Neutron absorption profile in a reactor moderated by different mixtures of light and heavy waters

Nagy, Mohamed S.; Aly, M. Naguib; Gaber, Fatma A.; Dorrah, Mahmoud E.

doi:10.1016/j.anucene.2014.06.005

Cited by 4 publications

(5 citation statements)

References 5 publications

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“…The spectral shift reactor control is involved in the neutron spectrum hardening at BOL; therefore, the excess neutrons are absorbed in the fertile isotopes rather than in burnable absorbers materials, then the neutron spectrum is shifted back to the thermal region at the EOL 13,14 . The neutron spectrum shift can be achieved mechanically by changing the moderator‐to‐fuel ratio 15,16 or by using a moderator of light‐heavy water mixture 17,18 …”

Section: Introductionmentioning

confidence: 99%

“…13,14 The neutron spectrum shift can be achieved mechanically by changing the moderator-to-fuel ratio 15,16 or by using a moderator of light-heavy water mixture. 17,18 The present study represents a new approach to use natural thorium in reactor reactivity regulation. In previous studies, the feasibility of thorium-based fuel has been investigated in different reactor types.…”

Section: Introductionmentioning

confidence: 99%

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Investigation of a new approach for regulating the reactivity and achieving economic feasibility using thorium in a blanket‐seed assembly of pressurized water reactors

Elazaka

Тихомиров

Savander

et al. 2021

Intl J of Energy Research

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Summary The traditional methods for controlling reactor excess reactivity are expensive and have defects during reactor operation. By altering the fuel structure and fissile material distribution, this work presents a new technique for managing excess reactivity at the start of the fuel life. MCNPX code edition 2.7 was used to investigate the neutronic characteristics of the suggested blanket‐seed assembly models and compare them with the reference PWR fuel assembly. Instead of U‐238, Th‐232 was suggested as a fertile nuclide. The impact of the proposed models on the infinite multiplication factor, fuel component concentrations, reactor‐grade plutonium, minor actinides, radial flux of thermal neutrons, and the radial distribution of power has been analyzed. The safety parameters, including the control rods worth, Doppler effect, moderator temperature reactivity coefficients, and the effective delayed neutron fraction, have been studied to reach the most optimum fuel structure.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Investigation of a new approach for regulating the reactivity and achieving economic feasibility using thorium in a blanket‐seed assembly of pressurized water reactors

Elazaka

Тихомиров

Savander

et al. 2021

Intl J of Energy Research

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“…To date, a limited number of studies (Tochihara et al, 1998, Engelder, 1961 have been conducted for "mixed coolant" (H 2 O+D 2 O), although it has never been practically employed (Nagy et al, 2014). Also, the 2003 MIT studies (Xu, 2003, Xu andDriscoll, 1997) observed the achievable burnup and initial reactivity behavior of PWR lattice over hydrogen-to-heavymetal ratio (H/HM) for the H 2 O coolant.…”

Section: Introductionmentioning

confidence: 99%

“…Also, the 2003 MIT studies (Xu, 2003, Xu andDriscoll, 1997) observed the achievable burnup and initial reactivity behavior of PWR lattice over hydrogen-to-heavymetal ratio (H/HM) for the H 2 O coolant. However, these studies (Tochihara et al, 1998, Nagy et al, 2014, Xu, 2003, Xu and Driscoll, 1997, Engelder, 1961 are limited to lower fissile enrichment (5%) and soluble boron system. Furthermore, for SBF SMR cores, there have not been many studies conducted to understand the reactor physics behavior of the mixed coolant (D 2 O+H 2 O) (Alam, 2018, Otto, 2013, Ippolito, 1990.…”

Section: Introductionmentioning

confidence: 99%

Neutronic feasibility of civil marine small modular reactor core using mixed D2O+H2O coolant

