REACTOR REGULATING SYSTEM RRS FOR 540MWe PHWRs

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REACTOR REGULATING SYSTEM RRS FOR 540MWe PHWRs

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Title: REACTOR REGULATING SYSTEM RRS FOR 540MWe PHWRs

1
REACTOR REGULATING SYSTEM (RRS) FOR 540MWe PHWRs

B.B.BISWAS
HEAD
REACTOR CONTROL DIVISION
BHABHA ATOMIC RESEARCH CENTRE
INDIA

2
Functions of RRS

Automatic Control of Reactor Global Regional
Power
Demand Power maneuvering
Power Measurement and Calibration
Neutron Flux profile monitoring and control
Execution of Setback Stepback
Provide Xenon override capability
Supervised withdrawal of Shut-off rods during
reactor startup

3
RRS Input, Output
R R S
IC, SPND Pow (Neutronic signals)
Triplicated
Bulk Power, EPE, Demand Power,
Thermal Power, Combined Zone Pow (ICMS)
Triplicated
bank IN/OUT ind, bank enable, SFC, Rod drive
enable,
Rod, Damper Pos (Reactivity Devices)
Duplicated
Valve lift for ZCC, ZCC level
ZCC Level, (LZCS)
Duplicated
Window ann., lamp ind.
Valve Pos (LZCS)
Single
Trip, Clutch test, Setback, Stepback signals
Flux Mapping System
Triplicated
HS, PB other Contact Inputs
Plant Info System
Triplicated
4
RRS System Requirements

1043 Contact Inputs
253, 632,141 Analog Inputs
56 Analog, 150 Relay Outputs
Class IB system
Fault tolerance, fail safe philosophy
Architecture
To meet Functional specification, Response times
To increase Availability
Without compromising safety
Failsafe action
Single failure criteria

5
RRS ARCHITECTURE

Multi nodal Distributed Architecture
Three Input Nodes (IPN) for Data Acquisition
Two Main Processing Nodes (MPN) for executing
control algorithm
Two Output Nodes (OPN) for field outputs
All the above are Embedded Nodes
Two Operator Consoles (OCN) for operator
interaction- PC based
Dual Redundant Data Links

6
RRS ARCHITECTURE- fig
7
Other Architectures

Triple Modular
Each Module gets only 1 signal
mean/median cannot be computed
2/3 or median selector required at the output
In our system, this will be voluminous (56 A/O
150 R/O)
Meets single failure criteria
Single Sensor failure means node failure
Dual Hot-standby
Acts on 2/3
All 3 channel I/P has to be brought to each
system
Independence of channels compromised
System I/O handling and processing power has to
be very high to satisfy the requirements

8
Advantages of Multinodal

Divide and Rule philosophy
Three I/P nodes taking care of 3 instrumented
channel signals respectively
Channel independence intact
Control algorithm on validated signals (2/3)
Redundancy for control nodes, output nodes
Functionality, Response times (performance
requirement) achieved using simple hardware
Indigenous hardware , proven design
Improved reliability

9
Reliability Advantage of Multinodal Approach
MPN
OPN
MPN
OPN

Hardware Volume v/2
Failure Rate f/2
Combined Failure Rate of 2 redundant units
f 2 /4

Hardware Volume v
Failure Rate f
Combined Failure Rate of 2 redundant units
f 2

Four-fold improvement in Reliability
10
Fault Tolerance wrt Architecture

Full functionality of the system is assured with
Single failure
Any 1 node of a type OR 1 Network
Double Failure
Any 2 Nodes of different types
Any 1 Node and 1 Network
Multiple Failure-(upto 5 failures)
1 Node each of different types and 1 Network
In CTU- module-wise switching
The availability of the system is increased many
folds

11
RRS- Failsafe output

Failsafe output leads to safe shutdown of
reactor
System is unavailable
failsafe output results from both OPNs
Double failure of same type of node
both networks failure

12
NETWORK in RRS

Dual redundant network
Card level redundancy
Not limited to link level
Equivalent to 2 different networks
Ethernet, 10Mbps
Twisted pair, RJ45
Connection through Hub/Switch

13
Network Load

No of nodes 9
No of logical connections- 29 per network
IPN-MPN 6 regular I/P data 450 bytes each
MPN-OPN 4 regular O/P data 300 bytes each
MPN-OCN 4 regular data 2400 bytes each
IPN-OCN 6 diagnosis data
MPN-OCN 4 diagnosis data, operator actions
OPN-OCN 4 diagnosis data
OCN-OCN 1 operator actions
Point-to-point- 25 connections!!
44,000 regular data bytes per sec (including
acknowledge)
4 network load

14
Network Protocol

Subset of TCP/IP protocol with Ethernet MAC
Every data is sent and acknowledged
Reliable communication with retransmit
Absence of a node/card is detected annunciated
Co-existence of embedded nodes with PC based
nodes
On change of Ethernet boards, OS takes care
Any OS with TCP/IP stack on PC

15
Network- Determinism Response

Small network 9 nodes
Less than 4 load- low load
Subset of TCP/IP modified for realtime response
Data transmitted on both net
Data received on both net
Latest data is taken for processing, by the
application layer
All the above contribute to Realtime Response of
the system

16
Other Modern aspects

Demand Power Maneuvering through OCN
Operator interacts thro Operator console for
power maneuvering
Manual operation of Reactivity devices through
OCN
All the reactivity devices are operated in
Computer-Manual by commands from Operator Console
RRS system wise
SR withdrawal on startup
ZCC devices control
Reactivity devices position measurement
Reactivity devices movement trouble detection
Setback, Stepback actions

17
Hardware