# Gauges and well logging

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Gauges and well logging
Potential exposure and radiation protection programme Day 6 –Lecture 5

Objective To discuss about potential for radiation exposure associated with nuclear gauges and well logging. To discuss aim, structure and requirement of the Radiation Protection Programme (RPP) as applied to working with gauges and well logging Lecture notes: Instructions for the lecturer/trainer

Contents Pathways of Exposure Radiation Protection Programme (RPP)
Routine Exposure Gamma Gauges Beta Gauges Neutron Gauges Radiation Protection Programme (RPP) Structure of RPP Classification of Areas Emergency Plans Lecture notes: Instructions for the lecturer/trainer

Pathways of exposure Internal Exposure External Exposure Ingestion
Absorption Inhalation

Nuclear gauges and well logging Routine exposure
External doses possible, although unlikely to be significant Internal doses unlikely, due to sealed source construction gamma and neutron sources special form Lecture notes: Instructions for the lecturer/trainer

Gamma gauges Typical external dose rate
111 GBq Cs-137 Contact dose rate up to 75 Sv/h Dose rate at 1m 1 Sv/h Describe the scenario to the group: Density gauge on a pipe - dose rate at the detector is 2 Sv/h. Company fits a new gauge on an identical pipe on an identical plant. - Source in the new gauge is 40 GBq Cs-137, - What dose rate would you expect at the detector? - A: expect 8 Sv/h, - This would be have to be checked with a radiation monitor. Delegates to attempt Question 1 (i to v) Output data for Am-241 : 5.4 mSv/h at 1m per 400 GBq

Gamma gauges - routine exposure
Assume, for example, that employee spends 6 hours per year with hands in contact with gauge = 0.45 mSv annual extremity dose Assume, for example, that employee spends 50 hours per year working 1 metre away from gauge = 0.05 mSv annual effective dose Lecture notes: Instructions for the lecturer/trainer

Gamma gauges - routine exposure
In reality, doses may be even lower than those indicated on the previous slide Consider that most process control gauges (level gauges, density gauges etc) are sited in areas that are not usually occupied Lecture notes: Instructions for the lecturer/trainer

Beta gauges Typical external dose rate
3.7 GBq Pm-147 Shutter open (beta) Dose rates will be higher for larger sources Between guide plates up to 10 Sv/h Dose rate at 0.5m <1 Sv/h Describe the scenario to the group: Density gauge on a pipe - dose rate at the detector is 2 Sv/h. Company fits a new gauge on an identical pipe on an identical plant. - Source in the new gauge is 40 GBq Cs-137, - What dose rate would you expect at the detector? - A: expect 8 Sv/h, - This would be have to be checked with a radiation monitor. Delegates to attempt Question 1 (i to v) Output data for Am-241 : 5.4 mSv/h at 1m per 400 GBq

Beta gauges Typical external dose rate (worst case)
46 GBq Kr-85 Shutter closed (Bremsstrahlung) Contact dose rate up to 2 mSv/h Dose rate at 1m up to 10 Sv/h Describe the scenario to the group: Density gauge on a pipe - dose rate at the detector is 2 Sv/h. Company fits a new gauge on an identical pipe on an identical plant. - Source in the new gauge is 40 GBq Cs-137, - What dose rate would you expect at the detector? - A: expect 8 Sv/h, - This would be have to be checked with a radiation monitor. Delegates to attempt Question 1 (i to v) Output data for Am-241 : 5.4 mSv/h at 1m per 400 GBq

Beta gauges - routine exposure
Assume, for example, that employee spends 6 hours per year cleaning gauge head (shutter closed), with hands in contact with gauge = 12 mSv annual extremity dose Assume, for example, that employee spends 50 hours per year working 1 metre away from gauge (shutter closed) = 0.5 mSv annual effective dose Lecture notes: Instructions for the lecturer/trainer

Neutron gauges Typical external dose rate
1.85 GBq Am-241/Be neutron and gamma dose rate Contact dose rate up to 30 Sv/h (source retracted) Operator position during use up to 15 Sv/h Describe the scenario to the group: Density gauge on a pipe - dose rate at the detector is 2 Sv/h. Company fits a new gauge on an identical pipe on an identical plant. - Source in the new gauge is 40 GBq Cs-137, - What dose rate would you expect at the detector? - A: expect 8 Sv/h, - This would be have to be checked with a radiation monitor. Delegates to attempt Question 1 (i to v) Output data for Am-241 : 5.4 mSv/h at 1m per 400 GBq

