Cut peppers in half lengthwise; remove and discard seeds and membranes. Cook peppers in boiling water to cover 5 minutes. Drain.
Cook orzo according to package directions, omitting salt and fat. Drain well.
Coat a large nonstick skillet with cooking spray; place over medium heat until hot. Add turkey, onion, and celery; cook until turkey is browned, stirring until it crumbles.
Place turkey mixture in a large bowl. Add orzo, raisins, and next 9 ingredients; stir well. Spoon turkey mixture evenly into pepper halves.
Place pepper halves in a 15- x 10- x 2-inch baking dish. Pour chicken broth into dish around peppers. Bake, uncovered, at 350° for 30 minutes or until thoroughly heated.