When the tour was announced, I felt a great deal of excitement although it seemed a bit scary at first. This tour had been on the list since I opened up to the world academically , fortunately, I hadn’t been able to explore the NRL as an individual for security restrictions. So, it was a great chance for me to go with the class. The exploration was divided mainly to a lecture and a field walk. After the security check, we were asked to wear radiation detectors that looked like pens with two optical openings on both ends and a scale measurement inside of it.

One of the important information is that the NRL is meant for commercial use and energy production. It’s used only for scientific experiments. Although in the past the NRL used to treat cancer via a procedure called Boron Neutron Capture Theory and was one of the best at it, the NRL has stopped this procedure due to a lack of doctors. However, it’s enough for the NRL to be the hope to improve nuclear reactors of the future. As far as sustainability is concerned, greenhouse emission reduction is a regarded by the researchers.

It was essential for me to know hoe the reactor works. As the lecturer explained, there are two methods of nuclear reactions one of which is nuclear fission of uranium atoms, which is the one used here. An nuclear fission is illustrated by the picture below.

In the nucleus of each atom of Uranium-235 fuel are 92 protons and 143 neutrons, a total of 235 particles so fantastically small that their size is difficult to imagine. Around this nucleus whirl 92 electrons, which are even smaller particles. If the nucleus were as big as a baseball, an electron on its outer rim would be a mere speck nearly a mile away.

The arrangement of particles within uranium is unstable and the nucleus disintegrates easily. When the nucleus absorbs an extra neutron, it breaks into two parts or splits. This process is known as fission (see diagram below). Each time a nucleus splits, it releases two or three neutrons. Hence, the possibility exists for creating a chain reaction.

The rate of fissions in the uranium nuclei is controlled chiefly by six control blades of boron-stainless steel which are inserted vertically alongside the fuel elements. Boron has the property of absorbing neutrons without reemitting any. When the control blades are fully inserted, they absorb so many neutrons from the uranium that there are not enough to cause a chain reaction. To put the reactor into operation, the control blades are raised very slowly. As they absorb fewer and fewer neutrons, more and more neutrons are available to cause the splitting of uranium nuclei, until finally enough neutrons are being released to sustain a chain reaction.

In addition to the fuel and control blades, one other factor is essential to the operation of the reactor. This is a moderator-coolant, which is ordinary or “light” water in the case of the MITR-II. Since uranium nuclei do not readily absorb neutrons moving at the high speeds with which they leave fissioning nuclei, it is necessary to slow them down with a “moderator”. For this purpose about one-half the volume of the reactor core consists of water.

One of the fascinating things was the control room. It is a room that filled up with monitors and switches and in this room you can keep track of everything happening in the reactor. The word SCRAM was used all around the reactor. This word stands for Safety Control Rod Axe Man, which is an old method used to shut down the reactor.

References

http://web.mit.edu/nrl/www/reactor/fission_process.htm