Radiation Damage In metals from Gamma rays

[Sebastiaan]

From my understanding gamma rays can damage metal, making it brittle. Fortunaly, this appears to be little, but sill if you have a lot (like in p-D fusion) it becomes a serious hazard. The question is, how much? Specificly I need to know how much damange it does in compairison to Neutron radiation damage. For the sake of argument we asume the worse case scenario that all gamma radiation is absorbed, now how much will it weaken Metal compared to high energenic neutrons (> 1 MVe).

 

[Astronuc]

Gamma rays do a lot less damage (displacements and displacement cascades) than neutrons of comparable energy.

This may help - http://holbert.faculty.asu.edu/eee560/RadiationEffectsDamage.pdf

Gamma heating is an effect.

 

[Sebastiaan]

I still wasn't able to get any numbers I can use. I know it's a lot less, but I need some estimation of order of magnitude. Something like Gamma radiation causes 0.1% of the damage of Neutron radiation.

 

[PopeAtom]

I think the results will vary for different types of metals. And if there is a relationship between the damage of neutron and gamma rays it would also vary i assume.
Maybe if you can determine the dose rate of the different types of particles and compare that.

 

[mathman]

The fundamental difference is that neutrons interact with nuclei (resulting in transmutation) while gamma rays interact with electrons (where the effect is between atoms).

 

[Astronuc]

Neutrons actually knock atoms of their lattice positions, and we refer to displacements per atom (dpa), which has been correlated to microstructural changes in various alloys, in addition to the transmutation.

Gamma rays basically ionize metals and effectively increase the electron temperature, but not the so much the temperature of the atoms.

 

[Sebastiaan]

Does this mean all damage from gamma rays on solid metal can be ignored?

 

[PopeAtom]

From my experience i would say so for real world applications with regard to brittleness ( if brittle is a damaging characteristic ). In most cases as Astronuc said , heat will be produced and this mechanism will usually anneal the brittleness effect out of the metal.

 

[Sebastiaan]

Well the intended purpose is not real world application but for hypothetical application with Gigajoules worth of gamma radiation being emitted.