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2010-09-08 15:13:16
Chapter5 Primary Coolant

Chapter5 Primary Coolant
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  1. 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
  2. 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
  3. 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
  4. 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
  5. What are some of the chemical products from the use of hydrazine
    • N2H4 + O2 > 2H2O + N2
    • 2N2H4 heat> 2NH3 + N2 + H2
  6. 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
  7. List 3 means of removing O2 from the RCS
    • Add H2 at power
    • Add Hydrazine at shutdown
    • De-gasification
  8. 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
  9. List 2 major methods of removing impurities in the RCS
    • ION exchange
    • Feed and Bleed
    • De-Gasification
  10. 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
  11. List the major specific parameters we control
    pH, disolved oxygen, hydrogen, total gas, conductivity, chlorides, flourine, boron and radioactivity
  12. What do we add in the primary to neutralize the acidic boric acid
    Lithium hydroxide Li7 because Li6 causes tritium
  13. What is the concern with total gas
    pocket of gas can cause cavitation in RCPs