Travelling wave reactor

TRAVELING WAVE REACTOR

Project guide By Dr.V.Mahesh T. Bhargav

Dean(Research)

AIM:

The goal of the TWR design is to greatly reduce proliferation risks and create new, affordable options for converting low-level waste into energy resources.

Terra Power’s mission is to develop this nuclear reactor to meet growing global electricity needs.

PRINCIPLE:

A travelling-wave reactor (TWR) is a type of nuclear reactor that turns depleted uranium into electricity , using a simple fuel cycle .

It converts fertile material into usable fuel through nuclear transmutation in tandem with the burn up of fissile material.

•The name refers to the fact that fission does not occur throughout the entire TWR core, but remains confined to a boundary zone that slowly advances through the core over time.

•TWRs differ from other kinds of fast-neutron and breeder reactors in their ability to use fuel efficiently without uranium enrichment or reprocessing, instead directly using depleted uranium, natural uranium, thorium, spent fuel removed from light water reactors.

•TWRs could theoretically run, self-sustained, for decades without refuelling or removing any spent fuel from the reactor and no human being is required.

CHARACTERISTICS:

Terra Power has developed TWR designs for low- to medium- (300 MW e) as well as high-power (~1000 MW e) generation facilities.

Human intervention is not required. It uses liquid sodium as a coolant and to carry

away heat .

Prototype design of Travelling Wave Reactor

CONSTRUCTION:

The main parts of TWR are :1. Reactor head2. The core3. Control rods4. Mechanical pumps 5. Heat exchangers6. Guard vessel

WORKING:

It is also called as "breed-and-burn" reactor, because first it breeds Plutonium from U-238 by nuclear transmutation and then burns it by fission reactions .

A small amount of enriched uranium-235 or other "fissile fuel" is used in this process to initiate fission.

Initially, the core is loaded with fertile material, with a few rods of fissile fuel concentrated in the central region.

After the reactor is started, four zones form within the core: 1.the depleted zone, which contains mostly

fission products and leftover fuel2.the fission zone, where fission of bred fuel

takes place3. the breeding zone, where fissile material is

created by neutron capture4. fresh zone, which contains unreacted  fertile

material

The energy-generating fission zone steadily advances through the core, effectively consuming fertile material in front of it and leaving spent fuel behind.

Meanwhile, the heat released by fission is absorbed by the molten sodium and subsequently transferred into a closed-cycle aqueous loop, where electric power is generated by steam turbines.

TWRs are also capable, in principle, of reusing their own fuel. In any given cycle of operation, only 20–35% of the fuel gets converted to an unusable form; the remaining metal constitutes usable fissile material.

Recast and reclad into new driver pellets without chemical separations, this recycled fuel can be used to initiate fission in subsequent cycles of operation, thus displacing the need to enrich uranium altogether.

• As the fuel's composition changes through nuclear transmutation, fuel rods are continually reshuffled within the core to optimize the neutron flux and fuel usage at any given point in time.

•Thus, instead of letting the wave propagate through the fuel, the fuel itself is moved through a largely stationary burn wave.

•Terra Power's design avoids the problem of cooling a highly variable burn region By replacing a static core configuration with an actively managed "standing wave" or "soliton",

Nature of Wave :

ADVANTAGES:

The Terra Power reactor burns the 99.3% depleted uranium and breeds plutonium at the same time, within the same 'cylinder'.

Terra Power has estimated that the Paducah enrichment facility stockpile alone represents an energy resource equivalent to $100 trillion worth of electricity

DISADVANTAGES:

TWRs may be prone to radioactive leaks and core meltdowns.

Even if reducing the cost of uranium were possible with TWRs, it would not make nuclear power cheaper

Promised delivery dates for TWRs are wildly unrealistic.

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