NederlandsLife Cycle innovations & Isotopes / Section FI - Physics
Radiation Transport and Reactor Physics are the key areas of expertise that are described on this page.
Physics
Radiation physics:
NRG's staff has a broad experience in the development and use of leading edge methods for radiation physics applications.
Based on several decades of experience in the field, the ORANGE software package was developed at NRG, which is based on the 3D Monte Carlo code MCNP. Besides all the features present in MCNP, ORANGE has the capability of generating (at no extra cost in computer time) 3D distributions of arbitrary radiation-related quantities. These include not only distributions of usual quantities like flux, reaction rates or radiation damage, but also radiation dose distributions for photons, electrons and neutrons.
Applications include the calculation of :
- Dose distributions in phantoms due to irradiation with photon- and electron beams,
- Detailed power profiles in nuclear reactors
- g-heating in HTR designs
- Reaction rate distributions in transmutation reactors (such as ADS)
Radiation shielding:
General radiation shielding problems in a wide range of areas within the nuclear industry are solved by our team of experts.3-Dimensional Monte Carlo methods form the main tool for these analyses. Both simple and complicated radiation-shielding problems are solved in an efficient manner.
Applications include:
- The g-shielding of hot cells,
- Neutron- and g-shielding from spent fuel storage racks,
- Radiation equipment design for the industry,
- Shielding from intermediate storage facilities for spent nuclear fuel.
Reactor Physics
Nuclear reactor physics is concerned with the behaviour of the neutron population in a nuclear reactor, its life cycle, and associated quantities like effective multiplication factor keff, reactivity, criticality, neutron (flux) density distribution in energy, space, angle and time and derived quantities like the (fission) power distribution in space and time. This includes taking into account the effects of thermal hydraulic feedback and the evolution of the composition of the nuclear fuel and other reactor materials. NRG's staff has a broad experience in the detailed computational analysis of several aspects of the mutual interaction of the neutron population in, and the (time-dependent) physical properties of the reactor core, such as its material composition and temperature and density distribution. NRG's staff has considerable experience in the use and also in the development of advanced methods, software tools and nuclear data libraries for the analysis of these complex phenomena. NRG's activities in the reactor physics field are mainly focussed on:
Core physics
This part of the reactor physics field is concerned with the behaviour of nuclear reactors under stationary and quasi-stationary conditions. The combined 3-D neutronic and thermal hydraulic behaviour is analysed of mainly PWR and HTR [REF-LINK?] cores during the operating cycle. This includes the modelling of the fuel management schemes and fuel (re-) loading patterns. For PWR's this analysis is mainly performed using the commercially available WIMS and PANTHER codes. Also NRG has developed a dedicated software tool, ROSA , for fast and efficient reloading pattern optimisation and core design of light water reactors.
For (pebble bed) HTR applications NRG has extended the capabilities of the PANTHER code by establishing a connection to an external HTR thermal hydraulics module, THERMIX-DIREKT, and by introducing the possibility to model the continuous reloading of, and the in-core flow pattern of fuel pebbles. These activities have resulted in the PANTHERMIX code system. Examples of NRG's specific research and development activities and applications:
- "Plutonium burning in a pebble-bed type nuclear reactor" (Ph.D thesis by E. Bende)
- Core physics and fuel cycle analysis of the South African Pebble Bed Modular Reactor (PBMR)
- Core physics and fuel cycle analysis of a continuous reload pebble bed HTR loaded with pure plutonium fuel, as part of the activities in the European Union 5th Framework Program project "HTR-N"
- Core physics, fuel cycle and also transient analysis of ACACIA, a small "cartridge core" pebble bed reactor
- Core physics and fuel cycle analysis of a Westinghouse 3-loop PWR, loaded with Th-Pu MOX, as part of the activities in the European Union 5th Framework Program project "THORIUM CYCLE"
- Development of a method, ELNINJO, for the production of microscopic and macroscopic group cross sections on the basis of reaction rates calculated by MCNP. This method has also been employed in the generation of point kinetic parameters for transient analysis of the High Flux Reactor (HFR)
- Development of an improved point kinetics method, "Point Genetics", for the description of the time dependent behaviour of Accelerator-Driven Systems (ADS).
Detailed inventory analysis
For detailed (1/2/3-D) inventory analyses NRG is developing the OCTOPUS system, which links a 1/2/3-D steady-state neutronics code, such as MCNP or WIMS, to a point depletion (or burn-up) code, ORIGEN-S or FISPACT, which keeps track of the evolution of the nuclide mixture in the irradiated material, associated with neutron-induced nuclear reactions, such as capture and fission, and decay.
The available tools are also used for the analysis and assessment of advanced (transmutation) systems loaded with advanced and non-conventional fuels, as well as for the analysis and design calculations of irradiation experiments and facilities at the Petten site.
Examples of NRG's specific research and development activities and applications:
- "Plutonium burning in a pebble-bed type nuclear reactor" (Ph.D thesis by E. Bende)
- Development of a method, CSS1SMAT/MAMAMEA [LINK?], for propagation of uncertainties and covariances in basic cross section data through a chain of neutron spectrum and burn-up calculations. This results in an error estimation (covariance matrix) for the nuclide densities at the end of the chain
- Detailed inventory analyses as part of the design of HFR irradiation experiments
Space-time kinetics and dynamics
The consequences of rapid changes in the core configuration and/or composition are the subject of this part of the reactor physics field. This includes the investigation of the effects of rapid changes in reactivity, e.g. caused by the ejection of a control rod in a PWR, in the framework of safety analyses. For the 3-D analysis of these fast transients at NRG the same tools are in use as for core physics, viz. WIMS and PANTHER/PANTHERMIX for PWR and HTR applications, respectively. This enables consistent modelling, especially in the analysis of transients starting at specified points in the operating cycle of the reactor.
Examples of NRG's specific research and development activities and applications:
- Participation in the OECD/NEA Nuclear Science Committee "3-D PWR Core Transient Benchmark: Uncontrolled Withdrawal of Control Rods at Zero Power".
- "Dynamics of the pebble-bed nuclear reactor in the direct Brayton cycle" (Ph.D thesis by E.C. Verkerk).
Criticality evaluation:
Especially in the field of criticality analyses the validation
of the calculational procedure is essential. NRG uses 3D Monte
Carlo methods for advanced criticality analyses. An extensive set
of criticality benchmarks forms the basis for the validation. It
covers a broad range of enrichments and fuel types. High-quality
nuclear data libraries are used, which leads to small discrepancies between
measured and calculated data.
Examples of NRG's specific research and development activities and applications:
- High-density spent fuel storage racks
- Waste storage from nuclear facilities
- The conversion from high-enriched uranium to low-enriched uranium fuel of the Petten High Flux Reactor.
Contact
Dr. Ronald P.C. Schram NRG - Life Cycle innovations & Isotopes (NRG-LCI) PO Box 25, 1755 ZG Petten, the Netherlands phone: +31 224 564362 , fax: +31 224 568608 e-mail: fai@nrg.eu