Chemistry

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 watergamma puts it back together

What are some of the chemical products from the use of hydrazine

N2H4 + O2 > 2H2O + N22N2H4 heat> 2NH3 + N2 + H2

List examples of affects from Air in leakage into the RCS

Causes H2 to become depleted2N2 + 5O2 + 2H2O > 4HNO3 pH goes downcauses CRUD bursts radiation levels and conductivity of RCS go upAir activated by neutron flux

List 3 means of removing O2 from the RCS

Add H2 at powerAdd Hydrazine at shutdownDe-gasification

Write the nuclear reaction of 16O in the neutron flux

16 8O (n,p) 16 7N 7.13 second half life 167N > 168O + B- + g

List 2 major methods of removing impurities in the RCS

ION exchangeFeed and BleedDe-Gasification

List some examples of how fission products can be released into the RCS

Fission recoiling natural U235 in claddingPorosity of welds or assemblyDiffusion 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

Lithium hydroxide Li7 because Li6 causes tritium

What is the concern with total gas

pocket of gas can cause cavitation in RCPs