Description of the Performance Demonstration Initiative (PDI) Program
The Nuclear Regulatory Commission (NRC) establishes rules and regulations for the operation of domestic nuclear facilities, which are published in the United States Federal Register under 10CFR50. The NRC has established the ASME Boiler and Pressure Vessel Code as the engineering authority for the design, construction, and operation of nuclear reactors. Section XI of the ASME Code contains the rules for in-service inspection of nuclear plant components. Appendix VIII describes the additional requirements for performance demonstration of UT examinations systems that integrate personnel, equipment, and procedures into a single entity. That entity is the PDI program owned by the utilities. EPRI is the operator of the PDI program.
In order to be used by a vendor during an examination, ultrasonic equipment and probes must successfully meet the requirements of the general procedure through performance demonstration on controlled samples as administrated at the EPRI PDI laboratory.
PDI Procedures for Piping for Detection and Length Sizing
There are two generic PDI procedures covering pipe welding examinations for detection and length sizing:
- PDI UT-1: Ferritic Pipe Welds
- PDI UT-2: Austenitic Pipe Welds
- Includes Austenitic piping susceptible to Intergranular Stress Corrosion cracking (IGSCC).
This document covers PDI UT-1.
The objectives of the examinations performed in accordance with procedure PDI UT-1 are to accurately detect and size the length of discontinuities within the specified examination volume from the outside surface. Per this procedure, the primary mode of propagation should be shear waves.
PDI UT-1 is applicable to pipes with diameters of 1.5 in. and greater and ferritic pipe welds with thicknesses ranging from 0.237 in. to 8 in. Search unit frequency should be 5 MHz for components with thicknesses of 0.5 in. or less, 5 MHz or 2.25 MHz for thicknesses greater than 0.5 in. to 2 in., and 2.25 MHz for thicknesses greater than 2 in. Search unit angles shall be 45, 60, or 70 degrees.
Qualified Equipment
Inspectors may utilize any combination of a qualified instrument and probe.
The EPOCH™ 650 flaw detector is qualified for use with all qualified 2.25 MHz and 5 MHz probes.
Qualified Evident probes are outlined in the following table:
| Model | Element Size (in.) | Frequency (MHz) | Wedges or angles |
| C540-SM | 0.500 | 2.25 | ABSA-5T-45°, 60°, 70° Steel |
| C541-SM | 0.500 | 5.00 | ABSA-5T-45°, 60°, 70° Steel |
| C542-SM | 0.250 | 2.25 | ABSA-4T-45°, 60°, 70° Steel |
| C543-SM | 0.250 | 5.00 | ABSA-4T-45°, 60°, 70° Steel |
| C549-SM | 0.375 | 2.25 | ABSA-7T-45°, 60°, 70° Steel |
| C551-SM | 0.375 | 5.00 | ABSA-7T-45°, 60°, 70° Steel |
| C403-SB | 0.500 × 1.000 | 2.25 | ABWS-2-45°, 60°, 70° Steel |
| A540S-SM | 0.500 | 2.25 | ABSA-5T-45° Steel |
| A543S-SM | 0.250 | 5.00 | ABSA-4T-45°, 60° Steel |
| A549S-SM | 0.375 | 2.25 | ABSA-7T-45°, 60°, 70° Steel |
Qualified Legacy Equipment
Note that the following models were also qualified to some extent during their lifetimes:
- EPOCH 600 flaw detector
- EPOCH 1000 flaw detector
- EPOCH II, III, 4, and XT flaw detectors
- SONIC 1200S, 136, and 137 flaw detectors
Customers should refer to PDI tables for specific qualification matrices.
Other EPRI Procedures
It should be noted that there are additional generic procedures.
PDI-UT-3 Through-Wall Sizing of Planar Flaws in Similar Metal Piping Welds
PDI-UT-4 Studs and Bolts from the Bore
PDI-UT-5 SB Inspection of Bolts and Studs
PDI-UT-6 Reactor Pressure Vessel Welds
PDI-UT-7 Through Wall and Length Sizing in Reactor Pressure Vessel Welds
PDI-UT-8 Weld Overlaid Similar and Dissimilar Metals
PDI-UT-10 Dissimilar Metal Welds
PDI-UT-11 Detection and Sizing of Reactor Pressure Vessel Nozzle to Shell Welds and Nozzle Inner Radius
Updates will be provided on a regular basis as we are actively pursuing these areas.
