ALARA Experience and Lessons Learnt Heinz Vincke DGSRP

ALARA Experience and Lessons Learnt Heinz Vincke DGS/RP, chairman of the Radiation Safety Officer Committee (RSOC) IEFC workshop 2011, 21 - 24 March 1

Outline • • • General principles of Radiation Protection Implementation of ALARA at CERN A job and dose planning tool Lessons Learnt New concepts, guidelines, tools… o Radiation Safety Support Officer (RSSO) o Design guidelines o Project: Radiological guidelines for materials IEFC workshop 2011, 21 - 24 March 2

General Principles of Radiation Protection 1) Justification any exposure of persons to ionizing radiation has to be justified 2) Limitation the personal doses have to be kept below the legal limits 3) Optimization the personal doses and collective doses have to be kept as low as reasonable achievable (ALARA) IEFC workshop 2011, 21 - 24 March 3

Risk acceptability ALARA: …. . As Low As Reasonable Achievable, taking into account economical and social factors … “the benefit has to be larger than the detriment it causes” IEFC workshop 2011, 21 - 24 March 4

Implementation of ALARA at CERN Already since December 2006: • systematic, formalized approach • since 2009 applied to ALL CERN radiation areas With the goal to optimize work coordination, work procedures, handling tools, and even the design of entire facilities. Consequently, a close(r) collaboration between RP and many departments in CERN is required. All work in radiation areas has to be optimised • • Supervised Radiation Area: general optimisation by shielding, optimised installation of workplaces… Controlled Radiation Areas: All work must be planned and optimised including an estimate of the collective dose and of the individual effective doses to the workers participating in the completion of the task (Dossier D'Intervention en Milieu Radioactif - DIMR). most of the ALARA elements were already used all over CERN in the past. IEFC workshop 2011, 21 - 24 March 5

CERN’s Approach to ALARA Visite de controle, 28 June 2010: IEFC workshop 2011, 21 - 24 March 6

ALARA at CERN – 3 levels ALARA procedures – 3 levels: o If the rad. risk is low <> very light procedure • DIMR Level I o If it is medium <> an optimization effort is required • DIMR Level II o If it is high <> an optimization effort is required, the procedure will be submitted to and presented at the ALARA committee • DIMR Level III For details see EDMS No: 810176 IEFC workshop 2011, 21 - 24 March DIMR: Dossier d'Intervention en Milieu Radioactif 7

ALARA committee � 9 ALARA committee meetings were held since 2007 �Conclusions and recommendations ◦ Many jobs are already optimized thanks to �experience �good co-ordination of the work by machine superintendents, project leaders, engineers, RSOs etc. ◦ Improvements endorsed �Improved design �Optimized handling tools �Remote visual inspection devices �Choice of material �Prolongation of shut-down IEFC workshop 2011, 21 - 24 March ALARA committee (7 members): • Chef d’installation (Chairman) • Scientifique secretary • 2 Representatives of the owner equipment group • 2 Members of RP • 1 External person, e. g. RSO of another department 8

Planning tool • Markus Widorski’s tool • Traceability Main goal of the process: dose optimization Future goal: approval process done via EDH IEFC workshop 2011, 21 - 24 March 9

An example … exchange of electrostatic septa in the PS IEFC workshop 2011, 21 - 24 March 10

Radiological Work Permit IEFC workshop 2011, 21 - 24 March 11

Lessons learnt IEFC workshop 2011, 21 - 24 March 12

ALARA III for Recurrent Jobs was not defined After four years of CERN’s ALARA approach: some recurrent maintenance or repair jobs had been already assessed by a pervious ALARA committee. Proposal: waiving of ALARA committee possible - provided the following procedure is respected: • RSO(s) in charge will arrange an ad-hoc meeting with stakeholders concerned (RP, equipment group(s)) to assess “similarity” with the already seen job – with respect to activity, risk and doses; • RSO in charge drafts a memo to the head of the RP group expressing the joint view of RSOs and RP representatives • RP group leader will conclude and send a recommendation to the Chef d’installation for his official approval (by mail or memo) • Equipment group must incorporate modifications (if any) and provide nevertheless a “retour d’experiencs” report in EDMS • RSO(s) in charge and RP will closely follow up the job and report back to the Chef d’installation IEFC workshop 2011, 21 - 24 March 13

Revision of ALARA Procedures is required • Include the conditions and the procedure to waive an ALARA 3 committee • Enforce the documentation for “retour d’experience” • Reflection on ALARA criteria by RP, RSOs and representative equipment owners (e. g. on dose rate criteria and contamination criteria, introduce criteria for the radiological risk in case of accident) o Partially done already, for example: “Description des actions a mettre en place suite a la chute d'une electrode d'extraction ”, EDMS 1113176 IEFC workshop 2011, 21 - 24 March 14

Time Constraints for Job and Dose Planning • Good job and dose planning needs time to o coordinate all stake holders (RSO, RP, PCR of companies, equipment group) o collect the data (job details, dose rate maps, FLUKA calculations, etc. ) o allow multi-criterial analysis -> timely planning is very important, especially for shutdown work, first assessment of ALARA level 3 -4 months before shut-down starts o in close collaborations with super-intendents, beam line physicists, RSOs etc. o of particular importance for long shut-downs IEFC workshop 2011, 21 - 24 March 15

