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timothy-nunn merged 9 commits into from
Oct 2, 2024
Merged

Implement wcll option using inputted pressure drop within dcll model #3306

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0b0dfa8
changes to blanket library and dcll model to allow for WCLL blanket s…
kj5248 Sep 4, 2024
1039460
added 4 pressure drop variables with defaults to primary_pumping_vari…
kj5248 Sep 4, 2024
da9ac03
added coolwh and emult as input variables as well as new pressure dro…
kj5248 Sep 4, 2024
a1637af
removal of KIT blanket options since they are no longer in PROCESS
kj5248 Sep 6, 2024
e67363f
update to docs to show change to thermo-hydraulic model to allow prim…
kj5248 Sep 6, 2024
c6f6acc
point towards heat transport section when talking about primary pumpi…
kj5248 Sep 6, 2024
e39448c
removes commented out line that is not needed in dcll.py
kj5248 Sep 6, 2024
fd7b459
addition to heat transport section for new pressure drop variables
kj5248 Sep 6, 2024
dda56e4
remove table column in heat transport docs
kj5248 Sep 6, 2024
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106 changes: 3 additions & 103 deletions documentation/proc-pages/eng-models/fw-blanket.md
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Expand Up @@ -44,11 +44,6 @@ electricity have been revised extensively.
using parametric fits to an MCNP neutron and photon transport model of a
sector of a tokamak. The blanket contains lithium orthosilicate
Li$_4$SiO$_4$, titanium beryllide TiBe$_{12}$, helium and Eurofer steel.
- `== 2` -- KIT HCPB model. It allows the energy multiplication factor `emult`,
the shielding requirements and tritium breeding ratio to be calculated
self-consistently with the blanket and shielding materials and sub-assembly
thicknesses, and for constraints to be applied to satisfy the engineering
requirements. For further details of this model.
- `== 3` -- CCFE HCPB model with tritium breeding ratio. It has the features of
the CCFE HCPB model above, with a set of fitting functions for calculating
tritium breeding ratio (TBR). It requires a choice of `iblanket_thickness`,
Expand All @@ -70,107 +65,10 @@ first wall and blanket is determined, and also how the calculation of the plant'
thermal to electric conversion efficiency (the secondary cycle thermal
efficiency) proceeds.

### KIT Blanket Neutronics Model

The model used if `blktmodel = 1` is based on the Helium-Cooled Pebble
Bed (HCPB) blanket concept developed by KIT (a second advanced model --
Helium-Cooled Lithium Lead, HCLL -- will be implemented in due course). The
blanket, shield and vacuum vessel are segmented radially into a number of
sub-assemblies. Moving in the direction away from the plasma/first wall, these
are:

Breeding Zone (BZ) (which includes the first wall), with radial
thicknesses (inboard and outboard, respectively) `fwith + blbuith`,
`fwoth+blbuoth`. This consists of beryllium (with fraction by volume `fblbe`),
breeder material (`fblbreed`), steel (`fblss`) and helium coolant. Three
forms of breeder material are available:

| `breedmat` | Description |
| :--------: | ------------------------------------- |
| 1 | lithium orthosilicate (Li$_4$SiO$_4$) |
| 2 | lithium metatitanate (Li$_2$TiO$_3$) |
| 3 | lithium zirconate (Li$_2$ZrO$_3$) |

The $^6$Li enrichment percentage may be modified from the default 30% using
input parameter `li6enrich`.

- Box Manifold (BM), with radial thicknesses (inboard and outboard,
respectively) `blbmith`, `blbmoth` and helium fractions `fblhebmi`, `fblhebmo`
(the rest being steel).
- Back Plate (BP), with radial thicknesses (inboard and outboard,
respectively) `blbpith`, `blbpoth` and helium fractions `fblhebpi`, `fblhebpo`
(the rest being steel).

Together, the BZ, BM and BP make up the `blanket`, with total radial
thicknesses `blnkith` (inboard) and `blnkoth` (outboard), and void (coolant)
fraction `vfblkt`; Note that these quantities are `calculated` from the
sub-assembly values if `blktmodel > 0`, rather than being input parameters.

Low Temperature Shield and Vacuum Vessel (lumped together for these
calculations), with radial thicknesses (inboard and outboard, respectively)
`shldith + d_vv_in`, `shldoth + d_vv_out` and **water** coolant fraction
`vfshld` (the rest being assumed to be steel for its mass calculation; the
neutronics model assumes that the shield contains 2% boron as a neutron absorber,
but this material is not explicitly mentioned elsewhere in the code -- so
its cost is not calculated, for example).

!!! Note "Note"
The fact that water is assumed to be the coolant in the shield, whereas
helium is the coolant in the blanket, leads to an inconsistency when
specifying the coolant type via switch `coolwh`. At present we mitigate this
by forcing `coolwh=2` (making water the coolant), as in this case the
coolant mass and pumping costs are higher, giving the more pessimistic
solution with regards to costs.

