Resolution of Generic Safety Issues: Issue 38: Potential Recirculation System Failure as a Consequence of Ingestion of Containment Paint Flakes or Other Fine Debris (Rev. 2) ( NUREG-0933, Main Report with Supplements 1–34 )
This issue was identified496 when AEOD expressed concerns about the use inside containment of a particular polymer coating that could flake off and fail when subjected to DBA conditions. In addition to the concern for paint flakes, AEOD also raised concerns about fibrous insulation and other debris that could pass through sump screens, but could not pass through the more restrictive clearances present in systems that take suction from the containment sump during the recirculation phase of accident mitigation.
Potential safety concerns stemming from the presence of paint debris in the containment building during a LOCA include the following: (1) blockage of containment emergency sump debris screens; (2) blockage of containment building spray system nozzles and system flow passages associated with residual heat removal/safety injection systems and their equipment; and (3) degradation of ECCS performance by the entrainment of fine particles of paint debris. This issue is applicable to all plants.
In the resolution of Issue A-43, the staff evaluated the performance of the containment emergency sump in providing a clean, reliable source of water during a LOCA and during long-term recirculation following a LOCA. Specifically, the evaluation included analysis of the transport of fine debris.
In its application to operate Comanche Peak Steam Electric Station, Units 1 and 2, Texas Utilities Electric Company (TUEC) performed an analysis in support of its request to amend its FSAR to eliminate the commitment that coatings inside the reactor containment building be qualified. This analysis considered the potential for, and effects of, debris blockage of the containment building emergency sumps. TUEC followed the guidance and methodology developed by the staff in the resolution of Issue A-43 and concluded that debris generated by the failure of all coatings inside the containment building under DBA conditions would not unacceptably degrade the performance of post-accident fluid systems. The staff's SER on the TUEC analysis was published in Supplement No. 9 to NUREG-0797.1332
The general concerns of sump blockage were addressed in the technical findings reported in NUREG-0897,1057 the revisions to Regulatory Guide 1.82,1058 SRP11 Section 6.2.2, and Generic Letter 85-22.1059 The TUEC analysis provided data1057 on the significance of containment sump blockage caused by paint flakes or other fine debris. Thus, this issue was DROPPED from further consideration as a new and separate issue. In an RES evaluation,1564 it was concluded that consideration of a 20-year license renewal period did not change the priority of the issue.