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