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PWR Component Numbering Scheme

Source

Rev 1 Modeling Guidance, Appendix A.24 — Component Numbering.

Overview

NRC staff developed a standardized numbering convention for PWR models. This is not required for a robust model but is considered good practice for:

  • Working across multiple PWR models with a known scheme
  • Re-using plotting scripts and output processing inputs
  • Copying control systems with minimal modification
  • Minimizing component numbering conflicts

Numbering Rules

  • All thermal-hydraulic components: 1000–1999 (reserves 3-digit IDs for PARCS coupling)
  • Fuel HTSTR components: 100–999 (3-digit for PARCS compatibility)
  • Component numbers increment by 5 (leaves room for extra components)
  • Numbers increment in the direction of typical liquid flow
  • HTSTR pipe walls: component# × 1000 + 1

Primary System (1000–1499)

Number Component
1000 RPV VESSEL
1010 Pressurizer
1011 Pressurizer heater (FLPOWER)
1015 Pressurizer surge line
1020 PORV VALVE components
1025 PORV BREAK components
1030 SRV VALVE components
1035 SRV BREAK components
1040 Pressurizer spray suction line
1045 Pressurizer spray (TDJ)
1090 Split break BREAK component
1091 Split break PIPE/SJC component
1092, 1093 DEG break BREAK components

Per-Loop Components (Loop N = 1N00 series)

Offset Component
+00 Hot leg
+05 SG inlet plenum
+10 SG U-tubes (or OTSG tubes)
+15 SG outlet plenum
+20 Intermediate leg A
+25 Pump suction A
+30 Pump A
+35 Cold leg A
+40 Accumulator tank A
+45 Accumulator line A
+50 Intermediate leg B (if 2 cold legs/loop)
+55 Pump suction B
+60 Pump B
+65 Cold leg B
+70 Accumulator tank B
+75 Accumulator line B
+80 HPSI A
+81 LPSI A
+82 HPSI B
+83 LPSI B
+84 Charging flow
+85 Letdown flow

Example: Loop 1 hot leg = 1100; Loop 2 pump A = 1230; Loop 3 cold leg B = 1365

Secondary System (1500–1899)

Per-loop secondary components use the (Loop+4)×100 series:

Offset Component
+00 SG downcomer
+05 SG downcomer-to-boiler flow path (SJC)
+10 SG boiler region
+15 SG separator (UTSG) / aspirator flow (OTSG)
+20 SG steam dome (UTSG) / boiler-to-upper-DC (OTSG)
+25 MSL/MSIV
+30 MSSV VALVE components
+35 MSSV BREAK components
+40 ADV VALVE components
+45 ADV BREAK components
+50 Turbine stop valve
+55 Turbine control valve
+60 Turbine inlet BREAK
+65 Turbine bypass valve
+70 Turbine bypass BREAK
+75 Main FW line
+80 Main FW FILL
+81 AFW flow
+85 Equalizing line

Example: Loop 1 SG downcomer = 1500; Loop 2 MSL/MSIV = 1625; Loop 3 FW FILL = 1780

RPV Internal Components (1900–1999)

Range Component
1900–1915 Core thimble tubes (up to 8 azimuthal sectors × 2 rings)
1920–1935 Control rod guide tubes
1940–1947 Reactor vessel vent valves
1970 Pressurizer boundary isolation valve (SS initialization)
1971 Steady-state pressure boundary condition
1999 Reactor power (POWER component)

Fuel HTSTR Components (100–999)

Pattern Component
R·100 + S·10 + B Ring R, Sector S, Burnup group B

Example: Ring 1, Sector 1, fresh fuel = 110; Ring 2, Sector 3, twice-burned = 232

Remaining numbers (100–999) reserved for PARCS-TRACE coupled calculations (~200 individual assemblies for PWRs).

Non-Fuel HTSTR Components

Number Component
1000001–1000008 RPV outer shell (per sector)
1000011–1000018 RPV barrel (per sector)
1000021–1000028 Core baffle (per sector)
1000031–1000038 Core thermal shield (per sector)
1515002, 1615002, ... SG primary separators
1520002, 1620002, ... SG secondary separators
1110002, 1210002, ... SG inlet tubesheets
1110003, 1210003, ... SG outlet tubesheets
×1000 + 1 Pipe wall HTSTR (auto-spawned)

Cross-References

This page faithfully extracts the component numbering scheme from Rev 1 Appendix A.24. The scheme uses 1000–1999 for T-H components (incremented by 5), 100–999 for fuel HTSTRs (PARCS-compatible), and formulaic per-loop numbering (Loop×100 offset for primary, (Loop+4)×100 for secondary).