Associazione EURATOM ENEA sulla FUSIONE Final Meeting of the contracts TW5- TSW-001 and -002 Garching. January 17 th, 2006 Final Meeting of the contracts

Associazione EURATOM ENEA sulla FUSIONEFinal Meeting of the contracts TW5- TSW-001 and -002Garching. January 17th, 2006

Final Meeting of the contracts TW3-TSW-001 and -002

and TW4-TSW-001 and -002

ENEA part of the Art.5.1.a. task, and reminder of former results and reports

L.Di Pace

ENEA CR Frascati

Garching, January 17th, 2006

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Outline

• Status of decommissioning• Decommissioning waste management• Metal recycling market• Radioactive scrap metal recycling & reuse• Clearance & recycling standards and

regulations• Radioactivity measurement techniques and

strategies• Fusion industry implications• Conclusions

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Status of decommissioning

• An entire generation of nuclear plants are ending the operating life;• Hundreds of thousand of t/a will be produced by nuclear plants

decommissioning within next 40 years;• Only a limited volumetric fraction will contain the most of the activity.

(99% of radioactivity concentrated in 1% volume). (Spent fuel is excluded)

Time distribution for generation of slightly radioactive solid material from USA power reactor decommissioning

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Decommissioning waste management

• 3 options are envisaged for the radioactive waste:a. Clearance, (unconditional, unrestricted release);

b. Conditional clearance: recycle, reuse in specified application and subject to regulatory control;

c. No release from regulatory control, (management as radwaste).

• Each option has economic impacts due to the associate pricing for handling and disposal.

– (average disposal cost in Europe in existing shallow land repositories is ~3000 €/m3)– disposing of slightly radioactive metal from decommissioning in USA could range from

3100 to 16000 US$ /m3 (depending from the repository)

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Metal recycling market #1

Steel is gold

• World population growth, ~ 9B within 2050, will require resources (including financial capital) to be used efficiently and effectively;

• Wastefulness will not be tolerated. The three Rs of Waste Management (Reduce, Reuse & Recycle) will become the basis of a new world philosophy;

• Metal, plastic and glass are recycled today in large quantities;

• Increase in the consume of recycled metal (~900·106 t/a for steel in 2002). (70% of steel produced in USA in 2003 are from recycling);

• Recycling allows great energy savings (60-75% for steel, ~95% for aluminium);

And we avail of it

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Metal recycling market #2

The usual way of recycling steel is by re-melting scraps in basic oxygen furnace (1) with pig iron from blast furnaces, or solely in electric arc furnaces (2).

(1)

(2)

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Radioactive scrap metal recycling #1• Issue already in the agenda in 80s –90s; OECD-NEA study

(1996) on 25 decommissioning projects in 9 different countries showed the following shortcomings:

– clearance approach on a “case-by-case” basis;– absence of consistent international release criteria or national

clearance standards.• Few thousands of tons of metals are generated from the

dismantling of a power reactor (non-radioactive or recyclable fraction 50-70%);

• Recycling of metals by re-melting (in electrical induction heating and electric arc furnaces); Mixing with non-contaminated scrap metal up to ~ 20% wt;

• Concrete debris are mostly non-contaminated and will pose no health risks.

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Radioactive scrap metal recycling #2

•Radioactive Scrap Metal melting allows:– A large reduction in the radioactivity of the

final ingot due to dilution and nuclides separation (in the slag and in the off-gas system);

– Activity homogenisation and volume reduction;

– Stabilised product suitable for final disposal.

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• International studies [OECD-NEA e ANL (USA)] showed advantages of the option recycle/reuse over dispose/replace as far as:

– Worker and public health (radiological risk much lower than conventional ones - fatalities and disabling injuries from workplace and road accidents);

– Energy and valuable natural resources savings;

– Reduced environmental impact.


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• From the public acceptability perspective both options have problems at the moment.

A portal truck monitoring system commonly used by steel mills to intercept incoming scrap metal

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Clearance & Recycling standards and regulations #1

• Council Directive 96/29/Euratom [Basic safety standards for the protection of the health of workers and the general public against the dangers arising from ionizing radiation, [OJ no. 159, 29.6.1996, p. 1-114];

• DisposalDisposal, recycling and reuse of material containing radioactive substances is subject to prior authorization;

• Any practice involving radioactivity requires justification;• If yes: reporting and prior authorization or exemption if

linked radiological risks are sufficiently low;• Clearance is the removal of radioactive materials or

radioactive objects within authorized practices from any further regulatory control by the regulatory body,

• The clearance levels are the recommended nuclide specific limits below which authorities could authorize clearance.

• They are based on radioprotection criteria.

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• Individual doses of some tens of µSv/a are considered trivial.

• To take into account multiple exposures:– Individual dose <10 µSv/a per practice;– Collective dose < 1 pers·Sv/a per practice.

• Radiological model to derive clearance limits of the single nuclide have to take into account all possible exposure scenarios: ingestion (direct and indirect), inhalation, and external -radiation & -skin-irradiation.

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• Documentation issued by international bodies (IAEA, EC, NEA-OECD e US NRC) related to “clearance” criteria and limits: – IAEA: TECDOC-855 [TECDOC-855] and SAFETY GUIDE

No. RS-G-1.7 [SAFETY GUIDE No. RS-G-1.7],– EC: RP89 [RP 89] RP113 , RP114, RP117, RP122 [RP 122]

– NEA-OECD [NEA-1996]

– US NRC: NUREG-1640 [NUREG-1640]

• EC RP 134 [RP134] – relative to the evaluation of the application of the concepts of exemption and clearance for practices according to title III of Council Directive 96/29/Euratom.

