Failures of Nuclear Reactors Materials

Under what conditions?

Materials in TMI-2 melted, but that was under extremely unusual conditions where the normal heat transfer mechanism was removed.

Under normal circumstances, the main problems are fatigue, 'normal' corrosion, intergranular stress corrosion cracking (IGSCC), irradiation-assisted stress corrosion cracking (IASCC), and erosion/corrosion. I don't believe there has been any strain-to-failure, and overload failures are usually preceeded by one of the corrosion/fatigue mechanisms mentioned.

The Minerals, Metals & Materials Society (TMS) has a special symposium devoted to environmental degradation of nuclear materials - Environmental Degradation of Materials in Nuclear Systems-Water Reactors. If possible try to locate the proceedings of this conference - the 12th (August 2005) is mentioned here http://www.tms.org/Meetings/Specialty/ED2005/home.html

 

Many materials change when in sitting in ionizing radiation/neutrons for a while.

Many plastics will become more brittle, others will become softer. Soap based greases will become more fluid like. Oils will become more viscous and gummy. Rubber loses strength. Plexiglass, styrofoam, teflon, nylon: all this type of stuff is majorly effected.

This makes selecting materials such as valve diaphrams or plastic solenoid valve internals very important.

Ductile to brittle transition temp raises when iron metels are subjected to neutron flux, meaning although the metal gains a higher ultimate strength, when it fails it will fail more like ceramics than soft metal. Also 'creep' effect is increased (tubes under pressure will elongate). This can be a major irritation for nuke plants.

 

As well as DHC, which hopefully today is not the problem it was.

 

For Candu's, probablility of DHC with the zirconium pressure tubes is minimized procedurally by moving through the 100-200 celcius range without delay on run up/run down. Above this temp the hyrogen goes into solution with the Zr, and as far as I understand, DHC will not occur. As well, it is shown that the pt's will leak before break, so early warning is seen, not to mention extensive inspection on shutdown. All this info is available publicly on the canteach.candu website, a great collection of info.

 

*chuckle*

Sorry, I just think it's really funny that the name "Homer Simpson" appears in a thread about failures of nuclear reactors. :rofl:

Carry on...

 

Yeah, I had the same reaction.

 

It's pronounced 'nucular'. Nucular.

 

Nope, I can only aspire to that level of greatness. My job title is valve turner and ticky box checker. I am also skill broadened in the area of Sump Level Maintenance.

 

Merry Christmas, Homer. I'm glad to see that you work at a nuclear power plant.

Happy New Year.

 

Not sure if it's just a joke, but OUR Homer Simpson also lives in a place called Springfield.

 

Merry Christmas and happy new year to You!! Thanks.



BTW:

He's OUR Homer Simpson!!! Eh!
http://ccr.ptbcanadian.com/simpsons/ [Broken]

 

"OUR" meaning the Homer that frequents physicsforums of course.