Radiation Protection aspects

S. Roesler (DGS-RP)

based on discussions with and information from

M.Brugger, G.Dumont, D.Forkel-Wirth, L.Gatignon, M.Magistris, D.Perrin, C.Theis, V.Tromel, H.Vincke, M.Widorski

East Area Day1 February 2012

2East Area Day – RP Aspects1 February 2012

Outline

1) Present situation and RP justification for consolidation

2) Dismantling and refurbishment

3) Design of new facility

4) Monitoring and operation

5) Summary and conclusions

- work planning and ALARA- work on radioactive material- Radioactive waste

- shielding- activation of components and optimization- air activation- cooling water activation

- RAMSES- buffer zones

31 February 2012

Present situation – target area

Not optimized according to modern radiation protection practices

- ageing components frequent repair, water leaks,...

- significant losses, long passages of beam through air, tight space, difficult access comparably high individual and collective doses unjustified activation of air

- corrosion contamination risks

- no ventilation system risk assessments difficult faster corrosion

- single water cooling circuit for target area and experiments unjustified exposure of experimenters to activated water large volume of activated water

A consolidation is urgently required and encouraged by RP

East Area Day – RP Aspects

41 February 2012

5East Area Day1 February 2012

61 February 2012

Present situation – mixed field test facilities

H4IRRAD

CNRAD

- no ventilation system- confined target area intensity limitations- high energy muon cone (109 p/pulse at 400 GeV)

- space constraints for placing equipment

- parasitic operation, access only during stops of CNGS- no fast access- no tests of power converters possible

Optimized within the constraints of the respective areas.Nevertheless, a dedicated test facility would be of advantage froman RP point-of-view.

East Area Day – RP Aspects

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Optimization includes

1 February 2012

Dismantling and refurbishment – ALARA(presently under revision)

Optimization is a legal requirement if accumulated individual dose exceeds 100 μSv/year (ALARA) (Safety Code F)

• work coordination• work procedures• handling tools• design • material

Level II+III: Detailed work-and-dose-planning (WDP/DIMR)Level III: ALARA committee Many dismanteling activities most likely

Level II interventions

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81 February 2012

Dismantling and refurbishment – ALARA

Example of a work-and-dose-planning document

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91 February 2012

Dismantling and refurbishment – radioactive material

Source: ORaP, Swiss legislation

Radioactive = specific and total activities exceed LE or dose rate at 10cm distance > 0.1 μSv/h

aiLEii=1

n

> 1Mixture of nuclides: LE values: ingestion of activity LE leads to a dose of 10 μSv

East Area Day – RP Aspects

101 February 2012

Dismantling and refurbishment – radioactive material and waste

• all material taken out from target or beam-line areas has to be considered as radioactive and placed in buffer zones

• classification of material by RP measurement (dose rate, induced activity, contamination)• if radioactive: - any work must be performed in appropriate workshops - equipment of workshop depends of type of work and radiological risks - use of centralized workshops (Bat 867) strongly preferred

• shielding to be re-used must be cleaned and painted by specialized company (removal of rust and corrosion products in order to avoid spread of activated particles)

• foresee storage space for radioactive components and shielding

• radioactive material that cannot be re-used will have to be disposed of as radioactive waste• estimate of the amount of radioactive waste (volume, activity) prior to dismantling• assess the presence of waste that requires special attention (e.g., radioactive waste with chemical risks)• in case container are needed they should be provided by the departments (take into account delay for delivery)

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Dismantling and refurbishment – Example: Q74-02

• Q74-02: first quadrupole magnet in T9 line, replaced in 2007, recently considered for re-installation

• Measurements (Jan 2012):

max. residual dose rate (contact) 650 µSv/h (40cm) 50 µSv/h surface contamination 24.4 Bq/cm2

1 February 2012 East Area Day – RP Aspects

121 February 2012

Design – shielding

Goal: Supervised Radiation Area in East Hall outside of shielding enclosure Non-designated Area outside of East Hall

