Disclosed are embodiments of a nuclear fuel element for use in various types of nuclear reactors. One embodiment ofthe nuclear fuel element comprises a plurality of solid nuclear fuel particles, such as tristructural-isotropic (TRISO) fuel particles, intermixed in a non-solid matrix that is substantially stagnant relative to the plurality of solid nuclear fuel particles. The non-solid matrix may comprise a liquid metal, a liquid metal alloy, and a liquid salt. Various embodiments of the non-solid matrix include tin, lead, sodium, aluminum, bismuth, and alloys thereof. A method of manufacturing a nuclear fuel and embodiments of a nuclear fuel core comprising the nuclear fuel element are also disclosed.