Void reactivity aspect and fuel conversion potential of heavy water cooled thorium reactor

Abstract

Summary Design study on heavy water cooled thorium breeding reactor has been investigated by adopting a nuclear equilibrium state model. Conversion ratio, as an important index, has been evaluated to estimate the breeding capability of the reactors. Void reactivity coefficient has also been investigated to evaluate performance index of safety aspect, which is based on the criticality performance of the reactors during voided condition. In addition, moderator‐to‐fuel ratio has also been employed to analyze its effect to the required enrichment, conversion ratio, and void reactivity coefficient as well as different burnups and fuel pin diameter effects. Void reactivity coefficient indicates a criticality condition of the reactor when some coolants are lost. If the negative value of void reactivity is achieved, it means that the reactor has less reactivity condition as well as less power production when lost of coolant occurred. Higher fuel conversion capability, that more nuclear fuel are produced, those additional fuel productions can be used for next operation or for other reactors. The results show that higher fuel conversion ratio can be achieved for less moderator‐to‐fuel ratio because of the harder neutron spectrum effect, while it requires more fissile content of 233U to maintain the reactor operation from fission reaction. Higher burnup gives less conversion ratio because some fissile materials are used to maintain longer reactor operation, and at the same time, it requires more initial required fissile 233U for higher burnup. In addition, it requires less fissile 233U for thicker fuel pin diameter, while its conversion ratio becomes higher, and void reactivity coefficient is more negative for thicker fuel pin diameter. The results also show that thorium utilization on heavy water cooled reactor gives all negative void reactivity values, which means that the system has a safety condition in terms of void reactivity condition. At the same time, it shows some feasible conditions for obtaining fuel breeding to increase the sustainability of nuclear fuel. Copyright © 2016 John Wiley & Sons, Ltd.

Study the neutronic feasibility of using Zr as an energy regulator instead of traditional methods

“…Consequently, it is important to investigate the void volume reactivity coefficient at different fuel pitches. The void reactivity coefficient must be investigated to evaluate the criticality performance of the reactor during voided condition 34 . The void reactivity coefficient is the change in reactivity due to the change of the void fraction.…”

Comparison of neutronic aspects in high‐temperature gas‐cooled reactor using ZrC and SiC Triso particle with 50 and 100 MWt power

“…In comparing to the performance of uranium fuel, performance of thorium fuel has some advantages such as higher fuel conversion capabilities due to the superiorities of fissile material of 233 U in comparing to other fissile material especially in thermal and epithermal spectra. In addition, thorium fuel also give better negative void reactivity and performance of burn‐up as well as in term of nuclear non‐proliferation concern and it can be used for symbiotic water cooled reactor and fast breeder reactor based on thorium based fuel utilization 23–28 . Another consideration of using thorium‐based fuel material is the safety aspect.…”

“…In addition, thorium fuel also give better negative void reactivity and performance of burnup as well as in term of nuclear non-proliferation concern and it can be used for symbiotic water cooled reactor and fast breeder reactor based on thorium based fuel utilization. [23][24][25][26][27][28] Another consideration of using thoriumbased fuel material is the safety aspect. The melting point of thorium-based material is higher than the uraniumbased one.…”

Comparison of homogeneous and heterogeneous thorium fuel blocks with four drivers in advanced high temperature reactors

“…With the development of nuclear energy, the utilization of thorium has been discussed in various types of reactors with varying intensity, particularly in pressurized water reactors (PWRs), boiling water reactors, heavy water reactors, Canadian deuterium natural uranium reactors, molten salt reactors (MSRs), hybrid systems, accelerator‐driven systems, high temperature reactors (HTRs), breeder reactors, as well as in fast reactors . Thorium has gained considerable amount of interest because of its many advantages that;characterize it as fuel.…”