Primary Containment and RPV Internals Flashcards
How can you verify the position of a fuel bundle?
- Serial # - readable from center 2. Channel fastener – on central corners secures channel to assembly 3. ID Boss – points towards center 4. Spacer buttons – adjacent to control rods maintain wide-wide gap 5. Cell to cell symmetry. Heights even across all bundles
How is 2/3 core height protection achieved?
2/3 core height protected by shroud and jet pumps; jet pump riser does not protect 2/3 core height
How is adequate flow maintained through all bundles?
Flow/Core orifices located in the fuel support pieces and minimize flow variation caused by changes to two phase flow resistance
List, in order, from RPV top to bottom penetrations (from instrument zero):
i. MSL tap (273”) ii. Steam Separator turnaround point (200-220”) iii. Recirc Discharge/Jet Pump Suction (-188.44”) iv. Recirc Suction (-205.5”)
What is the primary function of the shroud?
provide for a floodable region
Which component supports the weight of the fuel during fuel moves?
Upper tie plate. Supports weight during fuel moves. Load chain transmits weight to upper tie plate during fuel handling ONLY when assembly hanging by bail handle.
What components support the weight of the fuel bundle?
Fuel bundle, Fuel Support Piece, CRD Guide Tube, CRD Housing, Stub tube, J-weld to RPV bottom head, Vessel skirt
What does the lower core plate support?
Peripheral fuel bundles
What is the RPV inventory/inch? What is the total mass of the fluid in the core during cold shutdown?
150 gal/inch 620,000 lbm
How does steam quality change through the RPV?
10-13% exiting core 95% exiting steam separators 99.75% exiting steam dryers
Explain the 3 flowpaths of natural circ
• Primary Loop: Up through core, down to downcomer, through jet pumps, under core plate, back to core • Secondary Loop: Flow through bypass region • Third Loop: down through cold peripheral bundle, below core plate, up through hot bundle
What RPV level is required for natural circulation?
200-220” Steam separator turnaround
Explain the difference between carryover and carryunder
Carryover: Moisture entrained in steam caused by high vessel level; affects turbine/radiation levels Carryunder: Steam entrained in downcomer liquid caused by low vessel level; affects NPSH for jet pumps and recirc pumps
What is 100% core flow?
• 77 Mlbm/hr total core flow
What is the limit for unidentified drywell leakage and where does it collect?
≤ 5 gpm unidentified averaged in 24 hours. Collected in the DWFDs. 8 hour limit.
RCS Tech Spec leakage limits?
a. No pressure boundary LEAKAGE; b. ≤ 5 gpm unidentified LEAKAGE averaged over the previous 24 hour period; c. ≤ 25 gpm total LEAKAGE averaged over the previous 24 hour period; and d. ≤ 2 gpm increase in unidentified LEAKAGE within the previous 24 hour period in MODE 1.
How much pressure boundary leakage is allowed?
None. M3 in 12, M4 in 36.
What is typical value for bypass flow at 100%?
• 7.7 Mlbm/hr bypass flow
What is typical value for driving flow at 100% power?
• 36 Mlbm/hr recirc. Flow (Driving Flow)
What is typical value for steam flow at 100% power?
• 12.8 Mlbm/hr steam flow
What is typical value for feedwater flow at 100% power?
12.75 Mlbm/hr
Where is TAF (from instrument zero)? Where is BAF (from instrument zero)?
-8.44” -158”
Increased carryunder can result in less what?
NPSH for recirc pumps
What is a hazard of operating with an inoperable/broken jet pump?
potential loss of core reflood capability in event of a LOCA (jeopardize 2/3 core height) and increase blowdown area
How many fuel assemblies are there in each Brunswick core? How many Control Rods?
560 137
How many fuel assemblies are supported by the lower core plate?
12 (peripheral assemblies only)
How can you tell a RPV Flange Seal leak has occurred and what causes the alarm?
A-02, window 5-6 will annunciate. This is caused by a failure of the inner seal and is detected by a pressure switch at 600#.
What is the purpose of RPV internals?
Properly distribute flow to the vessel Locate and support fuel assemblies Provide a volume to be flooded following a LOCA Facilitate Refueling Function as a radioactive material barrier
What is the design basis for RPV internals?
