The Effect of Irradiation Induced Structural Material Deformations on Core Restraint Design

Kalinowski, J.E.

doi:10.1115/1.3227364

Cited by 2 publications

(6 citation statements)

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“…This bending deformation is called bowing [4]. LMFBR core environments are subjected to a large temperature rise from the core inlet to the core outlet, with the increase in temperature and temperature gradient occurring primarily in the fuel region [5]. Figure 1 depicts axial thermal gradients on two walls of a ducted assembly.…”

Section: Grid Plate Expansion and Bowing Due To Thermal Gradientsmentioning

confidence: 99%

“…However, neutron irradiation exposure can influence steel materials to creep under much lower temperatures. Irradiation creep is the gradual deformation due to the sustained loading induced by contact restraints on deformation in a nuclear reactor [5]. Irradiation swelling and creep are unique temperature and flux dependent material properties which depend on the molecular structure of a specific material and require experimental testing to develop material correlations for prediction.…”

Section: Irradiation Creep and Swellingmentioning

confidence: 99%

“…Control core assembly bowing and ensure predictable and safe reactivity response during steady state and transient events [9], [12], [13] b. Provide large enough gaps at the load pads to ensure net negative reactivity feedback during transients [5], [14] c. Limit maximum step reactivity insertion to stay within fuel damage limits [14] 2. Control Rod Movement a.…”

Section: Objectives Of the Core Restraint Systemmentioning

confidence: 99%

“…Limit bowing to prevent excessive contact of assembly ducts to allow refueling [14] b. Limit the magnitude of the forces required to remove and insert core assemblies during refueling below the design limits of the core assemblies or the refueling equipment [5], [9], [12]- [14] 4. Irradiation Effects a.…”

Section: Objectives Of the Core Restraint Systemmentioning

confidence: 99%

“…Provide gaps between ducts large enough to accommodate duct dilation (overall diameter change due to thermal expansion, internal pressure, swelling, creep, etc.) [5] 5. Structural Limits a.…”

Section: Objectives Of the Core Restraint Systemmentioning

confidence: 99%

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Review of Tools for Modeling Core Radial Expansion in Liquid Metal-Cooled Fast Reactors

Wozniak¹,

Shemon²,

Grudziński³

2020

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Core radial expansion in liquid-metal cooled fast reactor systems is a well-known phenomenon that produces strong reactivity feedback effects. It is crucial from a safety standpoint to design a reactor with the proper core restraint system to guide expansion of the fuel assemblies into a formation that produces negative reactivity feedback in accident conditions. However, the modeling of core radial expansion and its associated reactivity feedback is extremely challenging. Liquid metal-cooled fast reactor designers (both industry and commercial) have pointed to improved modeling of core radial expansion as a key modeling challenge for these types of reactors. The Department of Energy Nuclear Energy Advanced Modeling and Simulation (DOE-NEAMS) program has an important role to play in helping to develop a robust, predictive tool for this phenomenon. A literature review has been performed to identify current simulation capabilities applicable to the prediction of core radial expansion in liquid metal-cooled fast reactors and the resultant reactivity feedback effects. An overview as well as a detailed description of the multi-physics phenomena underlying core radial expansion is given in the first two chapters. The objective of this report is to identify existing software that has been or could be applied to the core radial expansion problem, and then to identify possible paths to develop a robust, coupled multiphysics tool for advanced analysis, in which all three physics (radiation transport, structural mechanics, thermal fluids) are taken into account considering feedback effects from each physics to the other. Several computer codes and workflows have been developed in the United States and abroad to perform individual aspects of radial expansion calculations or to perform loosely coupled analysis. No code system currently exists which tightly and robustly couples the neutronics, thermal hydraulics, and thermal mechanical physics with enough detail to fully resolve the complex core radial expansion reactivity feedback effects. The future availability of such a code system is of vital importance to fully understanding the reactivity feedback effects that occur due to radial expansion, and consequently to optimizing the design of the core restraint system. A potential code development path forward using MOOSE-based tools is suggested in order to leverage the natural tight coupling and robustness of MOOSE-based applications. Additionally, potential gaps for modeling and common assumptions are listed which require further investigation to ensure accuracy for prediction of deformations.

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Section: Grid Plate Expansion and Bowing Due To Thermal Gradientsmentioning

confidence: 99%

Section: Irradiation Creep and Swellingmentioning

confidence: 99%