# Presentation: 267155

## MCNPX 2.5.0

- G. W. McKinney
- J. W. Durkee, J. S. Hendricks, _M. R. James_, D. B. Pelowitz, L. S. Waters
*Los Alamos National Laboratory*
*Los Alamos, NM *
- F. X. Gallmeier
*Oak Ridge National Laboratory*
*Oak Ridge, TN*
*2**nd** High Power Targetry Workshop,October 10-14, 2005*

## Contributors

**Code Development Team**
- Joe W. Durkee, Harry W. Egdorf, Franz Gallmeier, John S. Hendricks, Gregg W. McKinney, Teresa L. Roberts, Laurie S. Waters, Joshua P. Finch
**Library Development Team**
- Mark B. Chadwick, Stephanie C. Frankle, Gerald M. Hale, Robert C. Little, Robert MacFarlane, Morgan C. White, Phillip G. Young
**Physics Development Team**
- David G. Madland, Stepan Mashnik, Richard E. Prael, Arnold J. Sierk, Jean-Christophe David, Alfredo Ferrari

## Outline

**Overview**
**New 2.5.0 Features**
**Heavy Ion Transport**
**Future Development**

## Overview

**Monte Carlo radiation transport code**
- Extends MCNP 4C to virtually all particles and energies
- 34 particle types (n,p,e, 5 Leptons, 11 Baryons, 11 Mesons, 4 LI)
- Continuous energy (roughly 0-100 GeV)
- Data libraries below ~ 150 MeV (n,p,e,h) and models otherwise
**General 3-D geometry**
- 1st & 2nd degree surfaces, tori, 10 macrobodies, lattices
**General sources and tallies**
- Interdependent source variables, 7 tally types, many modifiers
**Supported on virtually all computer platforms**
- Unix, Linux, Windows, OS X (parallel with PVM or MPI)

## Accelerator Application

**MCNPX is well-suited for high-energy accelerator modeling**
- Large beta-test team and user community.
- Many years of experience in accelerator community, esp. at LANSCE facility.
- Multiple physics models provide a wide variety of options.
- Bertini, CEM,INCL4, ISABEL, FLUKA.
- Calculates values of interest such as fluxes, shielding, detector response, radioisotope inventories, cross sections, etc.
- Active development program.

## Development History

**MCNP & LAHET Merger Project****	****1995**
**Version 2.1.5****	****	****November 14, 1999**
- HISTP/HTAPE3X, Mesh & radiography tallies, CEM
**Version 2.3.0****	****	****April 27, 2002**
- Proton libraries
**Version 2.4.0****	****	****August 1, 2002**
- Update to MCNP 4C, Fortran 90, Windows PC support
**Version 2.5.0****	****	****March 21, 2005**
- Twenty-eight features

## New 2.5.0 Features (28)

**User-interface enhancements (15)**
- 5 new source options
- 4 new tally options
- 3 new graphics options
- 3 other miscellaneous improvements
**Physics enhancements (9)**
- 4 new model physics features
- 2 new neutron physics features
- 3 new photon physics features
**Infrastructure enhancements (4)**

## User-Interface Enhancements

**Five new source options**
- Positron sources
- Spontaneous fission sources
- Multiple source particles
- Default VEC for cylindrical sources
- Extension of the TR keyword

## Multiple Source Particles / TR Extension

**Distribution for PAR and TR Keywords**
**1  0    -1    imp:n=1**
**2  0     1    imp:n=0**
**1 SPH 0 0 0 100**
**mode n p**
**sdef  ****par=d1 erg=fpar=d2 tr=fpar=d3**
**      ****x=d4 y=d5 z=0 cell=1**
**si1   L n   p**
**sp1     1   1**
**ds2   L 1.0 2.0**
**ds3   L 1   2**
**si4   -50 50**
**sp4     0  1**
**si5   -50 50**
**sp5     0  1**
**tr1   -50  50 0**
**tr2    50 -50 0**
**nps  10000**
**tmesh**
** ****rmesh2  n p**
** ****cora2  -100 99i 100**
** ****corb2  -100 99i 100**
** ****corc2  -1 1**
**endmd**

