RCS Flashcards
What are the RCS penetrations below centerline?
- RHR Suction from Loop 2 Hot Leg
- Loop flow instruments (High Side Tap)
- Drain Lines
- NR Thot Scoops
- Half Loop level indication connection (NLI-122)
What loops does Pzr spray come from?
Loops 3 and 4 CLs
What loops have Mid Loop Level Indicator penetrations?
Loops 3 and 4 CL (Intermediate legs)
What loop has Pzr Surge line penetration?
Loop 3 HL
What loop has RHR suction penetration?
Loop 2 HL
** (Does not extend into flowpath)**
What loop has NLI-122 half loop indicator penetration?
Loop 2 HL
What loop has Normal Charging penetration?
Loop 4 CL
What loop has alternate charging penetration?
Loop 1 CL
What loop has normal LD penetration?
Loop 4 CL (Intermediate Leg)
What is the design basis of the Rx Vessel Head Vent?
- vent a volume of h2 equal to half the volume of the RCS in 1 hr at system design # and temp
- 1/4” orifice prevents leakage > capacity of 1 CCP
When is RVLIS for Narrow Range Used?
No RCPs running.
Gives indication from top to bottom of vessel
When is RVLIS for Wide Range Used?
With RCPs running
- Looks for Void Fraction (50%)
When is RVLIS for the Upper Range Used?
When all RCPs Off
- Generally used in EOPs to assess whether a RV head void exists for natural circulation cooldown procedures.
What are the inputs to the subcooling meter?
- Auctioneered HI CETCs or WR RTD temps
- Auctioneered LO RVLIS WR press
What is the normal Tavg for both units?
- Unit 1: 571ºF
- Unit 2: 574ºF
Per TS 3.4.3 (RCS Pressure vs Temperature), what is the fastest the RCS can be heated up?
< 60ºF/Hr
Per TS 3.4.3 (RCS Pressure vs Temperature), what is the fastest the RCS can be cooled down?
< 100ºF/Hr
What is the temperature for minimum RCS Temper per 3.4.2 (RCS min temp)? What must be done if violated?
> 541ºF
If violated, be in MODE 2 with keff < 1.0 within 30 mins
What does TS 3.4.6 (RCS Loops, Mode 4) require?
2 RCS or RHR loops (2/6) One I/S
all loops can be removed for 1 hour / 8 hr if other requirements met
What does 3.4.7 (RCS Loops, Mode 5 Loops Filled) require?
1 RHR loop + 1 more RHR loop
OR 2 S/G water level 420” > WR
RHR pp can be out for 1 hour / 8 hr if other requirements met
What does 3.4.8 (RCS Loops, Mode 5 Loops drained) require?
2 RHR loops OPERABLE
1 RHR loop in operation
All RHR can be out for < 30 minutes
when switching loops if requirements are met.
What’s the purpose of RVLIS?
- Verify adequate core cooling exists during accident
- Inputs to subcooling monitor
- Determines when Accumulators should be isolated to prevent nitrogen injection to RCS.
- Can be used for Reactor Vessel Heat fill and vent.
Which RVLIS correlation do you use when filling and venting RCS?
UPPER Plenum RVLIS with RCPs off when filling and venting RCS with RCP bump method
What are the RCS leakage limits per TS 3.4.13 (RCS Operational Leakage)?
RCS operational LEAKAGE shall be limited to:
- NO pressure boundary
- 0.8 gpm unidentified
- 10 gpm identified
- 150 gal/day for 1 S/G
What loops are the Pressurizer Spray Line Scoops on?
Loops 3 and 4 CLs
penetration into flowpath
What loops are the Reactor Coolant sampling Scoops on?
Loops 1 and 3 HLs
penetration into flowpath
What is required per TS 3.4.15 (RCS Leak Detection)?
**
Required to detect a 1 gpm leak within 4 hours
- 1 Containment Sump monitor in each sump
- 1 Particulate Rad Monitor – most sensitive for small leaks
- 1 Gaseous Rad Monitor
What is the primary purpose of the RCS?
