Preliminary study of sintering zero‐rupture Fully Ceramic Microencapsulated (FCM) fuel

Abstract

The demonstration of industrially feasible zero‐rupture Fully Ceramic Microencapsulated (FCM) fuels has been achieved via layers of fuel particles vertically stacked and consolidated by Pulsed Electric Current Sintering. Uniaxial shrinkage, a key component of fuel arrangement, was analyzed via SEM, XRD and computational analyses, using cylindrical geometries from 0.25 to 1.5 “height‐to‐diameter” (h/d) aspect ratio. Bulk densities of ~3.1 g/cc were achieved on pellets at h/d ~0.25, using a ramp rate of 100°C per min to 1825°C and holding for 10 minutes with 10 MPa applied pressure. Using the same parameters, this value reduced to ~2.8 g/cc at h/d ~1.5. More extensive percolation of oxide sintering additives and earlier closure of interconnected pores in extreme ends of the pellet was attributed to higher temperatures in those regions. The top and bottom of the pellet densify before the center, also resulting reduced displacement between the fuel layers in these regions. Parametric studies of sintering with different temperature and time, with support of computational analyses, was used to map expected temperature distribution and sintering behavior. These tools will be used for further optimization of FCM fuel fabrication.

Densification and enhancement of SiC particulate‐reinforced fine‐grain SiC ceramic

“…The farther away from the punch, the lower the sintering pressure and the ceramic RD. Moreover, during the SPS sintering process, the temperature distribution of the powder compact is also nonuniform 36 . The temperature of the top and bottom parts are higher than that of the center part.…”

Niobium carbide as a technology demonstrator of ultra‐high temperature ceramics for fully ceramic microencapsulated fuels

“…Alternatively, random‐in‐plane packing where each layer does not make contact can also achieve competitive packing of particles. The key to avoiding fuel failure is understanding of uniaxial shrinkage, which is the subject of a more comprehensive work . This is distinct from earlier generation of TRISO particles that were randomly packed and unable to achieve consistent zero‐rupture fuel due to a likely increasing probability of rupture as a function of particle packing.…”

Fabrication and properties of SiC-based accident-tolerant fuel with precisely-regulated TRISO particles dispersion

“…The positions of TRISO particles are randomly distributed in matrix and by no means be specific controlled. Nowadays, a few studies have achieved regularly-arranged TRISO particles in the matrix by employing state-of-the-art technologies [13][14][15][16][17]. Chao L et al [13,14] introduced stereolithography-based addictive manufacturing (SLAM) to produce the MgO-PuO2 dispersion nuclear fuel pellets to ensure a highly uniform distribution of the nuclear fuel microspheres, where the MgO matrix acted as a structural material that holds pellets in their threedimensional shape.…”

“…Chao L et al [13,14] introduced stereolithography-based addictive manufacturing (SLAM) to produce the MgO-PuO2 dispersion nuclear fuel pellets to ensure a highly uniform distribution of the nuclear fuel microspheres, where the MgO matrix acted as a structural material that holds pellets in their threedimensional shape. Ang C et al [15,16] proposed a moulding method for stacking preforms equipped with radially reinforced TRISO particle planes into cylindrical pellets. Liu C et al [17] fabricated multilayer fully ceramic microencapsulated fuel pellets using tape casting, with TRISO particles in an orderly arrangement.…”