**1.0 MeV Neutrons**

**2.0 MeV Photons**

## Default VEC for Cylindrical Sources

**Cylindrical Source with Default VEC**
**1  0    -1 2  imp:n=1**
**2  0    -2:1  imp:n=0**
**1 SPH 0 0 0 100**
**2 SPH 0 0 0 1**
**sdef pos=0 0 0 rad=90 axs=0 0 1 ext=0**
**     ****dir=1 nrm=-1**
**nps  100**
**tmesh**
** ****cmesh1:n traks**
** ****cora1 1 98i 100**
** ****corb1 -1 1**
** ****corc1 1 358i 360**
**endmd**

## User-Interface Enhancements

**Four new tally options**
- Lattice tally speedup
- Anticoincidence pulse-height tally
- Coincidence capture pulse-height tally
- Residual nuclei pulse-height tally

## Anticoincidence Pulse-Height Tally

**Anticoincidence PHT 1 MeV Photons => Plastic/BGO**
**1 1 -7.130 -1       imp:p=1**
**2 2 -1.032  1 -2  3 imp:p=1**
**3 0         1 -2 -3 imp:p=1**
**4 0         2       imp:p=0**
**1 SPH 0 0 0 5.0**
**2 SPH 0 0 0 6.0**
**3 RCC -7 0 0 4 0 0 3.0**
**mode p e**
**sdef sur=2 nrm=-1 par=p erg=1.0**
**nps  100000**
**m1   83000 -0.671 32000 -0.175 8000 -0.154**
**m2   6000 -0.9153 1000 -0.0847**
**f26:e  2                  $ Plastic energy dep.**
**ft26   GEB 0 0.1098 0**
**sd26   1**
**f36:e  1                  $ BGO energy dep.**
**ft36   GEB 0 0.1098 0**
**sd36   1**
**f18:e  1                  $ Plastic/BGO PHT**
**e18    0. 1.0**
**fu18   0. 99i 1.0**
**ft18   phl 1 26 1 1 36 1**
**fq18   u e**

## Anticoincidence Pulse-Height Tally

**+                                     ACS/BGO Pulse Height Response - all particles                            **
**           ****tally type 8    pulse height distribution.                   units   number    **
**           ****particle(s): photon      electron   **
**           ****this tally is modified by   ft  phl**
** **
** ****cell  1                                                                                                               **
**       ****energy:       0.0000E+00           1.0000E+00             total                                             **
**    ****user bin**
**    ****0.0000E+00   1.30000E-04 0.2773   8.84300E-02 0.0102   8.85600E-02 0.0101**
**    ****1.0000E-02   6.80000E-04 0.1212   4.40000E-04 0.1507   1.12000E-03 0.0944**
**    ****2.0000E-02   7.90000E-04 0.1125   3.70000E-04 0.1644   1.16000E-03 0.0928**
**    ****3.0000E-02   6.90000E-04 0.1203   5.90000E-04 0.1302   1.28000E-03 0.0883**
**    ****4.0000E-02   8.70000E-04 0.1072   4.60000E-04 0.1474   1.33000E-03 0.0867**
**    ****5.0000E-02   7.80000E-04 0.1132   3.30000E-04 0.1740   1.11000E-03 0.0949**
**    ****6.0000E-02   8.40000E-04 0.1091   3.20000E-04 0.1767   1.16000E-03 0.0928**
**    ****7.0000E-02   9.30000E-04 0.1036   3.60000E-04 0.1666   1.29000E-03 0.0880**
**    ****8.0000E-02   7.60000E-04 0.1147   4.60000E-04 0.1474   1.22000E-03 0.0905**
**    ****9.0000E-02   8.00000E-04 0.1118   4.30000E-04 0.1525   1.23000E-03 0.0901**
**    ****1.0000E-01   9.20000E-04 0.1042   4.20000E-04 0.1543   1.34000E-03 0.0863**
**    ****1.1000E-01   9.80000E-04 0.1010   3.80000E-04 0.1622   1.36000E-03 0.0857**
**    ****1.2000E-01   8.60000E-04 0.1078   4.60000E-04 0.1474   1.32000E-03 0.0870**
**    ****1.3000E-01   8.70000E-04 0.1072   4.60000E-04 0.1474   1.33000E-03 0.0867**
**    ****1.4000E-01   9.30000E-04 0.1036   5.20000E-04 0.1386   1.45000E-03 0.0830**
**    ****1.5000E-01   9.30000E-04 0.1036   4.30000E-04 0.1525   1.36000E-03 0.0857**
**    ****1.6000E-01   8.40000E-04 0.1091   5.90000E-04 0.1302   1.43000E-03 0.0836**
**    ****1.7000E-01   9.50000E-04 0.1025   5.90000E-04 0.1302   1.54000E-03 0.0805**
**    ****1.8000E-01   1.08000E-03 0.0962   6.70000E-04 0.1221   1.75000E-03 0.0755**
**    ****.**
**    ****.**
**    ****.**

