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CLEARANCE IN THE FRAMEWORK OF DECOMMISSIONING OF NUCLEAR POWER PLANTS IN GERMANY Thomas Pöhlsen Clearance of Radioactive Material

Clearance Practises in Germany...CLEARANCE PATHS IN GERMANY 6 Thomas Pöhlsen Unconditional clearance of Solid material, oils, coolants Demolition waste > 1000 t/a Ground area Buildings

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Page 1: Clearance Practises in Germany...CLEARANCE PATHS IN GERMANY 6 Thomas Pöhlsen Unconditional clearance of Solid material, oils, coolants Demolition waste > 1000 t/a Ground area Buildings

CLEARANCE IN THE FRAMEWORK OF

DECOMMISSIONING OF NUCLEAR

POWER PLANTS IN GERMANY

Thomas Pöhlsen

Clearance of Radioactive Material

Page 2: Clearance Practises in Germany...CLEARANCE PATHS IN GERMANY 6 Thomas Pöhlsen Unconditional clearance of Solid material, oils, coolants Demolition waste > 1000 t/a Ground area Buildings

WHY IS CLEARENCE OF IMPORTANCE IN GERMANY?

– IN THE FRAMEWORK OF DECOMMISSIONING

Thomas Pöhlsen 2

Supervised

area

Control

area

272

.10

0 M

g

127

.54

0 M

g

Masses in a NPP – example:

Page 3: Clearance Practises in Germany...CLEARANCE PATHS IN GERMANY 6 Thomas Pöhlsen Unconditional clearance of Solid material, oils, coolants Demolition waste > 1000 t/a Ground area Buildings

WHY IS CLEARENCE OF IMPORTANCE IN GERMANY?

– IN THE FRAMEWORK OF DECOMMISSIONING

Thomas Pöhlsen 3

272

.10

0 M

g

127

.54

0 M

g

97,2%

Clearance options:

• unconditional clearance

• clearance for disposal (landfills / incinerators)

• clearance for recycling (melting of metals)

• clearance of buildings for demolition

• clearance of ground area

2,4%

0,4%

rad. waste

further use under a licence

Masses in a NPP – example:

Supervised

area

Control

area

Page 4: Clearance Practises in Germany...CLEARANCE PATHS IN GERMANY 6 Thomas Pöhlsen Unconditional clearance of Solid material, oils, coolants Demolition waste > 1000 t/a Ground area Buildings

CLEARANCE IN THE REGULATORY FRAMEWORK

4

Radiation Protection Ordinance (StrlSchV), § 29:

radioactive / contaminated material may only be used as non-radioactive

material if clearance is granted by the competent authority

clearence <-> 10 µSv/a criterion for individuals of the population

(in math. models: expectation value ≤ 10 µSv)

nuclide-specific clearance levels for eight different clearing paths

for different materials and different restrictions (in Bq/g, Bq/cm²).

Competent authorities may call in an independent expert (AtG § 20)

TÜV NORD works as an independed expert for several Nuclear

Licencing and Supervisory Authorities in Germany

Internationally TN is a full service provider in the field of nuclear safety.

in preparation: a new ordinance for clearance to transpose the

Council Directive 2013/59/Euratom into national law

Atomic Energy

Act (AtG)

Radiation Protection

Ordinance (StrlSchV) Licences State-of-the-art

technology rules

(ISO, DIN …),

Guidelines, …

Page 5: Clearance Practises in Germany...CLEARANCE PATHS IN GERMANY 6 Thomas Pöhlsen Unconditional clearance of Solid material, oils, coolants Demolition waste > 1000 t/a Ground area Buildings

CLEARING PATH: CLEARANCE FOR DISPOSAL OF

SOLID MATERIAL ON LANDFILLS

Thomas Pöhlsen 5

Restrictions: Material to be disposed

on a landfill, up to 1000 t/a, …

Higher clearance values than for

unrestriced clearance

(e.g. Co-60: 2 Bq/g instead of 0.1 Bq/g)

Page 6: Clearance Practises in Germany...CLEARANCE PATHS IN GERMANY 6 Thomas Pöhlsen Unconditional clearance of Solid material, oils, coolants Demolition waste > 1000 t/a Ground area Buildings

CLEARANCE PATHS IN GERMANY

Thomas Pöhlsen 6

Unconditional clearance of

Solid material, oils, coolants

Demolition waste > 1000 t/a

Ground area

Buildings for further use

Clearance for disposal of

Solid material on landfills

Solid and liquid material in incinerators

Clearance of buildings for demolition

Clearance of scrap metal for recycling (melting)

1 Bq/cm²

(1 Bq/cm²)

(1 Bq/cm²)

(1 Bq/cm²)

0.1 Bq/g

0.09 Bq/g

0.03 Bq/g

0.4 Bq/cm²

Clearance values for Co-60

3 Bq/cm²

0.6 Bq/g

6 Bq/g / 2 Bq/g

7 Bq/g / 2 Bq/g

up to

100 t/a / 1000 t/a

Surface contamination:

averaging up to 1000 cm²

Averaging

up to:

300 kg

1000 kg

1000 kg

1 m²

300 kg

300 kg

1 m² (or more)

300 kg

Page 7: Clearance Practises in Germany...CLEARANCE PATHS IN GERMANY 6 Thomas Pöhlsen Unconditional clearance of Solid material, oils, coolants Demolition waste > 1000 t/a Ground area Buildings

HOW IS COMPLIANCE WITH CLEARANCE LEVELS

DEMONSTRATED? – CLEARANCE PLAN

Thomas Pöhlsen 7

further applicable

documents giving

detailed description

of the step

personnel involved

in treatment or

monitoring

Rules for participation

for independent

experts / supervisory

authority

chronological list

of the treatment

and monitoring

steps

Page 8: Clearance Practises in Germany...CLEARANCE PATHS IN GERMANY 6 Thomas Pöhlsen Unconditional clearance of Solid material, oils, coolants Demolition waste > 1000 t/a Ground area Buildings

HOW ARE CLEARANCE

MEASUREMENTS PERFORMED

Thomas Pöhlsen 8

Performing measurements in compliance

with state-of-the-art technology rules

(ISO 11929, DIN 25457-1 to -7)

Combined measurements may be

used: e.g. radioactive surface

contamination monitor + gamma-

sensitive measuring system

Key results:

Activity concentration

< clearance levels

with 95 % conf. lev.

