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Systems > RPS > Flashcards

RPS Flashcards

1
Q

What is the purpose of the RPS System?

A

Initiates a scram to preserve the integrity of the fuel cladding and primary system and to minimize the energy, which must be absorbed to prevent criticality following a LOCA

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2
Q

How many RPS trip systems exist and channels per trip system?

A

2 trip systems - A & B - 2 automatic and 1 (A3/B3) manual) channels per trip system

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3
Q

What are the design functions of RPS?

A

Prevent release of radioactive materials
Prevent fuel damage following single element malfunction
Function independently of other plant instrumentation
Function safely following any single component failure

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4
Q

How quickly can a half scram signal be reset? How quickly can a full scram signal be reset?

A

half-scram - immediately

Fully Scram has a 10 second time delay for reset

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5
Q

What is the condition of RPS relays on a scram?

A

Relays de-energize

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6
Q

What is the logic scheme for all RPS Trips other than NI?

A

One out of two twice

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7
Q

What is the RPC logic scheme for NI Trips?

A

IRM’s one out of 4; APRMs - one out of 3

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8
Q

What normally pressurizes the scram air header?

What happens on a loss of pressure?

A

Intrument Air; loss of pressure the Scram inlet and outlet valves go open - dicharge volume vents and drains go closed

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9
Q

Which Scram Solenoid pilot valves are associated with which RPS channel?

A

117 - A Channel

118 - B channel

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10
Q

How many CRs are associated with each RPS Channel “Group”

A

Approximately 25%

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11
Q

What is the purpose of the Scram Dump Valves?

A

Reposition to port air off the scram discharge volume vent and drain valves - thus closing them

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12
Q

What powers the scram dump valves - 20A/B valves?

A

Powered by RPS A/B

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13
Q

What powers the SSPVs?

A

117 powered by RPS BUS A

118 powered by RPS BUS B

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14
Q

What is the purpose of the Back-up scram valves? Power source?

A

Ensure control rod insertion by de-pressurizing the scram air header when both RPS channels trip simultaneously. - backup to 117 and 118 valves incase they don’t reposition
Powered by 2A-1 (19A) and 2B-1 (19B)

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15
Q

Where does the 19A/B Backup scram relays fall in the relay scheme?

A

THey are in parallel to the 10 second reset time delay - Both relays energized on full scram

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16
Q

What is the normal condition o fthe SDV Vent/drain valves?
Scram dump valves?
Backup Scram Balves
SSPVs?

A

SDV - Normally - De-energized - Instrument Bus
Backup Scram - Normally Den-energized - 2A-1/2B-1
Scram Dump Valves - Normally Energized - RPS A; RPS B
SSPVs - Normally Energizzed - RPS A; RPS B

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17
Q

How are teh RPS Subchannels Tested?

A

4 keylock test switches - one for each channel - located on the 902-15/17 panels - will introduce half-scram by de-energizing 108 relays

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18
Q

What are the SCRAM Signals for RPS?

A 
Turbine Stop Valves Not Full Open (<90%)
Turbine Generator Load Reject - 40% load mismatch as measured at Tb 1st stage pressure - FASTC <590#
SDV Hi-Hi 
MSIV Not Full Open
Low Condenser Vacuum
DW Pressure Hi
RX Pressure Hi
RX Level Lo (+8")
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19
Q

What is the RPS Turbine Stop Valve Closure Scram designed to prevent?
How many valves need to close to cause half-scram? full scram?

A

Designed to prevent fuel damage resulting from a pressure increase due to a rapid closure of the turbine stop valves:
1 SV not full open results in no action:
Specific combinations of 2 may cause half scram - if add to 5 will not - another other WILL be half scram
ANY COMBINATION OF 3 OR 4 will be FULL SCRAM

20
Q

What is the Bypass for Turbine Stop Valve Closure and Tb Generator Load Reject Scrams?

A

Automatically bypassed when Tb Power is <38.5% for 10 seconds
- 4 pressure switches sense FASTC oil pressure at supply of control valves and de-energize the same relay as the generator reject scram - set point at 590# PSIG
When Rx power <38.5% pressure/power transient from turbine trip not enough to violate MCPR

21
Q

What conditon does the Turbine Stop Valve Closure Bypass alarm identify? What is still possible?

A

Alarm comes in at <38.%% when only ONE pressure switch is activated. A full scram is still possible

22
Q

What is the Generator Load Reject Scram? Can it be bypassed?

