| This work was part funded by the RCUK Energy Programme [grant number EP/P012450/1]. This work has been carried out within the

framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014-2018 under

grant agreement No 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission.

Nuclear data needs and

applications in fusion researchLee W. Packer, M. R. Gilbert, B. Colling, T. Eade, J. Naish, C. R. Nobs, T.

Stainer, A. Valentine, O. Vilkhivskava+ other contributors

|

1. Introduction – fusion and nuclear simulation needs

2. Nuclear codes and data to predict nuclear phenomena

• Radiation transport codes

• FISPACT-II inventory code

• Nuclear data – JEFF, FENDL, TENDL

• Benchmarking

3. 14 MeV experimental benchmark activities

• Decay heat validation using the JAEA FNS decay heat experiments

• Technological exploitation of JET operations

• Activated water coolant (N-16 and N-17) measurements

• Tritium breeding mock up experiments

Overview

JEFF stakeholders workshop 6-7 June, Paris 20192

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Culham Centre for Fusion Energy

JET

MAST-U

Fusion research arm of UKAEA

| Slide 4

DONES

JT-60MAST-U

Fusion mission: roadmap

|Slid

e 5

Role of neutronics and nuclear data in fusion

17 Feb 2014

• Neutrons will be present in very large quantities in DT fusion

devices – >1.8E20 n/s in the ITER plasma

• This reaction releases 17.6 MeV, 80% of this energy is taken

by the neutron.

– Vitally important to know where the neutrons go, how much energy is

deposited in materials, levels of activation…

• Neutronics involves the simulation of nuclear effects in matter

through various nuclear interaction mechanisms.

• Predictions rely on nuclear data

• For fusion device design, safety and performance there is a

need to calculate essential nuclear quantities:

– Nuclear heating (from neutrons inducing interactions that heat

components)

– Activation of materials and waste arisings

– Gamma shutdown dose rates due to neutron activation of

materials (relevant to maintenance operations)

– Nuclear damage and gas production (neutron reactions cause

displacements and produce He, which affect material properties)

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ITER nuclear modelling and analysis

6

• Modelling performed from detailed CAD models and simplified to semi detailed level before integration into MCNP via a universe implementation.

• Use MCNP6 for RT simulation but we are testing alternatives such as SERPENT

• FENDL 3.1c and d is the reference library for ITER analysis

Integrated reference model (C-Model

R180430)

Envelope structure contains each

Tokamak component individually

Single blanket module

HNB3

Examples of simplified sub-models

Work by Alex Valentine

Plotted using D1SUNED

JEFF stakeholders workshop 6-7 June, Paris 2019

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beryllium pebbles

lithium silicate pebbles

< European dual-coolant

blanket concept [FZK].

European helium-cooled

pebble-bed blanket

[FZK]. >

DEMO: Tritium Breeding Blankets

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Neutron spectra in tokamaks

• 14 MeV fusion neutrons lose energy by elastic and in-elastic scattering

events with material in the device surrounding the plasma

• Hence even at the first wall there will be a large range of neutron energies

• In ITER the first wall flux will be around 1x1015n/cm2/s from DT fusion.

M Gilbert et al., Neutron-induced transmutation effects in W

and W-alloys in a fusion environment, Nucl. Fusion 51 (2011)

2D + 2D →3He + n (Q = 3.27

MeV)

2D +3He →4He + 1H (Q = 18.3

MeV)

2D + 3T →4He + n (Q = 17.6

MeV)

< Calculated neutron spectra

at the first wall in a DEMO

power plant, in ITER (DT) and

in ITER (DD) plasma

operations

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Role of simulation tools: predicting radiation

environments

Neutron flux map Activation gamma dose map

Simulations inform on environment – to guide development of suitable technologies

Need to predict:

• Neutron/gamma fields, nuclear heating, damage, gas production

• Activation levels during and after operations, and for decommissioning

considerations

Benchmarking important; DT facilities, JET, SINBAD, validated ND

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• Serpent-2 and MCNP comparison

Serpent and MCNP Benchmarking

10 JEFF stakeholders workshop 6-7 June, Paris 2019

• Negative cross section values for average heating

numbers (in the ACE files) flags a warning in Serpent

2.

• In particular tungsten (as used in DEMO first wall).

• MCNP reads the same ACE file but does not report

any issue with the negative value.

• It is not clear how Serpent 2 interprets these values

and whether this is the same as MCNP.

• The result is that with Serpent 2 and JEFF (3.2 & 3.3)

data we see negative nuclear heating values in the

range 1-10 MeV and significant differences to MCNP.