**Plastic**

**B**
**G**
**O**

## Anticoincidence Pulse-Height Tally

**Pulse-Height Tally**

**Accepted Spectrum**

**Rejected Spectrum**

## Coincidence Capture Pulse-Height Tally

**Coincidence Capture Tally Pu-239 in H2O/B-10**
**1  1 -1.0   -1    imp:n=1**
**2  2 -1.0    1 -2 imp:n=1**
**3  0         2    imp:n=0**
**1 SPH 0 0 0 10**
**2 SPH 0 0 0 20**
**sdef  par=sf pos=0 0 0 rad=d1**
**si1   0 10**
**sp1   -21 2**
**m1    1001 2 8016 1 ****94239 1.e-4**
**m2    5010 1**
**nps   100000**
**f8:n  2**
**ft8   CAP -8 -8 5010**
**t8    1e2 1e5 1e8            $ 1us, 1ms, 1s**
**print**

## Coincidence Capture Pulse-Height Tally

** ****weight normalization by source fission neutrons =         215705**
** ****cell:     2                                                                          **
** ****time bin: 1.0000E+02**
** ****neutron captures on 10b **
**                            ****captures         captures          multiplicity fractions**
**                ****histories  by number        by weight        by number        by weight       error**
** ****captures =  0      38079          0      0.00000E+00      3.80790E-01      1.76533E-01      0.0040**
** ****captures =  1      39130      39130      1.81405E-01      3.91300E-01      1.81405E-01      0.0039**
** ****captures =  2      17769      35538      1.64753E-01      1.77690E-01      8.23764E-02      0.0068**
** ****captures =  3       4429      13287      6.15980E-02      4.42900E-02      2.05327E-02      0.0147**
** ****captures =  4        555       2220      1.02918E-02      5.55000E-03      2.57296E-03      0.0423**
** ****captures =  5         38        190      8.80833E-04      3.80000E-04      1.76167E-04      0.1622**
**    ****total          100000      90365      4.18929E-01      1.00000E+00      4.63596E-01      0.0031**
**      ****factorial moments              by number               by weight**
**             ****10b                9.03650E-01 0.0031      4.18929E-01 0.0031**
**        ****10b(10b-1)/2!           3.47660E-01 0.0076      1.61174E-01 0.0076**
**     ****10b(10b-1)(10b-2)/3!       7.02900E-02 0.0183      3.25862E-02 0.0183**
**  ****10b(10b-1) .... (10b-3)/4!    7.45000E-03 0.0520      3.45379E-03 0.0520**
**  ****10b(10b-1) .... (10b-4)/5!    3.80000E-04 0.1622      1.76167E-04 0.1622**

