SALEM
SALEM STUDY SYSTEM
Systems > Service Water

Service Water

⚠️ DRAFT

Service Water

Function

Provides cooling water from the Delaware River (ultimate heat sink) to remove heat from plant systems. Safety-related, Seismic Category I. (UFSAR 9.2.1)

Key Loads

  • Containment fan coil units (CFCUs) — minimum 1300 gpm per unit during accident conditions
  • Component cooling water heat exchangers
  • Diesel generator jacket water coolers
  • Turbine auxiliaries cooling (non-safety)
  • Various other plant heat exchangers

Key Design Points

  • Ultimate heat sink: Delaware River
  • Safety-related supply for post-accident cooling
  • Two independent loops required for single-failure capability
  • Supplies backup water source for AFW system
Exam — 2023 Q24
Service Water from CFCUs is the ONLY source of water into containment NOT isolated by Phase A or Phase B containment isolation signals. Fire Protection and Primary Water are isolated by Phase A; CCW is isolated by Phase B. Following a LOCA with both Phase A and B actuated, SW to CFCUs is the only remaining water source into containment — this is the cause of unexpected containment water level rise addressed in EOP-FRCE-2.
Exam — 2023 Q50
CFCU SW flow orifices maintain constant SW flow rate through CFCUs in both high and low speed operation. Because SW flow is the same regardless of CFCU speed, SW header pressure is also the same when a CFCU switches between high and low speed. (Prior to orifice installation, low speed had higher SW flow.)
Exam — 2023 Q51
SW122 (SW Inlet Control Valve to CCW HX) fails OPEN on loss of instrument air (fails closed on loss of 125VDC). Loss of air to SW122 → valve fails open → increased SW flow through CCW HX → lower CCW temperature → lower RHR HX outlet temperature → increased RCS cooldown rate. Per AB.CA-0001, SW122 can be manually operated.
Exam — 2019 Q26
21SW122 (21 CC Hx Control Valve) fail positions: ONLY a loss of control air causes 21SW122 to go FULLY OPEN. SEC Mode III Operation and loss of 125 VDC power both cause 21SW122 to go fully CLOSED. All three conditions (loss of air, SEC Mode III, loss of DC) cause 21SW122 to move to a full-travel position, but only loss of air goes OPEN — the other two go CLOSED. Candidates must distinguish the fail-open (air) from fail-closed (DC/SEC) modes.
Exam — 2022 Q16
OHA B-48 (SW VLV RM FLOODED) indicates leak in SW valve room on 78' Mechanical Penetration Area. CFCU piping passes through this room before entering containment. A SW leak in this room is most likely from CFCU piping.
Exam — 2020 Q53
Unit 1 SW pump power supplies: 15 and 16 SW Pumps are powered from the 1A 4KV Vital Bus. 12 SW Pump is on the C Bus with AUTO-start capability on low SW header pressure. A 1A 4KV Bus Differential with #3 SW Bay already C/Ted (15 and 16 SW Pumps already isolated) has no additional impact on SW system operation — the correct procedure entry is AB.4KV-0001, not AB.SW-0005 or AB.SW-0004. Unit difference: on Unit 2, 21 and 22 SW Pumps are BOTH on the 2A 4KV bus — a 2A bus loss would lose BOTH pumps. On Unit 1, 15 and 16 SW Pumps are on 1A bus but are associated with #3 SW Bay.
Exam — 2018 Q24
SW nuclear header leak isolation per AB.SW-0001 Attachment 4: when leak is downstream of 21SW22 (NUCLEAR HEADER), the crew will CLOSE 21SW22 and ENSURE CLOSE 21SW23 and 22SW23 (TIE VALVES) (Step 2.0). After isolation, SW cooling is NOT available to 21CFCU and 22CFCU. Trap: if the leak is UPSTREAM of 21SW22, the procedure directs OPEN the tie valves (Step 3.0) to maintain cross-header supply. Downstream = close ties; Upstream = open ties. Only 23 CFCU can be cooled by both SW headers — 21 and 22 CFCUs are not cross-connected.
Exam — 2020 Q52
SW Nuclear Header isolation with 21SW22 closed: EDG supply valves (21SW21 & 22SW21) are UPSTREAM of Nuclear Header Inlet Valves (21SW22 & 22SW22) — closing 21SW22 does NOT isolate EDG SW supplies. All 3 EDGs remain supplied by both 21 and 22 SW Headers. For CFCUs: 23 CFCU can be supplied from EITHER 21 or 22 SW Header (check valve locations), but the remaining CFCUs on the 21 Nuclear Header are isolated. Result: all 3 EDGs on both headers, only 3 CFCUs on 22 SW Header (22, 24, 25 CFCUs + 23 CFCU via cross-connect). Not all 5 CFCUs can be supplied by either header — only 23 CFCU has the check valve arrangement allowing cross-header supply.
Exam — 2020 Q14
SW Bay leak with degraded pump availability: OHA B-29, "21-23 SW PUMP SMP AREA LVL HI" indicates leaking #2 SW Bay requiring isolation. AB.SW-0001 (Loss of SW Header Pressure) immediately transitions to AB.SW-0003 (Service Water Bay Leak) for bay isolation. An OPERABLE SW loop requires two SW pumps powered from separate buses. Per S2.OP-SO.SW-0005 P&L 3.2: when a SW Bay is removed from service in Modes 1-4 and the "B" bus SW pump in the operable bay is unavailable (23 or 24 SWP), LCO 3.0.3 is applicable. With #2 Bay isolated AND 24 SWP C/Ted, both SW loops are inoperable. TS 3.7.4 (one loop inoperable, 72 hrs) does NOT apply — TS 3.0.3 applies because no operable loops remain.
JPM — 2020 RO-A3
SW leak isolation using P&ID 205342: leak on 2 inch drain valve 21SW268 (21 NUC HDR FROM FCV DRAIN) downstream of 21SW76 (21 CFCU SW Outlet Valve) in SW Valve Room, Auxiliary Building. Minimum nine valves to isolate: 21SW472, 21SW355, 21SW50 (sheet 3), 21SW414 (sheet 5), 21SW78, 22SW76, 21SW76, 21SW646, 22SW646 (sheet 6). Must trace all flow paths on multiple P&ID sheets including cross-connected headers.