• Investigation: negative heating values in W JEFF ace file

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DEMO waste studies

11 JEFF stakeholders workshop 6-7 June, Paris 2019

• JEFF-3.3 is the reference library for EU DEMO analysis

| Footer12JEFF stakeholders workshop 6-7 June, Paris 2019

Nuclear inventory simulation tools

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• Validation & Verification (V&V) is an important part of the development and release of the FISPACT-II platform

• A suite of automated validation benchmarks have been created to test new releases of both the FISPACT-II code and the nuclear data libraries

• against international experimental databases

• Results are compiled into open access pdf reports (see fispact.ukaea.uk)

• thousands of pages in total providing a near-complete coverage of the physics landscape for neutron interactions

FISPACT-II V&V

13

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FISPACT-II validation

14

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Visualisation of FISPACT-II output

Slide 15

Nuclide chart evolution over time following a fission pulse (decay heat

map)

Calculates the

time evolution

of materials –

under

irradiation and

through

radioactive

decay

http://www.ccfe.ac.uk/EASY.aspx

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FISPACT-II release and training

• Now at version 4.0 (released February 2018)

• Available at the NEA databank

• New JSON output format for easy (computer) parsing

• Including via python scripts developed as an open-source PYPACT utility(https://github.com/fispact/pypact)

• High energy library extensions from 200 MeV to 1 GeV (HEIR)

• Next course 19-21 June 2019 at the OECD NEA

16

2018 FISPACT-II workshop hosted by the OECD/NEA

databank in Paris

Contact: mark.gilbert@ukaea.uk

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Integro-differential validation

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Fusion experiments: Technology

exploitation at JET

JEFF stakeholders workshop 6-7 June, Paris 201924

Irradiation of real ITER materials (ACT)

• New irradiation station assembly to be irradiated at JET 26 positions are filled with a variety of dosimetry foils from 4 institutes (ENEA, CCFE, NCSRD, IFJ) and a selection of ITER materials

• Detailed analysis from previous characterisation work under the collaboration. See Nuclear Fusion 58 (9) 2018 096013

Neutronics experiments (NEXP)

• New sensitivity study for aspects of JET model – results to be compared with SDDR and streaming measurements.

• Detector calibration activity for N-16 measurement – involving Cm-244-C-13 source

Detectors for tritium breeding modules (TBMD)

• Focus on measurement of short-lived products

• Plan to irradiate a selection of dosimetry foils (Bronze, Al90/Ce10, Nb, Cr, In) at the KN2 6U location in the next JET campaign.

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An experimental campaign at ENEA is expected Nov/Dec 2019 aims to:

• provide a means to validate computational tools and nuclear data

• assess the prediction accuracy in providing fundamental data for the nuclear design, optimization and performance evaluation of DEMO, comprising safety, licensing, waste management and decommissioning issues.

Fusion experiments: Water Cooled Lithium

Lead (WCLL) neutronics mock-up

experiment

25

The nuclear design and performance of breeder blankets fully rely

on the results provided by neutronics calculations.

CCFE have been tasked with diagnostic activities to

support the experiments, primarily dosimetry foils

The foils will be embedded in the experimental region

and used to monitor the local flux.

Following irradiation at ENEA, spectroscopy

measurements will be performed at ADRIANA.

JEFF stakeholders workshop 6-7 June, Paris 2019

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Fusion experiments: Measurement of 16N

during irradiation of First Wall mock-ups

26

Neutron detector

Gamma detector

The collaboration aims to measure 16N and 17N production in

water activated by DT neutrons and compare with calculations to

reduce uncertainties in the calculation of radiation dose maps due

to activated water.

The main sources of uncertainty currently being due to modelling

and nuclear data, and hence safety factors between 8.2 and 4.7

are applied.

Safety factors applied for the IBED

activated water radiation maps

• Experiment scheduled 24th-28th June

• Project completion: 2nd August 2019

16N reaction rates 17N reaction rates

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• Nuclear codes and data are essential to develop fusion technology

• Involved in various studies requiring nuclear codes and data to predict nuclear phenomena

• Existing devices, JET, MAST

• Future devices, ITER

• Demonstration power plants, DEMO

• Developing the FISPACT-II inventory code

• Extensive collaborative validation activities

• UKAEA are involved in several collaborative experimental benchmark studies which support this

• Decay heat validation using the JAEA FNS decay heat experiments

• Technological exploitation of JET operations

• Activated water coolant (N-16 and N-17) measurements

• Tritium breeding mock up experiments

Summary

27 JEFF stakeholders workshop 6-7 June, Paris 2019