Well, I’m not going to say you’re wrong, since I don’t know. But here is a webpage that discusses it. Says that each reactor has 144 metric tons of uranium oxide:
http://yeswaterisfuel.com/2011/03/24/amount-of-radioactive-material-at-fukushima/
I am not sure how that converts into U235. I suspect your number is the amount of radioactive water on the site. That’s really a different animal because the lighter radioactive elements like iodine, tritium, strontium, etc. have shorter half-lives (8 days, 12.3 years, and 28 years respectively, I believe).
Irrespective, though, there is a big difference between uranium that is located in a reactor and uranium that is spread over the countryside because an a-bomb went off. Apparently even spreading it over the countryside does not make the land uninhabitable for 10,000 years, as demonstrated by Hiroshima, Nagasaki, as well as all of the nuclear tests that have been done over the years.
The spent fuel pools are of significant concern, Marvin Resnikoff, a radioactive waste management consultant, said in a Wednesday press briefing organized by the nonprofit organization Physicians for Social Responsibility. Resnikoff noted that the pools at each reactor are thought to have contained the following amounts of spent fuel, according to The Mainichi Daily News:
• Reactor No. 1: 50 tons of nuclear fuel
• Reactor No. 2: 81 tons
• Reactor No. 3: 88 tons
• Reactor No. 4: 135 tons
• Reactor No. 5: 142 tons
• Reactor No. 6: 151 tons
• Also, a separate ground-level fuel pool contains 1,097 tons of fuel; and some 70 tons of nuclear materials are kept on the grounds in dry storage.
The reactor cores themselves contain less than 100 tons of fuel, Resnikoff noted.
http://www.scientificamerican.com/article.cfm?id=nuclear-fuel-fukushima
This web site has a chart of what it claims is the total weight of fuel in the fuel pools; based on a weight of 170kg per assembly. The pools contain multiple loads, so it's clear the reactors didn't have that much fuel. Also reactor one is smaller than the others, so it has less fuel.
Also, less than half the mass of a fuel rod is uranium.
This site says there is .127 tones per assembly, which is 127 kg. It also says there are 534 assemblies per core in 2 and 3, and half that (267) in reactor 1. That's 68 tons total for reactor 2 and 3, and 34 tons for reactor 1.
Like I said, every site has a different number, but no reputable site I've seen has a number as high as 144.