Modes & ESFAS (Engineered Safety Function Actuation Systems)

Question 1

“S” Safety Injection (SI)

→Origin
→Reset
→Notes

Answer 1

Origin:
→Manual - 1/2 CB hand switches
→Hi-1 CNTMT pressure (2/3; ch 1 doesn’t play) 3.2 psig
→Low PZR pressure (2/4) 1820 psig (see P-11)
→Low Steamline pressure (2/3) 605 psig on any 1 SG (rate sensitive; see P-11)

Reset:
→60 sec timer timed out for each train
→P-4 signal present for each train
→1 momentary pushbutton for each train

Notes:
→Ensures maintenance or recovery of Rx vessel water level
→Boration to ensure adequate shutdown margin
→SI cannot be reset until auto SI signal has cleared or been blocked. Blocking is done by the P-4 signal
→Reset blocks all auto actuation signals for that train & unlatches the latching slave relays until P-4 signal is reset
→Generates: Rx Trip, Turbine Trip, Phase “A”, FW Isolation signals, MDAFW Actuation, CNTMT Vent Isolation, CR Emergency Recirculation

Question 2

Turbine Trip and FW Isolation Signal

→Origin
→Reset
→Notes

Answer 2

Origin:
→Safety Injection
→Hi-Hi SG Level (see P-14)
→Rx Trip w/ Low T-ave; P-4 with 2/4 loops @ 564°F (FW Isolation only, no turbine trip from this signal)

Reset:
→1 momentary pushbutton for each train for Rx Trip w/ Low T-ave reset
→If generated by P-14, then P-14 must be clear and must cycle Rx trip breakers to reset signal
→If generated by SI, then SI must be reset and must cycle Rx trip breakers to reset signal

Notes:
→Prevents overfilling SG
→Prevents damage to Main Turbine from water in steam lines
→Prevents excessive cooldown of RCS
→Generates Turbine Trip, MFW Pump trip and FW Isolation.
→ Reset signal overrides Rx Trip w/ low TAVG signal

Question 3

Phase “A” CNTMT Isolation Signal

→Origin
→Reset
→Notes

Answer 3

Origin:
→Manual- 1/2 CB hand switches
→Safety Injection

Reset:
→1 momentary pushbutton for each train

Notes:
→Isolates all non-essential lines into and out of CNTMT; Does not isolate CCW to RCPs
→Reset signal overrides actuation signal as long as actuation signal is present

Question 4

MSL Isolation

→Origin
→Reset
→Notes

Answer 4

Origin:
→Manual- 1/2 CB hand switches
→Low Steam line pressure (2/3) 605 psig on any 1 SG (rate sensitive; see P-11)
→HI-2 CNTMT pressure (2/3; ch 1 doesn’t play) 6.2 psig
→Negative Steam line Pressure Rate (2/3) 100 psig/sec decreasing w/ 50 sec time constant (rate sensitive; see P-11)

Reset:
→1 momentary switch for each train
→Actuation signal must not be present

Notes:
→Prevents continuous uncontrolled blowdown of more than 1 S/G therefore limiting RCS cooldown
→Closes MSIV’s and upstream (BEF) drip pot isolation valves
→Limits mass and energy released into containment in the event of a steam line break inside containment
→Once Negative rate in place, MSL Isolation will occur but not a Safety Injection since it is blocked

Question 5

CVI CNTMT Vent Isolation signal

→Origin
→Reset
→Notes

Answer 5

Origin:
→uRE-5502 or uRE-5503 Hi Rad alarm (clears after 10 sec)
→Safety Injection
→Manual Phase “A” ½ CB hand switches
→Manual CNTMT Spray Actuation 2/2 CB hand switches @ ½ MCB locations

Reset:
→1 momentary switch for each train

Notes:
→Shuts dampers, closes valves and stops fans associated w/ CNTMT ventilation
→When CVI is reset due to RE input, then it will actuate again if SI input is received
→Reset signal overrides actuation signal as long as actuation signal is present

Question 6

CR Emergency Recirculation Signal

→Origin
→Reset
→Notes

Answer 6

Origin:
→Manual on CV-03
→SI in either unit * Blackout Signal in either unit
→XRE-5895A/B or XRE-5896A/B (Noble Gas Only) Hi Rad alarm

Reset:
→1 momentary switch for each train on CV-03

Notes:
→Places Control Room in closed loop recirculation to limit operator exposure
→Reset signal overrides actuation signal as long as actuation signal is present