A few other input parameters are useful for tuning purposes, as follows:

| Parameter | Description |
| :----------------: | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| `fvolsi/fvolso` | area (and volume) coverage factors for the inboard and outboard shields, respectively. |
| `fvoldw` | multiplier for volume of vacuum vessel, used in mass calculations to account for ports, etc. |
| `npdiv` | number of divertor ports, used in the calculation of the tritium breeding ratio. |
| `nphcdin/nphcdout` | number of heating/current drive ports on the inboard and outboard sides, respectively, used in the calculation of the tritium breeding ratio. These may be either 'small' (`hcdportsize = 1`) or 'large' (`hcdportsize = 2`). |
| `wallpf` | neutron wall load peaking factor (maximum/mean), used in the calculation of the blanket lifetime. |
| `ucblbreed` | unit cost (\$/kg) of the breeder material |

#### KIT model outputs and available constraints

The KIT blanket model has the following available constraints

| Constraint No. | F-value | F-value No. | Limit | Description |
| :------------: | :-------: | :---------: | :---------: | ---------------------------------- |
| 52 | `ftbr` | 89 | `tbrmin` | Min required `tbr` |
| 53 | `fflutf` | 92 | `nflutfmax` | Max allowed TF fluence |
| 54 | `fptfnuc` | 95 | `ptfnucmax` | Max allowed heating of TF coils |
| 55 | `fvvhe` | 96 | `vvhealw` | Max allowed He concentration in VV |

The KIT blanket neutronics model provides the following outputs:

| Output | Units | Itvar. | Description |
| :---------: | :------: | ------ | ------------------------------------------------------------------------ |
| `pnucblkt` | MW | - | Total nuclear power deposited in blanket |
| `pnucshld` | MW | - | Total nuclear power deposited in shield |
| `emult` | - | - | The energy multiplication factor in the blanket |
| `tbr` | - | - | Tritium breeding ratio |
| `blbuith` | m | 90 | Inboard blanket thickness |
| `blbuoth` | m | 91 | Outboard blanket thickness |
| `tritprate` | - | - | The tritium production rate in grammes/day is calculated. |
| `nflutfi` | n/m$^2$ | - | The fast neutron fluence on the inboard TF coils |
| `nflutfo` | n/m$^2$ | - | The fast neutron fluence on the inboard TF coils |
| `shldith` | m | 93 | Inboard shield thickness |
| `shldoth` | m | 94 | Outboard shield thickness |
| `pnuctfi` | MW/m$^3$ | - | Nuclear heating power on inboard TF coil |
| `pnuctfo` | MW/m$^3$ | - | Nuclear heating power on outboard TF coil |
| `vvhemini` | appm | - | Min He concentration in the inboard VV at the end of the plant lifetime |
| `vvhemaxi` | appm | - | Max He concentration in the inboard VV at the end of the plant lifetime |
| `vvhemino` | appm | - | Min He concentration in the outboard VV at the end of the plant lifetime |
| `vvhemaxo` | appm | - | Max He concentration in the outboard VV at the end of the plant lifetime |
| `bktlife` | fp-yrs | - | Blanket lifetime in full power years assuming max damage ~60 dpa |

## Thermo-hydraulic model for first wall and blanket

!!! Note "Note"
This is only called for primary_pumping = 2
This is called for primary_pumping = 2 and 3

Summary of key variables and switches:

Expand Down Expand Up @@ -244,6 +142,8 @@ where $\texttt{tkfw}$ is the thermal conductivity of the first wall material and

The temperature difference between the channel inner wall (film temperature) and the bulk coolant is calculated using the heat transfer coefficient, which is derived using the [Gnielinski correlation](https://en.wikipedia.org/wiki/Nusselt_number#Gnielinski_correlation). The pressure drop is based on the Darcy fraction factor, using the [Haaland equation](https://en.wikipedia.org/wiki/Darcy_friction_factor_formulae#Haaland_equation), an approximation to the implicit Colebrook–White equation. The thermal conductivity of Eurofer is used, from "Fusion Demo Interim Structural Design Criteria - Appendix A Material Design Limit Data", F. Tavassoli, TW4-TTMS-005-D01, 2004"

!!! Note "Note"
The pressure drop calculation is only performed for primary_pumping = 2, as for 3 it is used as an input, as explained in the heat transport section.

### Model Switches

Expand Down
13 changes: 12 additions & 1 deletion ...entation/proc-pages/eng-models/power-conversion-and-heat-dissipation-systems.md
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Expand Up @@ -62,7 +62,18 @@ for the primary coolant.
mechanical power used) is specified by the parameter `etaiso`. Note that the mechanical pumping
power for the shield and divertor are still calculated using the simplified method (a fixed
fraction of the heat transported).
- If `primary_pumping` = 3, the mechanical pumping power is calculated using specified pressure drop. The pressures and temperatures are set by the user.
- If `primary_pumping` = 3, the mechanical pumping power is calculated using specified pressure drop.
The pressures and temperatures are set by the user.
- When used with the DCLL model a different set of pressure drop variables are used, which are outlined below:

| Variable | Units | Default | Description |
| :----------: | :---: | ------- | -------------------------------------------------------------------------------- |
| `dp_fw_blnkt` | Pa | 1.5D5 | Pressure drop in FW and blanket coolant including heat exchanger and pipes |
| `dp_fw` | Pa | 1.5D5 | Pressure drop in FW coolant including heat exchanger and pipes |
| `dp_blkt` | Pa | 3.5D3 | Pressure drop in blanket coolant including heat exchanger and pipes |
| `dp_liq` | Pa | 1.0D7 | Pressure drop in liquid metal blanket coolant including heat exchanger and pipes |

- The defaults for these variables are geared towards a WCLL concept, so different values should be used with Helium cooling.

`secondary_cycle` : This switch controls the calculation of the thermal to electric conversion
efficiency in the secondary cycle.
Expand Down
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