Term
| Purpose of instrument air |
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Definition
| Provide plant with a continuous supply of oil-free compressed air. |
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Term
| Source of breathing air in drywell |
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Definition
| Service air by personnel air lock and underneath the reactor vessel. |
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Term
| "During normal plant operation, what is in the instrument air lines? Why?" |
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Definition
| Nitrogen. This eliminates a source of air leakage inside the drywell and the resulting need for containment purging. |
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Term
| Instrument air low pressure |
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Definition
| 80 psig; PS-1469 closes four control valves located on various system lines in order to supply max air to the following: FW Regulator and Bypass Valves; Feed pump seal system; scram valves; CRD flow control valves; MSIVs and Reactor Auto-Pressure Relief Valves (inside drywell); Condensate Demin Bypass Valve; Recombiner trains. |
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Term
| Operating requirement for cooling tower and discharge structure air compressors |
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Definition
| Both cooling tower compressors and the discharge air compressor must be in service at all times when the cooling towers are in service. |
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Term
| Connection between #11 Cooling tower air compressor and the discharge canal sample pumps. |
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Definition
| #11 Cooling Tower air compressor is required to prime discharge canal sample pumps. |
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Term
| List the systems that require instrument and service air to be operable to be considered operable themselves |
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Definition
Fuel pool cooling and cleanup; RWCU; HWC; TIP; Circ Water; Cond't and Feed; Cond demins; liquid rad waste; off-gas holdup; solid rad waste; plant makeup; heating and ventilation.
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Term
| General precaution regarding instrument air when personnel are working inside the drywell. |
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Definition
| Handswitch on instrument nitrogen control panel must be in AIR position and spool piece removed from Nitrogen supply. |
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Term
| Power supply to instrument and service air isolation valve handswitches for CV-1474, CV-1748, CV-7956 |
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Definition
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Term
| Operating limitation when drywell is inerted and instrument nitrogen is shutdown. |
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Definition
| Drywell oxygen should be sampled daily |
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Term
| Function of alternate nitrogen system |
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Definition
Provides a SAFETY RELATED backup pneumatic supply to the following: Primary containment and atm control system purge and vent valve t-ring seals and actuators in RB to Torus Vac breakers; six of eight SRVs (all but D and G); Inboard MSIVs; Hard pipe vent system isolation valves and rupture disc.
Furthermore, the purpose of this system is to provide pneumatic supply to the above components DURING ACCIDENT CONDITIONS when the non-safety related supplies of instrument air and instrument nitrogen may not be available. These components all require a pneumatic supply to maintain their operability |
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Term
| Components supplied by Train A of alt Nitrogen |
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Definition
T-ring seals of inboard primary containment and atm control purge and vent valves, t-ring seals and actuators of RB to Torus vac breakers, SRVs A, B, and E.
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Term
| Components supplied by Train B of alt N2 |
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Definition
T-ring seals of outboard primary containment and atm control purge and vent valves, actuators of the inboard MSIVs SRVs C, H, and F
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Term
| Location and purpose of check valve in each alt N2 manifold. |
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Definition
| Separates three upstream bottles from the fourth downstream bottle. This prevents backflow during bottle changeout from a fully charged fourth bottle into the other three depleted bottles (the fourth bottle being changed out first), and maintains system operability while nitrogen bottles are being changed out. |
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Term
| Normal alt N2 header pressure |
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Definition
| 95-100 psig. Bottle pressure is reduced to approximately 150 psig by an in-line regulator, then controlled at 95 psig by a pressure control valve. |
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Term
| Alt N2 relief valve setpoints |
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Definition
| There are two relief valves, one between pressure control valve and pressure regulator set at 200 psig (protects PCV); and one downstream of the pressure control valve set at 120 psig (protects T-ring seals and SRV actuator diaphragms) |
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Term
| Train B N2 LO PRESSURE SRVS, INBD MSIVS, OTBD T-RINGS, HPV setpoints and automatic actions. |
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Definition
| This alarm comes in at 200 psig (low) and 91 psig (low). SV-4235 will close at 200 psig which isolates B alt N2 bottles from SRVs C, H, F and inboard MSIVs (thereby isolating Alt N2 to the T-ring seals of outboard primary containment and atm control purge and vent valves) |
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Term
| Train A N2 LO PRESSURE SRVS, INBD MSIVS, OTBD T-RINGS, HPV setpoints and automatic actions. |
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Definition
| This alarm comes in at 200 psig (low) and 91 psig (low). SV-4234 will close at 200 psig which isolates Train A alt N2 bottles from SRVs A, B, E and inboard MSIVs (thereby isolating Alt N2 to the T-ring seals of inboard primary containment and atm control purge and vent valves, and t-ring seals and actuators of RB to Torus vac breakers. |
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Term
| Does alt N2 provide a backup to Instrument air/N2? |
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Definition
| No. Two check valves in the instrument air/N2 line just upstream of the point where it ties into the alt N2 system prevent this. |
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Term
| Normal and backup pneumatic supply to drywell components. |
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Definition
| Instrument nitrogen provides the normal pneumatic supply to drywell components, and Alternate Nitrogen is automatically available as the SAFETY RELATED backup supply to the specific components served by alt N2. |
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Term
| Discuss the reason for supplying alt nitrogen to Primary containment and atm control system purge and vent valves and RB to Torus Vac breakers. |
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Definition
| These valves are primary containment isolation valves. They will not adequately perform their function unless they are closed and their t-ring seals are pneumatically pressurized. |
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Term
| Discuss the three pressure indicators at each alt nitrogen rack. |
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Definition
One indicates system pressure upstream of the pressure regulator (i.e. nitrogen bottle pressure); Another senses between the pressure regulator and PCV; And the other senses pressure downstream of the PCV. NOTE: the Downstream pressure instrument is actually sensing instrument nitrogen pressure which is 10 PSI higher than alternate nitrogen.
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Term
| Discuss nitrogen operation during outages. |
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Definition
| During plant outages when the drywell is de-inerted, the alt nitrogen system is valved out of service. This, along with the removal of the nitrogen spool piece from the instrument nitrogen system, is done to remove all sources of nitrogen from the drywell during times when personnel can be in the drywell. |
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Term
| Which systems are affected by Alt Nitrogen not being operable? |
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Definition
| Main steam, Reactor Pressure Relief, Primary Containment |
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Term
| What does the ops manual say is the reason for the solenoid isolation valve closure at 200 psig? |
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Definition
| To maintain Alternate Nitrogen supply to Primary Containment Atmospheric Control purge and vent valve T-ring seals. |
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Term
| Power supply to various alternate nitrogen solenoid valves and pressure switches. |
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Definition
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Term
| Minimum operating pressure for Alt Nitrogen header |
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Definition
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Term
| Allowable operating range for inlet pressure to the Alt Nitrogen Pressure control valves |
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Definition
| 110-180 psig. Preferred pressure at the inlet is approximately 150 psig (see B.08.04.03-05.E.6) |
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