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Home > NRC Library > Document Collections > NUREG-Series Publications > Staff Reports > NUREG 0933 > Section 3. New Generic Issues- Issue 38: Potential Recirculation System Failure as a Consequence of Ingestion of Containment Paint Flakes or Other Fine Debris (Rev. 2)

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 1–35 )


Historical Background

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.

Safety Significance

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.

Possible Solution

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.


0011. NUREG-0800, "Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants," U.S. Nuclear Regulatory Commission, (1st Ed.) November 1975, (2nd Ed.) March 1980, (3rd Ed.) July 1981.
0496.Memorandum for H. Denton from C. Michelson, "Concerns Relating to the Integrity of a Polymer Coating for Surfaces Inside Containment (IE Draft Bulletin No. 80-21)," August 29, 1980. [8210120370, 8009110599]
1057.NUREG-0897, "Containment Emergency Sump Performance," U.S. Nuclear Regulatory Commission, (Rev. 1) October 1985.
1058.Regulatory Guide 1.82, "Water Sources for Long-Term Recirculation Cooling Following a Loss-of-Coolant Accident," U.S. Nuclear Regulatory Commission, June 30, 1974 [7902090041], (Rev. 1) November 30, 1985 [8512100138], (Rev. 2) May 31, 1996 [9605210504].
1059. Letter to All Licensees of Operating Reactors, Applicants for Operating Licenses, and Holders of Construction Permits from U.S. Nuclear Regulatory Commission, "Potential for Loss of Post-LOCA Recirculation Capability Due to Insulation Debris Blockage (Generic Letter 85-22)," December 3, 1985. [ML031150731]
1332.NUREG-0797, "Safety Evaluation Report Related to the Operation of Comanche Peak Steam Electric Station, Units 1 and 2," U.S. Nuclear Regulatory Commission, (Supplement 9) March 1985.
1564.Memorandum for W. Russell from E. Beckjord, "License Renewal Implications of Generic Safety Issues (GSIs) Prioritized and/or Resolved Between October 1990 and March 1994," May 5, 1994. [9406170365]