OANPP 2014-Lecture 6- Waste Management

8/12/2019 OANPP 2014-Lecture 6- Waste Management

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Basic Conventional Definition of Wastes

substances or objects which are disposed of orare intended to be disposed of by the provisionsof the law

Disposal meansany operation which may lead to resourcerecovery, recycling, reclamation, direct re-use oralternative uses

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Radioactive Waste

Such are waste that contain radioactivematerial. Radioactive wastes are usually by-products of nuclear power generation and otherapplications of nuclear fission , such as researchand medicine.

Radioactive waste is hazardous to most forms oflife and the environment, and is regulated bygovernment agencies in order to protect humanhealth and the environment.

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Radioactivity diminishes with T1/2, so waste is

typically isolated and stored for a period of time

until it no longer poses a hazard. The period of time waste must be stored

depends on the type of waste i-e,

1. Low level waste

2. High level waste

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Waste Management There are three categories of radioactive

waste,

1. Low Level Radioactive Waste

2. Intermediate level waste

3. High Level Radioactive WasteColleges, research and medical applications account for less than 25% of

the low level Radioactive wastes created

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Low Level Radioactive Waste

Low level radioactive waste consists of micro

curie, milli curie and at times curie level activitywaste

Low level radioactive waste is classified on the

concentration and type of radio nuclides involved

Low level radioactive wastes can be in the form

of solids, liquids, or gases

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Low-level wastes include paper, rags, tools,

clothing, filters, and other materials which

contain small amounts of mostly short-livedradioactivity.

Materials that originate from any region of an

Active Area are commonly designated as LLW.

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The principal sources of low level rad waste are

the reactor coolant (water) and the components

and equipment that come in contact with thecoolant

Low Level Waste (VLLW) range from 1 to 100

Bq/g

Following are the major classes of it,

1. class A

2. class B

3. class C 9

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Class A Low-level Radioactive Waste

It is the least hazardous, containing mostly

short-lived radio nuclides

Class A waste will be disposed of in concrete

canisters that will maintain their shape and

strength for hundreds of years.

It is generated from hospitals and industry, as

well as the nuclear fuel cycle. 10

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Class B Low-level Radioactive Waste

It is more hazardous than Class A waste.

Most of it comes from nuclear reactors. It must be in a stable form for disposal and will

also be disposed of in concrete canisters.

Class C low-level radioactive waste Itis the most hazardous and must be handled

accordingly.

It also must be disposed of in a stable form

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Treatment of LLW

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All classes of LLW contains the following waste

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Liquid Solid Gas

Equipment leak

off points

Contaminated

rags, tools,

clothing, etc.

Equipment

vents

Equipment

vents anddrains

Spent filter

cartridges

Liquid waste

system(evaporator gas

stripper)

Floor drain

system

Spent

demineralizer

resins

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Early LLRW Disposal

Cardboard boxes

and open drums in

unlined ditches.

LLRW from

Hanford, c. 1950


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LLRW may be incinerated or compacted (solid

nature)

such waste like work clothes, gloves, and paperused to clean the nuclear power station floors,

occur with operation and maintenance at nuclear

power stations is stored in steel-lined concrete

containers that are set above the ground orsometimes underground

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Drum Crusher

Setting a LLRW drum in place

Reduced Volume


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Intermediate Level Radioactive Waste

It contains higher amounts of radioactivity and in

some cases requires shielding. The major constituents of low level radioactive

waste are activation products (crud) and a very

small percentage of fission products (if any leak

out of the fuel)

Intermediate-level wastes includes resins,

chemical sludge and nuclear fuel, cladding etc

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It may be solidified in concrete or bitumen for

disposal.

As a general rule, short-lived waste (mainly non-fuel materials from reactors) is buried in shallow

repositories, in steel-lined concrete containers

that are set into the ground.

while long-lived waste (from fuel andreprocessing) is deposited in specified geological

repository.

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Desirable Characteristics for Land Burial

Following are the main features required for easy

land burial of waste1. Relatively water-impermeable soil to reduce the

chance that radionuclide are leached and

transported from the disposal area into

groundwater

2. Disposal above water table; isolating the wastesfrom precipitation, groundwater, and surfacewater.

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High Level Radioactive Waste

The waste is produced by nuclear reactors.

It contains fission products and transuranicelements generated in the reactor core.

It is highly radioactive and often thermally hot.

HLW accounts for over 95 percent of the totalradioactivity produced in the process of nuclear

electricity generation.

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The spent fuel must be kept under water due to

the heat being generated by the decay of the

fission products and to limit the radiation levels in

the area of the spent fuel pool.

The spent fuel pools are usually located onsite.

However, due to the amount of fuel some power

plants must store, there are some offsite storagepools.

Presently, there are no disposal facilities for

commercial high level radioactive waste but they

are in exploring process like Yucca mountain, US29

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After several years, the heat generated by the

decay of the fission products decreases

sufficiently to allow the storage of the spent fuel

in an air-cooled, dry storage facility.

These facilities must be designed to remove the

heat from the spent fuel and be designed to limit

the radiation in the areas around the facilities.

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The fuel would be

inside the canister.

Outside of it there islead shield and

placed in a facility

which is properly

ventilated.

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Yucca Mountain

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Yucca Mountain

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Giant Casks

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Finlands Onkalo Permanent Disposal Site

Documents

OANPP 2014-Lecture 6- Waste Management