Transient Analysis of Sulfur-Iodine Cycle Experiments and Very High Temperature Reactor Simulations Using MELCOR-H2

Rodriguez, Sal; Gauntt, Randall O.; Cole, R. K.; Gelbard, Fred; McFadden, Katherine; Tom, Drennen,; Martin, Billy; Louie, David; Archuleta, Louis; El‐Genk, Mohamed S.; Tournier, Jean‐Michel; Espinoza, Flor A.; Revankar, Shripad T.; Vierow, Karen

doi:10.13182/nt09-a6970

Cited by 9 publications

(7 citation statements)

References 4 publications

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“…Both cores consist of an annular fuel region that is surrounded and moderated by graphite and cooled by downward-flowing helium. A schematic of a typical plant layout for the cogeneration of electricity and hydrogen using a thermo-chemical sulfur-iodine (SI) process is shown in Figure 10, which includes the nuclear reactor and the primary helium loop, a secondary loop for the production of electricity, and for providing thermal energy for the production of hydrogen [Rodriguez et al, 2009].…”

Section: Swirling Jets For Mitigation Of Hot Spots and Thermal Stratifimentioning

confidence: 99%

“…Consequently, this research will hereafter focus solely on the prismatic core VHTR. The prismatic core design is based on research from the General Atomics gas turbine modular helium reactor (GT-MHR) [McEligot and McCreery, 2004;Rodriguez et al, 2009;INL, 2009]. About 2/3 of the graphite blocks function as the inner and outer reflectors, while the rest form the annular fuel core ( Figure 11) [MacDonald et al, 2003].…”

Section: Swirling Jets For Mitigation Of Hot Spots and Thermal Stratifimentioning

confidence: 99%

“…Vortex research in Cartesian coordinates includes the Green-Taylor vortex [Taylor and Green, 1937] and the helicoid vortex developed in Section 5.1.1 [Rodriguez andEl-Genk, 2008a, 2010d]. Various researchers selected spherical coordinates [Tsukker, 1955;Gol'Dshtik and Yavorskii, 1986;Hwang and Chwang, 1992], but the vast majority of the research found in the literature is in cylindrical coordinates [Rankine, 1858;Lamb-Oseen, 1932;Burgers, 1948;Loitsyanskiy, 1953;Gortler, 1954;Newman, 1959;Sullivan, 1959;Batchelor, 1964;Squire, 1965;Chepura, 1969;Martynenko, 1989;Aboelkassem, Vatistas, and Esmail, 2005;Rodriguez andEl-Genk, 2008a, 2010d]. Cylindrical coordinates are chosen primarily due to its geometric simplicity and excellent mapping of the vortex behavior onto a coordinate system-in particular, as a 3D vortex spins azimuthally as it stretches about the z axis, the vortex velocity field shape fills up a cylindrical geometry.…”

Section: Vortex Modelingmentioning

confidence: 99%

“…An inspection of the literature over the past 150 years shows that the above equations are generally the departure point for generating analytic solutions for axisymmetric swirling flows (vortices) [Rankine, 1858;Lamb-Oseen, 1932;Burgers, 1948;Loitsyanskiy, 1953;Gortler, 1954;Newman, 1959;Sullivan, 1959;Batchelor, 1964;Squire, 1965;Chepura, 1969;Martynenko, 1989;Aboelkassem, Vatistas, and Esmail, 2005;Rodriguez andEl-Genk, 2008a, 2010d].…”

Section: Vortex Modelingmentioning

confidence: 99%

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Swirling jets for the mitigation of hot spots and thermal stratification in the VHTR lower plenum.

