Efficient Monte Carlo simulation of {sup 16}O neutron activation and {sup 16}N decay gamma-ray detection in a flowing fluid for on-line oxygen analysis or flow rate measurement
Journal Article
·
· Nuclear Science and Engineering
OSTI ID:220657
- North Carolina State Univ., Raleigh, NC (United States)
A Monte Carlo code named MCNAFF (Monte Carlo Neutron Activation in Fluid Flow) has been developed and tested for flow rate measurement and general composition determination of a flowing fluid by neutron activation analysis. Specifically, oxygen determination in a flowing fluid is treated, including simulating the emission and transport of neutrons in the fluid, the activation of {sup 16}O to {sup 16}N, the subsequent flow and dispersion of the {sup 16}N in the flow channel, the downstream decay of {sup 16}N, and the subsequent detection of the emitted decay gamma rays. This code is very efficient, partly because (a) the continuous single history approach has been taken, which follows a single history from emission of a neutron, through the production and decay of the {sup 16}N and the emission of a characteristic gamma ray, and finally to the full energy detection of the gamma ray and (b) the principle of forcing can be and is used throughout so that almost every history results in a partial success. The present MCNAFF code is capable of calculating gamma-ray detection yields per neutron emitted to the same accuracy as an approach by Perez-Griffo, Block, and Lahey, which numerically solves the partial differential equations for modeling particle dispersion and diffusion and calculates separately by Monte Carlo both the neutron absorption and gamma-ray detection process. The MCNAFF code is estimated to be about two orders of magnitude faster and should be more convenient to use because all calculations are accomplished in a single step.
- OSTI ID:
- 220657
- Journal Information:
- Nuclear Science and Engineering, Journal Name: Nuclear Science and Engineering Journal Issue: 3 Vol. 122; ISSN NSENAO; ISSN 0029-5639
- Country of Publication:
- United States
- Language:
- English
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