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Take a world bakcup and try disabling the Big reactors mod. If this does not work then check the backups folder in the sf2 instance and restore to the most recent backup.
I assume you are using the curse launcher. Set it use the jar launcher instead of the exe and change it to use the most recent java. Also make sure you have it installed.
The end of the log is missing can you post that.
There is an issue with veinminer and the pack maintainer Darkosto has contacted the mod author but he never got back to him.
In the 2.5.5 update, veinminer has been removed and replaceed with another mod.
Remove the pump, using mcedit, from line #39 of your log. Google is your friend for help with mcedit. If you are unable to do it then revert to a backup.