A

Loss of generator load could cause a turbine overspeed, therefore the control valves will react by closing causing a reactor pressure increase if power is greater than the bypass valve capacity. The anticipatory scram prevents fuel damage and lifting of safety valves.

Scram signal comes from pressure sensing switch sensing EHC (FASTC) fluid pressure between CV fast acting solenoid and disk dump valve
Bypassed when reactor power <38.5% at 1st stage for 10 sec

23
Q

How many valves must close for Gen. Load Reject Scram?

A

Single valve gives half scram - Full Scram from 1 or 2 and 3 or 4.

24
Q

What turbine first stage pressur indicates RX power of ~38.5%?

A

210psig

25
Q

In what condition may the Turbine First stage pressure be an incorrect indication of RX power?

A

If bypasses are open, then the bypass may be incorrect because more than 210psig may be coming from Rx, but less than 210 goes to Tb first stage.

26
Q

What is the RPS Scram Discharge Volume High Level Scram?

What powers intruments?

A

Designed to ensure enough volume in scram discharge system to receive control rod drives discharge upon scram. Prevents hydraulic lock on scram. set point of ~40gallons
DP Level switches powered by 24/48 VDC battery system

27
Q

What will bypass the SDV Hi Level Scram?

A

Mode Switch in refuel or Shutdown and KEYLOCK to bypass.

28
Q

What is still possible with the SDV Level Scram Bypassed? How?

A

A full scram is possible if Bypass is being used and a loss of EITHER RPS BUS

29
Q

What is the Condenser Low Vacuum Scram? How many sensors and where are they?

A

Scrams when senses <21.5” Hg - 4 sensors - 2 per trip system - A on condenser section 1 and 2, B on 2 and 3

30
Q

What is the Lo Vacuum/MSIV Closure Bypass?

A

Active when Rx Mode out of RUN

31
Q

What is still possible with the Low Vacuum/MSIV Closure Scram Bypass being used? How?

A

If bypass is being used, a full scram WILL occur with a loss of EITHER RPS BUS

32
Q

What is the MSIV Closure (NOT FULL OPEN) Scram?

A 
Scram assures that reactor will not operate without main heat sink (condenser).
If MSIV goes <90% open, scram signal IF:
combination of MSIV's does not add to 5.
If single MSIV, no half scram
if 2 MSIV - potentially half scram
ANY 3 MSIV - FULL SCRAM
33
Q

If a single MSIV goes full closed at full power, what will happen?

A

Potentially a scram, but not because of RPS signal. Will be because of High steam flow in other lines

34
Q

What is the DW Hi Pressure Scram?

A

2# - to minimize possibility of fuel damage and reduce amount of energy added to coolant and primary containment.
Abnormal pressure could indicate rupture or leak from reactor coolant system to DW.

35
Q

What is Rx Hi Pressure Scram?

A

Setpoint - ~1055-1060# - increased pressure threatens integrity of vessel - 4 pressure switches - 1 out of 2 twice

36
Q

WHat is Rx Lo Water Level Scram?

A

+8” - assures Rx will not operate w/out sufficient water in core - using MR ATS instruments

37
Q

What are the NI SCRAMS?

A

APRM HI-HI or INOP Trip - any mode
IRM Hi-Hi or INOP Trip - Rx not in RUN
APRM Dnscl w/ Companion IRM Hi-HI or INOP w/Md in RUN
1 out of 2 twice

38
Q

What are teh companion APRM/IRMs and RPS channels

A 
IRM-APRM - RPS
11-1-A1
12-2-A2
13-3-A1
14-3-A2
15-5-B1
16-6-B2
17-4-B1
18-4-B2
39
Q

When will a SRM HI-HI indicate a scram?

A

When shorting links removed

40
Q

What can happen with the RPS shorting links removed?

A

TRIP (FULL SCRAM) with any one NI trip

41
Q

What must be available to reset a scram?

A

RPS power must be available and scram reset swith contacts and either backup scram relays de-energized or scram delay (10 sec) de-energized

42
Q

What two components are energized at the same time when a full scram signal received?

A

10 second time delay and backup scram relays - in parellel to each other

43
Q

WHat is the normal pressure kept on the scram air header? source?

A

75-80psig via IA

44
Q

What happens to RPS on loss of ATS?

A

RPV Low level and RPV Hi Pressure Relays drop out on both units - full scram
SDV Hi level trip relays drop on U3 only

45
Q

What happens to RPS on loss of 24/48vDC?

A

Scram on U2 due to loss of SDV Hi Level relays dropping

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