SALEM
SALEM STUDY SYSTEM
Systems > Control Air

Control Air

⚠️ DRAFT

Control Air

Function

Provides clean, dry compressed air for instrument and control valve operation throughout the plant. Includes service air and station air subsystems.

Exam — 2018 Q25
CA330 (Containment Supply Inlet Valves) fail CLOSED on a loss of Control Air (not on loss of 125 VDC or 28 VDC power). With BOTH 11CA330 and 12CA330 closed, each PZR PORV CAN still be operated — each PORV has 2 accumulators sized for 100 opening/closing cycles (50/accumulator). Trap: CA330s are Containment Isolation Valves — candidates may confuse their fail mode with a DC power loss, but they fail on loss of air, not loss of DC.
Exam — 2018 Q26
ECAC automatic start setpoint: < 85 psig control air pressure. 88 psig is the MANUAL start setpoint per AB.CA-0001 — not the auto start setpoint. At 86 psig, the ECAC has NOT reached its auto start setpoint. To MANUALLY start the ECAC from the control room, the MINIMUM pushbutton manipulation is depressing A then B (two-button sequence). A single button (B ONLY) is not sufficient.
Exam — 2022 Q53
SAC power supplies: #1 SAC from 1H 4KV Group Bus, #3 SAC from 1G 4KV Group Bus (both Unit 1), #2 SAC from 2G 4KV Group Bus (Unit 2). On loss of all Unit 1 4KV Group Buses, #1 and #3 SACs are lost but #2 SAC auto-starts (or continues running) and one SAC is capable of supplying BOTH units' station air and control air headers at approximately 100 psig. ECACs auto-start at 85-90 psig and maintain headers if ALL SACs are lost.
Exam — 2022 Q77
MS10 atmospheric dump valves remain operable from the control room during loss of all control air: each MS10 has a nitrogen bottle rack with four bottles at >=2000 psig that provides backup air supply. CA330s fail CLOSED on loss of air (isolating containment air), but MS10s have DC battery power for control and nitrogen for the air operator. Bottle rack capacity designed for minimum 72 hours of MS10 operation. Per EOP-LOPA-1, maximum cooldown rate using MS10s is 100F/hr.
Exam — 2022 Q79
On loss of instrument air, 2MS132 (23 AFP Turbine Steam Inlet Valve) fails OPEN, causing the turbine-driven AFW pump to start at power. Cold AFW injection into the SGs causes reactor power to exceed 3459 MWt (reactor overpower condition). Per S2.OP-IO.ZZ-0004, reduce turbine load to lower reactor power below the administrative limit.
Exam — 2022 Q88
On loss of all control air with a centrifugal charging pump in service: CV55 fails OPEN and CV71 fails CLOSED. With letdown isolated, the charging pump delivers higher flow to the RCP seals → PZR level RISES. Per AB.CA-0001: locally adjust CV54 (Centrifugal Charging Pump Flow Control Valve) to control charging flow, OR transfer to 23 PDP charging pump (speed controller failed at low speed stop — minimizes seal flow and extends time before PZR reaches 90%).
Exam — 2020 Q54
ECAC power supplies: #1 ECAC is powered from the 1C 460V Vital Bus. Loss of 1C 4KV to 460V breaker 1C4D would result in loss of #1 ECAC. Do not confuse ECAC power supplies with Station Air Compressor (SAC) power supplies — #1 SAC is powered from 1H 4KV Group Bus, #1 Station Air Compressor from 1H group bus (4KV). The 1E 460V Group Bus powers Station Air Compressors, NOT the ECACs.
Exam — 2020 Q15
ECAC header sensing and CAS actions: #2 ECAC senses CA Header A and #1 ECAC senses CA Header B. Per AB.CA-0001: if 2B CA Header is ≤ 88 psig, notify Unit 1 NCO to start #1 ECAC. CAS (Continuous Action Statement): if BOTH CA headers lower to < 80 psig, trip the reactor. Trap: #1 ECAC is for 2B header (not 2A), and #2 ECAC is for 2A header (not 2B) — the ECAC number does NOT match the header letter. Also, the CAS requires BOTH headers < 80 psig, not EITHER header.
