Ing' Mario Palomba 1

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Ing. Mario Palomba (1)
ENEA Triga RC-1 Control System
(1) ENEA Triga RC-1 C.R. Casaccia Via
Anguillarese, 301 00060 S.Maria di Galeria,
Rome Italy
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TRIGA RC-1 Reactor
Control Instrumentation
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Vienna, May 23-25th 2007
IAEA-TWG-NPPCI
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TRIGA RC-1 Reactor
TRIGA RC-1 Main Features - 1
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TRIGA RC-1 Reactor
TRIGA RC-1 Main Features - 2
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TRIGA RC-1 Reactor
Reactor Staff
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TRIGA RC-1 Reactor
Vertical Section
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TRIGA RC-1 Reactor
Horizontal Section
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TRIGA RC-1 Reactor
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TRIGA RC-1 Reactor
Standard Core Configuration
Standard Fuel Elements (N109) Fuel Follower
Control Rod (N3) Boron Carbide Control Rod
(N1) Instrumented Elements (N3) Graphite
(N11) Neutron Source (N1) Central Thimble
(Air or Water) Rabbit
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TRIGA RC-1 Reactor
Fuel Elements Inventory
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TRIGA RC-1 Reactor

• Triga RC-1
• Main Standard Activities
• Neutron Radiography Tomography
• Neutron Activation Analysis
• Radioisotopes production for medical
  applications
• Training for University students and reactor
  operators.

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TRIGA RC-1 Reactor
Control Instrumentation

• Control System General Characteristics
• Nuclear Power Instrumentation
• 1 Starting Channel (0-1 W)
• 2 Wide Range Linear Channels (0.5 - 5 x 106
  W)
• 1 Safety Channel (10 kW 1.1 MW)
• Radiation Monitoring Instrumentation
• Water (Primary/Secondary Loops) Air Activity
  (Reactor Hall/Experimental Channels)
• Environmental Radiation Level (Reactor
  Hall/Experimental Channels)
• Conventional Parameters Instrumentation
• Temperatures (Fuel Elements, Primary/Secondary
  Loops/Cooling Towers)
• Flow Rates (Primary/Secondary Loops, Water
  Cleaning System)
• Levels (Reactor Pool/Shielding Tank)
• Conductivities (Primary Loop/Shielding Tank
  Loop)

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TRIGA RC-1 Reactor
Control Instrumentation
Power Level
Starting Channel
Linear Channel 1
Linear Channel 2
Safety Channel
Source Level
Utilization range of Triga Nuclear Channels for
Power Measurement
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TRIGA RC-1 Reactor
Control Instrumentation
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TRIGA RC-1 Reactor
Control Instrumentation
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TRIGA RC-1 Reactor
Control Instrumentation

• Safety Design Criteria
• GENERAL CRITERION Fail to safety
• (electrical continuity in circuits, low voltage
  in detectors, lack of electrical power and s.o.)
• The Safety Criteria are related to the following
  2 Operating Conditions
• START-UP (0-100 kW)
• HI-POWER (100kW 1 MW)

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TRIGA RC-1 Reactor
Control Instrumentation
START-UP (0 W 100 kW) All the protection
systems are connected in series sigma
connection and the Safeguard Interventions occur
if even only ONE of the controlled parameters is
out of the allowable range. HI-POWER (100 kW 1
MW) All the protections systems are connected
in 2/3 coincidence and the Safeguard
Interventions occur if TWO of the THREE
controlled parameters are out of the allowable
ranges. This type of protection is effective
because after the start-up phase, the reactor is
intrinsically stable (not diverging) because its
negative prompt temperature coefficient in this
condition the 2/3 coincidence criterion allows to
avoid spurious SCRAMS that could occur for
electrical/physical anomalies.
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TRIGA RC-1 Reactor
Control Instrumentation

• SAFETY CONTROLS
• There are three levels of Safety Interventions
• SCRAM
• Control Rod Withdrawal Block / Control Rod
  Motorized Insertion
• Optical / Acoustic Alarms

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TRIGA RC-1 Reactor
Control Instrumentation

• SCRAM CONTROLS
• The SCRAM of the reactor is activated
  automatically only from POWER Monitors and
  Low-Low-Water Level Alarm.
• A manual SCRAM Button, in a well visible
  position, is under the Operator control.
• The Power Monitors activate the SCRAM when
• Starting Channel
• The Power Indication is gt 90 of maximum current
  range
• The Hi - Voltage value of the detectors lt 90 of
  the nominal value
• Wide Range Linear Channels (2)
• The Power Indication is gt 90 of maximum current
  range
• The Hi - Voltage value of the detectors lt 90 of
  the nominal value
• The Low-Low-Water Level Alarm activates the SCRAM
  when the pool water level is more than 30 cm
  under the normal water level.

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TRIGA RC-1 Reactor
Control Instrumentation

• Control Rod Withdrawal Block / Control Rod
  Motorized Insertion
• This control is activated substantially in order
  to avoid the driving of the reactor when the
  sensitivity of the power monitoring
  instrumentation is not enough accurate, for
  example if
• Starting channel power indicator lt 10 of maximum
  current range
• Linear channel(s) power indicator(s) lt 10 of
  maximum current range
• Loss of tension at the Control rods driving
  magnets etc.
• Optical / Acoustic Alarms
• All the Optical/Acoustic alarms are connected to
  SCRAM, BLOCK, Motorized Insertion and
  Conventional/Radiological Parameters Controls.
• When some parameter (unless when
  SCRAM/BLOCK/Motorized Insertion occur) is out of
  the allowable range (low water level, low water
  flow, high radioactivity etc.), an acoustic alarm
  and an optical signal are activated.
• After that, the Operator decides the action to
  undertake.

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TRIGA RC-1 Reactor
Control Instrumentation

• Renewing of the Triga RC-1CI System
• Problems The CI System of the reactor is very
  old (gt40 years) and it is subjected to frequent
  maintenance interventions. Nevertheless, because
  of safety intrinsic characteristics of the Triga
  reactors, there are NO RELATED SAFETY PROBLEMS.
• Possible solutions
• Substitution of the whole CI System with a new
  Digital System
• Substitution of the whole CI System with a new
  Standard Triga Control System
• Renewing of the CI System replacing each
  single subsystem.

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TRIGA RC-1 Reactor
Control Instrumentation
Renewing of the Triga RC-1 CI System Solutions
a) b) Each one of these two solutions could
be very attractive BUT the COSTS and the
UNAVAILABILITY OF THE REACTOR FOR LONG TIME
(there are a lot of problems regarding licensing)
make them hardly practicable
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TRIGA RC-1 Reactor
Control Instrumentation

• Renewing of the Triga RC-1 CI System
• Solution c) The Renewing of each single
  subsystem allows so many notable advantages
• The cost is much lower diluted with respect the
  substitution of whole CI System
• The availability of the reactor would be
  suspended only during the maintenance periods
• NO REGULATORY BODY authorization is required Is
  only necessary to communicate that a component
  has been replaced with a new one that has the
  same characteristics
• In parallel of the renewed CI System it is
  possible to built a digital new System only in
  order to monitor, to digital record and to
  elaborate the plant data (no active control on
  the reactor)
• The data could be utilized to carry out
  calculations, reactor simulations, training for
  students in developing new advanced Control
  Systems.

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Thank You !!!