It is well known that waves in excitable media, such as pulses propagating on a nerve axon or expanding rings in 2-dimenshional chemical reaction-diffusion (RD) systems, can annihilate one another upon collision. It has been long believed that any stable traveling pulse rising in a two component excitable RD system with one critical point possesses annihilation property. We present a two component RD model of such a system with a simple exothermic reaction process and show that when the propagation velocity is very slow, 1 dimensional traveling pulses repel one another and 2 dimensional expanding rings no longer persist and break down into complex patterns by using computer assisted analysis.