are the concerns associated with Nitrogen-16?

Answer 5

• N¹⁶ is a very high gamma emitter.

Question 6

What are the hazards associated with tritium?

Answer 6

• Absorbed easily by the body
• Hard to detect
• you can’t filter it out.