Oconee Indeck Parameters
This appendix describe the control logics set in the indeck3.i of the Oconee RELAP model. The last update of indeck3.i is on August 17, 2006. In the indeck3.i, the first and majot portion is the original Oconee deck. The ISL’s modification (search key word “ISL CHANGES” in the indeck3.i) follows the original deck. The midfication I (i.e., James Chang) made is at the end of the deck (search key word “James” within the deck). The control logics discussed in this appendix are the ultimate logics from all above changes. The discussion is oriented to the components to be controlled instead of control cards set within the indick3.i.
HPI (Junctions 711, 716, 721, and 726)
In the real Oconee plant there are three HPI pumps (two online and one backup) connected to the primary system. The two online pumps pump coolant into a loop each. The operator is able to align the backup HPI pump to any of the two loops to provide addition HPI flow.
These three HPIs are modeled in the Oconee deck by fout junctions (i.e., 711, 716, 721, and 726). The flow of each junction can be adjusted to simulate whether the backup pump is adding additional coolant flow. Figure G1 shows the logics in indeck3.i that control the mass flow of Junction 711. As seen in Figure G1, the mass flow of Junction 711 is calculated by multiplying the values of four parameters:
- State of operator (or hardware reliability) control HPI. This values is determined by the value of X_HPIA1. If X_HPIA1 is greater than zero, then the value is one; otherwise the value is zero. Thus, set X_HPIA1 less than zero would disable HPIA1. The initial value of X_HPIA1 is set to one.
- Auto or manual activate HPIA1: when RCS pressure is below the set point, the HPIA1 would automatically activated. However, prior to the automatic activation of HPI, the operator also can activate HPI. This can be done by set the value of X_SI larger than zero that would result in manually activating all HPIs. The initial value of X_SI is set to zero.
- Calculate HPI flow rate based on head pressure: by setting X_HPIA value to 1 (one) or 2 (two) would calculate without and with, respectively, backup HPI pump flow. Inside the input deck, the backup HPI is assumed to be aligned to Loop A. In the indeck3.i the initial value of X_HPIA is set to one (i.e., without backup HPI operating).
- Operator adjustment on HPI flow rate: by adjusting the value of X_HPI the final total HPI flow rate is adjusted by times the value of X_HPI. The value range of X_HPI should be between 0 (zero) and 1 (one).
The flow rate calculation logics of Junction 716 (HPI_A2) is similar to Junction 711 described above, and is shown in Figure G2.
Figure G1 the HPIA1 (Junction 711) flow control logics
Figure G2 the HPIA2 (Junction 716) flow control logics
The junctions 721 (HPI_B1) and 726 (HPI_B2) have similar control logics as the of Junctions 721 and 726. However, since the backup HPI is aligned to Loop A, the value of parameter X_HPIB has no effect on HPI flow rate in Loop B. The flow control logics applied to Junction 721 and 726 are shown in Figures G3 and G4, respectively.
Figure G3 the HPIB1 (Junction 721) flow control logics
Figure G4 the HPIB2 (Junction 726) flow control logics
RCPs (Pumps 165, 135, 265, and 235)
In the real Oconee plant, the RCPs will not be tripped automatically due to loss of RCS suncooling. However, the operators are trained to trip (i.e., tuen off) RCPs when the RCS is loss of subcooling to protect the RCPs). In the ISL modification, the RCPs are set to be tripped when RCS is loss of sobcooling. Such logics are removed. In current indick3.i the RCPs only can be tripped by operators or hardware failure.
The user should pay attention that RCP_165 is in loop A1, and RCP_135 is in loop A2. The same situation also applies to loop B.
Figure G5 shows the RCP_165 control logic. Set X_RCPA1 value less than zero would trip RCP_165 individually. Set X_RCPs value less than zero would trip all four RCPs. The controls is reversible. Thus, setting both X_RCPS and X_RCPA1 values greater than zero would restart RCP_165. The similar logic applies to the other three RCPs.
Figure G5 the control logic for RCP 165.
MSIV (Valves 821 and 921)
MSIVs can be manually controlled by two parameters:
- Set X_MSA (or X_MSB for MSIV_B) to 0.0 (zero) would manually close the MSIV
- Set X_MSIVFC’s value greater than zero would keeps the valve open event the turbine is tripped. This is used to model hardware failure on MSIV fail-open.
- In normal situations, the MSIVs are set to close after turbine trip.
Figure G6 shows the control logic for MSIV_A (i.e., Valve 821).
