Early US Intel assessment suggests strikes on Iran did not destroy nuclear sites

You don’t need to be a genius to figure out that centrifuges installed 70–80 meters underground will be largely unaffected by bombs which are believed to have an effect down to a depth of 60 meters.

Really? I think calculating the achieved overpressure to whatever structure underground after 6x 30k pound bomb impacts is far into the “genius” category. I’d wager you’d need a team of pretty smart people to even begin to get a wrong model of that.

No genius needed, but all those involved are motivated to lie about it. The bombs have a depth range and 200ft (60m) is the optimistic depth for ideal conditions. These were far from ideal conditions as the location was specifically chosen to resist this. That and ultra high performance concrete is now a thing. This is why the entrance and exists were bombed and those are easy enough to dig back out again. The attack was telegraphed so advanced preparations were made. It is rumored that the entrances and exits were packed with dirt in advance to minimize the damage.

I wonder why the US wouldn't lie about the effective depth range. Seems kinda dumb to telegraph to your enemies how far to dig.

It's a pretty dumb ordnance, gravity delivered GBU57 is a physics bound problem. The dimensions etc are known, you can give it the most optmistic assumptions, i.e. complete steel for max penetration, release at altitude where it reach max terminal velocity without grid fins deployed, run that through ndrc/young pentration equations etc. There aren't any super secret parameters for subterfuge like electronic warfare. Eitherway there's public videos of GBU57 in action - grid fins deployed to hit a traffic cone - defense autists counted frames, did napkin math, it's more or less what's purported ~ mach 0.8-1.2 penetrator designed for ~60m concrete. IIRC the assume sphere cow math for heavier all steel, no grid fin (i.e. not accurate), max out at mach ~2, doubles energy, penetrates ~80m.

On the other hand, Fordow's construction time is known... as far as I know, many years before fgcc / uhpc and other "advanced" concrete formulas PRC formulated against US penetrators. And Israel probably has entire blue print, so who knows. E: quick lookup and GBU57 seems to be revealed shortly after guestimate of when Fordow started construction, possible Fordow could update design in anticipation, but then again, B2s were known entity and Iran's engineers can probably guestimate out what the maximum size/weight penetrator US could deliver on B2s before knowing GBU57 existed.

What if it has some sort of a booster to increase its kinetic energy just before the hit?

Also the behavior might improve in an area already weakened by a ventilation shaft/previous hit (first bomb turns 40 meters into fine gravel + detonates weakening quite a large are, second and third bomb easily go deeper)