## Coincidence Capture Pulse-Height Tally

** ****time bin: 1.0000E+05**
** ****neutron captures on 10b **
**                            ****captures         captures          multiplicity fractions**
**                ****histories  by number        by weight        by number        by weight       error**
** ****captures =  0      64457          0      0.00000E+00      6.44570E-01      2.98820E-01      0.0023**
** ****captures =  1      27555      27555      1.27744E-01      2.75550E-01      1.27744E-01      0.0051**
** ****captures =  2       6212      12424      5.75972E-02      6.21200E-02      2.87986E-02      0.0123**
** ****captures =  3       1263       3789      1.75657E-02      1.26300E-02      5.85522E-03      0.0280**
** ****captures =  4        362       1448      6.71287E-03      3.62000E-03      1.67822E-03      0.0525**
** ****captures =  5         86        430      1.99346E-03      8.60000E-04      3.98693E-04      0.1078**
** ****captures =  6         46        276      1.27953E-03      4.60000E-04      2.13254E-04      0.1474**
** ****captures =  7         12         84      3.89421E-04      1.20000E-04      5.56315E-05      0.2887**
** ****captures >  7          7         58      2.68886E-04      7.00000E-05      3.24517E-05      0.3780**
**    ****total          100000      46064      2.13551E-01      1.00000E+00      4.63596E-01      0.0050**
**      ****factorial moments              by number               by weight**
**             ****10b                4.60640E-01 0.0050      2.13551E-01 0.0050**
**        ****10b(10b-1)/2!           1.41880E-01 0.0172      6.57750E-02 0.0172**
**     ****10b(10b-1)(10b-2)/3!       5.36700E-02 0.0533      2.48812E-02 0.0533**
**  ****10b(10b-1) .... (10b-3)/4!    2.53200E-02 0.1255      1.17383E-02 0.1255**
**  ****10b(10b-1) .... (10b-4)/5!    1.20200E-02 0.2487      5.57243E-03 0.2487**
**  ****10b(10b-1) .... (10b-5)/6!    5.08000E-03 0.4377      2.35507E-03 0.4377**
**  ****10b(10b-1) .... (10b-6)/7!    1.80000E-03 0.6758      8.34473E-04 0.6758**
**  ****10b(10b-1) .... (10b-7)/8!    5.10000E-04 0.8837      2.36434E-04 0.8837**

## Residual Nuclei Pulse-Height Tally

**Residuals for 1.2 GeV Protons => Pb**
**1 1 -11. -1 imp:h 1**
**2 0       1 imp:h 0**
**1 so .01**
**mode h n**
**sdef par h erg=1200**
**     ****vec 0 0 1 dir 1**
**m1 82208 1**
**phys:h 1300 j 0**
**phys:n 1300 3j 0**
**nps 10000**
**f8:h 1**
**ft8  RES 1 99**
**lca  7j ****-2**** 0 **

**All Isotopes**

## Residual Nuclei Pulse-Height Tally

**All Pb Isotopes**

## User-Interface Enhancements

**Three new graphics options**
- Lattice index labeling
- WWG superimposed mesh plots
- Color contour and mesh tally plots

## Color Contour and Mesh Tally Plots

**HEU Cans in a Hex Lattice**
**1 1 -8.4      -1      u=1    imp:n=1**
**2 0           -2      u=1    imp:n=1**
**3 2 -2.7      -3 1 2  u=1    imp:n=1**
**4  3 -.001     3      u=1    imp:n=1**
**10 3 -.001    -6 lat=2 u=2   imp:n=1 fill=-2:2 -2:2 0:0**
**     ****2 2 2 2 2 2 2 1 1 2 2 1 1 1 2 2 1 1 2 2 2 2 2 2 2**
**11 0          -8             imp:n=1 fill=2**
**50 0           8             imp:n=0**
**1 rcc 0  0 0  0 12 0  5**
**2 rcc 0 12 0  0 8  0  5**
**3 rcc 0 -1 0  0 22 0  6**
**6 rhp 0 -1 0  0 22 0  9 0 0**
**8 rcc 0 -1 0  0 22 0  30**
**m1   1001 5.7058e-2 8016 3.2929e-2 92238 2.0909e-3  92235 1.0889e-4**
**m2   13027 1**
**m3   7014 .8 8016 .2**
**kcode 10000 1 10 40**
**ksrc 0 6 0   18 6 0   -18 6 0   9 6 15   -9 6 15   9 6 -15   -9 6 -15**
**tmesh**
** ****rmesh12**
** ****cora12  -30. 53i 30.**
** ****corb12  0. 12.**
** ****corc12  -30. 35i 30.**
**endmd**

## Color Contour and Mesh Tally Plots

**~5% Enriched**

## Color Contour and Mesh Tally Plots

## User-Interface Enhancements

**Three other miscellaneous improvements**
- READ card
- HISTP card extension
- DXTRAN/Detector underflow control

## Physics Enhancements

**Four model physics improvements**
- Mix & match of libraries and models
- CEM upgrade to 2K
- INCL 4/ABLA physics models
- Secondary-particle production

## Mix & Match of Libraries and Models

**Mix and Match**
- 5th entry on PHYS:N (3rd on PHYS:H) is superseded.
- Code will choose cutoff based on individual library’s upper energy.
- MX card allows the user to substitute isotopes or specify model physics based on individual M card entries.
- Isotope substitution can be done for nuclides where no table data is available.
- No neutron data table exists for Ge. As-75 could be used where the material cards call for Ge (see example).
- Available for neutrons, protons, and photons (photonuclear) only.

