Provided is a fuel design configured to have a thickness that is equal to or less than a mean-free path of electrons emitted by a radioactive energy source to prevent electrons produced thereby from being stopped within the fuel design and thus decreasing the intensity of bremsstrahlung radiation generated within the fuel design. Additionally provided is a two-phase shielding system including a first shield formed of a first material having a thickness exceeding a mean-free path of an electron emitted from a radioactive source material so as to prevent the electron from passing through the first shield, and a second shield formed of a second material configured to prevent bremsstrahlung radiation generated by the electron from passing through the second shield.

The present disclosure is directed to a nuclear thermionic avalanche cell (NTAC) systems and related methods of generating energy comprising a radioisotope core, a plurality of thin-layered radioisotope sources configured to emit high energy beta particles and high energy photons, and a plurality of NTAC layers integrated with the radioisotope core and the radioisotope sources, wherein the plurality of NTAC layers are configured to receive the beta particles and the photons from the radioisotope core and sources, and by the received beta particles and photons, free up electrons in an avalanche process from deep and intra bands of an atom to output a high density avalanche cell thermal energy through a photo-ionic or thermionic process of the freed up electrons.

A drillhole plug includes a frame or housing of a corrosion-resistant material and sized to fit within a milled portion of a directional drillhole that includes a hazardous waste repository; and a material that fills at least a portion of the frame or housing. The material exhibits creep such that the material fills one or more voids between the frame or housing and a subterranean formation adjacent the milled portion of the directional drillhole.

A nuclear battery is provided. The nuclear battery comprises a radiation source layer, a first electrical insulator layer, a casing layer, a first electrode, and a second electrode. The radiation source layer comprises a composition configurable to emit beta radiation. The first electrical insulator layer is disposed over the radiation source layer. The casing layer is disposed over the first electrical insulator layer. The casing layer comprises a composition configured to inhibit traversal of beta radiation. The first electrode is in electrical communication with the radiation source layer. The second electrode is in electrical communication with the casing layer. A voltage potential is present between the first electrode and the second electrode when the radiation source layer emits beta radiation.

A radioisotope power source is disclosed. In one embodiment, the power source includes a dielectric liquid held within a vessel, a radioisotope material dissolved as an ionic salt within the dielectric liquid thereby forming an ionic salt solution, and a thermal-to-electric power conversion system configured to receive thermal heat generated from the decay of the radioisotope material and to generate electrical power.

A device for producing electricity. The device comprises a source of tritium radioisotopes, an element Th maintained at a temperature Th, and an element Tc maintained at a temperature Tc; Tc lower than Th. The source generates heat and is disposed in thermal communication with the element Th to maintain the temperature Th. First and second doped elements, each doped with a different dopant type, are oriented in parallel relative to the heat flow path between the element Th and the element Tc and electrically connected in series According to the Seebeck effect, a voltage is generated between the first and second doped elements due to a temperature differential between the Tc and Th, causing current to flow through the serially-connected doped elements. Helium generated during generation of the radioisotopes is vented from the device.

A power generator system includes one or more heat transfer members configured to contact: a heat source in a hazardous waste repository of a directional drillhole that stores nuclear waste in one or more nuclear waste canisters, and a heat sink in the hazardous waste repository; and one or more thermoelectric generators thermally coupled to the one or more heat transfer members and configured to generate electric power based on a temperature difference between the heat source and the heat sink.

A radioactive power generation system is disclosed, the system comprising a radioactive power generator and a releasable antiproton containment. The radioactive power generator includes a radioisotope material. The releasable antiproton containment comprising a plurality of antiprotons contained in isolation from the radioisotope material. The releasable antiproton containment is configured to selectively release the antiprotons from the releasable antiproton containment such that the antiprotons can annihilate the radioisotope material in a fission event to reenergize the radioactive power generator.

A modified Nuclear Thermionic Avalanche Cell (NTAC) to reduce back-scatter losses of avalanche electrons emitted by a NTAC. The present invention provides a novel topological surface configuration for electron collector layers in NTAC devices. Sawtooth configurations of the surface configurations of electron collector layers allow for the recapture of back-scattered electrons, increasing the efficiency of NTAC devices as well as reducing thermal loading and increasing NTAC efficiency.

A power generator system includes one or more heat transfer members configured to contact: a heat source in a hazardous waste repository of a directional drillhole that stores nuclear waste in one or more nuclear waste canisters, and a heat sink in the hazardous waste repository; and one or more thermoelectric generators thermally coupled to the one or more heat transfer members and configured to generate electric power based on a temperature difference between the heat source and the heat sink.