Neutron gauges - routine exposure
Assume, for example, that employee spends 50 hours per year with hands in contact with gauge (source retracted) = 1.5 mSv annual extremity dose Assume, for example, that employee spends 250 hours per year using the gauge = 3.75 mSv annual effective dose Lecture notes: Instructions for the lecturer/trainer

Well logging Typical external dose rate
37 GBq Am-241/Be neutron and gamma dose rate 10 cm from tool up to 2.1 mSv/h Surface of source transport container up to 150 Sv/h Describe the scenario to the group: Density gauge on a pipe - dose rate at the detector is 2 Sv/h. Company fits a new gauge on an identical pipe on an identical plant. - Source in the new gauge is 40 GBq Cs-137, - What dose rate would you expect at the detector? - A: expect 8 Sv/h, - This would be have to be checked with a radiation monitor. Delegates to attempt Question 1 (i to v) Output data for Am-241 : 5.4 mSv/h at 1m per 400 GBq

Well logging - routine exposure
Time with source exposed likely to be only a few seconds per operation. Assume, for example, that employee spends 8 hours per year with hands at 10 cm from exposed source = 16.8 mSv annual extremity dose Assume, for example, that employee spends 50 hours per year close to transport container = 7.5 mSv annual effective dose Lecture notes: Instructions for the lecturer/trainer

What is an RPP? Structure of the RPP Assignment of responsibilities Role of the Qualified Expert Classification of areas Local rules and supervision (RPO) Radiation monitoring Record Keeping Emergency plans Audit and review Lecture notes: Instructions for the lecturer/trainer

What is an RPP? A programme that reflects the application of management responsibility for radiation protection and safety Key factor for the development of a safety culture Effectiveness depends on management commitment Essential to undertake a prior radiological evaluation and safety assessment before developing the RPP

Structure of the RPP assignment of responsibilities
classification of areas local rules supervision arrangements, including RPO appointment arrangements for area monitoring arrangements for individual monitoring

Qualified Experts to provide advice on contents of RPP
Structure of the RPP record keeping education, information and training emergency plans health Surveillance quality Assurance reviewing/ auditing the RRP Qualified Experts to provide advice on contents of RPP

Management Obtain necessary authorizations Provide necessary facilities, personnel, equipment and training establish and maintain a “safety first” culture Radiation Protection Officer (RPO) Implement the RPP Implement the local rules Provide information and training

Operators and Workers Become familiar with equipment, safety and warning systems Become familiar with any local rules and adhere to them Notify the RPO of any unusual occurrences Use all safety equipment provided Clients Provide a safe working environment and adequate time for the job

Role of the Qualified Expert
Provides advice on observance of the BSS Registrants/licensees to identify suitable Qualified Expert(s) Registrants/licensees to inform the Regulatory Authority of their arrangement with Qualified Expert

Classification of Areas
A controlled area is an area where procedural controls are required in order to restrict radiation exposures A supervised area is one that does not require classification as a controlled area, but where exposure conditions should be kept under review. Primary mechanism for restricting radiation doses is the control of access to areas where there is a potential for significant exposure. IAEA BSS defines two types of radiation areas : controlled and supervised areas. Need to classify determined by means of a prior safety assessment. Controlled areas : where specific protective measures/safety provisions required for controlling normal exposures and/or prevention or limiting the extent od any potential exposures

Controlled areas Examples of controlled areas associated with nuclear gauges are: around portable gauges (eg soil moisture probes and nuclear density gauges) during use and transport inside portable source stores around fixed gauges during some maintenance operations inside vessels on which level gauges are fitted Primary mechanism for restricting radiation doses is the control of access to areas where there is a potential for significant exposure. IAEA BSS defines two types of radiation areas : controlled and supervised areas. Need to classify determined by means of a prior safety assessment. Controlled areas : where specific protective measures/safety provisions required for controlling normal exposures and/or prevention or limiting the extent od any potential exposures

Controlled areas Examples of controlled areas associated with well logging are: around the borehole head during use inside the source store around the logging tool during source loading operations around the source containers during transport of equipment Primary mechanism for restricting radiation doses is the control of access to areas where there is a potential for significant exposure. IAEA BSS defines two types of radiation areas : controlled and supervised areas. Need to classify determined by means of a prior safety assessment. Controlled areas : where specific protective measures/safety provisions required for controlling normal exposures and/or prevention or limiting the extent od any potential exposures

Controlled Area Requirements
Demarcation Restriction of access Signs Monitoring Local rules Controlled areas must be physically delineated - including physica boundaries/signs/notices at all access points clearly stating that the area is controlled For enclosures the walls, doors and roof will form the boundary. Site radiography - temporary barriers to be erected to form the boundary and natural boundaries may be used (walls/fences). The area may extend in the vertical plane!

