The drawing shows a part of magnetic core, to be used in a central core leg of a shunt reactor. In such radially laminated core the laminations have varying lengths and are positioned radially, in wedge-shaped sections. Such arrangement is especially useful for reduction of flux fringing in laminated cores.
Several such radially laminated discs would be used for construction of single core leg, with the air gaps distributed between them.
The drawing was adapted from:
See also: 
radially_laminated_core_-_magnetica.png
You are permitted and indeed encouraged to use this image freely, for any legal purpose including commercial, and with any modifications (the permission is hereby given, so there is no need to ask for it explicitly again), but you MUST always give the following credits:
S. Zurek, Encyclopedia Magnetica, CC-BY-4.0
We would appreciate if you let us know of any use: info@e-magnetica.pl