"Fools dwelling in darkness, but thinking themselves wise and erudite, go round and round,
by various tortuous paths, like the blind led by the blind."

Chapter II Verse 5
Katha Upanishad

a total of somewhere between 20 trillion and 40 trillion becquerels of radioactive tritium have gotten into the Pacific Ocean since the Fukushima disaster first began

Perhaps the radiation is from coal burning in asia.

"Releases in 1982 from worldwide combustion of 2800 million tons of coal totaled 3640 tons of uranium (containing 51,700 pounds of uranium-235) and 8960 tons of thorium.
For 1982 the total release of radioactivity from 154 typical coal plants in the United States was, therefore, 2,630,230 millicuries... Global releases of radioactivity from the predicted combustion of 637,409 million tons of coal through 2040 would be 2,721,736,430 millicuries."
http://web.ornl.g...ain.html

-Not to mention all the conventional pollution, mercury, heavy metals and such, which end up in the oceans and could account for your dead fish and sick seals..

Why not convert all that stored radioactive water into concrete and pile up those concrete blocks, conveniently sheltered? Concrete blocks do not leak and have no problems with earthquakes... They will slowly leach over time, but more controllably than liquid water.

I would call it a cheap, fast and proven immediate (although not definitive) solution and an improvement over the current situation.

In time (20 years or more), these blocks can be put in a geological repository, together with high activity waste.

Only a little research shows that your idea is not original.

"Soluble salts, primarily sodium nitrate (similar to fertilizer), make up about 93 percent of the 37 million gallons of material in the radioactive waste storage tanks...

"This salt solution will be treated to remove cesium and strontium. These two contaminants are sent to the Defense Waste Processing Facility, where they are combined with the sludge, turned into glass and poured into canisters...

"...the salt solution is mixed with cement, fly ash and blast furnace slag to form grout. The grout is then pumped into large concrete vaults divided into sections (called cells); here, it cures into stable concrete (called "saltstone")."