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== '''1.1''' '''Customer Feedback''' ==
== '''1.1''' '''Customer Feedback''' ==
The CNSC Laboratory solicits [[CNSC Laboratory ISO Accrediation|customer feedback]] on an annual basis as one of the measurements of performance of the Laboratory Management System (LMS) ([Pcdocs://E-DOCS/4412335/R e-Docs-#4412335]) in regards to instrument management and calibration services. Customers can provide feedback to the Laboratory to address any issues which require immediate attention any time as needed, however, the annual survey provides an opportunity for customers to feedback on any aspect of the laboratory’s services including data quality and turnaround times. Any immediate problems as reported by the customers are to be documented and corrected through the non-conformance and corrective action processes following the Laboratory procedure P409 ''Corrective Action and Preventive Action'' in a timely manner by the Management System Officer (MSO).
The CNSC Laboratory solicits customer feedback on an annual basis as one of the measurements of performance of the Laboratory Management System (LMS) ([Pcdocs://E-DOCS/4412335/R e-Docs-#4412335]) in regards to instrument management and calibration services. Customers can provide feedback to the Laboratory to address any issues which require immediate attention any time as needed, however, the annual survey provides an opportunity for customers to feedback on any aspect of the laboratory’s services including data quality and turnaround times. Any immediate problems as reported by the customers are to be documented and corrected through the non-conformance and corrective action processes following the Laboratory procedure P409 ''Corrective Action and Preventive Action'' in a timely manner by the Management System Officer (MSO).
Customer feedback is solicited to conform with the requirements of standards ISO/IEC 17025:2017, “General Requirements for the Competence and Testing of Calibration Laboratories”, and “SCC Requirements and Guidance for the Accreditation of Testing Laboratories – April 2018.”
Customer feedback is solicited to conform with the requirements of standards ISO/IEC 17025:2017, “General Requirements for the Competence and Testing of Calibration Laboratories”, and “SCC Requirements and Guidance for the Accreditation of Testing Laboratories – April 2018.”
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'''A.1. Preamble'''
This appendix presents an overview of variety of contamination monitoring equipment available within the Laboratory for fixed contamination monitoring, and swipe sample analysis for loose contamination monitoring (gross alpha and gross beta) to meet internal and external customer’s technical requirements. This appendix also discusses about the differences in the sensitivity of various models to different radiations and dimensions of the active surfaces of the detector probes in order to select appropriate calibration sources. A brief description of reference transfer equipment is also included in this appendix.
'''A.2. CNSC Laboratory Inventory'''
The CNSC Laboratory calibrates a variety of surface contamination survey meters and field sampling instruments. Survey instruments typically contain one or two detectors of specific types, such as a pancake Geiger-Mueller (GM) tube, a thin end-window GM tube, a thin window scintillation probe with a Bismuth Germanate (BGO) or Sodium Iodide (NaI(Tl)) crystal, or a large-area gas filled or scintillator proportional counter. Field sampling instruments typically contain either a NaI(Tl) or ZnS(Ag) scintillator with a tray designed to accept swipe samples.
A pancake GM tube with a sensitive area typically of 15 cm<sup>2</sup>, is used particularly for surface monitoring for alpha and beta (i.e.: particle) radiation, as well as gamma (photon) radiation. Sensitivity of these probes is particularly low for photon measurements.
A thin end-window GM tube with a sensitive area of approximately 6 cm<sup>2</sup> has approximately the same sensitivity to particle radiation as the pancake probe, but it has a smaller, flat annular shape with a small window area that is utilized with a maximum of gas space. This geometry could effectively increase the sensitivity for photons to some extent, but typical end-window GM tube sensitivity will not be comparable to that of thin-window scintillation probes.
A thin-window scintillation probe exhibits excellent sensitivity for detection of low energy gamma photons, and is commonly used in nuclear medicine departments for detection of medical isotopes such as Tc-99m, Ga-67, Tl-201, In-111 and I-125, in addition to other low energy photon emitters such as Co-57, Cr-51.
A large–area, gas filled proportional detector of typical sensitive area on the order of 150 cm<sup>2</sup> is used for detection of alpha, beta and gamma radioactive contamination on various surfaces, but primarily for scanning large areas of interest. Various fill gasses are used in different models, thereby varying the response to different radiation types. For example, a heavy noble gas such as Xenon is very responsive in detection of photons and high-energy beta particles.
