New SPS scraping system: preliminary RP remarks

Helmut VinckeDGS-RP

Contents

• RP considerations for the BA6 scraping operation

• Considerations for the BA1 scraping operation

• Scraping BA6 versus BA1 from the RP point of view

• RP tools to choose “good” materials for designing the scraping systems

• Summary

Prompt dose rate issues in BA6

• No issue for personnel (in contrast to previously planned LSS4 installation) since no adjacent working area is present

• Radiation to equipment issues have to be studied.

Residual dose rate

5

First estimation concerning residual dose rate: Generic studies concerning the SPS beam impact on a 1 m long carbon collimator*

*Estimates are based on the report “CERN-SC-2004-018-RP-TN”:Remnant dose rates in the area of a TCDI collimator after 200 days of normal operation and after an accidental beam loss; Helmut Vincke

Beam operation: 3E16 protons on collimator during 200 days.

5 cooling times1. 1 hour2. 12 hours3. 1 days4. 1 week5. 1 monthBeam

Concrete wall

TCDI (carbon) collimator

Beam line elements

Irradiation situation of this study resembles to a certain extent the unshielded scraping situation in BA6.

Parameters considered:

6

3E16 protons on equipment within 200 days

Cooling time

Dose rate between wall and beam line

Dose rate: maximum

value

1 hour 2400 mSv/h 96 mSv/h12 hours 1800 mSv/h 72 mSv/h1 day 1440 mSv/h 60 mSv/h1 week 840 mSv/h 36 mSv/h1 month 600 mSv/h 18 mSv/h

• The area surrounding the scraper and the following objects in the tunnel will show high radiation levels after scraping operation • Short term irradiations with higher beam loss rate than the average annual beam loss will cause higher short term residual dose rate levels as shown above

Dose rate after 3E16 protons in 200 days + 1 month of cooling

mSv/h

1.2E+055.4E+042.6E+041.2E+045.4E+032.6E+031.2E+035.4E+022.6E+021.2E+025.4E+012.6E+011.2E+015.4E+002.6E+001.2E+005.4E-012.6E-011.2E-015.4E-022.6E-021.2E-02

Results

BA6 radiation survey data comparison: 2012 versus 2004

Beam extraction in 2012: • Annual intensity of < 2E17 protons were extracted in BA6, • low losses due to fast extraction

Beam extraction in 2004: • Annual intensity: 1.3E18 protons on T1 target, • slow extraction in BA6 beam loss level: several %. several 1E16 protons lost

during the extraction operation

Losses in 2004 in BA6 are comparable to losses due to future beam scraping

End of 2004 beam operation to West Area stopped. This resulted in a drop of lost particles in this area reduction of residual dose rate in BA6

Comparison of the situations in BA6 in the years 2012 and 2004

Radiation survey data comparison 2012 versus 2004

ZSMST

MSE

MKE

Conclusions:

• Losses from slow extraction caused high radiation levels in BA6.• 8 years after slow extraction in BA6: maximum radiation levels were strongly reduced.• For unshielded scraping operation in BA6 we have to expect radiation levels similar to

those of 2004. appropriate shielding of scraping system required

Scraping operation in BA1

In case there are significant losses compared to the regular losses on the dump system, the residual dose rate in LSS1 would increase when being compared to residual dose rates after “no scraping operation years” (e.g.: 2010)

Scraping in BA1 (Section 117) started in 2011.

Impact on residual dose rate environment: Is there any significant effect in terms of dose rate compared to the dose rate environment given by the dump operation?

Comparison of residual dose rates seen in 2010, 2011 and 2012 around LSS1

Comparison of dose rates 30 hours after beam operation: “no scraping operation years” (2010) with “scraping operation years” (2011 and 2012).

No strong difference between dose rates after beam operations in 2010 and 2011Only a slight increase in section 117 visible.

Shift of peaks are explained by inaccurate positioning system

17.5 mSv/h

Comparison of dose rates after “no scraping operation years” (2010) with “scraping operation years” (2011 and 2012).

Comparison of 2010, 2011 and 2012 confirms comparison result between 2010 and 2011.Only a slight increase in section 117.

Shift of peaks are explained by inaccurate positioning system

Comparison from the RP point of view: Scraping system in BA1 versus scraping system in BA6

BA1:

Advantage: Scraping operation would not significantly change the radiation levels in BA1 since area is already highly radioactive due to the dump operation.

Disadvantage: Since scrapers are placed in a highly radioactive zone, heavy maintenance work on the scraping system will result in a significant amount of dose to personnel.

BA6:

Advantage: Scraping system in BA6 will be a passive system. Hence, not much of maintenance work is required.

Disadvantage: In case scrapers are not properly shielded the area will become a highly radioactive area (similar to the situation during West Area operation)

Development of scraping system

Choice of material for scraper and its surroundings is very critical for the production of activation. Materials which are less activation prone shall be used for the construction of scraping system.

For the design of components placed in accelerators RP asks equipment groups to use the following tools:

• The RP material catalogue classifying materials in terms of radiological hazardor • the ActiWiz program, allowing to perform radiological classifications for

materials which cannot be found in the catalogue

14

ActiWiz

1.) Select parameters of the material location in the accelerators2.) Define material composition3.) Click “Calculate”

Program to evaluate radiological hazard for arbitrary materials with a few mouse clicks

Output of ActiWiz: Material categorization

15

Radiological hazard assessment of materials allowing to compare their radiological impact

Aluminum 5083 Copper CUZnO5 Steel 316Ti

OperationalWaste

16

Material catalogue based on the ActiWiz hazard assessment of materials

Material catalogue classifying materials in terms of radiological hazard

Classification of most common metallic and construction materials used at CERN

Catalogue provides guidelines for selection of materials to be used in CERN’s accelerator environment

Authors: Robert Froeschl, Stefano Sgobba, Chris Theis, Francesco La Torre, Helmut Vincke and Nick WalterAcknowledgements: J. Gulley, D. Forkel-Wirth, S. Roesler, M. Silari and M. Magistris

Web-based catalogue: ActiWeb

17Information and a download area about ActiWiz, the RP material catalogue and ActiWeb can be found under: http://rpactiweb.cern.ch

Interactive web-based version of catalogue allowing you to compare the radiological

impact of predefined materials

Summary• First residual dose rate estimates of scraping operation in BA6 were carried out.

• A significant increase of the residual dose rate level has to be expected in case an unshielded scraping system is used

• The current system in BA1 did not significantly change the residual dose rate levels in BA1

• For the design of new beam line components, the equipment groups are asked to use ActiWiz or the RP material catalogue to assess the radiological impact of various materials