[bvw]

That was at Twin Falls, Idaho.

[djf]

Yup. SL-1

But I just googled, it was Army, not Navy.

Pulled the rod out too far, it went critical from a normal nominal operating range of about half a megawatt, to over 20 gigawatts, in about a twentieth of a second!

[Bob]

That was at Twin Falls, Idaho.

If I'm not mistaken, that was the SL-1 research reactor in 1961. Three operators were killed by the accident. (This came up in a discussion on another thread.)