Nuke Quotes

Imagination is more important than knowledge.

-Albert Einstein.

Adequate engineers to serve India's Nuclear Mission

India has, and always had, well trained and excellent engineers to go for its Nuclear Mission. Some of the famous R&D and training centres include:

Bhabha Atomic Research Centre

Indira Gandhi Centre for Atomic Research

Raja Ramanna Centre for Advanced Research

Variable Energy Cyclotron Centre

Atomic Minerals Directorate for Exploration and Research

Global Centre for Nuclear Energy Partnership







Source : HBNI, India

 

Nuke Quotes

"Nothing in life is to be feared – it is only to be understood. Now is the time to understand more, so that we may fear less."
-- Marie Curie

Introduction To Nuclear Fission

Fission means ‘cleavage’ or ‘splitting’, hence in simple words nuclear fission is a nuclear reaction or a decay process (radioactive in nature) in which the nucleus of an atom splits into smaller and lighter nuclei, often producing sub-atomic particles which may be free neutrons and photons (gamma rays), and leading to a release of a large amount of energy.

It is an exothermic reaction which can release energy both as electromagnetic energy and as kinetic energy of the fragments. In order for fission to produce energy, the total binding energy of the resulting elements must be greater than that of the starting element. Heavy elements, such as uranium, thorium, and plutonium, undergo both spontaneous fission (a form of radioactive decay) and induced fission, a form of nuclear reaction.

The amount of free energy contained in nuclear fuel is millions of times the amount of free energy contained in a similar mass of chemical fuel such as gasoline, making nuclear fission a very dense source of energy.

Basic types of fission reactions:

Binary Fission: Those producing two charged fragments.

Ternary Fission: those producing three charged fragments (happens just 2 to 4 times per 1000 events!!).

For the nuclides, "Fissile" is distinct from "fissionable"

Fissile isotopes: Isotopes that undergo fission when struck by a thermal, slow moving neutron are also called fissile.

Fissionable isotopes: Elemental isotopes that undergo induced fission when struck by a free neutron are called fissionable.

According to the fissile rule, heavy isotopes with 90 ≤ Z ≤ 100 and 2 × Z – N = 43 ± 2, with few exceptions, are fissile (where N = number of neutrons and Z = number of protons).

²³⁵U and ²³⁹Pu are generally used as nuclear fuels as they can sustain chain reactions and can be obtained in large enough quantities to be useful. ²³⁸U, the most abundant form of uranium, is fissionable but not fissile: it undergoes induced fission when impacted by an energetic neutron with over 1 MeV of kinetic energy. So no chain reaction is possible with this isotope.

 





Nuclear Fission



Uranium Fission

The fission of U-235 in reactors is triggered by the absorption of a low energy neutron, often termed a "slow neutron" or a "thermal neutron".

Why choosing a so called ‘neutron bullet’ for fission?

Now, two particles emitted by radioactive elements are the Alpha particle and the neutron. The Alpha particle is essentially a Helium (2+) nucleus & carries an overall positive charge. So, due to repulsion from the nucleus, the Alpha particle won’t be able to get there .And because neutron is electrically neutral and thus would not get repelled from a positive nucleus, it can reach the nucleus to trigger reaction.

When a neutron strikes a 235U nucleus, it is at first absorbed into it. This creates 236U. 236U is unstable and this causes the atom to fission. The fissioning of 236U can produce over twenty different products like 92Kr , 142Ba, 92Sr,  140Xe.

 

Nuke News (14 August) - Uranium supplies good for the long haul

(Dated 26 July 2012)

Uranium oxide 'yellowcake' in production

     

World uranium resources are ample to meet requirements for the foreseeable future but timely investment in facilities will be needed to make sure production keeps pace with growing demand, according to a new edition of the flagship Red Book.

Officially named Uranium 2011: Resources, production and demand, this is the 24th edition of a periodic assessment published by the OECD Nuclear Energy Agency (NEA) and the International Atomic Energy Agency (IAEA). Universally known as the Red Book, it is currently published every two years and draws together official data on uranium exploration, resources and production, and uranium demand related to its use in nuclear reactors. The new edition covers data to the end of 2010.

Total identified uranium resources have increased by over 12% since the last edition, which covered data up to 2009, although lower cost resources have decreased significantly because of increased mining costs. Nevertheless, with total identified resources standing at 7,096,600 tU recoverable at costs of up to $260 per kg, identified resources are sufficient for over 100 years of supply for the world's nuclear fleet. (An additional 124,100 tU of resources have been reported by companies but are not included in official national figures.) So-called undiscovered resources - resources expected to exist based on existing geological knowledge but requiring significant exploration to confirm and define them - currently stand at 10,400,500 tU.

(by World Nuclear News)



Source: MIT study on The Future of Nuclear Fuel Cycle

Nuclear Energy - An Introduction

It’s really so fascinating to see how such a small nuclei (diameter of the Uranium nucleus is about about 15 fm (femtometre is 10⁻¹⁵ m) is capable of producing such massive amounts of energy. Sometimes I even feel that the word ‘massive’ isn’t quite capable of explaining the gigantic power it holds in such a miniature volume!!

First things first...So, what is nuclear energy?

Nuclear energy is the energy which is the product of a nuclear reaction. So how does this nuclear reaction take place? Actually here two atomic nuclei or a nucleus of an atom and a sub-atomic particle like a neutron, proton, or high energy electron from outside the atom, collide (head-on collision) to produce immense amount s of energy.

The two main types of nuclear reactions are – Nuclear fission and Nuclear fusion.

Nuclear fission releases energy when a single heavy nucleus splits into two smaller ones, while nuclear fusion is a process, in which two single nuclei combine together to form another heavier nucleus and release high amount of energy.

High temperature requirements are very critical for these reactions. To have nuclear reactions, at least one of the nuclei must be "naked", with all its electrons removed. This can be accomplished by bringing matter to very high temperatures (at least 100,000 degrees).

Now, these were just the very basics of nuclear energy and amazingly a lot more needs to be researched, studied and explained in this inspiring field which is surely a very promising and a clean source of energy for all our future needs. It’s great to see how the field has developed over a period of time with highly dedicated amount of work put into it. Though nuclear energy has every ability to quench our power requirements, but the nuclear mishaps we have seen till date challenge us to study and research more into the field so as to avoid any of those in near future and to make nuclear energy extraction a profitable yet  safe process.