## Mix & Match of Libraries and Models

**Mix & Match for 100 MeV Neutrons => BGO Crystal**
**1 1 -7.130 -1 imp:n=1**
**2 0         1 imp:n=0**
**1 RCC 0 0 0 0 0 8.433 3.932**
**sdef sur=1.3 vec=0 0 1 dir=1 erg=100**
**nps 1000**
**m1     83209.24c 0.2105 8016.24c 0.6316 32000 0.1579**
**phys:n 101 3j -1**
**c    mx1:n     j               j            33075**
**c    phys:n 101 3j 20 $ Models above 20 MeV**
**c    mx1:n     j               j            33075**
**c    phys:n 101 3j 150 $ Models above 150 MeV**
**mode n p**
**f4:n 1**
**e0 1 100log 100**
**f21:p 1.2**
**m1     1002 1    1003 1    6012 1    20040 1**
**mx1:n  j         model     6000      20000**
**mx1:h  model     1001      j         j**
**mx1:p  6012      0         j         j**

## Mix & Match of Libraries and Models

**Mix & Match**

**As for Ge (150)**

**As for Ge (20)**

**Neutron Flux in BGO**

## CEM Upgrade to 2K (from 95)

**CEM 2k**
- Improvements in elementary cross sections, nuclear masses and pairing energies.
- Algorithm improvements decrease time required for some problems by a factor of 6.
- Utilizes measurements from the GSI experiments on isotope production.

## CEM Upgrade to 2K (from 95)

**CEM for 1.2 GeV Protons => Pb**
**1 1 -11. -1 imp:h 1**
**2 0       1 imp:h 0**
**1 so 1.0**
**mode h n**
**sdef par h erg=1200 vec 1 0 0 dir 1**
**m1 82208 1**
**phys:h 1300 j ****1**
**phys:n 1300 3j ****1**
**nps 100000**
**lca    8j 1**
**f1:n   1**
**ft1    frv 1 0 0**
***c1    175 34i 0**
**f11:n  1**
**e11    1. 30log 1200.**
**f21:h  1**
**ft21   frv 1 0 0**
***c21   175 34i 0**
**f31:h  1**
**e31    1. 30log 1200.**

## CEM Upgrade (version 95 to 2K)

**2K (2.5.0)**

**95 (2.4.0)**

**95 (2.4.0)**

**2K (2.5.0)**

**Neutron (Black/Red) and Proton Production**

## CEM Upgrade (version 95 to 2K)

**2K (2.5.0)**

**95 (2.4.0)**

**95 (2.4.0)**

**2K (2.5.0)**

**Neutron (Black/Red) and Proton Production**

## INCL 4/ABLA Physics Models

**INCL 4/ABLA is a combined intranuclear cascade/evaporation model.**
- User can specify combinations of existing models andINCL 4/ABLA (see example).
- Implemented by agreement with CEA
- Primarily useful in the 200 MeV – 2 GeV range.
- Somewhat slower than Bertini and CEM2K.

## INCL 4/ABLA Physics Models

**Various Physics Models for 1.2 GeV Protons => Pb**
**1 1 -11. -1 imp:h 1**
**2 0       1 imp:h 0**
**1 so .01**
**mode h n**
**sdef par h erg=1200 vec 0 0 1 dir 1**
**m1 82208 1**
**phys:h 1300 j 0**
**phys:n 1300 3j 0**
**nps 100000**
**f1:n  1**
**ft1   frv 0 0 1**
***c1   167.5 9i 17.5 0 T**
**e1    1 50log 1300**
**LCA   7j -2 0     $ Bertini/Dresner**
**LCA   7j -2 0     $ Bertini/ABLA**
**LEA   6J  2**
**LCA   2j  2 4j -2 $ ISABEL/Dresner**
**LCB   4j  1300**
**LCA   2j  2 4j -2 $ ISABEL/ABLA**
**LCB   4j  1300**
**LEA   6J  2**
**LCA   7j -2 2     $ INCL4/ABLA**
**LEA   6j  2**
**LCA   7j -2 2     $ INCL4/Dresner**
**LCA   7j -2 1     $ CEM2K**

## Secondary-Particle Production

**Neutron Production**

## Physics Enhancements

**Two neutron physics improvements**
- Fission multiplicity
- S(,) secondary-energy smoothing

## S(,) Secondary-Energy Smoothing

**Improvement in S(********,********) algorithm in code**
- User interface is unchanged but underlying secondary energy treatment is improved.
- The structure in the S(,) data is often in discrete energies resulting in non-physical spikes in the thermal neutron spectrum.
- New algorithm smooths over non-physical structure in data to provide smoother and better low-energy neutron spectra.

