Thermal-hydraulic aspects of RMB design

J. Lupiano Contreras; F. Francioni; A. Doval

–INVAP- Argentina

P.E. Umbehaun, W.M. Torres, A. C. Prado, A. Belchior. Jr

-IPEN/CNEN- Brazil

IGORR 2014

RMB Reactor

• 30 MW Open-Pool

• PURPOSE:

– Research

– Material and fuel Testing

– Radiosiotope production

HEAT GENERATED IN FA AND MO RIGS AND

DESPOSITED ON STRUCTURES MUST BE REMOVED !!!

RMB: Upper view

Core TH design

Operating conditions

• Full Power (30 MW)

• Steady state

• Forced convection

• Up-flow

Design criteria for steady state

• RDR = PRD/Pmax ≥ 2

• DNBR = q”DNB / q”max ≥ 2

• ONBR = q”ONB/q”max ≥ 1.3

Design requirements

• Coolant velocity in FA ≤ 10 m/s

• Cladding temperature ≤ 150 °C

• Temperature difference through the oxide layer ≤ 120 °C

• Thickness of oxide layer ≤ 50mm

Core TH design Reactor core: Upper view

Core TH design Thermal model : TERMIC v. 4.3

Hot channel:

• Cosine power profile distribution

• PPF =3 to uncouple from neutronic

calculations and account for all

possible core configurations

• Statistical treatment of uncertainties

Objective:

• To determine the minimum

coolant velocity satisfying the

design criteria

Core TH design

Hydraulic Model: CAUDVAP v. 3.6

GLOBAL MODEL:

To determine

• Flow distribution in

equivalent channels

• Average velocities

• Pressure drop in reactor

core and pressure distribution

in channels

Core TH design Partial model

• To determine velocities in

cooling channels

• From windows to top

Core TH design: Results

Hot channel

Parameter Value Design criteria

Total coolant flow in core 3100 m3/h -

Average coolant velocity in FA 9.4 m/s ≤ 10 m/s

Temperature increase 22°C -

RDR 2.3 ≥ 2.0

DNBR 2.5 ≥ 2.0

ONBR 3.6 ≥ 1.3

Maximum wall temperature 109 °C ≤ 150

Maximum thickness of oxide layer 36 mm ≤ 50 mm

Temperature difference across oxide layer 63°C ≤ 120°C

Core TH design

Anticipated Operational Occurrence:

• Operational transient: LOFA

• FSS actuated when Q=0.9Qss

• Transition from forced to natural circulation cooling mode

Core TH design

Computational tool

• RELAP 5/ MOD 3 for dynamic model of the CCS

Design requirements

• Temperature in cladding material ≤ 450°C

Design criteria for abnormal conditions

• BOR = q”BO/q”max ≥ 1.3

• BPR = BP/Pmax ≥ 1.3

Core TH design

CORE modelled as 3 pipes:

• 1 Hot channel

• 1 Average channels

• 1 By pass channel

Nodalization of CCS

SCC as Boundary Condition

Flap valves open for a specified (Ppipe-Ppool)

Heat exchangers as pipes

PUMPS with the specific Bingham Co. component

Core TH design: Results

Parameter Value Design criteria

Opening time for FV after pump shutdown > 90 seconds -

Moment of inertia of fly-wheel 100 kg∙m2 -

Maximum wall temperature 125°C ≤ 450

BOR 2.4 ≥ 1.3

BPR 2.8 ≥ 1.3

Core TH design: Results

Core TH design: Results

OCIF and BR TH design

Operating conditions

• Full Power (30 MW)

• Steady state

• Forced convection

• Down-flow

Design criteria for steady state

ONBR ≥ 1.3 for 99Mo OCIF

Wall temperature in BR and in the rest of OCIF ≤ 90°C

Design requirements

• Maximum pressure drop: 70 kPa

OCIF TH design

Computational tool

• TERMIC v. 4.3 for thermal design

Cosine power profile

distribution

Hot spot with PPF = 1.4

99Mo TH design: Results

Parameter Value

Minimum coolant velocity 4 m/s

Temperature rise in channel 14°C

Maximum wall temperature 111°C

ONBR 1.3

Total pressure drop 57 kPa (≤ 70 kPa)

BR TH design

Computational tool

• Thermal desktop

Cosine power profile distribution

PPF =2.5

Internal cooling

With / Without sample

Thermal model

BR TH design

Computational tool

• CAUDVAP v3.6

Hydraulic model

BR TH design: Results

Parameter Value

Minimum coolant velocity 2.6 m/s

Temperature rise in channel 5.0°C

Maximum wall temperature 58°C (≤ 90°C)

BR TH design: Results

Parameter Value

Minimum coolant velocity 2.1 m/s

Temperature rise in channel 5.0°C

Maximum wall temperature 73°C (≤ 90°C)

OCIF TH design

Computational tool

• RELAP 5/ MOD 3 for dynamic model of the ICPCS

Design criteria for anticipated operational transients

MCHF= q”CCFL / q”max ≥ 1.3

It applies to 99Mo OCIF

OCIF TH design

• 1 Hot Moly

• 1 Average Moly

• 1 By pass channel

Nodalization of ICPCS

SCC as Boundary Condition

Flap valves open for a specified (Ppipe-Ppool)

Heat exchangers as pipes

PUMPS with the specific Bingham Co. component

OCIF TH design: Results Parameter Value

Opening time for FV after pump shutdown ~ 140 seconds

Moment of inertia of fly-wheel 50 kg∙m2

MCHF 1.4 ( ≥ 1.3)

Further questions ?

Thank you very much!

Core TH design: cooling channels Channels in CR+CRGB: Conservative approach

Core TH design: Results

CR + CRGB

Parameter Value

Minimum – Maximum coolant velocity 4.1 – 4.6 m/s

Calculated coolant velocity 4.3 m/s

Temperature increase 31°C

ONBR 1.4

Maximum wall temperature 110 °C

Vmin determined by ONBR design criteria

Vmax determined by Drag force < 90% of net weight

Core TH design: Results Pressure distribution