Did a mysterious radioactive cloud originate from a nuclear powered missile?

Last October a mysterious radioactive cloud spread over Europe [1,2]. The source was traced to the Ural mountains between Russia and Kazakhstan. Although the amount of radioactive fallout in Europe was minuscule and harmless, there must have been a significant amount of radioactive material released at the source.

Today Putin announced Russia developed a nuclear powered missile with unlimited range [3]. The missile was reportedly tested in late 2017. Did Russia spew radioactive jet waste over their country during a field test of their nuclear powered missile?

News Sources:

1. https://www.npr.org/sections/thetwo-way/2017/11/10/563286253/mysterious-radioactive-cloud-over-europe-hints-at-accident-farther-east

2. https://www.washingtonpost.com/news/worldviews/wp/2017/11/21/that-harmless-radioactive-cloud-over-europe-did-come-from-russia-after-all

3. https://www.npr.org/sections/parallels/2018/03/01/590014611/experts-aghast-over-russian-claim-of-nuclear-powered-missile-with-unlimited-rang