IAWC FAILED TO IMMEDIATELY REPORT TWO SEPARATE RELEASES OF CHLORINE TO THE NRC. VIOLATION OF SECTION 103 OF CERCLA AND 304 OF EPCRA- COMPANY FAILED TO REPORT RELEASE OF A REPORTABLE QUANTITY OF CHLORINE TO THE NATIONAL RESPONSE CENTER ON 2 SEPARATE DATES. DURING ROUTINE MAINTENANCE ROUNDS OF 2/12/1998 AN EMPLOYEE DISCOVERED THAT THE VACUUM REGULATOR ON ONE OFTHE CHLORINE TANKS WAS CHATTERING, AND ALSO NOTICED A CHLORINE SMELL IN THE ROOM. THE EMPLOYEE HIT THE REGULATOR TO STOP IT FROM CHATTERTING AND ALSO NOTED THAT THE CHLORINE ALARM SYSTEM WAS NOT WORKING. THE NEXT MORNING WHEN THE EMPLOYEE ARRIVED AT THE FACILITY HE SMELLED CHLORINE AT THE GATE. HE CALLED FOR BACK UP AND ALONG WITH A CO-WORKER EVENTUALLY MITIGATED THE RELEASE. THE SAME REGULATOR VALVE MALFUNCTIONED AND WAS REPLACED. IAWC DID NOT NOTIFY THE NRC OF THE 2/12/1998 RELEASE AND NOTIFIED THE NRC OF THE 2/13/1998 RELEASE SEVERAL HOURS AFTER IT OCCURRED.