Exam — 2020 Q45
BF19 (Main Feedwater Regulating Valves) behavior on loss of all station air: BF19s start to close at 80 psig control air header pressure. Per AB.CA-0001 CAS: monitor BF19s for closure and inability to control SG level, or if both CA headers drop below 80 psig, trip the reactor. 85 psig is the ECAC auto-start setpoint, NOT the BF19 closure threshold — do not confuse. BF19s receive air from Unit 1 via redundant (Lunkenheimer) air panels, but on total loss of ALL station air, no Unit 1 CA is available. A check valve prevents either unit's ECAC from supplying the BF19 turbine building control air header, so ECACs cannot maintain BF19 air supply even if running.
JPM — 2020 IP-j
SBO Diesel Control Air Compressor start (SC.OP-SO.CA-0001): during loss of offsite power with no ECACs running, start the SBO compressor at the SBO Compressor Building. Key sequence: open engine intake louvers, drain 1CA1920, open 2FZSBO10 battery charger breaker, air dryer ON, record hourmeter, UNLOADER to START, then PRESS AND HOLD BY-PASS VALVE pushbutton → SBO-IGN-SWT to START → verify oil pressure >15 psig → RELEASE BY-PASS VALVE. Discharge alignment: 1CA1913 → 1CA1886 → 2CA584 pressurizes Aux Building 1A and 2A Control Air headers. UNLOADER to RUN to load.
Exam — 2018 Q61
AB.CA-0001 trend analysis: ECAC manual start (Step 3.10) when 2A CA Header ≤ 88 psig. CAS reactor trip when BOTH headers < 80 psig. With declining CA headers, must track each header independently — the trip requires BOTH headers below 80 psig, not just one. 100 psig = Station Air Compressor start threshold (Step 3.7), not ECAC start.
Exam — 2019 Q61
ECACs are manually started when CA headers lower to 88 psig. 100 psig is the threshold for starting the remaining Station Air Compressor, not the ECAC manual start setpoint. Check valves in the CA system prevent ECACs from supplying the BF19 headers — ensuring proper BF19 operation is NOT a reason to start ECACs.
Exam — 2019 Q27
CA330 (Control Air Isolation Valves) operability and isolation: IAW LCO 3.6.3 (Containment Isolation Valves), CA330s are required to be OPERABLE in MODES 1-4 ONLY. The CA330s automatically close on a Phase A Containment Isolation signal, which is generated when containment pressure FIRST exceeds 4 psig. Trap: 15 psig is the Phase B setpoint — CA330s close on Phase A (4 psig), NOT Phase B (15 psig). Also, LCO 3.6.3 applies in Modes 1-4, not ALL MODES.
Exam — 2018 Q93
Number 1 ECAC provides air to 1B and 2B Control Air Headers ONLY — check valves prevent the ECAC from supplying Station Air. Per S1.OP-AB.CA-0001, the CRS will direct performance of Attachment 12, "Local Control Of SG Pressure and Level", when BOTH 1A and 1B Control Air Headers indicate less than 80 psig. Trap: EITHER header below 80 psig is not sufficient — BOTH must be below 80 psig before Attachment 12 is directed.
Exam — 2018 Q90
BF19 (SG FW CONT V) failure on loss of control air: BF19s fail CLOSED → SG levels lower. AB.CA-0001 CAS directs: if crew manually trips the reactor because SG levels cannot be maintained, perform EOP-TRIP-1 AND AB.CA-0001 concurrently. BF19s fail CLOSED (not open). Do not confuse BF19 failure position with other air-operated valves that fail open (MS132, DR6, AF11, etc.).

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