When a neutron -> proton, it is called a Beta - (minus) decay.
Beta decay converts a neutron to a proton, an electron, and an electron neutrino.
Electron capture is the absorption of an electron by an atomic nucleus if that nucleus is neutron poor. An electron is captured, usually from an inner electron shell of that atom, and it will convert a proton in the nucleus into a neutron. We know that a neutron is converted into a proton and an electron in neutron decay, so it might be looked at as something of an opposite nuclear reaction where a proton and an electron combine to form a neutron.
In a nuclear fission reaction, a freely moving neutron undergoes neutron capture and initiates the nuclear fission of a fuel atom.
neutron
neutron absorber
Beta decay converts a neutron to a proton, an electron, and an electron neutrino.
Electron capture is the absorption of an electron by an atomic nucleus if that nucleus is neutron poor. An electron is captured, usually from an inner electron shell of that atom, and it will convert a proton in the nucleus into a neutron. We know that a neutron is converted into a proton and an electron in neutron decay, so it might be looked at as something of an opposite nuclear reaction where a proton and an electron combine to form a neutron.
In a nuclear fission reaction, a freely moving neutron undergoes neutron capture and initiates the nuclear fission of a fuel atom.
Simply put, electron capture is a nuclear change that an atom might undergo when there are "too many" protons in its nucleus. This atom is unstable, and an electron from an inner orbit will actually be "pulled into" the nucleus. Once there, the electron will "combine" with a proton, and the proton will be transformed into a neutron. This will result in the formation of a new element as a result of the nuclear transformation.
Neutron particle is needed to begin nuclear chain reaction.
neutron
neutron absorber
A neutron is absorbed by an atoms nucleus
neutron chain reaction
A Neutron.
carbon-12
It is often stated that mass is transformed to energy. This is wrong, since both mass and energy are conserved in a chemical reaction - or in a nuclear reaction. The Wikipedia article on "binding energy" clarifies this.