Coupling of an innovative small PWR and advanced sodium-cooled fast reactor for incineration of TRU from once-through PWRs

Abstract

Summary In the nuclear industry, safely managing spent fuels discharged from PWRs (pressurized water reactors) is an ongoing challenge. In this paper, a synergistic coupling of innovative small long‐cycle PWRs and advanced sodium‐cooled fast reactors is considered to reduce the accumulated TRUs (transuranics) by transmuting them with electricity production. In the coupling strategy, the innovative small PWRs employing UO2–ThO2 and fully ceramic micro‐encapsulated fuels are used to deeply burn TRUs from commercial PWRs, while advanced SFRs (sodium‐cooled fast reactors) with actinide recycling are designed to further transmute the TRUs discharged from innovative small PWRs. This work focuses on the core physics analysis of new SFR burner cores using different TRU feeds discharged from small PWRs. Additionally, quasi‐static reactivity balance analyses are performed to understand the safety of the SFR burner cores. The mass flows of TRUs in the nuclear park, which is composed of PWRs, small long‐cycle PWRs, and SFR burners, are analyzed to evaluate TRU inventory reduction. The results of this study show that the advanced SFR burners with all the TRU feed types discharged from the small long‐cycle PWRs have a high TRU consumption rate. They satisfy all of the conditions for self‐controllability under unprotected accidents with a reasonable number of control rods. This coupling strategy requires ~35% less power in conjunction with the advanced SFR burners in the nuclear park and increases the support ratio of SFR burners by ~42% than does the coupling of commercial PWRs and SFR burners. Copyright © 2015 John Wiley & Sons, Ltd.

Core design options of an ultra-long-cycle sodium cooled reactor with effective use of PWR spent fuel for sustainable energy supply

“…Also, Table summarizes the results of the quasi‐static reactivity balance analysis , performed to check the self‐controllability under unprotected transients (i.e., Unprotected Loss‐of‐Flow (ULOF), Unprotected Loss‐of‐Heat‐Sink (ULOHS), and Unprotected Transient Over‐Power (UTOP)), under which the control rods cannot be inserted to shut down the core. Self‐controllability means that the reactor leads to a passive safe shutdown state only through the reactivity feedback effects without exceeding the limits for ensuring core integrity.…”

“…The reason why this decomposition analysis is given only at EOC is because it is interesting to quantitatively show the effects of the leakage increase that resulted from the shift in axial power distribution toward the upper sodium plenum at EOC. In the decomposition methodology of sodium void reactivity worth, the reactivity change induced by sodium voiding is decomposed into the leakage, capture, fission, and (n,2n) reaction components, and their contributions are estimated by directly evaluating the normalized fractions of these reaction and leakage rates to the unity fission production rate of the normal (not voided) and voided states . The detailed method is well described in our previous papers and is thus not repeated here.…”

“…In the decomposition methodology of sodium void reactivity worth, the reactivity change induced by sodium voiding is decomposed into the leakage, capture, fission, and (n,2n) reaction components, and their contributions are estimated by directly evaluating the normalized fractions of these reaction and leakage rates to the unity fission production rate of the normal (not voided) and voided states . The detailed method is well described in our previous papers and is thus not repeated here. The results of the decompositions of the sodium void reactivity worth for the reference and Option IV cores are compared in Table .…”

“…In this work, Transuranics (TRU) and uranium extracted via reprocessing from the PWR spent fuel are considered to be effectively utilized and coupled with thorium in the ultra‐long‐cycle core, which has been newly designed using the axial blanket‐driver‐blanket (ABDB) burning strategy to be operated over 40 − 50 EFPYs without refueling . Thus, this reactor can act as an effective long‐term intermediate storage of the PWR spent fuels with sustainable electricity production over an ultra‐long operational cycle.…”

An Advanced Sodium-Cooled Fast Reactor Core Concept Using Uranium-Free Metallic Fuels for Maximizing TRU Burning Rate

“…The moderator rods are introduced to improve the Doppler effect and to reduce sodium void reactivity by softening the core neutron spectrum. In addition, detailed decomposition analysis of coolant void reactivity based on neutron balance with normalization to the production rate was performed to better understand the effect of coolant voiding on reactivity [13,14,21] and the quasi-static reactivity balance analyses were performed to evaluate the inherent safety features of the cores [4,16,22,23]. Finally, we analyzed the performances for the fuel cycle that is comprised of SFR burners and PWRs to show the mass flows for the actinides and the characteristics of the wastes going to the repository [24].…”