Transfers the heat generated in the core to the steam generators (SG) where steam is generated to drive the turbine generator
What are the safety functions of the RCS?
- Credited as a Fission Product Barrier for Emergency Plan classification level assessment.
- Provides flow path for Decay Heat Removal purposes to maintain the reactor in a safe shutdown condition.
Given the following:
- Unit 1 is operating at 60% power
- Loop 3 Delta-T indication fails LOW
- Loop 3 Tavg indication fails HIGH
What failure could cause these indications?
Tcold failed high
If seal line resistance is less than tech specs required, what is the potential problem?
Boron Injection Tank flow may be less than required for core cooling
Technical Specification 3.4.6, RCS Loops - Mode 4, requires that a minimum of two reactor coolant loops or RHR loops be operable at all times.
The basis for this requirement is that two loops are:
Required to ensure the one loop required to remove decay heat is available in the event of a single failure.
The Plant is in HOT STANDBY (MODE 3)
Plant COOLDOWN from HOT STANDBY to COLD SHUTDOWN (MODE 5) will begin within the next half hour
How many RCPs MUST be in operation with Tavg > 541°F and why?
4; To ensure the required Tavg instruments are operable.
Which RCS Instrumentation input into RPS
Narrow Range
Thot, Tcold and Pressures
- Tave = P12 interlock for dumps, SLI
- Delta T = Rod Insertion Limits
- RCS Pressure = P11interlock, Rx Trip, SI
What is the purpose of the Reactor Vessel Head Vent System (NSOs)?
Removes non-condensable gas or steam from the Rx vessel head under accident conditions.
State why RVLIS wide range pressure is used preferentially when computing subcooling and making decisions in EOPs.
Located outside containment to eliminate inaccuracy which would occur due to heatup during accident conditions if location were inside containment.
Per TS 3.4.3 (RCS Pressure vs Temperature), what must be done if the heatup or cooldown rates are violtaed in Modes 1-4?
Restore within 30 mins
Per TS 3.4.3 (RCS Pressure vs Temperature), what must be done if the heatup or cooldown rates are violtaed in Modes 5-6?
Restore IMMEDIATELY and evaluated before Mode 4
What is the purpose of the pressure and temperature limits perscribed in TS 3.4.3 (RCS Pressure vs Temperature)?
To avoid normal operating conditions that could cause nonductile failure
Which penetrations extend into the flowpath?
- WR & NR RTD Thermowells
- Pressurizer Spray Line Scoops on loops 3 and 4
- Reactor Coolant Sampling Scoops on loops 1 and 3
NOT RHR SUCTION!!!!!!
Per TRO 8.7.14 (PPC Derived Reactor Thermal Power), what are the inputs for thermal power?
- Steam Pressure
- Blowdown Flows
- Charging Parameters
- LD Parameters
- RCS Paramaeters
- VCT Temperature
- Pressurizer Pressure
- LEFM (FW Flow, temp, pressure)
- Venturi (FW Flow, temp, pressure)
What is the basis for the RCS Minimum temperature for criticality ( 541°F) requirements in TS while operating in Mode 1?
All low power safety analyses assume initial RCS loop temperature ≥ the HZP temperature of 547°F. The minimum temperature for criticality limitation provides a small band, 6°F, for critical operation below HZP. This band allow critical operations below HZP during unit startup and does not adversely affect any safety analyses since the MTC is not significantly affected by the small temperature difference
The unit is in MODE 3. How many RCS Loops are required to be OPERABLE and in operation in MODE 3 with the Rod Control System capable of rod withdrawal?
Two RCS loops are required to be OPERABLE and the two loops must be in operation.
The unit is in MODE 3. How many RCS Loops are required to be OPERABLE and in operation in MODE 3 with the Rod Control System NOT capable of rod withdrawal?
Two RCS loops are required to be OPERABLE and the one loop must be in operation.
Where are THERMAL SLEEVES located?
- Pzr Spray Line at Pzr
- Pzr Surge Line at Pzr and at RCS
- Normal Charging (Loop 4)
- Alternate Charging (Loop 1)
- RHR/Accumulator/SI Taps (2 and 3 Cold Leg)
