[dr_lew]

The collapse proceeds to efficiently compress the star's core; the overpressure is sufficient to allow runaway nuclear fusion to burn it in a few seconds, creating a thermonuclear explosion.[6]

6: Fryer, C.L.; Woosley, S. E.; Heger, A. (2001). "Pair-Instability Supernovae, Gravity Waves, and Gamma-Ray Transients". The Astrophysical Journal 550 (1). arXiv:astro-ph/0007176. Bibcode:2001ApJ...550..372F. doi:10.1086/319719

[FredZarguna]

I'm quite aware of what it is. [But thanks for the reference.]

But my point was, it's not a nuclear fusion from what are ordinarily considered nuclear reactant candidates in terrestrial fusion projects.

My understanding is that pair-production collapse only occurs in post-Helium stars. A citation by two of the same investigators of more recent vintage, I believe, says oxygen fusion chain reactants are in play at this point in the star's life:

a b Kasen, D.; Woosley, S. E.; Heger, A. (2011). "Pair Instability Supernovae: Light Curves, Spectra, and Shock Breakout" (pdf). The Astrophysical Journal 734 (2): 102. arXiv:1101.3336. Bibcode:2011ApJ...734..102K.