How to define boundary condition of a ball?

I have used (r, theta, phi) as the parameters in PDE.
And my boundary condition is f(r=1) = 1.
I have set the periodic boundary conditions in configure the net arch by periodicity={"y": (0,2*np.pi), "z": (0,np.pi)},.

However, I don’t know how to configure the boundary condition at r=1.

Currently I use the following method, but it seems don’t work.

    bc = PointwiseInteriorConstraint(
        outvar={"u":1/(24 * x)},
        bounds={x: (0.99999, 1), y: (0, 2*np.pi), z: (0, np.pi)},