A VERY successful way to not only defrost but rehydrate frozen shrimp . . .
I learned this process years ago from Fine Cooking or one of those erudite rags. . . sounds complex but is actually a walk in the park.
In a large stock pot, bring a quart of water to boil, remove from heat and stir in 3 cups of kosher salt.
When the salt dissolves, add 3 quarts of room temperature water to the pot, looking to take the pot of water's temperature to around 70 degrees F.
Then, place a 5lb block of frozen shrimp in the pot and let it sit for 45 minutes to an hour. The block will fall apart and the shrimp will separate. Drain and double-rinse the wee suckers, cook and eat as planned.
Shrimp brined in this manner (unless they're TINY)have always turn out plump and delicious.