In a mixing bowl, combine the cooked chicken, diced celery, halved grapes, mayonnaise, mustard, salt, and black pepper. Mix well until all ingredients are evenly coated.

Lay a tortilla wrap on a flat surface. Spoon a generous amount of the chicken salad mixture onto the center of the wrap.

Fold the sides of the wrap over the filling and then roll it up tightly from the bottom to the top.

Repeat with the remaining wraps and chicken salad mixture.

Slice the wraps in half and serve immediately, or wrap in foil for a portable meal.