This is a really short story, one page at most.
A man invents a portable device that creates an impenetrable force field.
To test it, he sneaks into a nuclear test site, and
the force field resists the nuclear blast, but the force of the explosion throws the inventor off the planet.
As additional information, something in the wording of the title of the story made me think that it may be part of a series or a chapter of a larger work.