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Nuclear Plant Life Extension

Group no: 05

Mohd Tayyab Saeed Vivek kumar

Vishal Varshney

Content

• Nuclear Energy• Nuclear Radiations• Ageing of plant• Ageing management• Life extension• Various plants working on extended life• Refrences

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Nuclear Energy

• Energy from nucleus.• Two methods:-

Fission

Fusion

Nuclear Fission - Occurs when neutrons impact and split the nuclei of certain atoms.

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n

n

n235U

n

n

n

235

U

fast neutron

Slow neutronfast neutron

fast neutron n

Fast Neutrons are unsuitable for sustaining further reactions

Slow neutron

n

Insert a moderator to slow down neutrons

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Nuclear Fission Chain Reaction

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Nuclear Reactors

• Nuclear Reactor - Device that permits a controlled fission chain reaction.

Radiation

Alpha ( ) - Moving particles composed of two neutrons and two protons.

Stopped by layer of skin Beta (β) - Consists of electrons.

Stopped by layer of Aluminium foil of 3mm.Gamma () - rays CANNOT be stopped.

They can be attenuated to safe limits using thick Lead and concrete

β

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Nuclear radiations composes gamma rays which causes • Cancer• Genetic alteration• Loss of fast growing cells such as skin cells,

intestinal lining and hair.• Poison the Ecosystem.

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Harmful effects of Radiations

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Reactors Worldwide

• Currently 441 nuclear power reactors in 31 countries.– Combined capacity of 363 gigawatts.– Provide 18% of world’s electricity.

• Currently 30 reactors under construction in 10 countries.

Nuclear Power Plant Life

• Normally, Nuclear Plant get a license of 40 years.

• After taking various ageing management plans the life of a plant can be extended upto 60 years.

• Researches for new monitoring techniques which may keep plant operation safely upto 80 years.

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What is Ageing?

• The International Atomic Energy Agency (IAEA) defines ageing as a continuous time-dependent loss of quality of materials, caused by the operating conditions.

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Effect of ageing

• Neutrons bombard the pressure vessel

Over period of years that bombardment can

cause reaction that displace atoms in the

material• Produce tiny voids• Reduce the metal’s toughness and its ability

to resist cracking

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Major Concerns

• Embrittlement• Cracking in the reactor pressure vessel and

its piping• Degradation of the concrete containment• Ageing Cables• Corrosion in burried water pipes

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Plans for managing ageing

• Aim: To provide for the timely detection and mitigation of significant ageing effects.

• Periodic inspection of pressure vessel, concrete containment structure, main pipes and cables.

• New monitoring techniques which are used to detect tiny voids or cracks.

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New Monitoring Techniques

• Acoustic Monitoring• Guided wave • Phased array• Diffused field

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Acoustic Monitoring

• When crack grows in metal, the rupture releases tiny pulses of acoustic energy

• In the same way as earthquake sends out seismic waves

• Sensors detect these waves and can monitor a developing flaw

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Guided wave

• Transducer generate ultra- sonic waves which propagate through metal pipe or the walls of pressure vessel

• Ultrasonic waves scattered provide indication of cracks or corrosion

• It wouldn’t require inspector to strip off insulation to inspect pipes

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Phased array

• In this technique a group of transmitters releases separate ultrasonic waves, which interact to form one larger wave front

• By controlling the timing and amplitude of the individual pulses,researchers can steer the wave front to scan a structure for flaws.

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Diffuse field• To monitor a coarse-grained material like

concrete, a single ultrasonic pulse is intro- duced into the materials.

• Receiver listen for the tiny echoes produced by the waves interactions with all the grains.

• To composite signal creates a distinct signature for that materials,which will change if the material degrades.

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Plant Life Extension

• These Engineering assessments have established many plants to operate much longer by managing its ageing effects.

• The life can be extended upto 60 years or even more.

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Some plants under extended life

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References

• “IEEE Spectrum” , pg no 24-29 , Aug 2012.• US ENERGY INFORMATION ADMINISTRATION, Annual

Energy Outlook 2001 with Projections to 2020, Rep. DOE/EIA – 0383 (2001), US (EIA) (2000).

• UNITED STATES- NUCLEAR REGULATORY COMMISSION, Licensing Renewal (2000) (Available at http://www.nrc.gov/nrc/reactor/lr/index.html).

• T. OTSUKA, “Current Status of Life Management Policies for Nuclear Power Plants Management in Japan”, IAEA Specialists Meeting on Strategies and Policies for Nuclear Power Plant Life Management, 28–30 September 1998.

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Thank You !!

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