zanocco carem technical aspects

8/10/2019 Zanocco Carem Technical Aspects

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CAREM THECNICAL ASPECTS, PROJET AND

LICENSING STATUS

Pablo Zanocco and Marcelo Gimnez

Comisin Nacional de Energa Atmica (CNEA)

Centro Atmico Bariloche - Argentina

1

Technical Meeting/Workshop on Technology Assessment o f Small

and Medium-sized Reactors SMRs) for Near Term Deployment.

Vienna, 5 9 Decem ber 2011


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2

Project status

Techical description

Safety approach and safety systems

- Nuclear safety analysis

Facilities and experimental devices to support

reactor design

Project and licencing status

Presentatin Guide


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CAREM is a CNEA (Atomic Energy National

Comission) project to design and build a smallnuclear power plant.

The first stage is the construction and operation of

the demonstration plant (100MWth), CAREM-25,

being the base for the development of thecommercial versions.

CAREM Project Status

3

Commercial modules power:

Natural circulation up to 150 MWe

Forced circulation up to 300 MWe


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CAREM concept was presented for the first time in

a IAEA Conference on Small and Medium Reactors,

Per, 1984

Integral PWR design

4

Enhance safety

internalization of Defense-in-Depth since the conceptual design

passive safety systems

Reduce costs against the economy of scale (systematically increase of

reactor power to reduce costs). To be an economicoptionfor small and

medium electrical grids

Simplified design

well-proven LWR technology: but re-designing the plant


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CAREM design criteria, or similar ones, has been

adopted by others plant designers, originating a new

generation of reactor designs, of which CAREM was,

chronologically, one of the first (Otto Hann)

The design basis is supported by the cumulativeexperience acquired by CNEA+INVAP+Utilities in:

Research Reactors design, construction and

operation

Pressurized Heavy Water Reactors (PHWR)operation, maintenance and improvement.

The construction of Atucha II NPP

5



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Evaluated in Generation IV International Forum

USDOE, 2001-2002), and selected in the Near Term

Deployment group 16 designs selected)

6

Argentine government decided to support the

construction of CAREM demonstration plant(CAREM-25):

On December 17th, 2009, the National Congress

declares of interest the design, construction and

start-up of CAREM-25.(National Law 26566/2009)


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RPV

Generadores

de Vapor

Classical loop-type PWR

Steam

Generators

Hydraulic

control rods

drive

mechanisms

Core

Control

rods

Steam

DomeSteam

Generators

RCS Pumps

Pressurizer

8

Technical Description

Integral-type PWR


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Integrated primary

cooling system

Primary cooling by

natural circulation

Self-pressurized

Hydraulic

control

mechanisms

Barrel

Steam

Generators

Core

Reactor Coolant System (RCS) pressure: 12,25 MPa

Core outlet, riser and dome temp ~ saturation = 326C

Demonstration plant: 100 MWth:

RCS mass flow rate: 410 kg/s

Steam Dome

Self-pressurization

9


Natural circulation version

No Boron in RCS for reactivity controland not required for cold shutdown


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Reactor

PressureVessel

10

Diameter: 3,2 m

Height: 11 m


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Steam

Generators

11


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Barrel

12


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Core

reflector

13


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Fuel

Elements

14

h l


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Absorbing

Elements

15

h i l i i


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Control Rods

support

Structures

16

T h i l D i i


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Hydraulic

Control

Rod Drive

17

T h i l D i ti


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Steam

Generators

Nozzles

18

T h i l d i ti


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Steam Generators

Technical description

12 identical Mini-helical

Once-through type,

secondary system in the tubeside

Secondary pressure: 4,7 MPa

Superheated steam: + 30C

(290 C)

Tubes of similar length to

equalize pressure-loss and

superheating

T h i l d i ti


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Steam

Generators

feeders

Steam

Collector

Steam to

theTurbine

20


Steam Generation

SG placed in interspersed

positions



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21


Active length: 1,4m

Absorbing elements:

spider: 18 rods Ag-In-CdFuel Assembly



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22

Fuel Assembly


Hexagonal FA with 127 positions: 108 fuel rods



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23

Core (Demonstration Plant):

61 FFEE

U235enrichment: 3.1%

25 absorbing elements (First Shut-down

system, reactor subcritical in cold shutdown):

16 to reactivity adjust and control

9 fast shutdown system

Fuel cycle: 510 full-power days, 50% of core

replacement, tailored to customer requirement




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Reactivity Adjust and

Control System (ACS):

belongs to the First Shutdown

System

Cylinder: inlet flow from the

Down-comer, movement by

steps, controlled by pulses over

a base flow

no strict requirement on totaldrop time

24

Hydraulic Control Rods Drive Mechanisms



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SAFETY APPROACH

ANDSAFETY SYSTEMS

25


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CAREM SAFETY ASPECTS

Defense in Depth concept is internalized in the design since the

conceptual engineering

Passive and Simple Safety Systems:

Grace period without electricity or operation actions

(for the demonstration plant= 36hrs, each

redundancy: x2)

