water and pressurized helium as coolants of fusion reactor ... · [ruth a.carvajal-ortiz et.al....

Water and pressurized Helium as coolants of fusion

reactor breeding blankets: chemistry issues and

purification technologies

Aleksandra Baron-Wiechec and Italo Ricapito

Aleksandra Baron-Wiechec | IAEA Workshop on Challenges for Coolants in Fast Neutron Spectrum Systems

Vienna, Austria | 05-07 July 2017 |

Content and Purpose

1. Water chemistry challenges for water cooled systems of DEMO Li-Pb BreederBlanket

2. Purification technologies for pressurized Helium as alternative DEMO Breeder Blanket coolant

2.

I. Ricapito, A. Aiello, J. Galabert, Y. Poitevin, A. Tincani

A.Baron-Wiechec, R.Burrows, A.Del Nevo, C.Harrington, A.Hojna, R.Holmes, E.Lo Piccolo, E.Surrey, R.Torella, S.Walters



Content and Purpose

Water chemistry challenges for water cooled systems of DEMO Li-Pb Breeder Blanket

1. Introduction2. Issues going to water chemistry of DEMO WCLL BB3. Preliminary water chemistry for DEMO WCLL BB4. Summary

DEMODemonstrator Power Plant

Blanket

Introduction

Breeder Blanket (BB) functions:-produce T for self sufficiency of the power plant-act as a radiation barrier-use 14MeV neutrons to produce power



14.1MeV

3.6MeV

BlanketShield VV First wall

Plasma

LiPb breeding zone Coolant



Introduction

For detailed information see Fusion Engineering and Design xxx (2017) xxx–xxx R. Mozzilloa, A. Del Nevo, E. Martelli, G. Di Gironimo

European DEMO BB (Breeder Blanket) – 4 concepts:- He Cooled Pebble Bed (HCPB)- He Cooled Lead Lithium (HCLL)- Dual-Coolant Lithium Lead (DCLL)- Water Cooled Lithium Lead (WCLL BB)

The WCLL concept, developed under the coordination of ENEA, uses a liquid metal (LiPb) as the tritium breeding material and water as a coolant.



Issues going to water chemistry of DEMO WCLL BB

Materialsintegrity

Radiationfields

Optimised water

chemistry Design & Safety



Materialsferritic-martensitic

Eurofer-97

Radiationfields

- duty cycle 8 x 2h burn up

+15min dwell time

- high temp. gradient- magnetic field

- reduced neutron activation- narrow pH window 7.0-8.0

- narrow operational temperatures window- pitting corrosion and SCC susceptibility- T permeation See poster for more details

- 14 MeV neutron- gamma from 16O(n,p)16N 6.1 and 7.1 MeV, hl 7s

- T production

Optimised water

chemistry

Issues going to water chemistry of DEMO WCLL BB

Design & Safety



Tools we have to tackle water chemistry challenges

1. Extensive experience over many decades in the fission power industry2. Corrosion and radiolysis modelling codes 3. Some scattered experimental data (testing)4. A lot of enthusiasm for the project



Results

1. Extensive experience over many decades in the fission power industry

Typical characteristics related to coolant chemistry based on a current knowledge ofLWR (light water reactors) and recent reviewed of a concept design of DEMO BBSee poster for more details

Coolant conditions Pressurised Water Reactor (PWR)

Water Water Energetic Reactor

(VVER)

Boiling Water Reactor BWR DEMO

Pressure /bar 155 75 155

Temperature /˚C 285-325 275-285 295-328

Neutrons Thermal neutron spectrum Thermal neutron spectrum 14MeV neutrons

Component life 60+ years 60+ years 5 years

Operation 12 to 24 month

fuel cycles

12 to 24 month

fuel cycles

2 to 8 hour burn/dwell

cycles

Coolant flow m/s 15 depends on reactor size depends on reactor size 2-5

Presence of magnetic

fields

no no yes

Water Demineralised

Temperature 300-320

Oxygen <10 μg/kg

Hydrogen 10 Nml/kg

LiOH 0-2 mg/kg

pHT 5.7-8.0

Conductivity As low as possible

Flow rate 2-5 m/s



Results

Preliminary water chemistry for DEMO WCLL BB

Suppression of the radiolysis ~ 0.8 ppm 10cc/kg (min. 0.2 ppm)