## Physics Enhancements

**Three photon physics improvements**
- Photon Doppler broadening
- Photonuclear physics model
- Variance reduction with pulse-height tallies

## Photonuclear Physics Model

**Photonuclear 10 MeV Photons => Pb**
**1  1 -7.86   -1    imp:n=1**
**2  0          1    imp:n=0**
**1 SPH 0 0 0 2**
**mode   n p**
**sdef   par=p erg=10.0**
**phys:p 3j 1**
**m1     82208 1**
**c    mx1:p  model**
**nps    1000000**
**f1:n   1**
**e1     1e-3 50log 10.**

**Photonuclear 10 MeV Photons => U-235**
**1  1 -7.86   -1    imp:n=1**
**2  0          1    imp:n=0**
**1 SPH 0 0 0 2**
**mode   n p**
**sdef   par=p erg=10.0**
**phys:p 3j 1**
**m1     92235 1**
**xs1 92235.27u 233.024994 bofod01u 0 1 54868 2946 0 0 0.0**
**c    mx1:p  model**
**nps    1000000**
**f1:n   1**
**e1     1e-3 50log 10.**

## Photonuclear Physics Model

**Library**

**Model**

**Neutron Production from U-235**

##  Variance Reduction with Pulse-Height Tallies

**Pulse-Height tally Variance Reduction has been a goal in Monte-Carlo codes for many years.**
- Implemented in MCNPX v2.5.0 and can result in dramatic speed improvements.
- Deconvolves the particle “trees” to get correct PHT.
- Not all variance reduction techniques supported.
- Unsupported VRTs result in a fatal error.

##  Variance Reduction with Pulse-Height Tallies

**VRT with PHT 1 MeV Photons Incident**
**1 2 -2.33 -1     imp:p,e 1**
**2 1 -2.7  -2 5   imp:p,e 1**
**3 1 -2.7 -3      imp:p,e 1**
**4 1 -1.35 -5 20  imp:p,e 1**
**5 0 2 3 -4 6 7 8 imp:p,e 1**
**6 0 4            imp:p,e 0**
**7 1 -2.7 -6      imp:p,e 1**
**8 1 -2.7 -7      imp:p,e 1**
**9 1 -2.7 -8      imp:p,e 1**
**20 1 -1.35 -20 21 imp:p,e 1**
**21 1 -1.35 -21 1  imp:p,e 1**
**1 rcc 3 3 9 0 0 0.25 0.4**
**2 box 0 0 0 12 0 0 0 12 0 0 0 12 **
**5 box 1 1 1 10.0 0 0 0 10.0 0 0 0 10.0 **
**3 rcc 0 0 -1 0 0 1.0 72.0   **
**4 sph 0 0 0 77.0 **
**6 rcc -9 44 0 0 0 16 5**
**7 rcc 30 30 0 0 0 12 10**
**8 rcc 9 -44 0 0 0 13 7**
**20 sph 3 3 9.1 1.8**
**21 sph 3 3 9.1  .9**

**wwp:p 100 4 4**
**wwn1:p .0002 .002 .02 .001 .02 -1**
**       ****.02 .02 .02 .0005 .0002**
**fcl:p -1 0 7r -1 -1**
**mode p e**
**m1 13027 1 $ (2.7 g/cc) Al **
**m2 14028 1 $ Si (detector element, 2.33 g/cc)**
**sdef erg=1 pos=0 0 21 par=p rad=d1 ext=0**
**     ****axs=0 0 1 vec=0 0 -1 dir=1**
**si1 0 72.0**
**sp1 -21 1**
**phys:p**
**phys:e 7j 0**
**f8:p 1**
**e8   0 1.e-5 .001 2i .007 .01 .015 .02**
**     ****7i .1 19i 1.1**
**nps  100000000**

