NBI Flashcards
What is the purpose of the NBI System?
Monitor water level, pressure, temperature and flows inside RPV to provide operator with sufficient information to protect vessel from undue stress
Where is Instrument Zero?
Bottom of Moisture Separator - 503” above vessel bottom (143” above TAF)
Where are NBI level instruments variables tapped into?
downcomer region
At NOC, what is the pressure drop across the moisture separator skirt (water elevation difference)?
7in H2O
What will cause MCR to have NO Rx Level Indication?
Loss of ESS, Instrument Bus and AC power.
What is the range for Narrow Range Level Instruments?
-60in to +60in
What is the range for Medium Range Level Instruments?
-60in to +60in
What is the range for the Wide Range Level Instruments?
-70” to 330in
What is the range for the Fuel Zone Level Instruments?
-340in to +60 in
What is the purpose of RVWLIS Backfill?
Provides continuous backfill to Narrow, Medium, and FZ reference legs to prevent gases from coming out of solution - inaccurate level indication
How many NR level instruments are there? per division? What is their condensing pot? is it hot or cold reference leg(DW or RB)? Hot or cold calibrated? What shares reference leg? What shares variable leg? Where are the instruments? What do they feed and where are they powered from?
2 Total 1 per division 13A/B Cold Ref. Leg Hot Cal Shares FZ Ref. Leg Shares MR Var. Leg Located on -5 &-6 rack ; indicate at 902(3)-5 panel Feed to FWLC Input; powered from FWLC, auctioneered from IB & ESS
How many MR level instruments are there? per division? What is their condensing pot? is it hot or cold reference leg(DW or RB)? Hot or cold calibrated? What shares reference leg? What shares variable leg? Where are the instruments? What do they feed and where are they powered from?
10;
5 per div.
All same div. share cond. pot (12A/B)
All cold ref.
All Hot Cal
Shares Ref. with all MR per div.
Shares Var. Leg with all but FZ
Instrument Loc:
ATS: 57 inst. on 5 rack; Only 57B in MCR
58 inst. on 6 rack; Only 58A in MCR
ATWS: D1: 23A&C - 5 panel - no indication
23B&D - Tx on 6 panel - no ind
Yarway: Mechanical - 5&6 racks (545)
Feed to & P/S:
ATS: 57A Indicate at 902-5 - 2A-1 PS
57B - local ind. only - 28-1
58 MR-A indication in MCR and feeds FWLC; PS 29-1
58B - PS 2B-1
ATWS: D1: 23A&C - 5 panel - Auct. IB/2A-1
D2 23B&D - Auct ESS/2B-1
Yarway - NO POWER
How many WR level instruments are there? per division? What is their condensing pot? is it hot or cold reference leg(DW or RB)? Hot or cold calibrated? What shares reference leg? What shares variable leg? Where are the instruments? What do they feed and where are they powered from?
1 1 - only on Div 1 11 Hot Ref - Affected by DW Temp increase Calibrated Hot Shares Ref with none Shares Var. with MR and NR Tx on 5 rack Feed to Indication Only - 902-4 (analog) 902-5 (digital) Power from IB
How many FZ level instruments are there? per division? What is their condensing pot? is it hot or cold reference leg(DW or RB)? Hot or cold calibrated? What shares reference leg? What shares variable leg? Where are the instruments? What do they feed and where are they powered from?
4 2 per division Shares Condensing pot with NR (13A/B) Cold Ref Leg Calibrated Cold Shares Ref w/NR Shares Var Leg with FZ Bartons Indication at Non-barton 902-3 and -5 - Tx at 2202-7/8; Barton only at rack Feed 2/3 Core Height Interlock and MCR Interlock PS A - 28-1; B - 29-1; Barton - NONE
How many Refuel Zone level instruments are there?
per division?
What is their condensing pot?
is it hot or cold reference leg(DW or RB)?
Hot or cold calibrated?
What shares reference leg?
What shares variable leg?
Where are the instruments?
What do they feed and where are they powered from?
1 ONLY 1 TOTAL Cal Cold Ref Leg Open to Atmosphere Shares Var with MR Indication Only - 2202-6 - Ind at 902-4 - NORMALLY OFF PS is IB
Which NBI Level Instrucments have local indications?
MR Yarways - 5/6 rack
FZ Bartons - 7/8 rack
What pressure instruments are used for NBI?
Narrow Range, 950psig to 1050psig
Med. Range, 0 to 1200psig
Wide Range 0 to 1500psig
Where do the NBI pressure instruments connect?
Downstream of the condensing pots for the Level Instruments (12A/B, 13A/B cond. pots)
What signals do the NBI pressure instruments feed?
ADS, ATWS, ECCS low pressure permissive, iso condenser, initiation, Rx Pressure Hi Scram, LPCI Loop select logic, DEHC dome pressure trans.
What jet pumps have calibrated flow sensors?
1, 6, 11, 16
What powers the Jet pump flow sensors?
IB
What are teh NBI Pressure Instrument power sources?
WR - 2A-1, 29-1 (3A-1, 3B-1)
MR - FWLC - ESS BUS
NR - FWLC - IB/ESS
When are teh Vessel Thermocouples typically most useful?
11 installed at various locations for heatup and cooldown
Powered by IB
What is the purpose of the Core Plate DP Sensor?
Senses and displays core dp on recoreder in MCR - powered by IB
display at 7 rack
What is the Vessel Head Flange leak Detection used for?
Used to quantify leakage by aligning valves to empty volume, then reclose them and time until alarm comes back in
drains to DWEDS
What NBI feeds the 2/3 Core Height Interlock and what does this do??
Fuel Zone - if Water level below this, the DW and Torus Sprays go closed to send all water to core
What happens with a Sensing leg leak or failure?
- These are d/p instruments, so any artificial change in d/p will affect them
- If the ref leg breaks (normally higher pressure) the d/p goes down, so the indicated level will go up
- If the variable leg breaks (normally lower press) the d/p goes up, so the indicated level will go down
- Most level instruments have cold reference legs in the RB (except WR), so an increase in RB temperature will decrease the density of the water in the reference leg, this leads to d/p going down and level going up
