Saturday, November 26, 2016

Fusion Nuclear Reactors

When I attended the Naval Academy many many years ago, there were no electives, only selection of a language. Nuclear engineering was just coming into being.. There was one course and it really consisted of atomic structure because very little else was known..
Didn't pay too much attention to its progress until 1958, when I became employed by Sylvania Corning Nuclear that I became interested in nuclear engineering again. At that time I was hired by the Research Laboratory to work on refractory metal alloys and beryllium that would be part of the first nuclear reactor that would propel an airplane. The feature was that the plane would never have to land, and there would be merely an exchange of crews and supplies. Good idea, except no one considered the weight. When they did and found the idea impractical, I now believed that I was out of a job. Therefore I found employment in the beryllium industry that was also heavily involved in the growing nuclear industry. Not sure that all has been declassified so am not going there.
It was not long after that the concept for a fusion nuclear reactor was conceived. As I recall, Princeton University was active and still is a key player.In a simple sense the concept was to concentrate and accelerate neutrons within a field shaped by super conducting magnets to collide, react and create electrical energy for public consumption. This is a simplistic explanation because I am far from being a nuclear physicist. However I am interested in materials and they have been stumbling blocks to its development.
 I previously discussed Generation IV reactors, which are conceived for introduction between 2020 to 2030. Fusion nuclear reactors are still not conceived to come on stream until 2050.
Reasons for this still evolve around material development. Superconducting magnets are still not advanced as desired to concentrate and accelerate the neutrons.In addition, alloys that stand the elevated temperatures and neutron wall loading are still in the infant stage of development.
MagnaTech believes that we have little to contribute to the development of super conducting magnets. However, we do believe that we can assist in improvement of structural materials required to sustain the harsh environment and conditions imposed by reactions occurring at the walls. The environment consists of complex combinations of high temperature , high stresses, reactive coolants and extensive radiation damage.What this means is that alloys that have strength sufficient at operation at temperatures as high as 500 C at stress levels imposed in a highly reactive corrosive environment are needed. Candidate materials for the structural components include reduced activation ferritic martensitic steels that can be joined to form complex structures.In addition the surface must be resistant to corrosion attack from possible liquid coolants and from radiation degradation. A tall order, but MagnaTech believes that we have technology available that can resolve some of these anticipated problems. Therefore MagnaTech is seeking opportunities to partner with others to advance our concepts to resolve some of the material problems resisting the development of these advanced fusion nuclear reactors. MagnaTech would therefore be delighted to engage in dialogue with other companies that would be interested in advancing this technology.

Saturday, November 5, 2016

More Cncerning Three D Printing

Three-D printing has been making inroads into part manufacturing since the beginning of this century. The impetus for this progress is because we need to make parts faster and cheaper. If only one part of a kind, such as a forging die is needed, now it appears to be that Three-D printing is the way to go. Also, if a complex, thin walled part that is made of expensive material and much waste as chip or scrap is generated  form the part, then again Three-D printing may be the answer. I attended a show in New Jersey last week and  examples of parts were on exhibit that demonstrated both situations discussed above.
However, Three-D printing requires not only a precise computer engineered model to produce a complex part, but  also  either an electron beam or a laser to melt the particles deposited as fine incremental layers that are built to generate the volume of the part desired. These components are expensive and mandatory start-up expenses that cost $600,000 to $1,000,000.
Powders are also expensive in respect to wrought, cast or forged alloys .These powders are mostly gas atomized, requiring protection to minimize surface oxidation. As a result, depending on the powder size distribution required to distribute the thin layers for melting, these powders may cost as much as $100 per pound. Although, there are increasing numbers of gas atomized powder producers, alloy compositions are more limited as opposed to wrought compositions, which are readily available commercially.
Once a decision has been made that the cost and time saved is justified, then production of the part may also yield additional problems. First, thickness of the powder layer and the direction of the laser or electron beam required to melt the powder layer requires careful consideration or else porosity, contamination between layers  or inconsistency in chemistry may result. The part, if used in a critical application where safety and lives are at risk, must satisfy the physical and the mechanical properties of the wrought alloys already satisfying the properties required of the part for performance. In this case, almost a secondary operation, known as hot isostatic pressing is required to assure a pore-free structure. Additional heat treatment may also be necessary to provide a uniform microstructure rather than a non-uniform cast structure. Required properties of existing specifications must be assured.
In addition to the internal core properties, the surface of the part may also require careful consideration and modification. Most parts in service fail either from corrosion, fatigue, impact or wear. Therefore careful consideration of the surface is  required. Three-D parts normally have rough surfaces that require some modification to provide a desired surface finish. In addition, some surface modification may be required to protect the working surface from the environmental factors causing the part to corrode, fatigue, wear or fracture from impact.
As we have described, there is still much work to be accomplished before advanced manufacturing becomes competitive with current processing. However, at least two prime manufactures within the past week have become more committed to continuing development of the current processes. General Electric has a consortium in process whereby they are studying how these processes can be used in their applications, such as turbine engines, windmill construction and other areas as well. An off the road equipment manufacturer has also challenged innovators to come up with ideas that will increase the use of advanced manufacturing processes to reduce cost and time for production for three of the components that are used on their equipment. Yes, there is much interest in advanced manufacturing and MagnaTech believes that we can assist in overcoming currently troubling problems..