Sir.
I had a Aunt and Uncle that had a walnut grove. I helped pick up walnuts as a kid and shucked walnut hulls in the winter. Helped cut and stack wood. I remember it took several years to dry. They burned walnut in a open fireplace. They had fruit trees also, and a pine grove. Burned all of it.
They died of old age so I guess burning the walnut did them no harm.

Bill@Yuma