How much energy is released during fission?

Answer 1

Fissionable material, that is, material with the ability to fission, occurs in some isotopes of heavy elements. The most useful ones are uranium-235 (U-235) and plutonium-239 (Pu-239).

In brief, when fission occurs, an atom of nuclear fuel (and we're talking about the fission of nuclear fuel here) splits. This splitting yields what are called fission fragments, and the atom splits approximately in two. Note that there are several options as regards what the atom splits into. It can split into "A" and "B" or it can split into "C" and "D" or a few other resultants. But regardless, the fission fragments recoil after fission occurs, and most of the energy of this recoil, which is kinetic energy on the atomic scale, is expressed as heat (thermal energy).

The fuel in a reactor, whatever it is, is tightly sealed in a metal jacket (cladding). The atoms of the fuel are being held rigidly, and when fission occurs, the recoil of the fragments is "contained" in the fuel itself. This mechanical energy gives rise to the appearance of thermal (heat) energy. The lion's share of energy released by fission is carried off in the recoil of the fission fragments, which is kinetic (mechanical) energy. Said another way, the fission fragments can't "go anywhere" in the fuel matrix, and the kinetic energy they come away with after fission is captured in the fuel and appears as heat.

There are also free neutrons released, and they carry off kinetic energy like the fission fragments. These neutrons are slowed down in the moderator to increase the chances that they will be captured by other fuel atoms and cause other fission reactions. They will continue the chain and cause more fissions following neutron capture events. Electromagnetic radiation in the form of gamma rays is also produced in nuclear fission. It must be shielded against. In review, most of the energy of fission appears in the kinetic energy of the fission fragments, and that kinetic energy is converted into heat within the fuel element.

A nuclear reactor is a core made up of an assembly of fuel bundles, which are made of fuel elements, usually using enriched uranium as the nuclear fuel. In the pressurized water reactor, this assembly is inside a pressure vessel, as water is used as the primary coolant, and also the moderator. It can be ordinary water or heavy water. We also see some reactor designs that use graphite as a moderator. Also in the reactor are the control rods.

The primary coolant is the heat transfer medium. It carries heat out of the core and into the steam generator and back to the core in a closed loop. The reactor is made to reach criticality on start up when control rods are pulled. The chain reaction within the fuel will produce a steady power output as a result of nuclear fission, and this will release heat. The heat is used to produce steam in a steam generator, and the steam is feed to a conventional steam turbine/generating unit to generate electric power.

For those investigators attempting to trace the transformations of energy, nuclear energy (the binding energy that holds atomic nuclei together) is converted into electromagnetic and kinetic energy in fission. The electromagnetic energy, which appears as gamma rays, is largely lost as we cannot "capture" and "use" it. The kinetic energy (mechanical energy) of the fission fragments is converted into thermal energy (heat) because the fission products are "trapped" in the fuel matrix and cannot "fly free" as they would in air. The thermal energy created in the fuel bundles heats the fuel, and the primary coolant picks up that heat and transports it to a steam generator. The steam generator turns secondary water into steam, and the steam is piped to a turbine. The thermal energy of the steam is converted into mechanical energy in the turbine, and the mechanical energy is transferred into a generator. The generator converts the mechanical energy into electrical (electromagnetic) energy, and that is the useful product we derive from nuclear fission.

Links are provided to other questions and to other web pages so you can check facts and learn more. You'll find the links below.

Answer 2

Scientists use a unit called the 'electron volt' to quantify energy of particles. this arose because particle accelerators operate with high voltages to accelerate charged particles. High energies are produced at high voltage so the practical unit is one million electron volts which is written Mev. The fission of a heavy nucleus such as U235 produces about 200 Mev per fission. This is the result of splitting the nucleus into fission fragments and releasing energy as heat.

In comparison, burning of a fossil fuel only produces a few ev per molecule burned, so you can see that fission produces millions of times more energy, enabling a single charge of reactor fuel to produce several thousand Megawatts thermal for perhaps two years between refuelling shutdowns.

Answer 3

The energy released in a typical fission reaction of U235 releases about 200 million electron volts (2 x 108 ev) or about 3.2 x 10-11 joules per atom. The heating potential of 1 kg of Uranium is equivalent to the heating potential of 2.5 million kg of coal.

Answer 4

In the fission of a uranium atom, about two neutrons are released. The reason we say that is because in some fission reactions, a single neutron is released, and in some two are released, and in some there are three releases. The "average" neutron release per fission is a bit over two neutrons.

We know that there are no "partial" nautrons released in nuclear fission. The number of neutrons released is measured in integers. But "about two" is probably the best answer to the question.

Answer 5

When a nucleus fissions, into mainly two smaller parts, a small amount of mass is destroyed and converted to energy. This energy initially appears as the recoil energy of the parts split off, that is kinetic energy, but the split items are quickly brought to rest in the mass of the nuclear fuel, and the kinetic energy is converted to heat.

Answer 6

In the US in 2007, 104 power reactors produced 806.5 billion KWh. Worldwide in 2006 the electricity production was 2659.7 billion KWh.

Source: Nuclear energy Institute, www.nei.org

Answer 7

yes