Temperature Reactivity Control of Calcium Hydride–Moderated Small Reactor Core with Poison Nuclides. (2nd September 2019)

• Record Type: Journal Article
• Authors: Kimura, Rei; Wada, Satoshi
• Is Part Of: Nuclear science and engineering. Volume 193:Number 9(2019)
• Page Start: 1013
• Page End: 1022
• Publication Date: 2019-09-02
• Subjects: Small modular reactor -- space reactor -- temperature reactivity -- hydride moderator -- poison nuclides; Nuclear energy -- Periodicals; Nuclear engineering -- Periodicals; Nuclear energy; Nuclear engineering; Periodicals; 539.705
• DOI: 10.1080/00295639.2019.1576454
• Languages: English
• ISSNs: 0029-5639

Abstract

Abstract: A small modular reactor (SMR) is a promising candidate for future nuclear energy; therefore, many organizations are developing SMRs. Some SMRs have a power output higher than 100 MW(electric). This paper, however, describes a much smaller reactor of less than 10-MW(electric) power output: a microreactor. The microreactor shares the same advantages as SMRs, i.e., passive safety, portability, and maintainability. This paper studies a calcium hydride (CaH2 ) heat pipe–cooled reactor in which heat pipes and CaH2 accomplish passive removal of generated heat, fuel inventory reduction, high-temperature operation, and prevention of a loss-of-coolant accident. The CaH2 allows operation at a core temperature of 800°C, which improves the efficiency of the reactor system. In the case of moderator function loss, hydrogen dissociation may occur at the higher temperature; however, negative temperature reactivity of the hydride-moderated core prevents reactor runaway. The negative temperature reactivity is realized by the poison nuclides 113 Cd and 151 Eu, which have a capture resonance peak at thermal energies in high-temperature operation. It was confirmed that the proposed method is capable of controlling the reactor over the whole burnup period.