04.02.2013 Views

Regional Basic Professional Training Course in Korea

Regional Basic Professional Training Course in Korea

Regional Basic Professional Training Course in Korea

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

<strong>Regional</strong> <strong>Basic</strong> <strong>Professional</strong> <strong>Tra<strong>in</strong><strong>in</strong>g</strong> <strong>Course</strong> (BPTC) on Nuclear Safety<br />

clustered <strong>in</strong> a nucleus and surrounded by electrons mov<strong>in</strong>g around <strong>in</strong> a variety of orbits.<br />

The protons are positively charged particles each hav<strong>in</strong>g a unit charge exactly opposite<br />

that of an electron. The mass of the proton is 1836 times that of the electron. Neutrons<br />

have no electrical charge and a mass just slightly larger than that of a proton. Outside of a<br />

nucleus, the neutron cannot exist alone, as it will be unstable and decay <strong>in</strong>to an electron, a<br />

proton and ananti-neutr<strong>in</strong>o. Figure 1.1 shows a schematic arrangement of the helium<br />

atom with two protons and two neutrons <strong>in</strong> the nucleus, plus two orbit<strong>in</strong>g electrons.<br />

FIG. 1.1. The atomic system of helium<br />

A particular atom is designated by its atomic number, Z, which represents the number of<br />

protons present, and by its mass number, A, which is equal to the number of neutrons, N,<br />

plus the number of protons:<br />

A = N + Z [1]<br />

The nucleons (protons and neutrons) <strong>in</strong> a nucleus are bound together by strong attractive<br />

force and the total energy of a nucleus is less than that of the separated particles. The<br />

b<strong>in</strong>d<strong>in</strong>g energy is the amount of energy given up when the nucleus is formed. What we<br />

produce <strong>in</strong> the nuclear fission reactors and fusion reactors is com<strong>in</strong>g from the b<strong>in</strong>d<strong>in</strong>g<br />

❙ 8 ❙

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!