Pre-Service Inspection and Testing (Concrete)

The pre-service (CC-5000) and in-service inspection and testing requirements for concrete containments (both reinforced and unbonded post-tensioned) are given in Subsection IWL-1000 of ASME Section XI of the Code. This section does not include requirements for bonded (grouted) tendons. This section should be used together with Subsection IWA for General Requirements to ensure structural and leak-tightness of the containment. Subsection IWE applies to containment liner (see discussion on steel containments in Section 3.2.7). USNRC RG 1.90 provides guidance for in-service inspection of prestressed concrete containments with grouted tendons (Fig. 3.3).

The pre-service inspection and testing is used to establish a successful start and to serve as a baseline for inspection and testing during operational service of the containment. The pre-service examination includes 100% of the concrete surfaces of the containment and post-tensioning system based on plant construction record. Pressure integrated leak rate testing (ILRT) or local leak rate testing (LLRT) is carried out per Appendix J of 10CFR Part 50 which provides containment leakage testing in terms of Type A, B, and C tests. The Type A test is a measurement of the overall integrated leakage rate of the primary containment; whereas Type B and C tests are local leak rate tests designed to detect and measure local leakage across each pressure- containing or leakage-limiting boundary for primary containment. See Chapter 4 of this Book for detailed discussion of ISI and periodic leak rate testing of containments.

FIG. 3.2

LINER AND ANCHOR BEHAVIOR AND TEST SIMULATION [19-20]

FIG. 3.3

TYPICAL RIERA LOADING CURVE FOR AIRCRAFT IMPACT [58]

A professionally registered Responsible Engineer is assigned the responsibility of evaluating the concrete and post-tensioning system to ensure the structural and leak-tightness of the concrete containment.

The visual examination should include inspection of concrete surfaces for any apparent distress/cracks/ voids, detailed condition of concrete around anchorages and detailed inspection of strands and anchorage hardware. ACI 349.3R provides detailed guidance and quantitative inspection criteria for concrete surface examination.

The structural integrity test (SIT) requirements given in Section CC-6000 of ASME Section III, Div 2 Code [1] are a pre-requisite for Code acceptance and stamping before start of operation. The test is performed at 1.15 times the containment design pressure to evaluate design compliance and quality of construction. A detailed test procedure is required that uses calibrated instrumentation to measure strains/displacements, crack widths, and ambient conditions. Cracks exceeding 0.01 inches in width are recorded before the test, at peak pressure and after depressurization. These and other representative measurements are compared against the acceptance criteria given in CC-6400.

 
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