PLANT OPERATOR, WAS USING A 6' SPUD BAR TO CLEAN OFF CAKED MATERIAL ON TOP OF THE R107 REACTOR. WHILE POKING WITH THE BAR HE NOTICED A PAIN IN HIS LOWER RIGHT BACK. HE CONTINUED WORKING THROU GHOUT THE WEEKEND AND BY 8/25/03 THE BACK PAIN GOT BAD ENOUGH FOR HIM TO SEEK CHIROPRACTIC HELP. THIS WAS REPORTED TO THE COMPANY ON 8-27-03 AND VERIFIED TO THIS ACTIVITY.