Figure G6: control logic for Valve 821 (MSIV_A)
AFW (Junctions 804, 813, 904, and 913)
Junction 804
X_MTREFWA value is use to model operator’s manual action on controlling the motor driven AFW_A flow after it is activated. The final flowrate is calculated by multiplying the automatic nominal flow rate to the value of X_MTREFWA Thus, when X_MTREFWA is set to 0 (zero) the Junction 804 is closed. Increase X_MTREFWA value will increase Junction 804 flow rate. The effect rage of X_MTREFWA on the Junction 804 flow is between 0 (zero) and 1 (one). Set X_MTREFWA value greater than 1 would still produce maximum nominal flow rate. When X_ MTREFWA’s value is set to -1 (negative one) the Junction 804 is set to automatic system control.
The following discussion uses the indeck3.i as an example to explain the setting for the control Junction 804.
The flow of Junction 804 is determined by the Control Variable 803 as shown in the following line in the indeck3.i
8040200 0 0 cntrlvar 803
The Control Variable 803 is a multiplication product of three other Control Variables 800, 801, and 802:
20508030 thrlefwa mult 1.0 0.0 1
20508031 cntrlvar 800 cntrlvar 801
20508032 cntrlvar 802
Control Variable 800 determines the EFW flow rate based on its head pressure Pressure of 853). The flow rate is determined by a table as shown below:
20508000 mefwacrv function 1.0 0.0 1
20508001 p 853010000 800
20280000 reac-t
20280001 0. .01548
20280002 1.9098e6 .01548
20280003 2.1443e6 .01515
20280004 2.8062e6 .01426
20280005 3.3715e6 .01381
20280006 4.7712e6 .01248
20280007 6.1432e6 .01092
20280008 7.5291e6 .00936
20280009 9.1355e6 .00613
20280010 9.9078e6 0.
Control Variable 801’s value is either one or zero depending on the state of logical trip 1796 (see below). When the logical trip 1796 is true, the Control Variable 801’s value is one; otherwise zero.
20508010 mtfwatrp tripunit 1.0 0.0 1
20508011 1796
Logical trip 1796 is a function of ligic trip 1776 and variable trip 586 (see below):
20617960 1776 or 586 n * mtr efw "a" on
Variable trip 586 is a maneual control. When X_MTREFWA is greater than zero, the variavle trip 586’s state is true; otherwise false (see below).
20605860 mtrefwa 1000000000 gt null 0 0.0 n
Logical trip 1776 is a complex logic which is function of a logical trip (1775) and a variable trip (471):
20617760 1775 and 471 n $ a ll - mtr on
Variable Trip 471 whos evalue is dependent on Control Variable 3318. When the Control Variable 3318’s value is greater or equal to zero, the Vraiable trip 471’s state is true; otherwise false.
20604710 cntrlvar 3318 ge null 0 0.0 n
The Control Variable 3318’s value seems having to do with automatically control the SG_A level at 24 inches level. It’s too complex to describe here.
Logical trip 1775’s state is dependent Logical Trip 1774 and Variable Trip 495.
20617750 1774 and -495 l * hw mass > 1178970
Vatiable Trip 495 represents whether the EFW water source (i.e., Refeuling water storage tank) has been used out. Logical Trip 1774’s state represent the EFW automatic EFW activation logic.
Control Variable 802 allow’s the operator to adjust the feedwater flow rate by control the value of X_MTREFWA.
20508020 manefwa function 1.0 0.0 1
20508021 mtrefwa 1000000000 802
20280200 reac-t
20280201 -1.0 1.0
20280202 0.0 0.0
20280203 1.0 1.0
The above logics are represented in Figure G7:
Figure G7: the original control logic for Junction 804 (Motor driven EFW for SG A)
However, it is unsure whether the SG level control set in the indeck represent the reality of the plant since there is indication in the EOPs asking operator to throttle EFW folw rate. Thus, the indeck is revised that the automatic EFW level control is disabled. In this revision, the EFW will automatically inject water into SG. Operator action is required to control the water level by changing the value of X_MTREFWA. The X_MTREFWA values and effects are explained in Table G1. The revised logic is shown in Figure G8.
Table G1 The optional X_MTREFWA values and corresponding effects
| X_MTREFWA value | Effects |
|---|---|
| X_MTREFWA >= 1.0 | Operator manually turns on MTR EFW A. MTR EFW A uses full rate injecting coolant into SG. The actual flow rate is dependent on the EFW pump head pressure. |
| 0.0 < X_MTREFWA < 1.0 | Operator throttle MTR EFW A flow rate. |
| X_MTREFWA = 0.0 | Operator manually shuts off MTR EFW A. MTR EFW A flow arte is completely shut off. |
| X_MTREFWA = -1.0 | MTR EFW A is set to be operated automatically (without automatic level control) |
Figure G8 the revised MTR EFW A control logic that removed automatic level control function for this study. The automatic inject water flow rate control based on SG water level is removed.