##  Variance Reduction with Pulse-Height Tallies

**Thin Si Detector**
**Inside an Al Box**

**1 MeV Photons Incident From Above**

##  Variance Reduction with Pulse-Height Tallies

**	****   ****Time(m)    FOM**
**Analog       12569            4**
**2 VRTs          424        631**
**3 VRTs          424      1814**

## Infrastructure Enhancements

**8-byte integers**
- Users can now run billions of particles
- Often required for parallel calculations
- Runs about 20% slower on most systems
**Support for new compilers**
- Mac OS X with IBM compiler
- Windows PC and Linux with Intel compiler
**Parallel processing with MPI**
- PVM option is still available
**MPI speedup for criticality problems**
- Eliminates collection of fission source after each cycle

## Future Development

**Eigenfunction convergence (2.6.A)**
**Transmutation (2.6.A)**
**Heavy-ion tracking and interaction physics (2.6.B)**
**Delayed neutron and gamma models (2.6.B)**
**Magnetic fields (2.6.C)**
**CEM upgrade to version 03 (2.6.C)**
**CAD interface (with spline-surface tracking)**
**Variance reduction techniques extended to models**
**Improve point detectors/DXTRAN for models**
**Extend electron data to 100 GeV**

## MCNPX HI Tracking

- A patch now exists for Version 2.5.0 that will enable tracking of HIs.
- “Heavy ions” cover most isotopic nuclei, except for those that already exist in the code (deuteron, triton, He-3, and He-4).
- The “#” sign is used for all HIs, regardless of ZAID.
- The default HI is Pb-208.
- Using “#” on the sdef card will start a Pb-208.
- Other ions can be started by specifying the ZAID as the particle type on the sdef card (e.g., sdef par = 6012 for a C-12).
- Flux tallies can be used for HIs, although the default behavior tallies all HIs together. Separate bins for HI identity can be created with an FU card.

## MCNPX HI Tracking – cont.

- The code initializes cross sections from a list of all potential trackable isotopes (He-5 through Fm-259).
- 2205 isotopes total
- All secondaries produced in the _model physics_ region are banked.
- This includes the residual nuclides array.
- The table physics region does not produce residuals.
- Residual nuclei outside of the table are automatically put into the “below” array (no transport, energy is deposited locally).

## LAQGSM

- LAQGSM  - Los Alamos Quark-Gluon String Model
- The LAQGSM model promises to be an improvement on the  ISABEL model.
- LAQGSM has been implemented as a physics option in MCNPX.
- It can calculate A1 + A2, pions, and nucleon interactions (photonuclear reactions expected in the next version).
- Upper-energy limit of ~1 TeV/nucleon (could also replace FLUKA for many (most?) high-energy applications).

## Energy Deposition Benchmark

- Fe-56 at 54 GeV energy deposited in H2O.
- MCNPX calculation is normalized to leading edge of curve.

## U-238  on Li-6—Mesh Tallies

- Flux Map				Energy Deposition

- Heavy Ion Flux

- Energy Deposition

## U-238 Incident on Li-6—Residuals

- Example problems.
- U-238 on Li-6 at 400 MeV/nucleon.
- 2-mm cylindrical beam directed on 3-cm-diam cylinder.
- Tallied n, h, alpha, He-3, d, t, and HIs on surface of cylinder.
- HIs divided into 92 user bins (one for each element).

## Status of Heavy Ion Tracking

- HI tracking is now possible with an experimental version of MCNPX.
- A new physics model, LAQGSM, has been implemented that benefits not just the HI transport, but also the high-energy physics for many particles.
- Results must be checked against data and good benchmark problems.
- Future work will be focused on completing a full-featured implementation.

## Summary – MCNPX 2.5.0

**MCNPX is an excellent tool for understanding issues surrounding the design and operation of accelerator sources.**
**Built upon well-established codes in the community.**
**Continues active development of new options and features. **

## Photonuclear Capabilities

- Libraries available for some nuclides
- H, C, O, Al, Si, Ca, Fe, Cu, Ta, W, Pb
- Feature implemented in 2000
- Models available for all nuclides
- Provided with the CEM2K INC package (April 2003)
- Actinide GDR parameters recently improved
- User can control use of libraries vs models
- Default is to use libraries, otherwise models
- Biasing available to enhance secondary production

