Angel Natavi
What version of Bryce are you using?
Before V6.0, Bryce couldn't export primitives.

V6. + can export any object except metaball constructs (trees, and objects made with at least some metaballs). Boolean objects need to be (C)ollapsed to export. After you (C)ollapse the object, 'Export Object" will be allowed in the file menu. The wireframe resolution of the selected object controls polygon counts for the mesh made from the collapsed boolean object.

EDIT - Save your file before collapsing!
 
Single primitives have to booleaned with something, so just make a cube (negative) and shrink it way down, put it inside a sphere (or whatever, positive), Group, (C)ollapse, then you can export from the file menu.

Friends don't let friends use booleans.