.sup.210Pb and .sup.227Ac are used in thermal energy production as precursor isotopes, which have been isolated and are allowed to age to the point of secular equilibrium with their progeny, referring to the decay product isotopes in the radioactive decay chain of each. Both .sup.210Pb and .sup.227Ac are in the radioactive decay chains of naturally occurring uranium isotopes, and are each subject to their own natural radioactive decay. While not particularly energetic through their own decay, they (1) are separable from their parent isotopes or may be created in a reactor, (2) have half-lives of around 22 years, and (3) are precursors (natural radioactive decay parents) to subsequent rapid and energetic decay processes. These two isotopes can offer significant advantages as RPS fuel compared to the currently used .sup.238Pu.

Methods of providing load following capability to commercial nuclear reactors. Materials that thwart nuclear reactor hotspots and transients by absorbing excess neutrons such as hard or high energy neutrons. Nuclear fuel additives to stabilize nuclear reactor transients. Materials that interact more strongly with high energy neutrons than they do with now energy or thermal neutrons.

Fuel bundles for a nuclear reactor are disclosed, and in some embodiments include a first fuel element including thorium dioxide; a second fuel element including uranium having a first fissile content; and a third fuel element including uranium having a second fissile content different from the first fissile content. Nuclear reactors using such fuel bundles are also disclosed, including pressurized heavy water nuclear reactors. The uranium having the different fissile contents can include combinations of natural uranium, depleted uranium, recycled uranium, slightly enriched uranium, and low enriched uranium.

Fuel bundles for a nuclear reactor are disclosed, and in some embodiments include a first fuel element including thorium dioxide; a second fuel element including uranium having a first fissile content; and a third fuel element including uranium having a second fissile content different from the first fissile content. Nuclear reactors using such fuel bundles are also disclosed, including pressurized heavy water nuclear reactors. The uranium having the different fissile contents can include combinations of natural uranium, depleted uranium, recycled uranium, slightly enriched uranium, and low enriched uranium.

A device for detecting transport boats includes a contact element for contacting a transport boat, and a connecting element spring mounted in a housing of the device, biased into an initial position and linearly displaceably guided via a guide of the housing. The contact element is connected to the spring mounted connecting element and is displaceable together therewith in such a way that contact of the transport boat with the contact element causes deflection of the connecting element against the bias from the initial position into a detection position. The device further includes a detection device adapted to detect reaching of the detection position by the connecting element.

A nuclear fuel cell includes a net neutron-producing material, a neutron-consuming material, and a neutron-moderating material. Upon exposure of the net-producing material, the neutron-moderating material, and the neutron-consuming material to a neutron source, a ratio of the net neutron-producing material to (i) the neutron-consuming material and (ii) the neutron-moderating material is operable to convert neutrons into charged particles without producing net neutrons.

A nuclear fuel cell includes a net neutron-producing material, a neutron-consuming material, and a neutron-moderating material. Upon exposure of the net-producing material, the neutron-moderating material, and the neutron-consuming material to a neutron source, a ratio of the net neutron-producing material to (i) the neutron-consuming material and (ii) the neutron-moderating material is operable to convert neutrons into charged particles without producing net neutrons.

A method of forming a water resistant boundary on a fissile material for use in a water cooled nuclear reactor is described. The method comprises mixing a powdered fissile material selected from the group consisting of UN and U.sub.3Si.sub.2 with an additive selected from oxidation resistant materials having a melting or softening point lower than the sintering temperature of the fissile material, pressing the mixed fissile and additive materials into a pellet, sintering the pellet to a temperature greater than the melting point of the additive. Alternatively, if the melting point of the oxidation resistant particles is greater than the sintering temperature of UN or U.sub.3Si.sub.2, then the oxidation resistant particles can have a particle size distribution less than that of the UN or U.sub.3Si.sub.2

A method of forming a water resistant boundary on a fissile material for use in a water cooled nuclear reactor is described. The method comprises mixing a powdered fissile material selected from the group consisting of UN and U.sub.3Si.sub.2 with an additive selected from oxidation resistant materials having a melting or softening point lower than the sintering temperature of the fissile material, pressing the mixed fissile and additive materials into a pellet, sintering the pellet to a temperature greater than the melting point of the additive. Alternatively, if the melting point of the oxidation resistant particles is greater than the sintering temperature of UN or U.sub.3Si.sub.2, then the oxidation resistant particles can have a particle size distribution less than that of the UN or U.sub.3Si.sub.2.

In one form, during the production of electrical energy from a stable uranium isotope by means of a fission chain reaction, extra neutrons are formed that can be used, in addition to electricity production, to also convert certain elements to other elements, specifically of some selected stable isotopes of particular elements to stable isotopes of other elements.

Neutron sources are used in the production of electrical energy in nuclear reactors, which are currently considered to be nuclear waste (they are absorbed in control rods in reactors and considered to be undesirable parts, that could start an uncontrolled fission reaction), or they are used to produce militarily sensitive fissionable plutonium, the commercial use of which is not allowed at present due to possible military abuse.