Bring a large pot, half full of water, to a boil. Add the salt, red pepper flakes, lemon, and shrimp. Boil the shrimp for five minutes , or until they're pink and firm. Remove the shrimp with a slotted spoon and drain them in a colander. Remove the tails.
Chop the shrimp into half inch pieces. Add them to a bowl along with the celery, onions, mayonnaise, and sriracha. Cover the bowl and refrigerate the shrimp salad for two hours.