# Presentation: 751020

## Simulations in support of RIA Target Area R&D(Part 2)

**Conceptual Design of 2-Step ISOL targets **
**Examples of Simulations with “Large-Scale” Models**
**\**
**Conclusions**

**Notes:**
I will briefly present RIA
I will present some preliminary results for 2-Step ISOL target
and show a few examples of “large-scale” simulations in support of target area design

## Conceptual Design of RIA Targets

**P, n, d, and ****ion transport**** and interactions in the targets, beam dumps, magnets, etc.**
**Transport in ****magnetic fields**** required**
**Calculation of ****isotope yields****, energy deposition, and ****radiation damage**
**Simulation of rare ****isotopes “extraction”**** from the target and transport to the experiments**
**Determination of the radiation fields, dose levels, and shielding requirements during operation**
**Calculation of radioactive inventory build up in the target, post-operation decay heat, and dose rates **
**Determination of cooling requirements and stress analysis**

**Challenging**** requirements for simulations:**

**Notes:**
Some of the simulations required for design are quite challenging:
For example – ion transport and interaction;
                   - ion transport in magnetic fields
		-  prediction of isotope yields
  		-  extraction of isotopes from the ISOL targets 
                  -  prediction of radiation damage

## Particle and ion transport
PHITS (RIST, Japan)
Includes heavy-ion transport and interaction
Allows magnetic fields
MCNPX (LANL)
MARS15 (Fermilab)

Activation calculations
Activation Analysis System (AAS) (ORNL, with MCNPX)
ACAB98 (LLNL)
DCHAINSP2001 (JAERI, with PHITS)

**PHITS (RIST, Japan)**
**Includes heavy-ion transport and interaction**
**Allows magnetic fields**
**MCNPX (LANL)**
**MARS15 (Fermilab)**
**Activation calculations**
**Activation Analysis System (AAS) (ORNL, with MCNPX)**
**ACAB98 (LLNL)**
**DCHAINSP2001 (JAERI, with PHITS)**

- RIA Targets Conceptual Design (Cont.)

**The codes we use for simulations**** **

**Notes:**
We used a variety of codes for simulations so far 
This list will likely expend as we’ll continue the work.

## Work on Conceptual Design of Two-Step ISOL Target for RIA

**A two-step target was first proposed by J.A. Nolen  (ANL)**
**Primary beam incident on a neutron-producing high-Z “primary” target**
**Neutrons induce fissions in a “secondary” target filled with fissionable material **
**Advantage: **
**thermally decouples primary beam region and fission region  (important at high power beams when cooling is a problem) **
**Decouples fission (secondary) and spallation (primary) regions, and therefore reduces isobar contamination in the production of neutron-rich fission products**

**Notes:**
I will continue with a preliminary results from 2-step ISOL target analysis

## Two-Step “Generic” Target 

**Secondary Target, **
**UC, **
**Δ****R = ****5cm, **
**L = 45cm**

**Primary Target,**
**Hg or W with H****2****O or D****2****O,**
**R = 1.27cm, **
**L = 15 cm**

**Primary Beam, r = 1cm, flat**

- Two-Step “Generic” Target

**Notes:**
A two-step target was first proposed by Jerry Nolen  from Argonne.

Basis idea is that primary beam hits high-Z target and produces neutrons
These neutrons then induce fissions in secondary target.

Here is a variation  of 2-step target – a “generic”  model  which we used in the calculations.

At high beam powers cooling of the target becomes difficult. 

The hope is that decoupling the primary beam interaction region from the fission region will help.

This decoupling of the fission (secondary) and spallation (primary) regions should reduce isobar contamination when neutron-rich fission products are studied.

Primary targets considered (to date):
Hg  (serves as target and coolant, can be reused, etc.)
W with H2O or D2O coolant
10% coolant
20% coolant
Secondary target - UC at 5 g·cm-3

Primary beams:
1-GeV protons
622-MeV/u deuterons
777-MeV/u He-3
Primary beam power  400 kW

## Primary targets considered (to date):

Hg  (serves as target and coolant, can be reused, etc.)
W with H2O or D2O coolant
10% coolant
20% coolant

Secondary target - UC at 5 g·cm-3

Primary beams:
1-GeV protons
622-MeV/u deuterons
777-MeV/u He-3

Primary beam power  400 kW

**Hg  (serves as target and coolant, can be reused, etc.)**
**W with H****2****O or D****2****O coolant**
**10% coolant**
**20% coolant**
**Secondary target - UC at 5 g****·****cm****-3**
**Primary beams:**
**1-GeV protons**
**622-MeV/u deuterons**
**777-MeV/u He-3**
**Primary beam power  400 kW**

- Two-Step “Generic” Target  (Cont.)