Rodríguez¹

2011

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The literature indicates that a prismatic-core very high temperature reactor can experience thermal stratification and hot spot issues in the lower plenum (LP). This research hypothesizes that the complex thermalhydraulic phenomena in the LP requires a sophisticated computational fluid dynamics (CFD) code with state-of-the-art turbulence models and advanced swirling jet technology to mitigate the two issues. The primary research goals were to increase the heat transfer and mixing capacity of swirling jets, extend swirling jet theory, and to apply those advancements for the mitigation of the thermalhydraulic issues. First, it was demonstrated that the Fuego CFD code successfully modeled a set of key LP thermalhydraulic phenomena. Thereafter, a helicoid vortex swirl model was developed to investigate the impact of the swirl number (S) on mixing and heat transfer. The development of azimuthal and axial velocities that are solely functions of S permitted the analysis of the central recirculation zone's (CRZ) impact on the LP flow field. At this point, several characteristics were found in common between the helicoid vortex and other axisymmetric, Newtonian, incompressible vortices found in the literature. This observation resulted in a more fundamental understanding of how vortices behave, and which traits can be exploited for the purpose of maximizing heat transfer and mixing. Because the CRZ is a strong function of the azimuthal and axial velocities, shaping those velocity profiles had a substantial impact. Eventually, this led to the discovery that vortices may be expressed as alternating series that expand geometrically with odd exponents. This helped corroborate that the 15 axisymmetric vortices discussed in this research are part of a vortex family with seven common traits. This also led to the development of new vortices that are based on one or two series terms that satisfy the Navier-Stokes equations and conservation of mass. In addition, the impact of Reynolds number and swirl decay were explored in order to further quantify their impact. Finally, the above theories and modeling insights were applied towards a comprehensive set of LP calculations that showed that the swirling jets mitigated the entrainment and hot spot issues, while resulting in a reasonable pressure drop. Contents

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Section: Swirling Jets For Mitigation Of Hot Spots and Thermal Stratifimentioning

confidence: 99%

Section: Swirling Jets For Mitigation Of Hot Spots and Thermal Stratifimentioning

confidence: 99%

Section: Vortex Modelingmentioning

confidence: 99%

Section: Vortex Modelingmentioning

confidence: 99%

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Swirling jets for the mitigation of hot spots and thermal stratification in the VHTR lower plenum.

Rodríguez¹

2011

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“…In order to assess the effects of certain operation transients on the neutronics, thermal hydraulics parameters, and the performance of a nuclear reactor, it is desirable to demonstrate robust capabilities for simulating these transients and performing complex safety analyses. This would require solving the six-group point kinetics equations, with the applicable reactivity feedback effects, as a function of space and time and integrating the solution in a system analyses code such as MELCO-H2 (Rodriguez et al, 2007(Rodriguez et al, , 2009 and RELAP5-3D (RELAP5-3D © Code Development Team 2012). Such an approach is quite complex and would require huge computational capabilities.…”

Section: Introductionmentioning

confidence: 99%

A point kinetics model for dynamic simulations of next generation nuclear reactor

El‐Genk

Tournier

2016

Progress in Nuclear Energy

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An accurate, fast-running and stable six-group, point kinetics (PK) model is developed and applied successfully to the dynamic simulation of operation of the prismatic core, high temperature next generation nuclear plant (NGNP) reactor. The model is unrestricted by the size of the time step, which could be as much as several seconds, accounts for Doppler Broadening and the fuel and graphite temperature reactivity feedbacks, and includes an active neutron source for zero-power reactor startup. An efficient and robust numerical technique that approximates the exponential matrix using 7 th orderaccurate Padé(3,3) function with a discretization error on the order of (t) 3 , solves the coupled nonlinear and stiff six-groups point kinetics equations. The PK model handles reactivity insertions in excess of a prompt critical,   / > $1.0, with unrestrictive time step size. Model results are successfully benchmarked using the Inhour solution for a step insertion of external reactivity. To simulate the transient response of the NGNP reactor following an external reactivity insertion and during a reactor startup, the PK model is coupled to 84-nodes thermal-hydraulics model of the reactor, also developed in this work. With a two seconds time step, the error of predicting the reactor thermal power is ~0.001%, increasing exponentially to ~ 0.08% and ~1.5% with increased time step size to 5 and 8 seconds, respectively. The present PK model has been successfully incorporated into MELCOR-H2 nuclear reactor analysis code to simulate transient operation of Very High Temperature Reactor (VHTR) for electricity generation, using a Closed Brayton Cycle turbomachinery, and the cogeneration of hydrogen using Sulfur Iodine (SI) thermochemical processes.

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Designs and CFD analyses of H2SO4 and HI thermal decomposers for a semi-pilot scale SI hydrogen production test facility

Shin

Lim²,

Lee

et al. 2017

Applied Energy

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Transient Analysis of Sulfur-Iodine Cycle Experiments and Very High Temperature Reactor Simulations Using MELCOR-H2

Cited by 9 publications

References 4 publications

Swirling jets for the mitigation of hot spots and thermal stratification in the VHTR lower plenum.

Swirling jets for the mitigation of hot spots and thermal stratification in the VHTR lower plenum.

A point kinetics model for dynamic simulations of next generation nuclear reactor

Designs and CFD analyses of H2SO4 and HI thermal decomposers for a semi-pilot scale SI hydrogen production test facility

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