05000282/FIN-2010002-05
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Finding | |
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Title | Licensee-Identified Violation |
Description | Licensee Procedure D52, Installation Guidelines for the Permanent and Temporary Sealing of Electrical/Mechanical Openings Between Established Fire Areas, establishes requirements for the implementation of fire watches for temporary fire penetrations. Contrary to the above, on September 13, 2009, the between the 11 and 12 battery rooms. The licensee reported this event to the NRC on December 21, 2009, pursuant to 10 CFR Part 50.72(b)(3)(ii)(B). The licensee initially documented this issue in LER 05000282/2009-007-00 and 05000282/2009-007-01. The inspectors performed a Phase 1 evaluation in accordance with IMC 0609, Appendix F with the finding screening to a delta core damage frequency greater than or equal to the corresponding value in Table A1.1. A regional fire protection specialist and a senior reactor analyst performed a Phase 2 evaluation of the safety significance associated with this issue. The inspector and the analyst conservatively did not credit the penetration as a fire barrier. The inspectors noted that the breached five-inch penetration was located close to the ceiling and that the equipment important to safety (i.e., the batteries) was generally located at the floor level. As such, the inspectors determined that hot gases from the room involved in a potential fire entering the exposed room through the penetration would be well above the equipment important to safety and would not impact it. The inspectors determined that a fire involving the cable which passed through the penetration would have to travel a minimum of five feet along the cable before coming into contact with any equipment important to safety. Based on review of IMC 609, Appendix F, Attachment 3, Guidance for Identifying Fire Growth and Damage Scenarios, the inspectors determined that potential damage to equipment important to safety would not occur for at least 30 minutes (due to a fire spread rate of 10 feet per hour). Based on review of IMC 609, Appendix F, Table 1.4.1, Duration Factors, the inspectors determined that the duration factor associated with this issue was 0.1. Using IMC 609, Appendix F, Fire Ignition Source Mapping Information: Fire Frequency, Counting Instructions, Applicable Fire Severity Characteristics, and Applicable Manual Fire Suppression Curves, the inspectors determined that potential ignition sources included hot work and transient fuels with ignition frequencies, F, of 2.3 10-5 (Hot Work Low) 1.7 10-4 (Transient Fuels Medium), respectively. Based on review of Table 2.7.1, Non-suppression Probability Values for Manual Fire Fighting Based on Fire Duration (Time to Damage after Detection) and Fire Type Category, the inspectors determined that the values for Probability of Non-Suppression were 0.11 and 0.017 for hot work and transient fuels, respectively. The inspectors conservatively assumed that the conditional core damage probability associated with the scenario was 1.0. Based on review of Step 2.9, Quantification and Preliminary Significance Determination, of IMC 609, Appendix F, the inspector determined the change in core damage frequency was 2.53 10-7 per year for the contribution from hot work and 2.89 10-7 per year for transient fuels with ignition frequencies with a combined contribution of 5.42 10-7. This is representative of an issue having very low safety significance |
Site: | Prairie Island |
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Report | IR 05000282/2010002 Section 4OA7 |
Date counted | Mar 31, 2010 (2010Q1) |
Type: | NCV: Green |
cornerstone | Mitigating Systems |
Identified by: | Licensee-identified |
Inspection Procedure: | |
Inspectors (proximate) | A Dunlop D Mcneil B Palagi M Phalen K Stoedter P Zurawski D Betancourt J Giessner |
INPO aspect | |
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Finding - Prairie Island - IR 05000282/2010002 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Prairie Island) @ 2010Q1
Self-Identified List (Prairie Island)
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