Reactor Pressure Setpoints/Actuations and Bases

Question 1

What happens at an RPV pressure of 60 psig?

Answer 1

RCIC system isolates

Question 2

What happens at an RPV pressure of 135 psig?

Answer 2

RHR Shutdown Cooling isolates

Question 3

What is the significance of an RPV pressure of 785 psig?

Answer 3

Tech Spec safety limit: With the reactor steam dome pressure < 785 psig or core
flow < 10% rated core flow: THERMAL POWER shall be < 23.8% RTP.

With the reactor steam dome pressure > 785 psig and core
flow > 10% rated core flow: The Minimum Critical Power Ratio (MCPR) shall be > 1.10
for two recirculation loop operation or > 1.11 for single recirculation loop operation.

Question 4

What happens at an RPV pressure of 807 psig?

Answer 4

MSIV isolation

Question 5

What happens at an RPV pressure of 926 psig?

Answer 5

Low-Low Set SRV B21-F051D closes

Question 6

What happens at an RPV pressure of 936 psig?

Answer 6

Low-Low Set SRV B21-F051C closes

Question 7

What happens at an RPV pressure of 946 psig?

Answer 7

Low-Low Set SRV B21-F051G and 3 other Low-Low set SRVs close

Question 8

What is the significance of 1025 psig?

Answer 8

Normal operating pressure at 100% power

Question 9

What happens at an RPV pressure of 1033 psig?

Answer 9

Low-Low Set SRV B21-F051D opens

Question 10

What happens at an RPV pressure of 1040 psig?

Answer 10

High pressure alarm

Question 11

What is the significance of 1045 psig?

Answer 11

Tech Spec 3.4.12, Reactor Steam Dome Pressure, shall be < 1045 psig. Restore within 15 minutes.

Question 12

What happens at an RPV pressure of 1065 psig?

Answer 12

Reactor Scram

Question 13

What happens at an RPV pressure of 1073 psig?

Answer 13

Low-Low Set SRV B21-F051C opens

Question 14

What happens at an RPV pressure of 1083 psig?

Answer 14

) Reactor Recirc Pumps downshift to slow speed. Reactor Recirc Pumps will trip off if 25 seconds elapse and APRMs are not downscale. 2) ARI initiates 3) Feedwater runback if 25 seconds elapse and APRMs are not downscale.

Question 15

What happens at an RPV pressure of 1103 psig?

Answer 15

Low-Low Set SRV B21-F051D opens to initiate the Low-Low Set logic

Question 16

What happens at an RPV pressure of 1113 psig?

Answer 16

9 SRVs open in relief mode, 4 of which are Low-Low Set

Question 17

What happens at an RPV pressure of 1123 psig?

Answer 17

9 SRVs open in the relief mode

Question 18

What happens at an RPV pressure of 1165 psig?

Answer 18

8 SRVs open in the safety mode

Question 19

What happens at an RPV pressure of 1180 psig?

Answer 19

6 SRVs open in the safety mode

Question 20

What happens at an RPV pressure of 1190 psig?

Answer 20

5 SRVs open in the safety mode

Question 21

What is the significance of 1250 psig?

Answer 21

RPV design pressure

Question 22

What is the significance of 1325 psig?

Answer 22

RPV Steam Dome pressure safety limit per Tech Spec 2.1.2

Question 23

What is the significance of 1375 psig?

Answer 23

Peak pressure at the bottom of the Reactor Coolant System based on 1325 psig in the Steam Dome

Question 24

What is the basis for the RHR Shutdown Cooling isolation at 135 psig?

Answer 24

Prevent RHR Pump seal damage (135 psig corresponds to a saturation temperature of 365F)

Question 25

When is the MSIV isolation at 807 psig active?

Answer 25

With the Mode Switch in RUN

Question 26

What is the basis for the Reactor Scram at 1065 psig?

Answer 26

Prevent exceeding the ASME max design pressure

Question 27

How do 1325 psig in the steam dome and 1375 at the lowest level in the Reactor Coolant System relate to each other?

Answer 27

The Reactor Coolant System design pressure is 1250 psig. ASME code allows for a maximum pressure transient of 110% which is equal to 1375 psig. 1375 psig at the lowest point in the Reactor Coolant System is equivalent to 1325 psig in the Steam Dome.

Question 28

What is the most limiting component in the Reactor Coolant System in regards to pressure?

Answer 28

Reactor Recirc suction piping is rated for 1250 psig