ARIES-AT Blanket Thermal-Hydraulic Design Assessment John Murphy - - PowerPoint PPT Presentation

ARIES-AT Blanket Thermal-Hydraulic Design Assessment

John Murphy Mohamed Sawan Igor Sviatoslavsky Mark Anderson Michael Corradini

Fusion Technology Institute The University of Wisconsin

APEX Project Meeting August 9th, 2001

Overview

• Calculation of blanket ∆T performed

– Compared to previous ARIES-AT estimate – Bulk heating compared favorably (within 3% deviation)

• - Surface heating needs to be examined further
• Updated analysis will be performed with APEX heating values

– MHD pressure drops estimated and used to size coolant flow rates – SiC/SiC temperature limits utilized for flow rate calculation

• Heat loads balanced against cooling requirements to determine

feasibility of advanced APEX designs

Configuration of First Wall and Pb-17Li Blanket

• First wall configuration with

Pb-17Li flows

• Pb-17Li flow paths

– Front: 3 sections

• 0.4 cm X 7 cm

– Back: 13 sections

• 0.4 cm X 1.4 cm

– Side: 8 sections

• 0.4 cm X 5 cm

– Middle: 1 section

• 17.8 cm X 24.5 cm
• Pb-17Li flows up the front,

back and side channels, then downward through the large central channel and out of the blanket

Calculation of Pb-17Li Blanket T

• Slug flow velocity profiles used for the Pb-17Li molten metal

– Flow velocities taken from ARIES-AT study – Slug flow confirmed by MHD analysis at UCLA – Upward side flow velocities estimated by averaging front and back

• Blanket assumed to be 8 meters tall, with molten metal used as the heat sink
• As slug of metal moves vertically in the blanket its exposure time to the heat

loads must be estimated

– This value is the distance it moves (~ 8 m) divided by its velocity – Flow exposure times

• front flow ~ 2 seconds
• side flow ~ 3.29 seconds
• back flow ~ 12.1 seconds
• middle flow (downward) ~ 72.7 seconds

Calculation of Pb-17Li Blanket T (continued)

• The exposure time and heating loads are used to determine the energy

deposited to the slug of fluid and its subsequent temperature change

• ρ Cp ∆Temperature (Volume) = Heating Rate (∆Time)
• Variable exposure times are used for each slug of metal mass, depending

which section of the blanket it resides in

• All heat deposited to the SiC/SiC structure is transferred into the adjacent Pb-

17Li flow, heating of structure between up and downward flows is split evenly

• Surface heat loads are applied to the first wall, along with nuclear heating

loads at various radial positions

– 80 % of maximum values used as a reasonable average – Nuclear heating values were used from a blanket study of the ARIES-AT

(ranged from 24 to 2 W/cm3 )

– Surface heating of first wall was estimated at maximum of 0.34 Mw/m2

Calculation of Pb-17Li Blanket T (continued)

• Based on the heat loading values and fluid exposure times an estimate of the

Pb-17Li temperature change could be made

• The flow upward moving flow gained 66.3 C, while the downward moving

flow gained 281.7 C

– The downward flow has lower nuclear heating densities but significantly longer exposure times to the loads, hence the larger temperature change

• Total blanket Pb-17Li temperature rise of 348.0 C
• The previous ARIES-AT study gave a value of 336 C for the outboard blanket

region (~ 3 % difference)

• Methodology has been confirmed and will be used to determine Pb-17Li

blanket temperature change for higher APEX heat loads

Calculation of SiC/SiC Max Blanket emperature

• Comparison of SiC/SiC maximum temperature estimate to ARIES-AT result
• First Position - Top of OB First Wall facing plasma where FW molten metal is

at highest T: – (Tmax- Tbulk )= Q” (δ/Κwall + Dh/Nu*Kmetal) [Tmax = 950 C (for Nu = 4.36)]

( THIS COMPARES TO 995 C for ARIES AT ANALYSIS)

• Second Position - Bottom of Inner Annulus at the outlet metal temperature

– (Tout - Tinner) = (Inner HT conductance)/(Total HT conductance)*(Tout-Tinlet) – Tinner = 1035 C (THIS COMPARES TO 996 C for ARIES AT ANALYSIS)

More detailed conduction calculations underway to refine estimate

APEX Modified Heat Load Calculation of Pb-17Li Blanket T

• Modified heat loads will be used to determine the heating of the Pb-17Li metal

and the first wall for the APEX blanket study

• New Pb-17Li flow rates will be calculated utilizing MHD pressure drop

estimates

– Flow rates are to be based on the cooling requirements for the SiC/SiC blanket

• The new temperature change in the blanket will be useful in determining the

viability of expanding the operating zone for the ARIES-AT design

• Future work

– Calculate temperature of Pb-17Li under “swirl” flow conditions – Determine max SiC/SiC temperature under above described conditions