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Nuclear Reactors
Nuclear reactors are devices that maintain nuclear reactions. They are used in creating power and elements.
890 Questions
How does hydrogen gas cause explosion on nuclear reactors?
In a nuclear reactor, hydrogen gas can be produced as a byproduct of the reaction. If the hydrogen gas mixes with oxygen in the presence of a spark or flame, it can ignite and cause an explosion due to its highly flammable nature. This phenomenon, known as a hydrogen explosion, can result in damage to the reactor containment and pose a risk to the reactor's integrity.
How does the uranium and plutonium react in the nuclear reactor?
To set off a fission reaction (the reaction that occurs in a nuclear reactor), a person must first pump a neutron into a heavy nucleus. So if a neutron is pumped into a uranium or plutonium nucleus capable of undergoing fission, the nucleus splits in two, and releases more neutrons, which hit more nuclei, which in turn send out even more neutrons, thus setting off a chain reaction where every time a neutron hits a nucleus, the nucleus splits in two and sends out more neutrons.
Why did they add boron to water to dump on the nuclear reactor?
Boron is a good absorber of neutrons and would be useful in preventing criticality, if the fuel had melted and was possibly going to form a critical mass. I don't know how likely this was, but it seems more of a precaution than a real necessity, at present anyway.
What can iodine tablets do against radiation?
Iodine tablets are taken by individuals who have just been or are being exposed to radioactive materials that include radioactive iodine. In nuclear fission reactors, uranium (or sometimes plutonium) fission to create energy. When these fuel atoms split (fission), there are a number of fission products that can result, including a radioactive isotope of iodine. In a reactor accident that includes a meltdown and the release of radioactive fission products into the environment, radioactive iodine can be present.
By taking iodine tablets, an individual who is exposed to radioactive iodine that was released in a nuclear reactor accident can avoid having his body absorb this radioactive material. Taking iodine tablets keeps iodine levels in the body high, and the thyroid gland, which absorbs iodine, high. This effectively prevents radioactive iodine from being absorbed and taken up by the thyroid. As absorbing radioactive iodine can lead to thyroid cancer, taking iodine tablets is a good shield against uptake of the radioactive isotope.
How can nuclear reactors be dangerous?
The purpose of a nuclear reactor is to create and sustain a fission chain reaction in order to produce heat to make steam to drive turbines and produce electrical power (extremely simplified explanation).
A fission chain reaction is the interaction of neutrons with fissile materials (elements that can be fissioned). Some enriched fuel (such as uranium-238) is introduced into the reactor core. It produces neutrons as radiation. If more fissile material is present ("fuel" such as uranium-235), that interaction repeats to make more neutrons, and so on. A nuclear reactor is designed to sustain a fission chain reaction and control the rate at which that reaction occurs.
The nuclear core of a reactor, where the nuclear fuel is, needs to be shielded so that the radiation and any radioactive components inside do not escape into the general environment.
The primary radiation type inside the core is neutron radiation. One of the best shields for neutron radiation is a hydrogen-dense substance, thus pure water is often used. Water, if circulated in a heat sink system, also serves as a heat-removal method (cooling system).
The enclosure for the core and the water pool is a containment vessel made out of something that is airtight and which shields against other kinds of direct radiation. Steel is a common material, perhaps supplemented by concrete and other reinforcement to guard against being damaged by an earthquake, explosion, or an airplane impact (for example).
There is usually an outer containment building that encloses the reactor containment vessel itself. This is a sort of "second line of defense" in case the reactor is breached. Containment buildings are designed to withstand extremely high internal pressures (such as superheated steam) and forces of almost any direction and realistic magnitude. The specific shape of buildings at a nuclear plant are part of their function. The concave towers that are so symbolic of nuclear power are a common design for cooling towers (and not the reactor core itself). Domes are a common shape for reactor containment buildings for a variety of reasons that have mostly to do with encouraging steam condensation.
What does keff mean in nuclear reactor world?
keff is defined as the neutrons in one generation due to fission divided by the neutrons from the previous generation. The denominator includes the source neutrons. Thus it is the fractional change in neutron population.
What were the effects of the Chernobyl accident on the people?
31 people were killed in the immediate accident and 1,800 children have thus far been diagnosed with thyroid cancer. In a study published in May 2001
Many people living in and around Chernobyl before the disaster suffered radiation poisoning and related radiation illnesses such as cancer.
When was Fukushima nuclear plant built?
Construction for the Fukushima Nuclear Power Plant started the 25th of July, 1967.
The plant was built by Kajima Construction Corporation, Ltd.
This is a Japanese construction company. Founded in 1840.
Fukushima I was fully operational in the year 1971.
Why is sea water used to cool nuclear reactors?
Sea water is used to cool nuclear reactors in emergency situations when fresh water is not available. We usually find very pure water used in nuclear reactors as a primary coolant. This water stays quite pure and retains little radiation after shutdown and cooldown. But if an emergency situation arises and the "regular" primary coolant (the fresh water) is lost, it must be replaced with any water to cool the reactor. Sea water is better than nothing.
What is the danger of a nuclear plant meltdown?
