adithya rameshNiranjan kumar.l

Nuclear WASTE:

Radioactive wastes are usually the waste materials containing radioactive material. It is the product of a nuclear process such as nuclear fission.

INTRODUCTION

Radio activity Certain elements that compose matter emit

particles and radiations spontaneously. This phenomenon is referred to as ‘radioactivity’

Three different kinds of rays; Alpha, Beta and Gamma rays are associated with radioactivity. The alpha rays consist of particles (nuclei of helium atoms) carrying a +ve charge, beta rays particles have –ve charge (streams of electrons) and gamma rays are charge less EM radiation

Radioactive elements decay at different rates.

Rates are measured as half-lives – that is, the time it takes for onehalf of any given quantity of a

radioactive element to disintegrate.

The longest half-life is that of the‘isotope’ 238U of uranium. It is 4.5 billion years. Some isotopes have half-lives of years, months, days, minutes, seconds, or even less than millionths of a second.

Penetration of radioactive rays

Introduction

Radio active waste

Radioactive wastes are waste that

contain radioactive material.

Radioactive wastes are usually by-

products of nuclear power generation

and other applications of nuclear

fission or nuclear technology, such

as research and medicine.

Radioactive waste is hazardous to

human health and the environment, and

is regulated by government agencies in

order to protect human health and the

environment.

So for the disposal of this radio active

waste lot of steps are needed

TYPE OF RADIO ACTIVE WASTE High activity, long life Medium activity, Long lifeLow activity, Long lifeMedium activity, Short life Low activity, Short life

RELATIVE WASTE VOLUME:

90% low level

waste

7% intermediate level waste

3% high level waste

low level waste

intermediate level waste

high level waste

Classification of radioactive waste Characterization

high intensity of β- or γ- radiation,

I. HIGH ACTIVITY, large α- activity

LONG LIFE high radio toxicity,

large making of heat

medium intensity of β- or γ- radiation,

II. MEDIUM ACTIVITY, large α- activity

LONG LIFE medium radio toxicity,

medium making of heat

low intensity of β- or γ- radiation,

III. LOW ACTIVITY, large α- activity

LONG LIFE low or medium radio toxicity,

negligible making of heat

medium intensity of β- or γ- radiation,

IV. MEDIUM ACTIVITY, negligible α- activity

SHORT LIFE medium radio toxicity,

medium making of heat

low intensity of β- or γ- radiation,

V. LOW ACTIVITY, negligible α- activity

SHORT LIFE low radio toxicity,

negligible making of heat

nuclear WASTE DISPOSAL

Currently, internationally preferred solution is for

geological disposal by interment in a mined and

engineered, multi-barrier repository . Engineered

disposal system has generally been constructed at

or near the surface for wastes with low-level

radioactivity and wastes with short-lived radioactivity.

It is being built or is planned to built deep

underground in geological formation for high-level

and long-lived wastes

The wastes can be stored in a repository for a long period of time

Transport of Radio Active nuclear waste

The radioactive wastes can be transported to the repositories or mines with the help of lead castle. The burial of radioactive waste has been an efficient method for its disposal, but the risks involved in it also have to be taken into account.

One of the problems that can occur is that a leakage in

the repositories can cause contamination in the water

table thereby which when reaching the surface can

affect crops.

Microbial action on nuclear waste

The view here is to implement BIO REMEDIATION in the disposal of radioactive wastes. Bio remediation is the process that uses micro organisms to return the natural environment altered by the contaminants. So during the disposal of radioactive wastes if bio remediation is implied then it would be easy to reduce the complexity of these waste materials. Since the decomposition of the nuclear wastes are a great hazard for us if we implement this method then the disposal of the nuclear waste would be easier.

Components of nuclear waste

•Hydro carbons

•Radio isotopes

•Uranium

•Mercury

•Cyanide

MICROBES THAT DECOMPOSES

MERCURY:

Specific stable isotope of mercury can be degraded by a mercury resistant marine bacteria Pseudomonas aeruginosa CH07. By these bacteria the mercury content of the radioactive wastes can be minimized. The volatilization of the mercury content can be reduced by the activity of these bacteria.

MICROBES THAT DECOMPOSES CYANIDE:

The bacteria's such as Pseudomonas putida, Pseudomonas pickettii, Pseudomonas paucimobilis, oxidizes the cyanide, breaking it down into harmless compounds.

2HCN+O2=2HCNO

HCNO+H2O=NH3+CO2

The direct oxidation of cyanide produces cyanate ions and it is being given by the equation

2CN2+O2=2CNO

These bacteria's can also react with cyanide in the anaerobic condition also. The process can be explained by the following equations

CN2+H2S+HCNS+H2

HCN+HS2=HCNS+H2

The HCNS then hydrolyze to form NH2, H2S and CO2.

URANIUM-EATING BACTERIAThe bacterial species of Geobacter are able to precipitate radionuclieds

like Uranium , Technium, and many other heavy metals. This bacteria not only nullifying the toxicity of Uranium also able to produce

electricity from it as they oxidize Uranium in order to gain energy.

Production of Energy The production of energy by the Geobacter is by the

process of transfer of electrons through their pili. Energy from bacteria can be collected through forced induction or with the help of bacteria present in water which is able to convert water into their respective components,hydrogen and oxygen. Thereby the produced hydrogen can be used a source of energy.