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Table from EC RP 134: Need for harmonisation of ClsCase of tritium: from 0.4 Bq/g in UK up to 1.0E+6 Bq/g in the Netherlands

Clearance levels (CLs) in [Bq/g]

Nu

clid

e

Bel

giu

m

Den

mar

k (°

)

Ger

man

y

Gre

ece

Ital

y (*

)

Lu

xem

bu

rg

Net

her

lan

ds

Fin

lan

d

Sw

eden

UK

EC

RP

122

241Am 1.0E-01 5.0E-02 1.0E-01 5.0E-02 1.0E+00 1.0E-01 1.0E-01 4.0E-01 1.0E-01 239Pu 1.0E-01 4.0E-02 1.0E-01 4.0E-02 1.0E+00 1.0E-01 1.0E-01 4.0E-01 1.0E-01 137Cs 1.0E+00 5.0E-01 1.0E+00 1.0E+00 5.0E-01 1.0E+01 1.0E+00 5.0E-01 4.0E-01 1.0E+00 90Sr 1.0E+00 2.0E+00 1.0E+00 1.0E+00 2.0E+00 1.0E+02 1.0E+00 5.0E-01 4.0E-01 1.0E+00 60Co 1.0E-01 1.0E-01 1.0E-01 1.0E+00 1.0E-01 1.0E+00 1.0E+00 5.0E-01 4.0E-01 1.0E-01 65Zn 1.0E+00 5.0E-01 1.0E+00 5.0E-01 1.0E+01 1.0E+00 5.0E-01 4.0E-01 1.0E+00 51Cr 1.0E+01 1.0E+02 1.0E+01 1.0E+02 1.0E+03 1.0E+01 5.0E-01 4.0E-01 1.0E+01 3H 1.0E+02 1.0E+03 1.0E+03 1.0E+00 1.0E+03 1.0E+06 1.0E+01 5.0E-01 4.0E-01 1.0E+02

238U 1.0E+00 5.0E-01 9.0E-03 1.0E+00 1.0E+00 1.0E-01 1.0E-01 1.11E+01 1.0E+00 232Th 1.0E-02 5.0E+00 2.0E-02 1.0E-02 3.0E-02 1.0E+00 1.0E-01 1.0E-01 2.59E+00 1.0E-02 228Th 1.0E-01 5.0E-01 1.0E-01 1.0E-01 1.0E-01 1.0E+00 1.0E-01 1.0E-01 2.59E+00 1.0E-01

228Ra+ 1.0E-02 1.0E+00 7.0E-02 1.0E-02 7.0E-02 1.0E+00 1.0E+01 5.0E-01 3.70E-01 1.0E-02 226Ra+ 1.0E-02 5.0E-01 3.0E-02 1.0E-02 3.0E-02 1.0E+00 1.0E-01 1.0E-01 3.70E-01 1.0E-02 210Pb 1.0E-02 5.0E+00 2.0E-02 1.0E-02 4.0E-02 1.0E+02 1.0E+01 5.0E-01 7.40E-01 1.0E-02 210Po 1.0E-02 5.0E+00 4.0E-02 1.0E-02 4.0E-02 1.0E+02 1.0E-01 1.0E-01 3.70E-01 1.0E-02

(°) for natural radionculides (*) clearance levels proposed for the decommissioning of Caorso NPP


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Radioactivity measurement techniques and strategies #1

• Aim: ascertain the absence of radioactivity and/or the compliance with proposed limits;

• Direct measurement on material or on representative samples, or by other means retained sufficient by the competent national authority;

• The objective of keeping individual dose <10 µSv/a entails that dose rates to be measured are a small portion of natural background; need to operate at the lower boundaries of instruments detection;

• For nuclides difficult to measure it could be possible to link them to other nuclides.

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• Specify the mass or surface on which average the measurement (distribution not homogenous);

• Surfaces of few dm2 and mass of few hundreds of kg (max. 1 m2 and 1 t) may be considered as appropriate for averaging the measurement;

• Minimum No. of measurements defined by the regulatory authority (i.e.: wall surface radioactivity);

• When measuring the surface activity, it should be considered the “total activity” (removable + fixed surface activity) as well as that penetrated into the material from the surface (i.e.: due to corrosion).

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• Chances to measure rays from the bulk;

• Limitation of the surface activity involves that of the bulk, by simply measuring the radiation on the surface;

• For low energy -rays or for - and -emitters the opposite problem might occur; they can go undetected if they are located under rust, corrosion or surface coatings;

• Other problems are: the geometrical complexity, the influence of the natural background, the accessibility of the item including their surfaces, and the sensitivity of the instrument relative to the criteria to be met;

• At any rate the state of the art in measuring of radioactivity is sufficiently developed to cope with the challenge.

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Conclusions• The experience of decommissioning of an entire generation

of nuclear facilities will be exploited by future fusion industry, (i.e. for recycling, reuse or disposal).

• The real waste management problem in fusion will be relative to the in-vessel components (IVCs).

• The fusion industry would have the advantage of being able to use activated metal, as it would be employed in a controlled environment, (radiation fields will be monitored).

• It seems more important to demonstrate the feasibility of IVCs recycling from the technical point of view, rather than to perform an economic assessment with the present-day terms.

• It would be greatly more important to concentrate the future activities on:1. the study of the fusion material and equipment cycle and; 2. on the regulatory framework, within which recycling of fusion material

could be performed.

Documents

Associazione EURATOM ENEA sulla FUSIONE Final Meeting of the contracts TW5- TSW-001 and -002 Garching. January 17 th, 2006 Final Meeting of the contracts