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Reactor Description


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SAFETY SYSTEMS

Function: reactor shutdown

- diversified -

First Shutdown System (FSS):

Ag-In-Cd rods, driven hydraulically

Fast rod drop into the core by

gravity action

Second Shutdown System (SSS):

Injects borate waterby drainage in

case of failure of the FSS

Reactor Description

Reactor Description


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SAFETY SYSTEMSFunction: reactor cooling and

depressurization

Passive Residual Heat Removal System

(PRHRS)

Condenser tubes

(two modules, 100% each)

Trip condition:- Pressure (LOHS)

- LOCA

Reactor Description

Reactor Description


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Low Pressure Injection System (LPIS)

Accumulator: pressure < 1.5MPa


Trip condition: LOCA

Pressure suppression containment SAFETY SYSTEMSFunction: reactor cooling and

depressurization

Passive Residual Heat Removal System

(PRHRS)

Condenser tubes


Trip condition:- Pressure (LOHS)

- LOCA

Reactor Description



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Hydraulic Control Rods Drives


Fast Shutdown System:

belongs to the First Shutdown

System

Cylinder: inlet flow from the

Down-comer

Piston two positions: top and

bottom

maximum total drop time: 2s

Hydraulic Fast Shutdown rods Drive Mechanisms



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31


SAFETY SYSTEMS

Pressure suppression pool

PRHRS Pool

SSS B

CONTAINMENT: pressure suppression

type, reinforced concrete with stainless

steel liner, design pressure 0,5 MPa



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SAFETY SYSTEMSCONTAINMENT:

FFEE transfer channel



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33

ec ca desc pt o

SAFETY SYSTEMS

Dry-well

Wet-well

SG Feed water

headers and main

steam collectors

CONTAINMENT:



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The First Reactor Protection System demands:

First Shutdown System

PRHRS

containment isolation ventilation system) LOCA)

SG isolation SGTR)

LOCA signal: PRHRS, accumulators EIS)

The Second Reactor Protection System demands:

Second Shutdown System

p

SAFETY SYSTEMS

Reactor Protection System: two independent and diverse modules:


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CAREM: Postulated Initiating Events categorization

CategoryOccurrence

(year-1)Acceptance criterion

AOO(Anticipated Operational

Occurrence)

Anticipated

(1- 10-2)

No core damage (DNB&CPR)

No RPV safety valve demand

DBE(Design Basis Events)

Unlikely

(10-2- 10-4)

No core damage, DNBR&CPR>1, No core

uncovery (Tclad 1

RCS pressure limit.

BDBA(Beyond Design Basis

Accidents )

Remote(10-4- 10-6)

AR 3.1.3 acceptability criterion (based onRisk evaluation)

SA(Severe Accidents )

Very remote

(


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General strategy keep main safety functions for AOO and

DBE

DinD level 3 (High pressure)

1-FSS (First Shutdown System)

2-SSS (Second Shutdown System)

Power control:


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Residual Heat Removal and Deppresurization

DinD level 3B: (Beyond Grace Period)1- Normal Residual Heat Removal System. From hot to cold shutdown

DinD level 3C: (Safety Systems extension)

1- Inventory reposition to PRHRS pools (Automatic)

2- Inventory reposition to PRHRS pools (Autonomous)


DBE

DinD level 2

1-Secondary system. Different possible combinations: Normal or alternative

feedwater, by-pass to condenser or steam venting.

2-Volume and purification system, cooling mode.

DinD level 3A (Grace Period)

1-Main line: Passive Residual Heat Removal System.

2-Diverse line: Depressurization with safety valves (transfer to coolant

injection function)


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Coolant Injection

DinD level 2A

1-Volume and purification system, injection mode.

DinD level 2B:

1-Injection to Control Volume Tank


1-Main line: Low pressure injection system (Accumulator).

DinD level 3B: (Beyond Grace Period)

1- Active Injection System

DinD level 3C: (Safety systems extension)1- Autonomous power supply for the Active Injection System (fire

extinguishing system)


DBE


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Containment


1-Contaimnent isolation

2-Steam condensation in suppression pools

DinD level 3B: (Beyond Grace Period)1-Cooling of suppression pools

2-Spray system for pressure limitation and radionucleides removal


DBE


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SEVERE ACCIDENT MITIGATION

Severe Accident mitigation:

-In-vessel Corium retention: RPV external cooling, by gravity

-Hydrogen passive autocatalytic recombiners

DinD level 4


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NUCLEAR SAFETY

ANALYSIS

41

212 140

190 180

200206

170

164

230

240

130

246 106

112

118

124

252

100

280 281

292

282

283

286

289

DomoZona central

DomoZona perifrica

Generadores de Vapor

Downcomer

Ncleo

Chimenea

Zonas del Primario

140



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-10 0 10 20 30 40 50

80

90

100

110

120

130

Potencia[MW]

Tiempo [s]

Disparo por alta potencia (108 % - PSPR)

Disparo por muyalta potencia (115 % - SSPR)

Disparo por alta presin (13 MPa - PSPR)

Lmite alta potencia (108 % - PSPR)

Lmite muyalta potencia (115 % - SSPR)

Reactivity insertion:

Design strengths.