Question 7

CR Emergency Ventilation Signal

→Origin
→Reset
→Notes

Answer 7

Origin:
→Manual on CV-03 coincident w/ CR Emergency Recirculation Signal

Reset:
→Manual hand switch on CV-03

Notes:
→Aligns CR ventilation system to replenish oxygen supply while in emergency recirculation
→done for 3 hours, every four days

Question 8

CR Ventilation Isolation Mode

→Origin
→Reset
→Notes

Answer 8

Origin:
→Manual on CV-03

Reset:
→Manual hand switch on CV-03

Notes:
→Totally isolates CR from all outside sources of air to prevent toxic gas or radioactivity from contaminating air while the system is in emergency recirculation

Question 9

“P” Signal

→Origin
→Reset
→Notes

Answer 9

Origin:
→Manual 2/2 CB hand switches @ 1/2 MCB locations (CB-02 & CB-07)
→Hi-3 CNTMT pressure (2/4) 18.2 psig

Reset:
→N/A

Notes:
→Initiates Containment Spray actuation signal and Phase “B” isolation signal
→System designed such that 2/2 driver cards per train coincidence required to initiate Containment Spray. However, Phase “B” initiating requires only 1/1 driver card per train.

Question 10

CNTMT Spray Actuation Signal

→Origin
→Reset
→Notes

Answer 10

Origin:
→“P” signal

Reset:
→1 momentary pushbutton for each train (CS reset pushbuttons)

Notes:
→Initiates Containment Spray
→Reset signal overrides actuation signal as long as actuation signal is present

Question 11

Phase “B” CNTMT Isolation Signal

→Origin
→Reset
→Notes

Answer 11

Origin:
→“P” Signal (from same hand switches/signals at CT Spray)

Reset:
→1 momentary pushbutton for each train (Phase “B” reset pushbuttons)

Notes:
→Isolates CCW Non-Safeguards Loop and RCP CCW isolation valves.
→Reset signal overrides actuation signal as long as actuation signal is present

Question 12

Auxiliary Feedwater Actuation Signal

→Origin
→Reset
→Notes

Answer 12

Origin:
→Blackout*
→Lo-Lo SG level (2/4) <38% U1, <35.4% U2 on any 1 SG (TDAFWP will also start with Lo-Lo on any 2 SGs)
→AMSAC*
→Safety Injection
→Trip of both MFPs

Reset:
→N/A

Notes:
→Auto start of Aux FW Pumps also initiates isolation of SGBD, sample lines, Condenser Hotwell flowpath, and split flow bypass valve

*Also starts TDAFWP

Question 13

AMSAC

→Origin
→Reset
→Notes

Answer 13

Origin:
→C-20, AND
→Narrow range level in 3 of 4 SGs <10% for 25 seconds, AND PT-505/506 >40% (TDDO 260 seconds)
→Above conditions are sensed by 2/3 Actuation Logic Processors (ALPs)

Reset:
→N/A

Notes:
→Protects against loss of all FW flow w/out Rx/Turbine Trip or initiation of AFW flow
→Initiates Turbine trip and AFW start
→Closes SGBD valves, sample valves, split flow bypass valves & CST to Hotwell MOVs

Question 14

What is MODE?

Answer 14

Basically gives the operating status of the plant when fuel is present in the reactor through a combination of:
→core reactivity condition
→power level
→avg RCS temp
→reactor vessel head closure bolt tensioning

Question 15

Mode 1

Answer 15

Power Operation
> 5% power
k-eff ≥ 0.99

Question 16

Mode 2

Answer 16

Startup
≤ 5% power
k-eff ≥ 0.99

Question 17

Mode 3

Answer 17

Hot Standby
RCS T-avg ≥ 350
k-eff < 0.99

Question 18

Mode 4

Answer 18

Hot Shutdown
200 < RCS T-avg < 350
k-eff < 0.99
(all reactor vessel head closure bolts fully tensioned)

Question 19

Mode 5

Answer 19

Cold Shutdown
RCS T-avg ≤ 200
k-eff < 0.99
(all reactor vessel head closure bolts fully tensioned)

Question 20

Mode 6

Answer 20

Refueling
RCS T-avg, % power, and k-eff are all N/A
One or more reactor vessel head closure bolts are less than fully tensioned.

Question 21

What is No Mode?

Answer 21

defueled