Junction 904
X_MTREFWB value is use to model operator’s manual action on controlling the motor driven AFW_B flow after it is activated. The final flowrate is calculated by multiplying the automatic nominal flow rate to the value of X_MTREFWB Thus, when X_MTREFWB is set to 0 (zero) the Junction 904 is closed. Increase X_MTREFWB value will increase Junction 904 flow rate. The effect rage of X_MTREFWB on the Junction 904 flow is between 0 (zero) and 1 (one). Set X_MTREFWB value greater than 1 would still produce maximum nominal flow rate.
Junction 813
X_TRBNEFWA value is use to model operator’s manual action on controlling the turbine driven AFW_A flow after it is actived. The final flowrate is calculated by multiplying the automatic nominal flow rate to the value of X_TRBNEFWA. Thus, when X_TRBNEFWA is set to 0 (zero) the Junction 813 is closed. Increase X_TRBNEFWA value will increase Junction 813 flow rate. However, the maximum value to be multiplied to the nominal flow is set to 2 (two). Set X_TRBNEFWA value greater than 2 would only have two times of nominal flow rate in Junction 813. The original control logic for turbine driven pump for SG A is shiwn in Figure G9.
Figure G9: the original control logic for Junction 813 (Turbine driven EFW for SG A)
The control logics shown in Figure G9 impose the automatic flow rate control for turbine driven EFW to SG A. For current ADS application, the automatic control is removed. The revised control logics for the turbine driven EFW A is shown in Figure G10.
Note, the turbine driven EFW pump requires steam to drive the the pump. The indeck3.i uses the void fraction (i.e., the steam quality) at the component 350 and 450 to determine whether steam is available (see VT_494 in the deck).
Figure G10 the revised TBR EFW A control logic that removed automatic level control function for this study. The automatic inject water flow rate control based on SG water level is removed.
Table G2 shows the optional values for X_TRBEFWA and X_TRBNEFW.
Table G2 The optional X_TRBEFWA values and corresponding effects
| X_TRBEFWA value | Effects |
|---|---|
| X_TRBNEF > 0 | Operator manually activating the turbine driven pumps |
| X_TRBNEF <= 0 | The state of turbine driven pump is automatically controlled. |
| X_TRBEFWA = 2.0 | TRB EFW A uses full rate injecting coolant into SG with combinational use of the backup turbine driven EFW pump. The actual flow rate is dependent on the EFW pump head pressure. This only works when the TRB EFW A is ON either activated automatically or manenually. |
| X_TRBEFWA = 1.0 | TRB EFW A uses full rate but without activating the backup TRB EFW injecting coolant into SG. The actual flow rate is dependent on the EFW pump head pressure. This only works when the TRB EFW A is ON either activated automatically or manenually. |
| 0.0 < X_TRBEFWA < 1.0 | Operator throttle TRB EFW A flow rate. This only works when the TRB EFW A is ON either activated automatically or manenually. |
| X_TRBEFWA = 0.0 | Operator manually shuts off TRB EFW A. MTR EFW A flow arte is completely shut off. |
Junction 913
X_TRBNEFWB value is use to model operator’s manual action on controlling the turbine driven AFW_B flow after it is activated. The final flowrate is calculated by multiplying the automatic nominal flow rate to the value of X_TRBNEFWB. Thus, when X_TRBNEFWB is set to 0 (zero) the Junction 913 is closed. Increase X_TRBNEFWA value will increase Junction 913 flow rate. However, the maximum value to be multiplied to the nominal flow is set to 2 (two). Set X_TRBNEFWB value greater than 2 would only have two times of nominal flow rate in Junction 913. Figure G11 and G12 show the original and revised control logic for the turbine driven EFW B. The revised logics remove the control of feedwater flow based on the SG water level.
Figure G11: the original control logic for Junction 913 (Turbine driven EFW for SG A)
Figure G12: the original control logic for Junction 913 (Turbine driven EFW for SG A). The automatic flow rate control based on the SG A water level is removed from the original settings.