Alam

Almutairi

Kumar

et al. 2020

Nuclear Engineering and Design

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In an effort to decarbonize the marine sector, there are growing interests in replacing the contemporary, traditional propulsion systems with nuclear propulsion systems. The latter system allows freight ships to have longer intervals before refueling; subsequently, lower fuel costs, and minimal carbon emissions. Nonetheless, nuclear propulsion systems have remained largely confined to military vessels. It is highly desirable that a civil marine core not to use highly enriched uranium, but it is then a challenge to achieve long core lifetime while maintaining reactivity control and acceptable power distributions in the core. The objective of this study is to design a civil marine core type of single batch small modular reactor (SMR) with low enriched uranium (LEU) (<20% 235 U enrichment), a soluble-boron-free (SBF) and using mixed D 2 O+H 2 O coolant for operation period over a 20 years life at 333 MWth. Changing the coolant properties is the way to alter the neutron energy spectrum in order to achieve a self-sustaining core design of higher burnup. Two types of LEU fuels were used in this study: micro-heterogeneous ThO 2 -UO 2 duplex fuel (18% 235 U enriched) and all-UO 2 fuel (15% 235 U enriched). 2D Assembly designs are developed using WIMS and 3D whole-core model is developed using PANTHER code. The duplex option shows greater promise in the final burnable poison design with high thickness ZrB 2 integral fuel burnable absorber (IFBA) while maintaining low, stable reactivity with minimal burnup penalty. For the final poison design with ZrB 2 , the duplex contributes ∼2.5% more initial

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“…We have considered two types of coolant: H 2 O and a mixture of 80% D 2 O + 20% H 2 O. To date, mixing light and heavy D 2 O waters as a "mixed coolant" isn't practically employed (Nagy et al, 2014), although some proposed reactor designs, such as Spectral Shift Control Reactor (SSCR) (Engelder, 1961) and the Mixed Moderator PWR (MPWR) (Tochihara et al, 1998) considered this technique. In addition, for the H 2 O coolant, important contributions are made by an MIT study (Xu, 2003), where optimization of the PWR lattice is performed for a range of H/HM.…”

Section: Introductionmentioning

confidence: 99%

Parametric neutronics analyses of lattice geometry and coolant candidates for a soluble-boron-free civil marine SMR core using micro-heterogeneous duplex fuel

Alam

Goodwin²,

Parks

2019

Annals of Nuclear Energy

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Civilian marine reactors face a unique set of design challenges in addition to the usual irradiation and thermal-hydraulic limits affecting all reactors. These include requirements for a small core size, long core lifetime, a 20% cap on fissile loading, and limitations on the use of soluble boron. One way to achieve higher burnup/longer core life is to alter the neutron spectrum by changing the hydrogen-to-heavy-metal ratio, thus increasing the conversion of fertile isotopes in the fuel. In this reactor physics study, we optimize the two-dimensional lattice geometry of a 333 MWth soluble-boron-free marine PWR for 18% 235 U enriched micro-heterogeneous ThO 2 -UO 2 duplex fuel and 15% 235 U enriched homogeneously mixed all-UO 2 fuel. We consider two types of coolant: H 2 O and mixed 80% D 2 O + 20% H 2 O. We aim to observe in which spectrum discharge burnup is maximized in order to improve uranium utilization, while satisfying the constraint on moderator temperature coefficient. It is observed that higher discharge burnup for the candidate fuels is achievable by using either a wetter lattice or a much drier lattice than normal, while epithermal lattices are distinctly inferior performers. The thorium-rich duplex fuel exhibits higher discharge burnup potential than the all-UO 2 fuel for all moderation regimes for both coolants. The candidate fuels exhibit higher initial reactivity and discharge burnup with the mixed D 2 O-H 2 O coolant than with the H 2 O coolant in the under-moderated regime, whereas these values are lower for the D 2 O-H 2 O coolant in the over-moderated regime.

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Neutron absorption profile in a reactor moderated by different mixtures of light and heavy waters

Cited by 4 publications

References 5 publications

Investigation of a new approach for regulating the reactivity and achieving economic feasibility using thorium in a blanket‐seed assembly of pressurized water reactors

Investigation of a new approach for regulating the reactivity and achieving economic feasibility using thorium in a blanket‐seed assembly of pressurized water reactors

Neutronic feasibility of civil marine small modular reactor core using mixed D2O+H2O coolant

Parametric neutronics analyses of lattice geometry and coolant candidates for a soluble-boron-free civil marine SMR core using micro-heterogeneous duplex fuel

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