Ultrasonic inspection tank

Resistance to microfissuring is strongly affected by plate structure it is excellent in a plate with fine and fibrous structure, as shown in Fig. 1. Because of severe safety requirements for LNG storage tanks, the quality of the majority of welds is specified to be monitored by ultrasonic inspection. The accuracy of ultrasonic inspection of weld defects depends mainly on the ultrasonic characteristics of the base metal, in which noises and attenuations are important. Distance amplitude correction curves, obtained in accordance with Section VIII of the ASME Boiler and Pressure Vessel Code and NV Rules, are shown in Fig. 1. Since the evaluation level is 20% of the reference level (R.L.), it is difficult to detect defects unless the noise level is below 20% of R.L. at every node. Noises and attenuations of ultrasonic responses increase with coarsened plate structure, and in plates with very... 

The objective of the reactor tank ultrasonic inspection progriam is to detect I6SCC of HAZ of the tank weldments. The original welds were 100% radiographed during fabrication and installation. InitiaT ly, UT scope of 40% of all accessible welds was adopted for all SRS reactors to sample all critical weld areas. This would include 100% of all main vertical welds and about 33% of the tank circumferential and nozzle attachment welds. 

Caustic Storage Systems. Storage tanks require carefiil inspection before use. Figure 13.1, an example of an inspection checklist, indicates some of the important items. Visual inspection will detect many faults. Welds, especially at roof and floor fines, should be tested by dye penetration or in accord with rqrplicable codes. Ultrasonic... 

Nondestructive examination techniques (ultrasonic testing (UT) and eddy current testing (ET)) shall be used to demonistrate that the reactor tank and the PWS piping will maintain their integrity under the operating conditions. The restart criteria for the reactor tank, based on the UT inspection, will be in accordance with WSRC-RP-89-208, "Tank UT Acceptance Criteria" (Reference 1). 

Other Restart Issues -- Issue DB 6.4. (Charlotte Criteria, Reference 2) requires review of the adequacy of technical information on vessel integrity status, including results of previous inspections. Ultrasonic testing (UT) of the reactor tanks shall be performed before reactor restart. Inspection acceptance criteria shall be per WSRC-RP-89-208 (Reference 3), as approved by DOE. 

WSRC-SRL-MAT-910032, Rev. 1, "Scope of K-Reactor Tank Ultrasonic/Eddy Current Inspection Adequacy for Restart-Response to Defense Nuclear Facilities Safety Board Inquiry", March 20, 1991. 

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