DESCRIBE the process of radiolytic decomposition and recombination of water.
Radiation causes pure water to decompose into hydrogen and oxygen. The decomposition is suppressed by adding excess hydrogen
DESCRIBE the process of radiolytic decomposition and recombination of nitric acid and ammonia.
If the amount of oxygen created from the decomposition of water is more than enough to deplete the hydrogen, the excess oxygen reacts with nitrogen (also a component of air) and forms nitric acid. In the case of addition of very large amounts of air, the amount of nitric acid produced may be more than enough to neutralize the normally basic coolant and cause it to become acidic
STATE the advantage of maintaining excess hydrogen in reactor water.
Excess hydrogen is added to suppress the decomposition of reactor water. It also reacts with any oxygen that enters the reactor coolant system, usually as a component of air in makeup water, provided the amount of oxygen is not excessive
Write the reaction for the radiolytic dissociation of water. Discuss both directions
2H2O n> <g 2H2(g) + O2(g)
neutron flux dissociates water
gamma puts it back together
What are some of the chemical products from the use of hydrazine
N2H4 + O2 > 2H2O + N2
2N2H4heat> 2NH3 + N2 + H2
List examples of affects from Air in leakage into the RCS
Causes H2 to become depleted
2N2 + 5O2 + 2H2O > 4HNO3
pH goes down
causes CRUD bursts radiation levels and conductivity of RCS go up
Air activated by neutron flux
List 3 means of removing O2 from the RCS
Add H2 at power
Add Hydrazine at shutdown
De-gasification
Write the nuclear reaction of 16O in the neutron flux
168O (n,p) 167N 7.13 second half life 167N > 168O + B- + g
List 2 major methods of removing impurities in the RCS
ION exchange
Feed and Bleed
De-Gasification
List some examples of how fission products can be released into the RCS
Fission recoiling natural U235 in cladding
Porosity of welds or assembly
Diffusion through cladding
List the major specific parameters we control
pH, disolved oxygen, hydrogen, total gas, conductivity, chlorides, flourine, boron and radioactivity
What do we add in the primary to neutralize the acidic boric acid