Local Rules Work in a controlled area must be carried out in accordance with written local rules, Local rules should include: name of person(s) responsible for supervising the work description of controlled and supervised areas general radiation safety measures dose investigation levels emergency plans Local rules ; describe organisational structure, procedures to be followed in the controlled area.

Supervised areas Examples of supervised areas associated with nuclear gauges are: around fixed gauges (gamma and beta) Primary mechanism for restricting radiation doses is the control of access to areas where there is a potential for significant exposure. IAEA BSS defines two types of radiation areas : controlled and supervised areas. Need to classify determined by means of a prior safety assessment. Controlled areas : where specific protective measures/safety provisions required for controlling normal exposures and/or prevention or limiting the extent od any potential exposures

Supervised Area Requirements
Delineation Signs Monitoring Controlled areas must be physically delineated - including physica boundaries/signs/notices at all access points clearly stating that the area is controlled For enclosures the walls, doors and roof will form the boundary. Site radiography - temporary barriers to be erected to form the boundary and natural boundaries may be used (walls/fences). The area may extend in the vertical plane!

Supervision Radiation Protection Officer (RPO) supervises the work
Ensures any local rules are followed Should be enough RPOs to ensure adequate supervision at all times Supervision : Regulatory Authorities often require that the employer appoints one (or more) RPOs to supervisie work (to confirm that local rules are complied with etc) RPOs Primary role : liase with radiographers and management be able to recognise need to seek further advise supervise radiation protection aspects of work RPOs should be someone : in line management position and involved with the work 9on a day to day basis) be familiar with the work who has received sufficient raining (radiation protection and safety)

Area Monitoring Monitoring of radiation dose rate required for all controlled and supervised areas Records of monitoring should be kept Purpose of monitoring is to ensure that radiation levels remain within expected limits Good idea to set action levels above which steps are taken to reduce the radiation dose rate Local rules : set of instructions that specify the manner in which work should be carried out to ensure adequate levels of protection & safety for worker/others reflect practical requirements of national legislation employer is responsible for issue

Individual monitoring
Required for all those who access controlled areas May require assessment of gamma and neutron dose Records of individual monitoring must be kept Purpose of monitoring is to demonstrate that exposures are adequately controlled Investigation level must be set Local rules : set of instructions that specify the manner in which work should be carried out to ensure adequate levels of protection & safety for worker/others reflect practical requirements of national legislation employer is responsible for issue

Individual dose meters
TLD - gamma, X, neutron and beta Film - gamma, X and beta OSL - gamma, X, neutron and beta PADC - neutron Consult Qualified Expert regarding type of dosemeter and wear period

Record keeping Source accountancy Dose rate monitoring results
updated frequently for portable gauges Dose rate monitoring results Checks on safety systems and warning devices Equipment maintenance Source leak test certificates Radiation monitoring instrument test certificate Local rules : set of instructions that specify the manner in which work should be carried out to ensure adequate levels of protection & safety for worker/others reflect practical requirements of national legislation employer is responsible for issue

Education, information and training
Training of RPO Radiation awareness training for other staff nature of the hazard extent of any controlled or supervised areas requirements of local rules emergency plans Local rules : set of instructions that specify the manner in which work should be carried out to ensure adequate levels of protection & safety for worker/others reflect practical requirements of national legislation employer is responsible for issue

Emergency plans Consider reasonably foreseeable accidents
Provide instruction to limit the consequences Rehearse periodically Local rules : set of instructions that specify the manner in which work should be carried out to ensure adequate levels of protection & safety for worker/others reflect practical requirements of national legislation employer is responsible for issue

Protection of the public
Emergency plans to consider possible accidents involving the public, eg loss or theft of a source necessary precautions actions to limit consequences liaison with Emergency Services

Audits and Reviews Aim : To enhance the effectiveness and efficiency of the RPP Objectives :To identify and correct problems that may prevent the achievement of the programme's objectives Conducted by competent persons Local rules : set of instructions that specify the manner in which work should be carried out to ensure adequate levels of protection & safety for worker/others reflect practical requirements of national legislation employer is responsible for issue

Summary Potential for radiation exposure associated with nuclear gauges and well logging routine use accidents Aim, structure and Requirement of the RPP as applied to working with gauges and well logging Any questions or comments? Lecture notes: Instructions for the lecturer/trainer