Nitrogen in PWR: Role & Equilibrium Activity

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SUMMARY

Nitrogen plays a crucial role in Pressurized Water Reactors (PWR) primarily through the unstable isotope N-16, which serves as an indicator of reactor power. N-16 achieves equilibrium activity rapidly, approximately within one minute, due to its half-life of 7.16 seconds. Its activity is directly influenced by the fast neutron flux, which correlates with the fission rate. PWRs maintain a slightly reducing water chemistry to minimize crud transport, with pH levels typically ranging from 6.9 to 7.4.

PREREQUISITES
  • Understanding of PWR (Pressurized Water Reactor) operations
  • Knowledge of nuclear decay and half-life concepts
  • Familiarity with neutron flux and its relation to fission
  • Basic principles of water chemistry in nuclear reactors
NEXT STEPS
  • Research the role of N-16 in Boiling Water Reactors (BWR)
  • Study the effects of pH on reactor water chemistry
  • Learn about neutron flux measurement techniques in nuclear reactors
  • Investigate the implications of crud transport in PWR systems
USEFUL FOR

Nuclear engineers, reactor operators, and researchers focusing on reactor chemistry and performance optimization in Pressurized Water Reactors.

Maokeng
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Can anyone help me to understand the function of nitrogen in PWR.

What I know about unstable N-16 is that it is used as an indication of power PWR. How fast does it achieve an equilibrium activity?

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The half-life of N-16 (which is produced by an n,p reaction of O-16) is 7.16 s, so equilibrium is achieved rapidly - in about 1 minute. But then it also decays quite rapidly, so a detector must be close to the core. It's activity would be a function of the fast flux, which itself is related to the rate of fission or power.

N-16 is a matter for BWRs, which use hydrogen (reducing) water chemistry, since N-16 is carried through the main steam line to the turbine. PWRs use a slightly reducing water chemistry to prevent crud transport, although the pH these days tends to be 6.9 - 7.4 depending on the plant.

Reference:
http://www.nndc.bnl.gov/chart/reCenter.jsp?z=7&n=9 (then use zoom 1 in upper right corner)
 
Thnx 4 yo speedy & what I find as an accurate answer to the question. Many more thanks for providing the link. Cheers!
 

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