A storable gas inflation/evacuation system and sealing system. The systems are removably connectible to a proximal portion of a guidewire assembly which has an occlusive balloon at a distal portion. The invention includes provision for indicating the presence of oxygen which is undesirable. The storable aspect concerns a sealable container isolating systems components from ambient atmosphere and an oxygen-sensitive material located within the sealable container. The oxygen-sensitive material is initially inactive but activated by exposure to radiation so as to visually change in response to post-radiation oxygen exposure.