Cook noodles according to package directions.
Drain tuna and set aside.
Cook onion, green pepper, red pepper, celery in butter in a large skillet till veggies are tender.
Whisk in flour, combining with butter. Cook for 1 minute.
Whisk in milk until sauce is well combined. Cook over medium heat until sauce begins to thicken.
Season sauce with salt and pepper.
Combine cooked noodles, tuna and sauce.
Pour into greased casserole dish.
Top with crushed chips.
Bake 350 for 20-25 minutes or until hot and bubbly.