Rod Ejection Accident is avoided (Only inadvertent control rod

withdraw transients are possible).

No boron in the coolant: no boron dilution

Negative reactivity coefficients (self-limited power increase)

Positive feedback between power and flow (natural circulation)

42

350



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0 400 800 1200 1600 2000 2400 2800 3200 3600

280

290

300

310

320

330

340

IPS-SBO-2009-10-14

Temperatura[C]

Tiempo [s]

Salida de ncleo

Salida de chimeneaSalida de GV (primario)

Entrada de ncleo

Saturacin en domo

Blackout / Total Loss of feedwater to SG

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Design strengths.

Thermal inertia (large Inventory/power relation): slow transients.

Negative reactivity coefficients (power decreases)

Passive safety systems: grace period (36 72 hs)

Opening of safety valves avoided

9CAREM SAFETY ASPECTS


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0 4 8 12 16 20 24 28 32 36

0

1

2

3

4

5

6

7

8

Nive

ldelquidocolapsado(m)

tiempo (h)

LOCA 0,0508 m

LOCA 0,0381 m

LOCA 0,0254 m

LOCA 0,0191 mLOCA 0,0127 m

Apertura Espuria

Tope de zona activa de ncleo

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Loss of Coolant events

Design strengths.

Integral primary systemSmall diameter of RPV penetrations

RPV penetrations above SG level (loss of liquid avoided)

Large Inventory/Power rate

Large LOCA phenomenology not presentNo subcooling depressurization/pressure waves

No core uncovery. No need of refill/reflood stages.

Simplified evaluation

No loop seal clearance, no SG reflux condensation, no

stratification in surge line, whole primary is in saturation.

No need of high pressure or fast injection

Passive safety systems: grace period (36 72 hs)



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Steam Generators tube rupture

Design strengths.

SG tubes inspection from the outside of the RPV

No whipping effect (higher pressure is outside)=> no others

tubes rupture expected

Design pressure for feedwater and steam lines, between

isolation valves, equal to primary system.

Selective isolation of SG group (N16 detection) and

equalization of pressures.



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4646

Main steam line break

Design strengths.

Low inventory in SG and high thermal inertia in primary

system

-Low impact in primary system, lower reactivity insertion



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Preclusion of some classical events (DinD level 1)

Integral primary system:

verylow dose of fast neutrons in the RPV wall (large down comer)

Core cooled by natural circulation: noLoss of Flow Accidents

Self-pressurized: simplification, nospurious trip of sprays

A lower number of active components increases plant availability and

load factor, reducing the frequency and kind of initiating events.

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Others characteristics that enhance safety:



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Characteristics that enhance safety given an AOO or DBE:

Integral primary system:

large thermal inertia

natural circulation intrinsically enhanced by the lay-out

Self-adaptive behavior of the RCS mass flow, following the power

evolution: enhance safety margins

Passive Safety systems and a large grace period

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Others characteristics that enhance safety (cont):


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Facilities and experimental devices

to support

reactor design

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RA-8 Critical facility (at Pilca): neutronic codes validation

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Natural Circulation and Self-pressurization RIG

CAPCN

Thermo-hydraulic dynamics in

conditions similar to CAREM-25

operational states.

(1:1 in height and pressure)


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Thermal-hydraulic response in conditions similar to CAREM operational

states.

Study of relevant parameters

Perturbations in the thermal power, heat removal and pressure relief.

O bservations: Around the operating point ,selfpressurized natural

circulation was very stable, even with important deviation on the relevant

parameters.

Natural Circulation and Self-pressurization Assessment

52


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CAPEM:

High pressure and high

temperature rig for testing the

innovative Hydraulic Control

Rod Drives

53

Hydraulic Control Rod Drive Mechanisms Facility

The construction and start-up at

full pressure and temperature

finished in 2011 Can be adapted for testing the

structural behavior of the FA


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Low Pressure Loop: Hydraulic losses &

Flow vibration test


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Thermal Limits and CHF Tests

TH LAB IPPE (Obninsk-Russia):

LP Freon Loop Test (+250)

HP Water Loop Test (25)

A facility under development


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Project and

Licensing Status

56

P j t d Li i St t


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Documentation equivalent to a Preliminary Safety Analysis Report

and the Quality Assurance Manual were presented to the ArgentineanRegulatory Body (Federal Authority) at the end of 2009.

57

Project and Licensing Status

The National Technological University of

Avellaneda is performing the Environmental

Impact Study (required by Local Authority)

P j t d Li i St t


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Site facilities being arranged to start the construction during the

first half of 2012 (Excavation work began this year)

A specific experimental plan will be performed during CAREM-25preliminary tests and commissioning.

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Project and Licensing Status

Contracts and agreements are under discussion

with different Argentinean stakeholders:

to perform detail engineering for buildings,containment and process systems

for RPV and main components manufacturing

59

CAREM 25 itiP j t d Li i St t


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CAREM-25 sitingProject and Licensing Status

59


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Reactor Building

(containment inside)

Main access

Turbine building

Auxiliary Building


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