Term
| Purpose of C.5-1100 (RPV Control) |
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Definition
Maintain adequate core cooling through core submergence Cooldown the RPV to cold shutdown conditions Ensure reactor is shutdown.
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Term
| Three key parameters controlled in C.5-1100 (RPV Control) |
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Definition
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Term
| Definition of Adequate Core Cooling |
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Definition
Preventing fuel clad rupture by (in order of preference): Core submergence 2/3 core height with Core Spray Injection at or above 2800 gpm Steam cooling with injection of makeup water to RPV
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Term
| Preferred method of core cooling |
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Definition
Submergence (level above top of active fuel, which is -126") |
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Term
| Entry points for C.5-1100 (RPV Control) |
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Definition
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Term
| Peak clad temperature limit using steam cooling with makeup water |
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Definition
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Term
| The only practical mechanism for containment cooling |
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Definition
| RHR flow through the heat exchanger with RHRSW in service. (Therefore, drywell and Torus spray also counts) |
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Term
| Alternate methods of determining reactor power when power is unknown |
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Definition
| Reactor period, steam flow, RPV Pressure, SRV valve position, torus heatup rate |
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Term
| The greatest banked rod position which the reactor will remain shutdown under all conditions |
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Definition
Maximum Subcritical Banked Withdrawal Position: position 04 or less. |
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Term
| Other ways to determine if reactor will remain shutdown |
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Definition
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Term
| Primary objective of C.5-1100 Level Branch |
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Definition
| Keep core submerged and thus adequately cooled. |
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Term
| [This] terminates any loss of reactor coolant through a break. |
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Definition
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Term
| [This] ensures that emergency injection sources are available. |
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Definition
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Term
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Definition
All pumps, valves, and aux equipment are properly lined up for existing plant conditions. NOTE: a given system may or may not be injecting. |
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Term
| Reasons ADS actuation is prevented (inhibited) |
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Definition
ADS actuation can impose a severe thermal transient on the RPV and may complicate efforts to control RPV level If only steam-driven systems are available for injection, ADS actuation may directly lead to loss of adequate core cooling and subsequent core damage The conditions assumed in the design of the ADS actuation logic (e.g., no operator action for 10 minutes after event initiation) may not exist when the actions specified in RPV Control are being carried out The operator can draw on much more information than is available to the ADS logic and can better judge...
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Term
| Define reactor water level unknown |
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Definition
| No valid indication on scale. |
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Term
| Drywell pressure limit is defined to be the lesser of: |
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Definition
Pressure capability of primary containment The maximum primary containment pressure at which vent valves sized to reject all decay heat from the primary containment can be opened and closed The maximum primary containment pressure at which ADS valves can be opened and will remain open.
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Term
| What is the basis for the water level +9 to +48 inches? |
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Definition
Controlling above 9 inches permits the scram to be reset and allows later use of shutdown cooling. Controlling below 48 inches preserves the availability of Feedwater, HPCI and RCIC and avoids moisture carryover into the main steam lines. Water hammer effects resulting from filling hot steam lines with comparatively cool water could exert excessive thermal and hydrodynamic loads on the SRVs, main steam piping, and MSIVs. |
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Term
| Suction temperature above which may damage HPCI. Also, state the basis. |
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Definition
180 degrees F (same for RCIC)
RCIC and HPCI lube and control oil are cooled by the water being pumped through their systems. Operation above this temperature my result in bearing damage or loss of control capability. |
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Term
| Suction temperature above which may damage RCIC. Also, the basis for this. |
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Definition
180 degrees F (same for HPCI) RCIC and HPCI lube and control oil are cooled by the water being pumped through their systems. Operation above this temperature my result in bearing damage or loss of control capability. |
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Term
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Definition
Highest TORUS TEMPERATURE which provides adequate NPSH for pumps taking suction from the torus. NOTE: normal/preferred suction for HPCI and RCIC is the CSTs. This limit only applies to HPCI and RCIC when they are aligned to the torus. |
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Term
| Definition of ECCS Vortex Limit |
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Definition
Lowest TORUS WATER LEVEL at which air entrainment is not expected to occur in the suction of the pumps aligned to the torus.
NOTE: normal/preferred suction for HPCI and RCIC is the CSTs. This limit only applies to HPCI and RCIC when they are aligned to the torus. |
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Term
| What is the preferred method for controlling RPV Pressure? Why? |
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Definition
Discharging steam to the main condenser using the main turbine bypass valves. They provide good control capability and do not add heat to the torus. |
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Term
| Three advantages to using Main Turbine Bypass Valves as the anticipatory pressure reduction step. |
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Definition
No other pressure control system: Is capable of reducing RPV pressure without adding energy to the containment, Has sufficient heat removal capacity, Can be quickly placed in service
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Term
| List the three conditions required to be able to use Main Turbine Bypass Valves in pressure reduction |
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Definition
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Term
| Definition of "rapid SRV cycling" |
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Definition
| Multiple, closely-sequenced valve actuations with the valves opening at the relief setpoint and closing as pressure drops below the reset setpoint. |
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Term
| What does preventing rapid SRV cycling minimize? |
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Definition
Dynamic loads on the RPV, the SRV tail pipes and supporting structures, and the primary containment RPV water level fluctuations Challenges to SRV operability
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Term
What is C.5-1100's solution to rapid SRV cycling? Why? |
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Definition
| Opening SRVs (one at a time) to reduce RPV pressure below the actuation setpoint. This process continues until RPV pressure reaches the pressure at which stem flow through the main turbine bypass valves is at 100% of bypass valve capacity (Normally 930 psig) If MSIVs are open, reducing pressure below this value will cause bypass valves to close. Heat which would otherwise be rejected to the main condenser would then be discharged to the torus. |
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Term
| Torus level associated with top of SRV discharge |
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Definition
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Term
| SRV preferred sequence and why? |
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Definition
F, C, G, E, H, B, D, A This sequence is used if possible to uniformly distribute heat load around the torus and equalize the number of actuations among SRVs |
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Term
| Which SRVs have accumulators? What are the actions required if there is a loss of continuous pneumatic supply to the SRVs? |
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Definition
D and G
Hand switches are placed in the position which closes the valves and allows them to lift only at their safety setpoints (AUTO for D; CLOSE for G). Division II Lo-Lo Set logic must also be manually bypassed to preclude Lo-Lo Set actuation of G SRV.
These actions conserve accumulators in case a blowdown is later required. |
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Term
| Torus water level associated with HPCI exhaust opening |
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Definition
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