Tech Spec LCOs

  • TS 3/4.7 — Plant Systems — TS 3.7.4 requires two independent SW loops OPERABLE in Modes 1–4
  • 1 loop inoperable: 72 hours to restore, or Hot Standby in 6 hours + Cold Shutdown in 30 hours
JPM — 2023 Sim-f
CFCU surveillance: SW flow minimum >=1465 gpm required for CFCU operability. When measured SW header DP falls between Exhibit 1 values, use the next higher DP value to determine minimum required flow.
Exam — 2022 Q52
SW122 (CC HX Inlet Valves) close on SEC Mode III (SI + LOOP/blackout) to prevent SW pump runout with all CFCUs running and only two SW pumps available (single active failure). During SEC Mode I (SI only), SW122s are throttled to maintain CC HX outlet temperature — they do NOT close or fully open. SW122s do NOT fully open on any SEC mode. They only close on Mode III (SI + LOOP), not on SI alone.
Exam — 2022 Q90
Unit difference — SW pump power supplies: 2A EDG supplies 21 AND 22 SW Pumps (both on the same bus). On Unit 1, SW pumps 15 and 16 have a different bus arrangement. If 23 SW Pump trips and the 2A 4KV Vital Bus locks out (bus differential), ALL Unit 2 SW pumps are lost — loss of all SW flow. Per S2.OP-AB.SW-0005: trip the reactor and stop all RCPs to limit heat input to the CCW system.
Scenario — 2020 #1
During LOPA-1, 2A EDG running with no SW pumps must be stopped to prevent overheating. After 2C EDG is returned from maintenance and energizes 2C 4KV Vital Bus, crew must immediately start 25 or 26 SW pump for EDG cooling (CT-25).
Scenario — 2020 #3
21 SW Pump C/T for pump repack (initial condition). 21 SW Accumulator Tank pressure drops to 137 psig (operable band is 138-157 psig) — declared inoperable, 21 and 22 CFCUs stopped and isolated. 23 SW Pump trips and 26 SW Pump fails to auto start on low pressure — RO manually starts 26 SW Pump. CRS enters TS 3.7.4 (72 hours) for 21 and 23 SW Pumps inoperable in one bay (only one operable SW loop).
Scenario — 2018 #1
#2 SW Bay leak during startup. OHA B-29 (22-23 SW PMP SUMP AREA LVL HI), B-13 (21 SW HDR PRESS LO). 25 SW Pump auto starts on low header pressure. Crew splits headers: open 21SW23 and 22SW23 (nuclear header crossover MOVs), close 21SW17 and 22SW17 (cross-connects). Leak isolated in #2 Bay by closing 21SW22 and 21SW20. Start Bay 4 pumps (24, 25, 26), stop #2 Bay pumps. SW available to DGs through 22SW21 and Turbine Area through 23SW20. CRS enters TS 3.7.4 (72 hr LCO) for one operable SW loop. PO removes one CCHX from service per AB.SW-0003 CAS item 4.0.
JPM — 2020 SRO-A3
Unit 1 SW loop operability with 13 SW Pump C/T and 1A EDG inoperable: per S1.OP-SO.SW-0005, two independent operable SW loops require one pump per vital bus and two pumps per bay. With 13 SW Pump C/T: A bus (15 & 16 Pumps) — YES, B bus (14 Pump) — YES, C bus (11 & 12 Pumps) — YES, #1 Bay (11 & 12) — YES, #3 Bay (15 & 16) — YES. Two SW loops remain operable, so TS 3.8.1.1 Action b.2 does NOT apply.
Exam — 2019 Q60
SW Nuclear Header leak location: with low SW pressure to loads on the 21 SW Nuclear Header (21 CC Pump, 21 CS Pump, 21 CFCU, etc.), the leak is downstream of 21SW22 (NUCLEAR HEADER inlet valve). Key one-line relationships: 2SW26 (TURB AREA SW MOV) is on the turbine area header (non-nuclear); 22SW22 is the 22 Nuclear Header inlet; 21SW23/22SW23 are Nuclear Header Tie Valves (connecting the two headers). Trap: the question requires correlating the affected loads to the correct nuclear header — all affected loads are served by the 21 header, so the leak must be downstream of 21SW22 (not 22SW22 or between the tie valves).

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