MCNP neutron energy deposition in water

In summary, the conversation discusses a simulation using MCNP to study neutron energy deposition in water. The user used 14-MeV neutrons and noticed a discrepancy in the energy deposition results. They suspected this may be due to MCNP not scoring the neutron's energy when a proton captures it. They also mention considering the energy deposition of deuterons and oxygen, but faced limitations with tracking oxygen in MCNP. Suggestions are given to check input parameters, seek assistance from the MCNP community, and consult literature for potential solutions.
  • #1
oksuz_
70
3
Hi,

I did an MCNP simulation to see the neutron energy deposition in water. I used 14-MeV neutrons, and big enough water body to make sure all the neutrons stay in the water and give all their energies to water. I used F6 tally. However, I got energy deposition of around 10.3 MeV, not 14 MEV. I suspected that maybe when a proton captures a neutron, MCNP does not score neutron's energy. And I included energy deposition of Deuteron and got ~20 KeV, Which is so small. I wanted to try the same thing for Oxygen, but MCNP does not track O individually ( as far as I know). Can anyone give me some suggestion? Maybe I am missing something.
 
Engineering news on Phys.org
  • #2
Does the tracking of the 14.1 MeV neutron have a cutoff energy below which it is not counted?

If the neutron is absorbed, there is both recoil of the resulting nuclide, as well as radiative capture (gamma ray). When a proton captures a neutron, the exited deuteron emits a 2.2235 MeV gamma, which is slightly less than the gamma energy required to separate the neutron from the proton (photo-dissociation). This gamma would deposit energy by Compton scattering or photo-absorption. Similarly, oxygen would emit a gamma ray when it absorbs a neutron. With respect to H2O, the cross-section is weighted according to the number of atoms in the molecule. Neutron scattering off water involves the protons, the oxygen to a lesser extent, and the whole molecule, at thermal energies.
 
  • #3


Hi there,

It sounds like you have done a thorough simulation and have some interesting results. Have you considered checking your input parameters to make sure everything is set up correctly? It's possible that there may be a mistake in your input that is causing the discrepancy in the energy deposition.

Also, have you tried reaching out to the MCNP community for assistance? They may have some insights or suggestions for you to try. You can also try posting your question on forums or discussion boards specific to MCNP to see if anyone else has encountered a similar issue.

Lastly, have you consulted any literature or resources on MCNP to see if there are any known limitations or known issues with tracking oxygen specifically? It may be worth looking into to see if there are any known workarounds or solutions.

I hope this helps and good luck with your simulation!
 

Related to MCNP neutron energy deposition in water

1. What is MCNP?

MCNP (Monte Carlo N-Particle) is a computer code used to simulate the transport of particles such as neutrons, photons, and electrons through various materials. It is commonly used in nuclear engineering and radiation physics research.

2. How does MCNP calculate neutron energy deposition in water?

MCNP uses a Monte Carlo method, which involves randomly sampling the interactions between neutrons and water molecules. This allows for a more accurate calculation of neutron energy deposition compared to deterministic methods.

3. Why is it important to study neutron energy deposition in water?

Neutron energy deposition in water is important in many fields, including nuclear reactor design, radiation therapy, and radiation protection. Understanding how neutrons interact with water is crucial in predicting radiation effects and developing safety measures.

4. What factors affect neutron energy deposition in water?

The energy and direction of the incident neutrons, as well as the composition and density of the water, can affect neutron energy deposition. Other factors such as temperature and pressure can also play a role in the interactions between neutrons and water molecules.

5. How can MCNP results be validated?

MCNP results can be validated by comparing them to experimental data or other simulation results. Additionally, sensitivity analyses can be performed to assess the impact of different input parameters on the calculated neutron energy deposition in water.

Similar threads

Replies
6
Views
401
  • Nuclear Engineering
Replies
2
Views
5K
  • Nuclear Engineering
Replies
1
Views
3K
Replies
8
Views
2K
Replies
3
Views
3K
  • Nuclear Engineering
Replies
1
Views
3K
Replies
2
Views
2K
Replies
2
Views
1K
  • High Energy, Nuclear, Particle Physics
Replies
15
Views
3K
  • High Energy, Nuclear, Particle Physics
Replies
1
Views
1K
Back
Top