She takes the vest off in defiance of rules because it is inhibiting her performance of some urgent task? That's usually how on-job injuries happen with machines: even if machinists are required to wear gloves, one will inevitably get frustrated with fumbling because of the gloves and take them off "just for a second, until I get this done". Next thing you know, there's a thumb somewhere on the ground. This also sounds like something Solveig would do. People of her personality type really do half believe that they are invincible sometimes.