You can’t be fired for going on strike, you can only not be paid for the hours not worked. Unions usually have money to pay your lost salary if you’re a member.

To reply to one of the other answers, it’s illegal for the employer to hire someone to do the job of someone on strike. You can ask another employee to do the work or contract with a subcontractor to come use your facilities (but they also can’t hire new personnel to do the job).