Characterization

Dismantling

Decontamination

Screening

Final Measurements

Approval / control by

supervisory authority

typically 100 % of material measured

Page 9: Clearance Practises in Germany...CLEARANCE PATHS IN GERMANY 6 Thomas Pöhlsen Unconditional clearance of Solid material, oils, coolants Demolition waste > 1000 t/a Ground area Buildings

CURRENT APPLICATIONS, EXAMPLES

Thomas Pöhlsen 9

Buildings for

demolition

Laborious procedures

Every wall area to be

measured

Infiltration of

contamination to be

taken into account

Special structures to

be evaluated

Page 10: Clearance Practises in Germany...CLEARANCE PATHS IN GERMANY 6 Thomas Pöhlsen Unconditional clearance of Solid material, oils, coolants Demolition waste > 1000 t/a Ground area Buildings

CURRENT APPLICATIONS, EXAMPLES:

CLEARANCE OF A GENERATOR (BWR)

Thomas Pöhlsen 10

Image: Vattenfall Europe Nuclear Energy GmbH

• Approx. 23 m x 5 m

• Approx. 650 Mg

• Stator:

Center & end caps

• Rotor

• Auxiliary units

• Steel body

• Lamination

• Windings

• Cooling systems

(gas & liquid)

• Painted in the control area

• Aim: non-destructive demonstration

of compliance with clearing levels

Page 11: Clearance Practises in Germany...CLEARANCE PATHS IN GERMANY 6 Thomas Pöhlsen Unconditional clearance of Solid material, oils, coolants Demolition waste > 1000 t/a Ground area Buildings

CURRENT APPLICATIONS, EXAMPLES:

CLEARANCE OF A GENERATOR (BWR)

Thomas Pöhlsen 11

Non-destructive

demonstration of

compliance with clearing

levels considering:

Outer surface

Liquid cooling system

Gas compartments

Combination of

considering the

operational history,

measuring accumulation

points

sampling (paint)

measuring the outer

surface (in-situ)

Image: Vattenfall Europe Nuclear Energy GmbH

Page 12: Clearance Practises in Germany...CLEARANCE PATHS IN GERMANY 6 Thomas Pöhlsen Unconditional clearance of Solid material, oils, coolants Demolition waste > 1000 t/a Ground area Buildings

Thomas Pöhlsen 12

Clearance for disposal in landfills often causes public interest:

Real conditions

at the location of the

disposal facility

Model parameters for

the conduction of

clearance values

the 10 µSv/a criterium may be checked

for every individual disposal facility

CLEARANCE FOR DISPOSAL

– A TOPIC OF PUBLIC INTEREST

Page 13: Clearance Practises in Germany...CLEARANCE PATHS IN GERMANY 6 Thomas Pöhlsen Unconditional clearance of Solid material, oils, coolants Demolition waste > 1000 t/a Ground area Buildings

NEEDS FOR FURTHER IMPROVEMENTS, IAEA

ASSISTANCE / TOPICS FOR INT. COOPERATION

Thomas Pöhlsen 13

International guidance on surface contamination values

SR 44 chapter 3.5: „… it has to be recognized that for specific situations such as the

clearance of metal or the reuse of buildings from nuclear installations, additional

criteria relating to the surface contamination may have to be applied that are not

reflected in the derived activity concentration values“.

International guidance on averaging masses (and averaging surfaces) also

taking into account confidence levels to be reached due to measurement

uncertainties for each sample and for larger amounts of material, e.g.:

for clearance it turns out that the consideration of uncertainties

(measurement uncertainties / natural background / initial level of polution)

often contributes significantly to conservatism and can be a challenge

when compliance with clearance values is demonstrated.

especially for H-3 and C-14 with clearance values from SR 44 and required

confidence levels of 95 % for each sample, clearance procedures are more

complex and costly than radiologically necessary.

An international recommendation and clearance values for deposition of

material on landfills.

Page 14: Clearance Practises in Germany...CLEARANCE PATHS IN GERMANY 6 Thomas Pöhlsen Unconditional clearance of Solid material, oils, coolants Demolition waste > 1000 t/a Ground area Buildings

SUMMARY

Thomas Pöhlsen, [email protected] 14

In Germany clearance is regulated in the Radiation Protection Ordinance,

§29 (StrlSchV).

Radiological basis: eff. dose max. in the order of 10 µSv/a for individuals

Clearance is of importance because about 97 % of the total mass in the

control area is cleared.

Clearance paths exist for

solid and liquid materials

conditional (landfills, incinarators, smelting, buildings for demolishion) and

unconditional clearance (material, buildings, ground, rubble)

International guidance for surface contamination values, averaging

masses / surfaces and confidence levels to be reached would be helpful.

TÜV NORD has a wide experience in clearance in Germany working as

independed experts for several Nuclear Licencing and Supervisory Authorities.

Internationally TN is a full service provider in the field of nuclear safety.