## Photonuclear Feature

## Eigenfunction Convergence

- ADS / LANL ADS reactor application
- Before - eigenfunction exhibits false convergence within fissile regions
- Fission source produced by power iteration method
- Can have a significant effect on burnup and shielding results
- Can only be overcome by running more particles/cycle
- Now - fission source distribution is biased to minimize false convergence
- Fission matrix is tabulated and split into symmetric/asymmetric parts
- Asymmetric component is dampened to minimize statistical variations
- Biasing parameters are derived and used in the next cycle
- Increases eigenfunction convergence by factors of 10-100

## 7-Can HEU Test Problem

**~5% Enriched**

## Eigenfunction from the Standard Method

- 1,000 particles/cycle
-  100 active cycles (30 settle)
-  Factor 3-4 flux tilt

- 100,000 particles/cycle
-  100 active cycles (30 settle)
-  ~10% flux tilt

## Eigenfunction from the New Method

- 1,000 particles/cycle
-  100 active cycles (30 settle)
-  ~10% flux tilt (converges ~100 faster than SM)

## Existing Burnup Capabilities

**Numerous “scripts” written to link MC codes to depletion codes**
- MOCUP (MCNP/ORIGEN2, INEL, 1995)
- MC-REBUS (MCNP/REBUS, ANL, 1998)
- OCTOPUS (MCNP/FISPACT, ECN NRG Netherlands, 1998)
- MCB (MCNP/Custom, RIT Sweden, 1999)
- MonteBurns2 (MCNP/ORIGEN2 or CINDER90, LANL, 1999)
- MCWO (MCNP/ORIGEN2, INEEL, 2000)
- BURNCAL (MCNP/Custom, SNL, 2002)
- MCODE (MCNP/ORIGEN2, MIT, 2002)
**Disadvantages of a “link” approach**
- Several input files to create and understand
- Numerous input/output files to manage
- Approximations to convert data from one format/code to another

## MCNPX/CINDER90 Interface

**MCNPX provides to CINDER90**
- 63-group fluxes in each material to be burned
- Isotopic atom densities and material volumes
- Absorption and fission reaction rates for each nuclide
- Average keff and fission , and fission Q
- Power level and burn time
**CINDER90 provides to MCNPX**
- Updated isotopic atom densities
- Burnup quantities
**User interface (BURN card)**
- BURN card without any entries defaults to 1 MW power for 1 day
- User can specify burn materials, power level, burn times, etc.
- Histories run per burn time are taken from NPS or KCODE card

## BURN Card

- BURN   POWER=2.0   TIME=15,30,30   MAT=3,4
- 		        OMIT=3,3,8017,92234,94239,4,1,92234
- Specifies a power level of 2 MW for a duration of 75 days (steps of 15, 30,
- and 30 days). Materials 3 and 4 are included in the burn with isotopes 17O,
- 234U, and 239Pu excluded from material 3 and isotope 234U excluded from
- material 4. Nuclides with an atom fraction less than 1e-10 are also excluded.
- To force the inclusion of a nuclide, simply list that nuclide on the appropriate
- material card with an insignificant atom fraction.

## 7-Can HEU Test Problem

**~5% Enriched**

## Comparison to MonteBurns

**Comparison to MonteBurns**

**MCNPX**

**MonteBurns**

## Actinide Inventories

**235****U**

**236****U**

**239****Pu**

## Fission Product Inventories

## Can Burnup

**Central Can**

**Outer Can**

## Delayed Neutron/Gamma Capability

- Delayed treatment for model and library interactions
- All events for model interactions
- Fission events for library interactions
- Delayed distributions provided by CINDER90
- Uses residual nuclides from model interactions
- Samples fission products for library fission events
- Includes virtually all possible decay chains
- Provides energy distributions in groups (300 n, 25 g)
- Provides time distributions (continuous => 70 bins)
- Biasing available to enhance delayed production

## 235U Library vs Model Delayed Neutron Energy Spectra

**235****U Library vs Model Delayed Neutron Energy Spectra**

******library**** = .0062**
******model**** = .0063**

## 235U Library vs Model Delayed Neutron Time Spectra

**235****U Library vs Model Delayed Neutron Time Spectra**

**Library (.61c) has 6 time bins**
**Cinder integrates into 70 bins**

## 235U Delayed Gamma Production per Fission

## 235U Delayed Gamma Production per Fission

**235****U Delayed Gamma Production per Fission**