Gamma - 16O(n,p)16N, adding hydrazine (N2H2) Other ways to reduce Oxygen



Results

Water Demineralised

Temperature 300-320

Oxygen <10 μg/kg

Hydrogen 10 Nml/kg

LiOH 0-2 mg/kg

pHT 5.7-8.0


Flow rate 2-5 m/s


A compromise betweenneutron depletion (consumption) and pH control Adding what consumed by neutrons to maintain pH





Results

Water Demineralised

Temperature 300-320

Oxygen <10 μg/kg

Hydrogen 10 Nml/kg

LiOH 0-2 mg/kg

pHT 5.7-8.0


Flow rate 2-5 m/s



Eurofer above 7 pH

To achieve pH of 8.0 at 300C – 23mg/kg LiOH is needed[Ruth A.Carvajal-Ortiz et.al. Nuclear Engineering and Design, Vol 248, 2012, 340-342]





Results

Water Demineralised

Temperature 300-320

Oxygen <10 μg/kg

Hydrogen 10 Nml/kg

LiOH 0-2 mg/kg

pHT 5.7-8.0


Flow rate 2-5 m/s



Eurofer above 7 pH

To achieve pH of 8.0 at 300C – 23mg/kg LiOH is needed[Ruth A.Carvajal-Ortiz et.al. Nuclear Engineering and Design, Vol 248, 2012, 340-342]

corrosion mitigation methods – effectiveness with Eurofer-97:

o Zinc injection? Noble metal addition?o Methanol injection?





Results

2. Corrosion and radiolysis modelling codes (PACTITER , FACSMILE)the PACTITER code (CMS)

A uniform corrosion rate as a function of the time

at the beginning ~9 µm/y,

at the end ~ 0.5-0.2 µm/y.

Preliminary water chemistry for DEMO WCLL BB- pure water, 2 ppm of LiOH- under deareated condition ( O2 < 10 ppb)- temperature : 285 °C and 325 °C- pressure: 150 bar- flow rate: 5 m/s

Assumption: the chemistry is completely under control



Results

Pits observed after 1000 hours of exposure in autoclave at 285°C. a few tens of µm depth and diameter ~ 80 µm.

2. Corrosion and radiolysis modelling codesPreliminary validation of the PACTITER code by autoclave testing at CMS

Risk of pitting corrosion or SCCis not included in any algorithm in the code

Good agreement between simulation and test experiment.

Test

Specim

en

After 100h

(µm/year)

After 400h

(µm/year)

After

1000h

(µm/year)

Total

weight loss

(g/m2)

1 4 1 0.4 - 3 4

2 3 0.8 0.6 3

3 6 1.5 1.1 6

Considering amount of water, specific design of piping, and temp duty cycle – variability can not be excluded.



Summary

Purpose for fission Relevance to DEMO WCLL

Boric acid/Borate Reactivity control, with higher concentrations at

the start of a cycle

Not present as reactivity control not required

Lithium hydroxide or potassium hydroxide Alkalising agents for pH control, particularly to

balance effect of boric acid addition

Necessary but concentration may be lower. Not

subject to the same upper concentration limits

arising from fission reactor fuel clad

Hydrogen, ammonia, or hydrazine reducing agents to supress the concentration of

oxygen and hydroxide free radicals for corrosion

mitigation

Necessary but optimum concentration of H and

effect on Eurofer-97 requires further

experimental work

Oxidising species Concentrations minimised for stress corrosion

cracking (SCC) control

Requirements will be the same or similar

Impurity Levels Concentrations minimised for stress corrosion

cracking (SCC) control

Requirements will be the same or similar

Zinc injection and noble metal addition Reduce radiation fields through reduction in

corrosion production generation, and mitigation

against SSC

Use of depleted zinc seems the most relevant

Other developments e.g. titanium dioxide or

methanol addition

alternatives to zinc and noble metal addition Possibly relevant depending on progress with

other mitigators



Summary

to be updated in tandem with the plant design and the developing technical basses.

The water chemistry programme is a live document

General issues which require further investigation:

-Determination of the optimum pHT control band in order to minimise corrosion ofEurofer-97, and corrosion product release rate.

-Definition of required water chemistry in detail, particularly for start-up and shutdownconditions.

-Detailed characterisation of corrosion product film morphology arising from Eurofer-97exposure to representative conditions

-Need for small-scale testing facilities for water chemistry and corrosion of irradiated Eurofer-97 evaluation.

-Validation of corrosion and radiolysis codes, with 14 MeV neutron irradiation



Thank you

water and pressurized helium as coolants of fusion reactor ... · [ruth a.carvajal-ortiz et.al....

Documents