Coupling MCNP-DSP and LAHET Monte Carlo Codes for Designing Subcriticality Monitors for Accelerator-Driven Systems Page: 2 of 5
This article is part of the collection entitled: Office of Scientific & Technical Information Technical Reports and was provided to UNT Digital Library by the UNT Libraries Government Documents Department.
Extracted Text
The following text was automatically extracted from the image on this page using optical character recognition software:
2 T. Valentine et al.
Concerns about the degree of subcriticality of an accelerator-driven fissile
system have mandated that methodologies be developed to measure the subcrit-
icality of the system. The Polytechnic University of Valencia and Oak Ridge Na-
tional Laboratory undertook an effort to develop a computational tool to inves-
tigate the time-dependent response of neutron detectors in an accelerator-driven
system. This is the first step necessary to develop a measurement methodology.
This paper provides a brief description of the research performed to develop a
time-dependent Monte Carlo calculation for accelerator-driven systems.
2 Monte Carlo Methods
The computation of the time-dependent detector responses in an accelerator-
driven system is best accomplished using Monte Carlo programs. Monte Carlo
codes preserve the exact nature of particle interactions within a fissile system
and are only limited by the ability to describe the geometry of the fissile system
and by the nuclear data to describe the particle interaction probabilities.
The accelerator-driven system of interest injects protons into a target assem-
bly to produce high-energy neutrons. These high-energy neutrons slow down in
the target assembly and transmute the nuclear waste. The Monte Carlo code
LAHET [1] is used to simulate the interactions of the protons within the target
region to produce high-energy neutrons. The LAHET code also simulates the
slowing-down of the high-energy neutrons. The Monte Carlo program MCNP-
DSP [2] is required to simulate the interactions for neutrons with energies less
than 20 MeV. This code is used to estimate the counting statistics for neutron
and/or gamma ray counters in fissile systems. Therefore, the coupling of LAHET
and MCNP-DSP provides a means to estimate the time-dependent response of
neutron and/or gamma ray detectors that may be used in the design of a sub-
criticality monitoring system for an accelerator-driven system.
3 Monte Carlo Code MCNP-DSP
The Monte Carlo code MCNP-DSP was developed from the MCNP [3] Monte
Carlo code to simulate a variety of subcritical measurements. In MCNP-DSP,
the variance reduction features were disabled to obtain a strictly analog particle
tracking to follow the fluctuating processes more accurately. Because typical bi-
asing techniques are employed to reduce the variance of estimates of first moment
quantities, they do not preserve the higher moments; therefore, analog Monte
Carlo calculations must be performed when analyzing subcritical measurements
whose measured quantities are directly related to the higher moments of the
neutron populations. Because the use of average quantities reduces the statisti-
cal fluctuation of the neutron population, average quantities such as the average
number of neutrons from fission are not used; instead, appropriate probability
distribution functions are sampled. The prompt particle tracking begins with
the source event. The source particles and their progeny are tracked to their
Upcoming Pages
Here’s what’s next.
Search Inside
This article can be searched. Note: Results may vary based on the legibility of text within the document.
Tools / Downloads
Get a copy of this page or view the extracted text.
Citing and Sharing
Basic information for referencing this web page. We also provide extended guidance on usage rights, references, copying or embedding.
Reference the current page of this Article.
Valentine, T.E.; Rugama, Y. Munoz-Cobos, J. & Perez, R. Coupling MCNP-DSP and LAHET Monte Carlo Codes for Designing Subcriticality Monitors for Accelerator-Driven Systems, article, October 23, 2000; Tennessee. (https://digital.library.unt.edu/ark:/67531/metadc718546/m1/2/: accessed April 18, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.