- }

**(by volume)**

## Produces 1.8 × 1015 fissions/s in secondary

Deposits:
106 kW in primary, 
71 kW in secondary

Maximum heating rate in primary ~4.3 kW/cm3

Dpa rate in steel “beam window” ~5 dpa/month

**Deposits:**
**106 kW in primary, **
**71 kW in secondary**
**Maximum heating rate in primary ~4.3 kW/cm****3**
**Dpa rate in steel “beam window” ~5 dpa/month**

- Two-Step “Generic” Target  (Cont.)

**Results for 400-kW beam of 1-GeV protons **
**on Hg primary**

**Notes:**
Here are some results for the 1-GeV proton beam on Hg target.

The average power density in secondary is ~18 kW/liter  (PWR ~ 340 kW/liter)

## Comparisons at Equal Beam Power

|  | Hg | 0.9 W + 
0.1 H2O | 0.9 W +   0.1 D2O |
| --- | --- | --- | --- |
| p,          
1 GeV | 1.00 | 1.03
(1.00)* | 1.03
(1.00)*  |
| d,
622 MeV/u | 0.99 | 1.05 | 1.05 |
| He-3, 777 MeV/u | 0.85 | 0.86 | 0.86 |

| Hg | 0.9 W + 
0.1 H2O | 0.9 W +   0.1 D2O |
| --- | --- | --- |
| 1.00 | 1.19
(1.32)* | 1.19
(1.30)* |
| 0.99 | 1.20 | 1.20 |
| 1.44 | 1.72 | 1.72 |

- Number of fissions in UC

- Energy deposited in primary

- *For 0.8 W + 0.2 H2O or D2O

- Note that results are normalized to p-on-Hg-target results.

**Notes:**
Here different beams are compared at equal beam power.
Results are normalized to 1-GeV proton on Hg.

Here we see that proton and d beam are about equivalent, in terms of number of fissions in the secondary target and heating of the primary target, while He-3 beam produces less fissions and considerably more heating.

Hg and W-with-water  are about equivalent, and using water or heavy water doesn’t make a difference.

## Heating Profiles Along the Target Axis

## Fission Density Distributions (per Beam Particle)

## Preliminary Heat Transfer Results

**Primary target cooled with water flow**
**Maximum heat load ~ 5kW/cm****3**
**Water takes up ~20 % of the primary target volume (coolant channel diameter ~1.6 mm, pitch 3.4 mm)**
**Temperatures: **
**Tungsten < 225****o****C**
**Water < 140****o****C**
**Water flow of ~ 2 liters/s**
**Pressure drop ~ 0.7 MPa,**
**Water velocity ~ 18 m/s**

**Notes:**
Preliminary heat transfer calculations for the primary target with maximum heat load of `5kW/cc
indicate that it can be cooled with water.
The parameter are shown here.

## Particle Current,777 MeV/u He-3

- Beam, W+H2O Target

## Decay Heat, 0.9 W + 0.1 D2O, 1-GeV p, After 28 Days of Operation at 400 kW 

## Photon Emission, After 28 Days of Operation and 1 Hour Cooling Time, 0.9 W + 0.1 D2O,      1-GeV p Beam at 400 kW 

## A two-step ISOL target for 400 kW beam appears feasible

1-GeV proton and 622-MeV/u deuteron beam are about equivalent

777-MeV He-3 beam produces less fissions and higher heating
Would probably require > 20% of water (by volume) in the primary for cooling

**1-GeV proton and 622-MeV/u deuteron beam are about equivalent**
**777-MeV He-3 beam produces less fissions and higher heating**
**Would probably require > 20% of water (by volume) in the primary for cooling**