Withstand loading and forces from operations and accidents NDT shifts are accounted for Floodable volume post LOCA Limit Deformation to ensure CRs and cooling systems can perform their functions Design shall ensure safety bases are satisfied
What is the purpose of the Fuel Support Piece (elephants foot) and its orifice?
It ensures a more even flow distribution under high flow conditions. “Adequate flow NOT equal flow to all fuel bundles”
What does suppression pool level initially do during a DBA LOCA and why?
Level initially rises due to the increased pressure pushing water out of the downcomer piping. Level falls once ECCS systems start taking suction from the torus.
Above what suppression pool temperature do Tech Specs require an immediate scram?
110dF
Above what suppression pool temperature do Tech Specs require RPV pressure to be below 200psig in 12 hours?
120dF
What is required for Primary Containment Operability?
PEALS Penetrations Operable or Closed Equipment Hatch Closed Airlock operable Leakage rates in spec Sealing mechanisms operable
What level is the suppression pool maintained at?
> - 31 inches and <= -27 inches
What is the requirement for Primary containment atmosphere?
Oxygen less than 4% volume in Mode 1 >15% RTP
Which results in a higher drywell pressure? DBA LOCA or a steam line break?
DBA LOCA
Which results in a higher drywell pressure? DBA LOCA or a steam line break?
DBA LOCA
What is the design pressure limit for the Drywell (NOT PCPL-A)
62psig
What is the design temperature limit for the Drywell?
300dF (340dF environmental)
What is the design internal pressure for the suppression pool?
62psig
What is the design internal pressure for the suppression pool?
62psig
The reactor building to suppression pool vacuum breakers open based on differential pressure between what?
Reactor building and Drywell
At what differential pressure do the suppression pool to drywell vacuum breakers open?
0.5psid between suppression pool and drywell
At what differential pressure do the reactor building to suppression pool vacuum breakers open?
0.5psid between reactor building and drywell
How many suppression pool to drywell vacuum breakers are required to be operable to open?
8 of 10
How many suppression pool to drywell vacuum breakers are required to be closed?
10 unless performing functional test
How does a group 2 isolation affect drywell floor and equipment drains?
close F019 and F020 and F003 and F004 and stops running pumps
What is the caveat about the Tigraph Recorder for the Wide Range instruments?
The recorder only takes input from N026B. Fails as is, LED will go blank If Div 2 is lost, if the input to the recorder is lost and it fails downscale.
What will trip drywell coolers?
LOCA signal loss of power or control power
How does a group 2 isolation affect drywell floor and equipment drains?
close F018 and F019 and stops running pumps
How many transfer pumps start on a drywell floor or equipment drain hi level alarm?
1 lead pump starts when in auto; no pumps start if in lockout
How many transfer pumps start on a drywell floor or equipment drain hi hi level alarm?
1 standby pump regardless of switch in auto or lock out
A loss of PNS will cause which drywell coolers to start?
All Unit 2 and 1B (dampers fail open)
What will cause all drywell coolers to start (in normal line ups)
scram (scram air header pressure 60 psig)
What will trip drywell coolers?
LOCA signal loss of power or control power
What does the lockout switch prevent on the RTGB and when will it not work?
Lockout prevents DW coolers from starting after a scram. It will NOT prevent Unit 2 and 1B DW coolers from starting on a loss of pneumatics
Which DW coolers are Div 1 and which are Div 2?
Div 1: A&D Div 2: B&C
How do DW cooler dampers fail on loss of pneumatics?
Fail open
How do reactor building to torus vacuum breaker butterfly valves fail on loss of pneumatics?
Fail closed
Describe the operation of RIP valves.
Red and Green lights give valve position Dual lights, top is solenoid status. Bottom is valve position. To re-open after isolation, pushbutton must be depressed twice.
Describe the operation of Excess Flow Check Valves.
They protect against line failure / leakage. Solenoid bypass to reset Red or Green light on RTGB for position indication of bypass solenoid Yellow light on pushbutton indicates bypass solenoid energized.
What comes off of the inner pipe within a pipe and where does the inner pipe go in the RPV?
Under core plate-SLC injection-Core Plate D/P-Jet Pump Flow
What comes off of the outer pipe within a pipe and where does the outer pipe go in the RPV?
Above core plate-CRD D/P-Core plate D/P-Core Spray Leak Detection
