What material stops a meltdown?

[Scar17s]

Hello all
A new phyisics guy here, with a question.
After a reactor meltdown, what material (Non burn through) is best material suited to contain the after-effects?
Besides lead.
Some say Earth that contains 45% clay.
I question that.
Please help
Thanks for your help and time

Bill
Just a simple, but always learning guy

 

[rootone]

I believe the metal Lead (Pb) is used quite a lot for shielding nuclear reactors.
Lead atoms can absorb a lot of stray neutrons by turning into other isotopes of Lead that are not very radioactive,

 

[Scar17s]

I am sorry I forgot to say besides lead. I will now edit my post ty

 

[Astronuc]

After a reactor meltdown, what material (Non burn through) is best material suited to contain the after-effects?

Well, ideally, a molten core does not breach the reactor pressure vessel, as was the case in the accident at TMI-2. In the case of Chernobyl, molten fuel did escape the vessel, and at Fukushima, we do not know, but it is speculated that some melting of two or three cores took place, and some escape the RPVs.

The new Gen-III+ designs do consider 'core catchers' to varying degrees. Notably, AREVA's EPR has a 'core catcher' design, although the composition of the particular material is not published.

Argonne National Lab (ANL) has done an evaluation of a code used to simulate a core catcher.
https://www.nrc.gov/docs/ML0909/ML090960360.pdf Reference 20 and 21 refer to studies of materials.

20. M. Sappok and W. Steinwarz, “COMAS Experiments as Contribution to the Validation of the EPR Mitigation Concept for Core Melt Accidents,” 6th International Conference on Nuclear Engineering (ICONE-6), San Diego, California, May 10-15, 1998.

21. W. Steinwarz, A. Alemberti, W. Häfner, Z. Alkan, and M. Fischer, “Investigations on the Phenomenology of Ex-Vessel Core Melt Behavior (COMAS),” Nuclear Engineering and Design, Vol. 209, pp. 139-146, 2001. (requires purchase)

See also - Experimental results on concrete-melt-interaction within the large scale COMAS project
( M. Sappok, W. Steinwarz, E.P. Warnke and G. Langer)
https://www.iasmirt.org/transactions/14/P03-2

Ideally, the material has a high melting point and minimal chemical reactivity. Insulation materials used in foundries might be applicable. Also, to ensure subcriticality, some amount of borates may be incorporated. Graphite would work as a sub-base material. A geometry that separates the flow into smaller flows may be employed. There would be also the issue of how much water would accompany the core melt into the catch vault.

 

[Scar17s]

Thank you all for taking the time to respond.
I learned i have stage 4.
So this post really doesn't matter anymore.
I wish you all peace and to live out your lifes to the absolute fullest you can.
I want to challenge all of you to do your absolute best to make life better

 

[jim hardy]

Sorry to hear about your condition.

Since you're interested in the subject of "Core Catchers" , look into Boron Nitride refractory material. I once toured a factory in Niagara Falls that makes the stuff and suggested they inquire of my industry if it's plausible.

A ceramic that's heat tolerant and absorbs neutrons? Sounds logical to me . Tile the floor with it .

 

[Scar17s]

Sorry to hear about your condition.

Since you're interested in the subject of "Core Catchers" , look into Boron Nitride refractory material. I once toured a factory in Niagara Falls that makes the stuff and suggested they inquire of my industry if it's plausible.

A ceramic that's heat tolerant and absorbs neutrons? Sounds logical to me . Tile the floor with it .

My Boron Nitride question is the crystal or hexagonal crystal family would infact leave gaps?
Maybe I am wrong here. Maybe multiple layers are used here?
Please explain further as the properties Boron Nitride is extremely interesting.
Please only respond if you have the free time to do so.

I wish not to take away valuable time from anyone. As just a student that recently dropped out I don't deserve more than that
As for me. Well my life happenings opened up a congeries of time
Thank you for posting! Jim

 

[jim hardy]

My Boron Nitride question is the crystal or hexagonal crystal family would infact leave gaps?
Maybe I am wrong here. Maybe multiple layers are used here?
Please explain further as the properties Boron Nitride is extremely interesting.

I know little about the material.
My father-in-law was a ceramic engineer. While showing me his plant (circa 1973) we went by one of the lines making Boron Nitride yarn . They melted it at extremely high temperature in an arc furnace and poured it past a steam jet that blew it into a fine fiber to weave into bulletproof cloth for body armor. (Whew! Run on sentence or what? )

I suggested to him the neutron absorbing properties of the solid ceramic could have application in my industry.
Boron 10 isotope which is about 20% of natural boron enthusiastically absorbs neutrons so it will shut down a critical reactor core.
It is a refractory material too, can be used for boiler insulation.
http://www.matweb.com/search/datasheettext.aspx?matguid=848d69d6dd3d49c1860e10300636edbb

Momentive Performance Materials BNC2 Boron Nitride (BN) Refractory Composite

Categories: Ceramic; Nitride
Material Notes: Boron Nitride is a unique engineering material. It is a soft, machinable ceramic which can be combined with other refractory ceramics including Aluminum Oxide, Silicon Nitride, Aluminum Nitride, Mullite and Titanium Diboride. This results in composites which are machinable, thermal shock resistant, and chemically compatible in a wide range of environments. In combination with Titanium Diboride, for example, BN can be used as a heating source for the aluminum metallization of films and papers. BN composites are also used as break-rings in the horizontal continuous castings of steel and nozzles in rapid solidification processes. Other composite applications include the following:

• High temperature refractory shapes
• Glass forming tools and refractories
• Molds, dies and refractories for metalforming
• Furnace vents, stacks and fixtures

Grades BNC 1 & 2 offer excellent corrosion and wear resistance, have excellent thermal shock capability and low CTE, are non-wetting and are self lubricating.

Information provided by Momentive Performance Materials, formerly GE Advanced Ceramics.

Vendors:

Seemed to me a practical material for a "Core Catcher" underneath a reactor.
Gaps and crystal structure won't matter to neutrons, only the presence of boron atoms. Ceramic engineers would pick whatever form gives best mechanical properties at high temperature.

old jim

 

[Andy SV]

I think a tungsten plate sitting on a copper slab with a tin liner between them
My reasoning being that the corium will not melt the tungsten and will spread across like a pancake the zink will allow for more heat retention making for a thinner corium cake and will then melt letting the tungsten sheet settle down on the copper slab.The copper will of course cool things down with massive heat conduction. And as for what to put on top, Tuns and tuns of sand.