The system descriptions in this section are extracted from design information supplied by members of the Expert Elicitation Panel. The PWR-specific system information is included in the following documents and drawings:

• Document No. EPRI-156-330: Degradation Mechanism Evaluation for Class 1 Piping Welds at Plant A. a [D.6]. This document summarizes the degradation mechanisms applicable to a Westinghouse 3- loop PWR.

• References [D.7-D.9] include design information as well as degradation mechanism information applicable to the HPI/NMU system of Plant A. b.

• Excel file entitled “PlantAWelds.” This Excel file includes weld lists for the RC system of Plant A. a. The lists are organized by weld identification numbers (as they appear on the isometric drawings identified below), nominal pipe size and pipe schedule. This Excel-file forms one of the bases for the PWR LOCA frequency model used to derive the LOCA frequency distributions.

• Isometric drawing numbers 1MS-22-2262 and CGE-1-4100A (RC Hot Leg), C-314-601 and CGE-1- 4500A (pressurizer surge line), and 17-MU-23 (HPI/NMU piping).

D. 1.4.1 Reactor Coolant (RC) System (Plant A. a) — The RC System evaluated in this study consists of three similar heat transfer loops connected in parallel to the RPV. Each loop contains a reactor coolant pump (RCP), steam generator, and associated piping and valves. In addition, the system includes a pressurizer, a pressurizer relief tank, interconnecting piping, and instrumentation necessary for operational control. The analysis in this report is concerned with a portion of one of the three RC loops; the portion from the RCP to the RPV (this is one of the hot legs). The pressurizer surge line connects the pressurizer to the RC cold leg Loop A. In summary, the piping sections that are subject to evaluation in this study consist of.

RC-HL: The analysis is concerned with 1-of-3 hot legs. The Loop A HL starts at the RPV, includes

an RCP and connects to the ‘A’ steam generator (S/G). The HL piping is fabricated from stainless steel piping. The section of the HL from the RPV to the RCP is of 31 inch inside diameter, while the section from the RCP to S/G is of 27.5 inch inside diameter piping.

Surge Line: The single surge line is fabricated form NPS14 stainless steel piping and connects to the 29-

inch RC cold leg.

D. 1.4.2 High Pressure Injection (HPI)/Normal Makeup (NMU) Line (Plant A. b) — In Plant A. b, each of the four RCS cold legs is equipped with high-pressure injection piping. Two of these 2 Уг inch (ID, or approximately NPS3-%) stainless steel piping lines provide the normal makeup flow to the RCS and they connect to the cold leg via nozzle assemblies. Each of the nozzles is comprised of a base nozzle and a safe — end. To prevent thermal cycling of the base metal each nozzle is equipped with a 1.5-inch thermal sleeve. The analysis is concerned with one of the two HPI/NMU lines.