On September 5, 2013 at or about 11:15 a.m. CT, a release occurred from Respondent's facility of approximately 63 pounds of chlorine gas (the release). Respondent had knowledge of the release on September 5, 2013 at approximately 5:00 p.m. CT. Respondent notified the NRC of the release on September 6, 2013 at approximately 9:34 a.m. CT. Respondent did not immediately notify the NRC as soon as Respondent had knowledge of the release. Respondent's failure to immediately notify the NRC of the release is a violation of Section 103(a) of CERCLA. The civil penalty was determined to be $12,230 to be paid in two installments with interest: $6,122.13 within 30 days of the effective date of this CAFO and $6,118.57 within 60 days of the effective date of this CAFO. Both payments have been made, and the case has been closed.