… and some more o Stop the work in case something goes wrong or in case of unexpected high dose levels. o Don’t try to fix problems which are discovered ‘on the spot’ right away. o Number of persons should be limited. ‘Observation’ or ‘Supervision’ only if really necessary. o Frequent meetings between the RSOs in the framework of the Radiation Safety Officer Committee (RSOC) meeting are very useful. ‘RP- entrance door’ into the departments. o Sufficient manpower for preparing work procedures or ‘retour d’experience’ is essential … good examples ISOLDE, Hi. Rad. Mat. IEFC workshop 2011, 21 - 24 March 16

Example There are many good examples…. Some of them are presented in tomorrows session IEFC workshop 2011, 21 - 24 March 17

CERN…the results Distribution of personal annual dose equivalent from 2005 on in intervals of increasing personal dose. The majority of monitored persons did not receive any personal dose. In 2009 only 54 persons exceeded an annual dose of 1 m. Sv. IEFC workshop 2011, 21 - 24 March 18

New guidelines, new concept… IEFC workshop 2011, 21 - 24 March 19

Radiation Safety Support Officer IEFC workshop 2011, 21 - 24 March • The position of an RSSO is identical to that of a Safety Linkman in safety code A 9. • The RSSO assists the group leader in executing his safety duties and works in close collaboration with the departmental Safety Officers and the experts in HSE Unit • The specific tasks of an RSSO will depend on the activities, areas and installations for which his group has the responsibility and on the radiological risks that are associated with them. Just an example: writing work procedures for maintenance • The RSSO gets the same training as the Radiation Protection Expert (RPE) of the LHC experiments. • The RSSO will receive additional specialized training on radiation safety matters. 20

ALARA design guidelines This document proposes a formalized approach to nuclear engineering guidance in the development of accelerators' components. It sets up a framework of decision criteria and guidelines in the form of a consistent collection of proven best design practices drawn up by CERN specialists. Document written by Luca Bruno IEFC workshop 2011, 21 - 24 March 21

PROJECT - RADIOLOGICAL GUIDELINES FOR MATERIALS TO BE USED IN CERN’S ACCELERATOR ENVIRONMENT What is the benefit & who benefits? What who Operational benefit Safety benefit • Possibly faster access • Lower dose rates • Less restrictions for manipulation & access End of life-cycle benefit • Smaller volume of radioactive waste • Lower financial burden All of us benefit, but it will require your help All your Project scope defined by memorandum EDMS N° 1097618 Project Leader: Helmut Vincke IEFC workshop 2011, 21 - 24 March 22

Strategy of the project 1. Categorization of radiation environment in terms of radiological hazard definition 2. Development of tool (Acti. Wiz) allowing for a fast radiological classification of materials located in various accelerator environments 3. Research on material data used in CERN’s accelerators requires your input! 4. Producing a material catalogue which provides: • Ranking of relevant elements in terms of radiological hazard • Ranking of materials used at CERN (can only as precise as the input information) Beyond the scope of the project: Possible release of Acti. Wiz to “clients” (e. g. design office, beamline physicists etc. ) IEFC workshop 2011, 21 - 24 March 23

Categorization of the radiation environment FLUKA calculation of 35 «typical» hadronic particle spectra (p, n, p+, p- - close to beamline, wall, shielding etc. ) LHC SPS Booster PS Radiological hazard assessment clearance and dose rate for all possible materials IEFC workshop 2011, 21 - 24 March 24

Radiological assessment 35 spectra * 4 irradiation periods * 6 cooling times FLUKA isotope calculations for 69 elements 2400 single Monte Carlo simulations 230. 000 hazard factors Acti. Wiz – software to evaluate hazards for arbitrary materials IEFC workshop 2011, 21 - 24 March 25

Information required from the equipment groups • • • In order to produce a catalogue, which quantifies materials in terms of their radiological hazard information about the chemical material composition is required. The accuracy of the hazard quantification depends on the accuracy of the chemical composition provided to RP. Trace elements can have a strong impact on the radiological hazard. For the catalogue only metals (e. g. aluminum, iron, etc. ), metal compounds and metallic alloys like steel, construction materials like concrete and some few organic compounds (kapton, etc. ) will be treated. Example of what material information provided to RP should look like: Material name Composition in wt-% AK Steel 316 Austenitic Stainless Carbon, C Chromium, Cr steel IEFC workshop 2011, 21 - 24 March Iron, Fe Manganese, Mn Molybdenum, Mo Nickel, Ni Nitrogen, N Phosphorous, P Silicon, Si Sulfur, S <= 0. 080 % 16. 0 - 18. 0 % 61. 995 - 72. 0 % <= 2. 0 % 2. 0 - 3. 0 % 10. 0 - 14. 0 % <= 0. 010 % <= 0. 045 % <= 0. 75 % <= 0. 030 % 26

Conclusion • ALARA is implemented well at CERN; close(r) collaboration between equipment groups, RSOs and RP is necessary • Job preparation and dose optimization takes time; timely planning is very important. • Writing or updating procedure, preparing job and dose planning documents, retour d’experience, etc. is a key element to improve ALARA… sufficient manpower is essential. RSSO concept will help in this respect. • Revision of ALARA procedures is needed. • A job and dose planning tool is available. • New tools and guidelines will be available soon… o Design guidelines & material guidelines IEFC workshop 2011, 21 - 24 March 27

Special thanks to Luca Bruno, Doris Forkel-Wirth, Stefan Roesler, Chris Theis and Helmut Vincke and to all RSOs for providing input/material. END IEFC workshop 2011, 21 - 24 March 28