Valve 775
- X_V775 > 0 nominal operation
- X_V775 <= 0 : manually close the valve
Valve 850:
- X_V850 > 0 nominal operation
- X_V850 <= 0 : manually close the valve
Valve 950:
- X_V950 > 0 nominal operation
- X_V950 <= 0 : manually close the valve
Valve 777:
- X_V777 > 0 nominal operation
- X_V777 <= 0 : manually close the valve
Valve 811:
- X_V811 > 0 nominal operation
- X_V811 <= 0 : manually close the valve
- To overwrite the automatic valve open control in order to manually open the valve 811 then set
- X_V811 = 1.0, and
- X_TBVA = 1.0
Valve 911 (TBV B):
- X_V911 > 0 nominal operation
- X_V911 <= 0 : manually close the valve
- To overwite the automatic control on V911 opening, set
- X_V911 = 1.0, and
- V_TBVB = 1.0
Valve 911 represents two TBVs in the same loop. The Valve 823 was created having a half of the open area of Valve 911 to facilitate the simulation of operator controlling one TBVs to cooldown RCS. The control logics for Valve 823 are described below:
- X_SGBSDV > 0 : Valve 823 open
- X_SGBSDV <= 0: Valve 823 close
Valve 807:
- X_V807 > 0 nominal operation
- X_V807 <= 0 : manually close the valve
Valve 907:
- X_V907 > 0 nominal operation
- X_V907 <= 0 : manually close the valve
Valve 801(PZR PORV):
- X_V801 > 0 nominal operation
- X_V801 <= 0 : manually close the valve
Valve 616 (PZR spray):
- X_SPRAY <= 0.0 nominal
- X_SPRAY > 0: force open valve 616
Valve 802 (PZR safety valve):
- no manual control for Valve 802
Pump 754:
- X_MFPA < 0 : trip (turn off) pump 754
- X_MFPA >= 0: nominal operation
Pump 760:
- X_MFPB < 0 : trip (turn off) pump 760
- X_MFPB >= 0: nominal operation
Pump 135 (RCP_A2):
- rcps (i.e., X_RCPS) < 0 and rcpa2 (i.e., X_RCPA2) < 0 would trip (turn off) RCP_A2
- Otherwise RCP_A2 is ON
Pump 165 (RCP_A1):
- rcps (i.e., X_RCPS) < 0 and rcpa1(i.e., X_RCPA1) < 0 would trip (turn off) RCP_A1
- Otherwise RCP_A1 is ON
Pump 235 (RCP_B2):
- rcps (i.e., X_RCPS) < 0 and rcpb2 (i.e., X_RCPB2) < 0 would trip (turn off) RCP_B2
- Otherwise RCP_B2 is ON
Pump 265 (RCP_B1):
- rcps (i.e., X_RCPS) < 0 and rcpb1 (i.e., X_RCPB1) < 0 would trip (turn off) RCP_ B 1
- Otherwise RCP_B1 is ON
Junction 191 (Makeup/letdown flow):
- X_V191 < 0 would shutoff makeup/letdown; otherwise the make up/letdown is functioning as designed.
- makeup/letdown will be automatically shutoff after safety injection is ON
- Note: Junction 191 models combination of make up and letdown
Initiating Event:
Within current indeck3.i there are several options to set initiating events for a simulation. These include:
LOCA (Loss Of Collant Accident):
There are three locations for having a LOCA accident:
- Hot Leg LOCA in Loop A:
- This is by opening valve 1120000 that can be done by setting X_HPVA greater than 0.0 (zero).
- The break area is set as a quarter inch in diameter (0.000326 ft^2).
- Hot Leg LOCA in Loop B:
- This is by opening valve 2120000 that can be done by setting X_HPVB greater than 0.0 (zero).
- The break area is set as a quarter inch in diameter (0.000326 ft^2).
- Surge Line LOCA:
- This is by opening valve 9970000 that can be done by setting X_LOCA greater than 0.0 (zero).
- The break area is set as a two inches in diameter (0.021817 ft^2)
MSLB (Main Steam Line Break):
- This is by opening valve 8310000 that can be done by setting X_MSLABRK greater than zero.
- The break area is set as a thirty four inches in diameter (6.305 ft^2) which is the main stean line diameter of the Oconee plant.
SGTR (Steam Generator Tube Rupture):
- Currently only set for SGTR in Loop A SG
- This is by opening valve 9950000 that can be done by setting X_SGATR greater than zero.
- The break area is set as a 0.79 inches in diameter (0.00338 ft^2). Setting for this size of break is to creat a break flow rate greater than which can be compensated by the change/letdown automatic control.
- Having a such size of break will cause reactor trip by the reach of the pressure/temperature operational boundary before reactor is tripped by low RCS pressure.
Reactor Trip:
This can be done by setting X_SCRAM greater than 0.0 (zero).
Reactor trip logics: The core power curve is set to be activated by LT_1770.
Turbine Trip:
This can be done by setting X_TURBINE smaller than 0.0 (zero).
Oconee indeck file names with corresponding changes:
| File Name | Content |
|---|---|
| indeck3.i | Added above listed control channels based on Oconee steady state deck used for PTS study. |
| indeck4.i | Remove the logics of automatic SGs’ water levels control based on the RCPs’ states |