What's the story Behind BSD-3-Clause-No-Nuclear-Warranty

Considering that BSD is already a warranty free license, what the goal of the No-Nuclear-Warranty clause?

What I can guess is that it's a trick to keep the license "Free" (contrary to the No-Nuclear-License clause) but still, practically, prevent using it in any nuclear plant project since strict technical and legal conformance are required.

Does any one have a clear historical explanation of why those 2 licenses (Nuclear-Warranty and Nuclear-License) were created and what was the goal of each?

Cf: https://spdx.org/licenses/BSD-3-Clause-No-Nuclear-License.html https://spdx.org/licenses/BSD-3-Clause-No-Nuclear-Warranty.html https://spdx.org/licenses/BSD-3-Clause.html