Brown ground chicken in a non-stick skillet and set aside. Drain any fat. Spray a large non-stick Dutch oven or pot with cooking spray and heat to high. Sauté onion 3 minutes. Add the red and green peppers, celery and garlic, continue to sauté for another 3 minutes. Add the tomato paste and heat 1 to 2 minutes, stirring continuously. Pour a little chicken broth (1/4 cup) or water into the pan to deglaze it. Mix the ground chicken with the vegetable mixture and add the tomatoes with their juice, beans and chili powder. Simmer uncovered until chili reaches your preferred consistency and then cover and continue cooking for 2 to 3 hours. Add the black pepper and adjust seasonings to taste