Hidayahtullah A. Robhani

The explosions of reactors at Japan's Fukushima Daiichi nuclear power station following the 9.0-magnitude earthquake and tsunami on March 11 have caused countries around the world to question the safety of their own nuclear plants.

A nuclear power plant in Japan. [File photo]

According to BBC, the function of a nuclear power plant is to make electricity. It does this the same way as coal, oil, and natural gas power plants do; namely, it heats water into steam in order to turn a generator. The difference is the way that it heats water.

Instead of burning fossil fuel, a reactor will heat water by bringing pellets of uranium close together until they form a critical mass. When uranium decays, neutrons and heat are released. If enough uranium is near by, then the neutrons will run into other uranium atoms, causing them to split apart, or fission, and release more neutrons and more heat. Nuclear reactors submerge the fissioning uranium in water. The fuel heats up the water, and the water boils and turns to high pressure steam, which turns the turbine.

There are two main types of reactors in use today: Boiling Water Reactors (BWRs) and Pressurized Water Reactors (PWRs).

The graphics of a nuclear plant [45nuclearplants.com]

In PWRs, the reactor and associated pipes and pumps are called the Reactor Coolant System (RCS), or the 'Primary Loop'. The RCS is a closed system in that nothing in the system is allowed to escape during normal operation, as it would be radioactive. Water in the RCS is not allowed to boil. Instead, the water is pressurized to prevent it from boiling. While pressurized, the water can now be heated to a temperature of several hundred degrees, and is sent to a steam generator.

The steam generator has two types of water in it: primary loop water, and secondary loop water. The two types of water are never allowed to mix. The primary water enters the steam generator through hundreds of small tubes. The tubes heat up and causes the secondary water to boil and turn to high pressure steam, which is used to turn the turbine and create electricity. The advantage of PWRs is that the RCS is the only part of the plant that is radioactive.

In BWRs, water in the RCS is boiled directly. The RCS water itself is turned to steam and is used to turn the turbine. The advantage of this system is that there are no steam generators involved, which means that there is less complexity, fewer components, and less maintenance to perform. The disadvantage is that the turbine is now contaminated with radioactivity.

The safety and security of the nuclear plants:

Each nuclear plant design features reliable and diverse safety systems and strong physical barriers to prevent incidents that could pose a threat to public health and safety. The same features that safeguard the public and the environment from a radiation release also defend the reactor from outside interference.

The reactor is typically protected by about four feet of steel-reinforced concrete with a thick steel liner, and the reactor vessel is made of steel about 6 inches thick. Steel-reinforced concrete containment structures are designed to withstand the impact of many natural disasters, including hurricanes, tornadoes, earthquakes and floods, as well as airborne objects with a substantial force.

Source : http://www.china.org.cn/environment/2011-03/17/content_22164702.ht

Kamis, 06 Desember 2012

What Are Nanorobots?

Each one of us has been to the doctor for some reason or the other. Imagine one day you go to a doctor for treating persistent fever and instead of prescribing medicines or an injection shot, the doctor refers to a medical team that implants a tiny robot in your bloodstream. Surprising isn't it? Let us find out how...

Surprising isn't it? Well, the good news is that we are not too far from these kinds of developments in the medical field.
What are nanorobots?

Nanorobots are just the adapted machine version of bacteria. Nanorobots measure six atoms across and are complicated to be designed and need to be engineered in such a way that they are autonomous in nature.
Nanorobots are small microscopic devices measured on the scale of nanometers. They are designed to function like bacteria or any normal virus. Nanorobots are small particles that have a small solar cell or some kind of battery. The nanorobots are made of tiny silicon pieces called as transducers. These transducers take in energy that is generated by the robot's solar cell and turns the energy into mechanical power.
Hard oxides and metals that are used for electronics are being considered to be used in making nanorobots in near future. The challenge faced by the scientists here is to reduce these materials to such a tiny structure. Metals behave in a different way when they are in their usual form and in a different way when they are reduced to smaller size.
Scientists are also trying to build nanorobots on bacteria model. In characteristics and function, bacteria will be a natural nanomachine that has gone haywire.
Benefits of Nanorobots
Nanorobots are the most useful objects that humans have invented. They are capable to rebuild the tissue molecules in order to close an open wound, rebuild the walls of ruptured veins and arteries and also find their way to the heart by travelling through your blood stream and perform important surgeries like heart molecular surgery without causing any discomfort to you.
Scientists are also of the opinion that nanorobots will help in brain research, cancer research and finding remedies for difficult ailments like AIDS, leukaemia and other major diseases. Nanorobots can indeed be the ray of light for those suffering from such major ailments. Cancer patients have to undergo this painful treatment called as chemotherapy which also has many side-effects. However, with the invention of nanorobots, the cancer patients will no longer be required to undergo such painful process, instead just take a small prick, let the nanorobot enter the blood stream and do the needful.
The nanorobots are efficient and make sure that they eliminate every infected cell without touching the good cells of your body.
Life is sure going to be simple and easy with the discovery of nanorobot. The scientists are still working on this "miracle cure" and hope to provide us a break-through in a at least the next 25 years.

source : http://www.humantouchofchemistry.com/what-are-nanorobots.htm