Thermal Sleeve Direct Wear Measurement

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Background

Reactor Pressure Vessel Head (RPVH) Thermal Sleeve (TS) flange wear failure is a known ageing phenomenon on PWR plants.

91Ó°ÊÓ offers a direct visual inspection system capable of accurately assessing Thermal Sleeve and adaptor wear, as well as locating any flange debris in the adaptor housing. The inspection tools are delivered by a tool carrier for an ALARA-optimized inspection.

Figure 1 - Giraffa and Serpentes inspection systems

Benefits

The main advantages of 91Ó°ÊÓâ€™s direct Thermal Sleeve Wear Measurement systems are:
- No human intervention under the RPVH (tool change on the outside of the RPVH stand manway)
- Low radiation exposure for technicians and low overall exposure dose
- Accuracy of Â± 1mm on wear measurement
- Delivery of the wear measurements immediately after acquisition
- Measure of Thermal Sleeve Wear dimensions from the outside
- Full video recordings of wear marks on the Thermal Sleeve outside
- Measures of outside wear marks or loose debris
- Full video recordings of the situation inside the Thermal Sleeve and adaptor housing
- Measures of wear and marks inside the Thermal Sleeve and adaptor housing
- Finding of loose debris inside the Thermal Sleeve and adaptor housing

Experience

WesDyne, the 91Ó°ÊÓ NDE company, developed the direct Thermal Sleeve Wear Measurements system in 2018. The inspection systems have successfully been used at a customer site in Europe, ensuring reliable wear measurements for safe plant operations.

Technology Description

The 91Ó°ÊÓ direct inspection system is used to get the full status of the Thermal Sleeve and RPVH adaptor wear. The inspection system consists of two different tooling systems:

Outside TS measurement â€“ Giraffa system
Inside TS and adaptor assessment â€“ Serpentes system

Outside Inspection

The Outside Giraffa system is used to measure:

[1] The distance between the top of the thermal sleeve cone and the bottom of the RPVH adaptor (for comparison to the original as-built dimension),
[2] The wear height on the sleeve outer surface, at the adaptor penetration level (including video recording of the wear zone inspection).

Figure 2 - Inspections with Giraffa system

Inside Inspection

The inside Serpentes system is used to visually survey:

[1] The internal surface of the thermal sleeve, looking for debris/mechanical damage,
[2] The RPVH adaptor housing and Thermal Sleeve seated surface to record material loss and to measure their individual dimensions by laser scanning.

Figure 3 - Inspections with Serpentes system

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