The danger in a nuclear plant meltdown is that failure of the containment system may follow the meltdown, and this will allow highly radioactive material out into the environment. Let loose, this material can injure or kill exposed individuals, and it can render large areas of land uninhabitable for long periods of time.
How are nuclear reactors kept safe?
There are many safety procedures put in place to keep a nuclear reactor safe, first of all control rods are used inside the reactor to stop the fission reaction running out of control and melting the reactor core, constant water(coolant) is kept pumping around the reactor cool and to help soak up some of the neutrons and x-ray scans are used to check that there are no natural cracks inside the reactor.
What types of nuclear reactors are used in the UK?
Mostly at present they are AGR's that is Advanced Gascooled Reactors, using carbon dioxide coolant, graphite moderator, and slightly enriched fuel clad in stainless steel sheaths. There is one PWR running and all new ones built will be PWR.
a reactor is generally termed as an autoclave reactor,when
it is a high pressure batch reactor.mostly this kind of reactors are used for sterilization the reactants..
How did Henri Becquerel discover nuclear power?
Henri Becquerel discovered nuclear power in 1896 while studying uranium salts. He observed that photographic plates wrapped in black paper near uranium emitted radiation that fogged the plates, leading to the discovery of radioactivity. This accidental discovery laid the foundation for the field of nuclear physics.
What is the importance of having nuclear reactor to generate electricity?
Nuclear powerplants produce around 2000-6000 Mega watts per unit. That is equivlent to 4000 Tons of coal. Nuclear Powerplants are the only Cleanest and highest energy producers to date. This is why Nuclear Powerplants are important, The world is dependent on it for Power and Electricity.
Are nuclear reactors dangerous?
Yes, but there are risks associated with every type of power plant. Its simply a matter of understanding those risks and dealing with them. In the case of nuclear reactors, we design whats known as "defense in depth", so that any hypothetical failure, or sequence of failures, including some improbable failures, can be handled.
What is meant by chain reaction in nuclear reactor?
Basically a chain reaction (nuclear or chemical) is a self sustaining auto-catalytic reaction.
In a nuclear reactor it is a neutron chain reaction, where each neutron released in every fission event can trigger another fission event. In a nuclear reactor the excess neutrons must be disposed of, which is the purpose of the control rods so that the reaction can be kept at some desired constant rate.
When did Enrico Fermi invent the first nuclear reactor?
Actually Leo Szilard invented both the nuclear reactor and atomic bomb in 1933, applied for a patent covering both in 1934 and was granted that patent (GB630726) in 1936. The British Admiralty (Navy) immediately classified his patent to protect it from the Nazis (and kept it classified until 1949). Szilard however never attempted to build either at the time because no fissionable material was known until it was discovered by a team working in Germany and Sweden discovered that uranium-235 could fission.
Szilard contributed to starting the Manhattan Project by writing the so called "Einstein Letter" the warned FDR that the Nazis might be working on an atomic bomb. (Though called the "Einstein Letter" the only things Einstein did was read the unsigned letter shown him by Szilard, approve what it said, and sign it. Szilard felt it would have more influence on FDR if signed by a much more well known scientist than himself.)
Enrico Fermi only built the nuclear reactor, he did not invent it. Fermi's first nuclear reactor (CP-1 for Chicago Pile #1) first operated on December 2, 1942 (less than a year after the Japanese attack on Pearl Harbor). Fermi almost certainly had access to Szilard's (then classified) patent, but how much he depended on is is unknown.
Note: following the discovery of nuclear fission using uranium-235 in 1939, several people independently and almost simultaneously reinvented the nuclear reactor and/or atomic bomb without any knowledge of Szilard's prior art covered by his patent. At that point it was rather obvious to anyone that understood physics what was required.
What were some of the uses for the first nuclear reactor?
The very first nuclear reactor was Chicago Pile 1. It was built for research and scientific use. The first nuclear reactor outside of a university was built (at Hanford, Washington) primarily to yield plutonium for the atomic bomb destined for Nagasaki, Japan.
Nuclear reactors were built primarily for electrical generation beginning in about 1951.
What is the main reason for the world wide slowdown in the construction of nuclear power plants?
Most of the world's nuclear reactors are of the type?
Most are lightwater moderated and cooled, these are the PWR and BWR. There also a substantial number of heavy water reactors, based on CANDU, and gas cooled reactors mainly now in the UK.
How does a nuclear reactor create heat?
Every time a nucleus of U-235 or Pu-239 fissions, energy is released which initially results in the fission products (ie the atoms of the two lighter elements formed in the fission) being forced apart with high kinetic energy. As they are in a matrix of the fuel itself, this kinetic energy is soon turned into thermal energy as the fragments quickly slow down through friction. Thus the fuel gets hot and transfers heat to the flow of water or gas which is called the coolant, since it prevents the fuel becoming overheated.
What Materials are needed to build a nuclear reactor?
Steel for the pressure vessel and pressure circuits, concrete for shielding and structural foundations etc, uranium and zirconium for the fuel. These are the main materials, of course there are many components like control rods and actuators, pumps, valves, instruments and so on.
