Was there a design flaw in the fuel tanks of the MiG-15/17/19/21? Wikipedia article on MiG-15:


  Another major design deficit was that the tank could develop under-pressure if more than half the fuel had been used, which could easily lead to tank implosions, destroying the aircraft.


MiG-17:


  Like its forebear, the MiG-17 inherited the major design deficit which could cause the fuel tanks develop to under-pressure if more than half the fuel had been used, which could easily lead to tank implosions, crushing the main fuselage of the aircraft mid-fight, with almost always fatal results.


MiG-19:


  Initial enthusiasm for the aircraft was dampened by several problems, the most alarming inherited from MiG-15/MiG-17 was the danger of mid-air tank implosions when more than half of the fuel had been used - the leaking fuel of the crushed fuselage fuel tanks located between the engines would then ignite, leading to a fatal explosion;


MiG-21:


  Additionally when more than half the fuel was used up, violent maneuveurs prevented fuel from flowing into the engine, thereby causing it to shutdown midflight.3 and risking tank implosions (a problem inherited from MiG-15/MiG-17 and MiG-19).


None of these entries has a citation.

I would like to know if these aircraft really did have a design flaw in the fuel tanks, and if so, what was it? What was wrong with the tank that made it susceptible to implosions once more than 50% of fuel was gone?
I found a reference to exploding fuel tanks on Mig-21's caused by overheating engines.

 "it had an unfortunate tendency to explode in mid-air. The problem was finally traced to a fuel tank placed under the engines that could cook up when the engines overheated."


  Like its forebear, the MiG-17 inherited the major design deficit which
  could cause the fuel tanks develop to under-pressure if more than half
  the fuel had been used, which could easily lead to tank implosions,
  crushing the main fuselage of the aircraft mid-fight, with almost
  always fatal results.


Tank implosion implies negative tank pressure. Under pressure or negative pressure is caused by improper fuel tank venting.

High pressure pumps sucking fuel out of an improperly vented tank can quickly develop negative pressure which can cause a tank collapse. If the tank was integral to the fuselage it could also cause an airframe failure. A collapsed tank could also leak fuel which could lead to catastrophic failure if the fuel found an ignition source.