CASMO5-M is a state-of-the-art lattice physics code for modeling multiple fuel assemblies, including fuel storage pool and rack configurations. Built on the foundation of CASMO5, CASMO5-M offers high fidelity, multi-assembly capabilities in an easy-to-use package.
Multi-Assembly Physics
Analyze spent fuel pool configurations, storage racks, and more with the powerful CASMO physics models.
Cutting-Edge Data
High-resolution, 586-group neutron library for enhanced accuracy and resonance treatments.
Next-Generation Analysis
CASMO5-M automatically generates all the data required by the advanced nodal core simulator, SIMULATE5.
Multi-Assembly Physics: Large-Scale Transport Calculations
CASMO5-M is an enhanced version of CASMO5 that extends the analysis scope by adding multi-assembly capabilities and higher-order Pn-scattering. CASMO5-M can be used study detailed multi-assembly depletion effects, complicated baffle/reflector effects, and gamma energy deposition in stainless steel reflectors in advanced reactor designs.
| Feature | CASMO5-M | CASMO5 |
| SIMULATE5 Support |  |
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| SIMULATE3 Support | |
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| Reflector calculation | |
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| 586-group ENDF/B-VII library | |
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| Model next-generation LWRs | |
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| Advanced resonance scattering | |
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| 2D Characteristics-based solver | |
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| Quadratic Gd depletion | |
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| Localized energy release per fission model | |
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| 18-group gamma calculation | |
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| Multi-assembly calculations | |
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| Storage rack and spent fuel pool calculations | |
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| Higher-order Pn scattering | |
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CASMO5-M can also be used to analyze spent fuel pools with explicit representation of depleted assemblies and fuel to perform burnup credit analysis, explicitly representing fresh and depleted assemblies and fuel storage rack components.
Unparalleled Accuracy: First-Principle Physics
CASMO5-M represents the culmination of Studsvik’s 25 years of experience in transport-based lattice physics. Using the well-established Method of Characteristics for its 2D transport solution, the increase in calculational energy groups helps CASMO5-M deliver unparalleled fidelity with production-level run times.
Several high-level physics enhancements have been added to CASMO5-M, making it the most accurate multi-assembly lattice physics code available.
Quadratic Gd Depletion
The strong spatial self-shielding of Gd-155 and Gd-157 require small depletion steps (and longer calculation time) for Gd-bearing fuel assemblies. CASMO5-M now includes a quadratic depletion model to overcome this difficulty, allowing for larger depletion step sizes without compromising accuracy.
Resonance Upscattering
Asymptotic elastic scattering models traditionally used in the epithermal energy range in NJOY and Monte Carlo codes lead to ~10% under prediction of Doppler coefficients of light water reactor lattices. CASMO5-M now corrects for this phenomenon using a more exact scattering kernel.
Energy Release Model
Lattice physics codes have typically used fixed energy release per fission values, which miss important features that impact reactor depletion results. CASMO5-M now explicitly computes the isotopic energy yields as lattice compositions evolve, maintaining the physical dependence on fuel exposure, Gd, and boron concentrations, MOX composition, and void fractions.
Pn Scattering
CASMO5-M includes a higher-order Pn scattering model to increase accuracy in problems where anisotropic effects are important, such as deep penetration problems, critical experiments, or low-leakage core designs.
Cutting-Edge Data: ENDF/B-VII Cross-Section Library
CASMO5-M has been updated with the latest available neutron and gamma data, fine-tuned to provide the most accurate solutions ever achieved with a lattice physics code. Using the most recent ENDF/B-VII nuclear data available, Studsvik has developed a high-resolution, 586-group neutron library for use with CASMO5-M.
This extensive update from the previous CASMO library improves accuracy and enhances resonance treatments. CASMO5-M now includes an updated 18-group gamma library for gamma-sensitive in-core detector modeling and gamma energy deposition calculations. Cross-section data is available for over 400 nuclides and materials including more than 200 explicitly defined fission products, 45 heavy nuclides, and an expanded array of detailed depletion chains.
Special attention has been paid to low- and intermediate-energy resonances of uranium and plutonium isotopes with a proprietary explicit resonance mapping below 10eV that includes over 400 energy groups. Resonance self-shielding has been added or improved for most material definitions and a first-of-its-kind heavy nuclide resonance upscattering model has been implemented to produce the highest-fidelity solutions.
Next-Generation Analysis: Support for SIMULATE5
CASMO5-M has been developed to support SIMULATE5, Studsvik’s advanced nodal simulator analysis code. CASMO5-M automatically generates all required neutron and gamma cross-section data banks, discontinuity factors, and control rod depletion data for SIMULATE5, comprising the most advanced light water reactor physics analysis system in the world.
The improvements in CASMO5-M, coupled with the enhanced models in SIMULATE5, have shown marked impact on several core simulator parameters including gadolinium worth, reactivity coefficients, and stronger void feedback, significantly reducing calculated-to-measured error.
Fully capable of modeling challenging heterogeneous fuel designs, such as high mixed-oxide (MOX) concentrations and high burnable poison concentrations, CASMO5-M and SIMULATE5 meet the demands of current and future reactor analysis. CASMO5-M is also capable of performing full-scope lattice physics calculations and can help support efforts in the following areas:
- Fuel management
- Core follow
- Plant operations
- Reload physics