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131 February 2012

Design – shielding

East Hall

Outside

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141 February 2012

Design – shielding

• shielding must not only satisfy limits but must also be optimized (ALARA) for workplaces around the facility

Safety Code F

• consider incidents/accidents (e.g., accidental beam-losses): stay well below legal limits for such events (6 mSv / 1 mSv inside / outside of hall) • if possible, shielding should be air-tight in order to separate air volumes

• preliminary shielding studies have been performed and are integrated into the present design; more detailed studies are needed, in particular for mazes, accidents and in order to optimize design

East Area Day – RP Aspects

151 February 2012

Design – activation of components

• calculation of residual dose rates for most critical areas (target area, irradiation areas)• estimation of job doses (e.g., for recurrent or major work) and optimization of design

Design goal: < 2mSv/person/intervention

(one week cooling)

Example: LHC collimators

• design optimizations don’t have to be expensive, e.g., connectors, valves easy to reach, cables away from loss points (if possible),…

• some residual dose rate predictions exist (mixed field facility), needed for other areas (e.g., target area)

East Area Day – RP Aspects

161 February 2012

Design – air activation

Goal: < 1 µSv per hour stay in Radiation Areas (< 0.1 CA) monitoring of releases into environment

1 µSv

10 µSv

100 µSv

2×1010 protons/s, 26GeV(generic study)

Dedicated ventilation systems needed fortarget area and irradiation facility

Requirements:

(general requirements on ventilation systems being discussedby Ventilation Working Group)

• no air flow between primary beam areas and occupied areas• closed ventilation during operation (~100% recirculation)• flush with fresh air before access• controlled release point with activity monitoring

Detailed study of air activation still has to be performed.

East Area Day – RP Aspects

171 February 2012

Design – water activation

Goal:

East Area Day – RP Aspects

• avoid unjustified contact of experimenters/workers with activated water• avoid dissemination of activated water

• separate cooling water circuits for primary and secondary beam areas• study to estimate water activation to be performed

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Operation – radiation monitoring

7 induced activity monitors*

Present situation (Arcon)

10 radiation area monitors

1 February 2012 East Area Day – RP Aspects

* One of which used also for the measurement of pulsed radiation

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Operation – radiation monitoring

Presently (Arcon)

Foreseen in consolidation budget

(300kCHF)

Needed(preliminary)

Ventilation monitoring station - 1 2

Induced activity monitors 7 7 7

Radiation area monitors 10 4 10

Alarm units 11 6 15

RP monitoring stations n/a* 2 3

Hand-and-foot monitors - - 2

• additional monitoring budget (150 kCHF) reserved in irradiation facility budget• final monitor numbers and locations to be defined as soon as RP studies for final layout are completed

1 February 2012 East Area Day – RP Aspects

* Old system based on VME chassis which cannot be compared to the new modular monitoring stations

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Operation – buffer zones

1 February 2012 East Area Day – RP Aspects

Two buffer zones for material from target area and irradiation facility:

• similar to those presently being integrated around PS complex• in proximity to access point• 40cm concrete shielding, controlled access• containing shelves, waste bins, PC with ethernet for traceability system

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Summary and conclusions

• The present East Area is not optimized according to modern radiation protection practices. (high losses, tight space, no ventilation, corrosion, single cooling circuit,...) • Thus, a consolidation (especially of the target area) is urgently required and supported by RP, if possible during LS1.

• Preliminary shielding studies have been performed and are integrated into the present design, further and more detailed studies are needed, in particular for mazes, accidents as well as for activation of components, liquids and air.

• The monitoring (RAMSES) budget requirement of 300+150kCHF seems appropriate. The manpower needs have to be revised once a draft schedule is available.

• A dedicated mixed-field facility for testing electronics equipment (replacing H4IRRAD and CNRAD) would be of advantage from an RP point-of-view.

• All work has to be well planned and optimized (ALARA, DIMR level I or II). RP is available for advice.

1 February 2012 East Area Day – RP Aspects