Nuclear Data Assimilation; Sensitivity/Uncertainty Analysis; Molten Salt Reactor; PROTEUS Experiments
Siefman D., Hursin M., Aufiero M., Bidaud A., Pautz A. (2020), On data assimilation with Monte-Carlo-calculated and statistically uncertain sensitivity coefficients, in Annals of Nuclear Energy
, 135, 106951-106951.
Siefman Daniel, Hursin Mathieu, Pautz Andreas (2019), Data Assimilation with Post Irradiation Examination Experiments, in Nuclear Data 2019
, Beijing, ChinaResearchGate, Beijing.
Siefman D., Hursin M., Rochman D., Pelloni S., Pautz A. (2018), Stochastic vs. sensitivity-based integral parameter and nuclear data adjustments, in The European Physical Journal Plus
, 133(10), 429-429.
Hursin Mathieu, Siefman Daniel, Perret Gregory, Pautz Andreas (2018), REPRESENTATIVITY ANALYSIS OF THE LWR-PROTEUS PHASE II EXPERIMENTS USING SHARKX STOCHASTIC SAMPLING METHOD, in ANS Best Estimate Plus Uncertainty International Conference (BEPU 2018)
, Lucca, ItalyResearchGate, Lucca, Italy.
Siefman Daniel, Hursin Mathieu, Aufiero Manuele, Bidaud Adrien, Pautz Andreas (2018), Convergence Analysis and Criterion for Data Assimilation with Sensitivities from Monte Carlo Neutron Transport Codes, in PHYSOR 2018: Reactors Physics paving the way towards more efficient systems
, Cancun, MexicoResearchGate, Cancun, Mexico.
Hursin Mathieu, Siefman Daniel, Perret Gregory, Rochman D, Vasiliev Alexander, Ferroukhi H (2018), DETERMINATION OF SOBOL SENSITIVITY INDICES FOR CORRELATED INPUTS WITH SHARK-X, in PHYSOR 2018: Reactors Physics paving the way towards more efficient systems
, Cancun, MexicoResearchGate, Cancun, Mexico.
Grimm Peter, Hursin Mathieu, Perret Gregory, Siefman Daniel, Ferroukhi Hakim (2017), Analysis of reactivity worths of burnt PWR fuel samples measured in LWR-PROTEUS Phase II using a CASMO-5 reflected-assembly model, in Progress in Nuclear Energy
, 101, 280-287.
Siefman Daniel, Hursin Mathieu, Grimm Peter, Pautz Andreas (2017), Case Study of Data Assimilation Methods with the LWR-Proteus Phase II Experimental Campaign, in M&C 2017 - International Conference on Mathematics & Computational Methods Applied to Nuclear Scienc
, Jeju, KoreaResearchGate, Jeju, Korea.
The validation of computer codes for reactor physics design and safety assessment is based primarily on “cold” critical experiments, supplemented by measurements from operating power plants. Extending the validity range of these codes towards new power reactor applications, where little or no operating experience exists, is one of the most challenging tasks in reactor physics today. The central question is: can we reliably project computational biases from our experimental data to an “application” case (e.g. a new power plant design), even if the database contains primarily experiments that are not necessarily “similar” to this target application? Moreover, is it possible to quantify the uncertainties of these biases (that are arising from errors/uncertainties both in experiments and in the nuclear data), particularly when it comes to important safety parameters of challenging plant designs?We propose an approach that tackles these questions from several directions, namely a) the improvement of the experimental database with high-fidelity measurements performed at the Swiss research facility PROTEUS ; b) the development of advanced tools for Sensitivity/Uncertainty (S/U) analysis, combined with nuclear data assimilation methods for bias projection, and c) the demonstration of the methodology on a demanding application case, i.e. a Molten Salt Reactor (MSR) start-up fuel study. The work shall be performed by two PhD students and a Postdoctoral researcher at EPFL, in close cooperation with experienced staff members at Paul-Scherrer-Institute (PSI). The experimental data mentioned in step a) were generated in more than 40 years of PROTEUS operation and represent a huge asset that yet awaits its full exploitation. It must be noticed, however, that due to the recent shutdown of PROTEUS the possibility for future critical experiments in Switzerland has essentially ceased to exist, which goes hand in hand with a gradual loss of know-how. This makes the preservation and utilization of the existing PROTEUS data an even more pressing issue. In this project, we will merge these data with those available from other resources (e.g. from IRPhEP, the OECD’s International Reactor Physics Benchmark Experiments Project [ ]) and build a consolidated and unique database, readily accessible for data assimilation tools.In step b), we will take full benefit of the joint EPFL/PSI activities at the Laboratory for Reactor Physics and System Behavior (LRS) and integrate the PhD students into the ongoing development work on the nuclear uncertainty/sensitivity analysis tool SHARKX [ ]. We will extend this software by a module for data assimilation/adjustment, based on a Generalized-Least-Square-Method (GLSM) and integrate sensitivity analysis based on Monte Carlo codes, recently implemented in SERPENT2 and MCNP6. This will lift the current restriction of SHARKX to Light Water Reactors (LWR), and provide an appropriate platform for modeling various PROTEUS configurations, as well as innovative reactor core designs. In step c), the extended S/U-tool suite together with the improved experimental database will serve as a platform for the assessment of biases and uncertainties of an advanced reactor application: the Molten Salt Reactor (MSR). For the MSR, an uncertainty study of the start-up fuel composition in the Thorium-Uranium cycle is foreseen. One of the options, how to launch the Thorium-Uranium cycle, is utilization of the TRansUranic elements (TRUs), in particular Plutonium from spent Light Water Reactor (LWR) fuel. Since the solubility of Plutonium in the foreseen MSR carrier salt is limited, a feasibility of this option may strongly depend on the fuel composition. Since Thorium experimental data are scarce and nuclear cross sections of the key isotope Th-232 are not very well known, bias projection and understanding the major sources of uncertainties are of paramount importance for the MSR fuel cycle start-up; we expect that the unique PROTEUS data measured for Th-232 in Plutonium-fuelled environment will be of high relevance for the reduction of computational biases. The authors of this proposal are well aware of the fact that the thermal hydraulic conditions in the application system have the potential to influence the bias prediction, in particular if local parameters are addressed. However, detailed thermal-hydraulic calculations on the target systems are not within the scope of this proposal: while a “holistic” approach that addresses all sources of bias is clearly most desirable, this would require a significantly larger amount of resources for the application target modeling than is being requested here. However, we propose to perform studies on simplified models (e.g. simplified yet representative geometries of the reactor application under consideration, with varying thermal-hydraulic conditions), and perform parametric studies with SHARKX to assess the impact of temperature and density variations on bias prediction. In addition, another research proposal was launched by the principal investigator’s laboratory at PSI and recently approved by the SNF (application number 200021_152612/1: “Small modular Molten Salt Fast Reactor design for closed fuel cycle”); in this framework, more in-depth studies will be performed on the thermal-hydraulic modeling aspects of Molten Salt Reactors, that will eventually be merged with the efforts proposed in the research plan at hand.