- Preliminary Conclusions from Two-Step ISOL Target Simulations

## Simulations with “Large-Scale” Models

**Study radiation fields**
**Determine necessary shielding**
**Assess activation of the magnets, beam dumps, and other structures**
**Provide input for overall facility design**

**Simulations were also carried out with large- **
**scale models with the objectives to:**

**Examples of these analyses are given in the following slides**

**Notes:**
The calculations were also carried out with “large-scale” models to support the design of target areas.

## Heating Rates Around ISOL Target (MCNPX)

**(Wcm****-3****)**

- 11m

- 15m

**Notes:**
The firs example shows the heating rates in the shielding around ISOL target.

## Neutron Flux Distribution in Large ISOL Target Model (MARS15) 

- 40 m

## Heating Rates Along Fragmentation Line, 400 MeV/u U-238 Beam on Li Target (PHITS) 

**Notes:**
This is one of the early calculations of the fragmentation line, performed basically to see how well the transport of ions through magnetic field will work. After passing through three quads and the dipole  the remaining primary beam heat the “beam dump” where it was was expected to.

## Yields for 400-MeV/u U-238 Beam on Li target (PHITS)

**Notes:**
Here the yields for the U beam on Li target are shown.

## Conclusions 

**RIA target areas R&D is proceeding utilizing a successful multi-institution effort**
**A variety of codes are being used to perform the various simulations; more will be added**
**Some inter-comparisons were performed with encouraging results; more will be needed (benchmarking)**
**A two-step ISOL target with water cooled tungsten primary and UC secondary target appears viable for beam powers up to 400 kW**
**Optimization analyses are needed**
**For a two-step ISOL target, primary beams of 1-GeV protons or 622-MeV/u deuterons give ~equal fission rates and heating**
**777 MeV/u He-3 beam results in less fissions and higher heating**
**Two-step ISOL targets are likely to use proton beams only**** **

## Supplementary Slides

## Comparisons per Beam Particle

|  | Hg | 0.9 W + 
0.1 H2O | 0.9 W +   0.1 D2O |
| --- | --- | --- | --- |
| p,          1 GeV | 1.00 | 1.03 | 1.03 |
| d,      622 MeV | 1.23 | 1.30 | 1.30 |
| He-3,
777 MeV | 1.98 | 2.00 | 2.00 |

| Hg | 0.9 W + 
0.1 H2O | 0.9 W +   0.1 D2O |
| --- | --- | --- |
| 1.00 | 1.19 | 1.19 |
| 1.23 | 1.49 | 1.49 |
| 3.37 | 4.00 | 4.00 |

- Number of fissions in UC

- Energy deposited in primary

- Note that results are normalized to p-on-Hg-target results.

**Notes:**
If one looks at number of fissions and heating per beam particle, the picture is completely different.

## Heating Profiles at Target Face, Pencil Beam with 1-cm Radius

## Particle Current,622 MeV/u d

-  Beam, W+H2O Target

## Particle Current,1000 MeV p

-  Beam, W+H2O Target

## Comparisons at Equal Beam Power

|  | Hg | 0.9 W + 
0.1 H2O | 0.9 W +   0.1 D2O |
| --- | --- | --- | --- |
| p,          1 GeV | 1.00 | 1.03
(1.00)* | 1.03
(1.00)*  |
| d,      622 MeV | 0.99 | 1.05 | 1.05 |
| He-3,
777 MeV | 0.85 | 0.86 | 0.86 |

| Hg | 0.9 W + 
0.1 H2O | 0.9 W +   0.1 D2O |
| --- | --- | --- |
| 1.00 | 1.02
(1.01)* | 1.03
(1.01)* |
| 0.96 | 1.01 | 1.01 |
| 0.87 | 0.85 | 0.85 |

- Number of fissions in UC

- Energy deposited in Secondary

- *For 0.8 W + 0.2 H2O or D2O

- Note that results are normalized to p-on-Hg-target results.

## RIA Targets Conceptual Design

**Optimize performance for production of rare isotopes**
**Minimize target change-out time**
**Ensure safe and reliable operation**
**Maintain flexibility to implement new target concepts**
**Minimize radioactive waste and hazards associated with the operation**

**Performance & operation requirements:**

**Notes:**
Here some basic requirements for the conceptual design of RIA target areas are listed.