Facebook Instagram Youtube Twitter

Nitrogen-16 Power Monitoring

In nuclear reactors, the thermal power produced by nuclear fissions is proportional to the neutron flux level. Therefore, from the reactor safety point of view, it is of the highest importance to measure and control the neutron flux and the spatial distribution of the neutron flux in the reactor correctly and by appropriate instrumentation. For this purpose, various nuclear instrumentations are installed. These measurements are usually performed outside the reactor core, but there are also measurements performed from inside the core. Therefore, nuclear instrumentations are usually categorized as:

bk8vietnamLiên kết đăng nhập
Decay scheme of N-16. Source: Richard B. Firestone. Table of Isotopes, EIGHTH EDITION. John Wiley & Sons, 1996. ISBN-13: 978-0471077305.

Both systems are based on the detection of neutrons. But there are power plants that measure the thermal power using nitrogen-16 power monitoring. An N-16 power monitoring has several advantages over the ΔT and excore power measurements. The system based on this method monitors the thermal power of the NSSS (Nuclear Steam Supply System) by detecting the level of nitrogen-16 present in the coolant system. Nitrogen-16 is an isotope of nitrogen generated by neutron activation of oxygen contained in the water. It has a short half-life of 7.1 sec and decays via beta decay. This decay is accompanied by the emission of very energetic gamma rays (6 MeV), which can readily penetrate the wall of the high-pressure piping and can therefore be easily measured by ion chambers located on the hot leg piping of each coolant loop.

1n + 16O → 1p + 16N   (activation reaction)

 16N → 16O + β + γ   (radioactive decay)

Isotopes of nitrogen-16 are formed by fast neutron activation of oxygen-16 contained in the water. Activation results from a threshold reaction requiring >10 MeV fast neutrons. The concentration of nitrogen-16 present in the primary coolant is in radioactive equilibrium, and it is directly proportional to the fission rate in the core, thus to the reactor power. This activation of the coolant water requires extra biological shielding around the nuclear reactor plant. The high-energy gamma-ray from nitrogen-16 causes major concern. This is why water that has recently been inside a nuclear reactor core must be shielded until this radiation subsides. One to two minutes is generally sufficient.

Similarly, as for the excore nuclear instrumentation system, this N-16 monitoring system must be calibrated. The accurate thermal power of the reactor can be measured only by methods based on the energy balance of the primary circuit or the energy balance of the secondary circuit. These methods provide the most accurate reactor power.


Radiation Protection:

  1. Knoll, Glenn F., Radiation Detection and Measurement 4th Edition, Wiley, 8/2010. ISBN-13: 978-0470131480.
  2. Stabin, Michael G., Radiation Protection, and Dosimetry: An Introduction to Health Physics, Springer, 10/2010. ISBN-13: 978-1441923912.
  3. Martin, James E., Physics for Radiation Protection 3rd Edition, Wiley-VCH, 4/2013. ISBN-13: 978-3527411764.
  5. U.S. Department of Energy, Instrumentation, and Control. DOE Fundamentals Handbook, Volume 2 of 2. June 1992.

Nuclear and Reactor Physics:

  1. J. R. Lamarsh, Introduction to Nuclear Reactor Theory, 2nd ed., Addison-Wesley, Reading, MA (1983).
  2. J. R. Lamarsh, A. J. Baratta, Introduction to Nuclear Engineering, 3d ed., Prentice-Hall, 2001, ISBN: 0-201-82498-1.
  3. W. M. Stacey, Nuclear Reactor Physics, John Wiley & Sons, 2001, ISBN: 0- 471-39127-1.
  4. Glasstone, Sesonske. Nuclear Reactor Engineering: Reactor Systems Engineering, Springer; 4th edition, 1994, ISBN: 978-0412985317
  5. W.S.C. Williams. Nuclear and Particle Physics. Clarendon Press; 1 edition, 1991, ISBN: 978-0198520467
  6. G.R.Keepin. Physics of Nuclear Kinetics. Addison-Wesley Pub. Co; 1st edition, 1965
  7. Robert Reed Burn, Introduction to Nuclear Reactor Operation, 1988.
  8. U.S. Department of Energy, Nuclear Physics and Reactor Theory. DOE Fundamentals Handbook, Volume 1 and 2. January 1993.
  9. Paul Reuss, Neutron Physics. EDP Sciences, 2008. ISBN: 978-2759800414.

See above:

Incore Instrumentation

bk8 casino mu88 bet asia link vào bk8 new88 đăng nhập vn88 pro