The measurement display of these survey meters can be digital or analog or both, with measurement units typically expressed in counts-per-second (CPS), counts-per-minute (CPM), or in units of surface contamination (Bq/cm<sup>2</sup>). In some cases, external connectors (i.e.: usually BNC/SHV/MHV connectors) are used to connect the detector (listed in Table 1) with the scaler/rate meter as separate modules. In other cases, the probe and the rate meter are packaged as a single, compact unit. Such instruments usually require radiological calibration, and other models require both electronic calibration and radiological calibration. Those survey meters that require electronic validation are calibrated using traceable pulse generators to verify electronic response and sensitivity. Radiological calibration of these instruments requires a variety of alpha, beta and gamma calibration sources of varying areas, as applicable to fit the geometry of the various instrument probe areas and window shapes and sizes.
Each of these portable radiation protection instruments is to be calibrated using calibrated reference sources that are traceable to an accredited National Metrological Institute (NMI). The specific activity of various calibration sources should give rise to two deflection points of 20% and 80% on each analog scale, or on each decade of a digital scale.
The range calibration coefficient, at a given contamination level for a specific isotope, is determined as the ratio of the instrument-corrected reading to the traceable, NMI-certified source (surface) emission rate. The applied surface emission rate is verified locally using a reference transfer measurement standard.
In addition to meeting all other requirements under the standard, the instrument calibration report will include:
* Range calibration coefficient for a given geometry for isotopes of interest
* Minimum Detection Limit (MDL) for isotopes of interest
* Dependency on separation distance between surface and detector
'''A.3. Use of Contamination Field Instruments at CNSC'''
Table 1 lists various surface contamination meters that are currently in use within CNSC divisions at HQ and in regional offices. These instruments facilitate inspectors in the verification of radiological contamination levels on surfaces, whether to conform to regulatory requirements, or to conform to any administrative control levels that a licensee may have defined under the licensee’s radiation safety program. Note that these regulatory requirements are defined in units of Bq/cm<sup>2</sup> for various classes of radionuclides.
'''''Table A.1: Contamination meters currently in use in different divisions within CNSC '''''
{| class="wikitable"
|'''Model '''
|'''Detector'''
|'''Comments'''
|-
|TBM-3S
|GM Pancake probe
|In service
|-
|TBM-6SP / LEG PROBE BG-1(N)
|GM Pancake probe/ BGO LEG probe
|In service
|-
|LB 124B
|Xenon-filled proportional counter
|In service, replaces LB-122
|-
|Automess 6150 AD/AD-17
|End window GM tube to use with Automess 6150AD survey meter
|In service
|-
|Automess 6150 AD/AD-K
|Large area contamination monitoring probe to use with Automess 6150AD
|In service
|-
|HP-260 / HP-360 /ASP-1
|GM Pancake probe
|In use at UMMD
|-
|HP-210 / PRM-6
|Shielded Pancake GM detector
|In use at SORO
|-
|RadEye B20 ER
|GM Pancake probe
|Recently introduced model
|}
Of the several instrument types listed in Table 1, the LB 124B (a large-area proportional counter) and the RadEye B20 ER (a pancake probe) can provide measurements of detected events in units of CPS or in terms of Bq/cm<sup>2</sup>. All other available instruments provide results in units of either CPS or CPM, which can then be converted to the required units of Bq/cm<sup>2</sup> by applying the appropriate efficiency calibration coefficient. CNSC inspectors utilize surface contamination meters for relative measurements in order to compare with established background levels while assuming the reasonable sensitivity of the probe to the isotope of interest as established in the Laboratory environment. If the reading with a contamination meter is two to three times the background value (or greater), then the surface will be closely monitored with a swipe sample that will be measured in a low-background area using a calibrated contamination meter. In this fashion, the inspector has capability to verify whether the contamination is loose (contamination is present on the swipe) or fixed (no contamination present on the swipe). The inspector can then determine what regulatory requirements may apply for the identified level of loose contamination.
Table 2 lists detectors which are used in different models in use at CNSC. It is interesting to note that a large number of models use GM pancake probes which are most sensitive to alpha radiation and beta radiation and significantly low efficiency for gamma sources for all practical purposes.
'''''Table A.2: Radiation sensitivity of contamination meters currently in use in different divisions within CNSC'''''
{| class="wikitable"
|'''Detector'''
|'''Models'''
|'''Radiation Sensitivity'''
|'''Area (cm<sup>2</sup>)'''
|-
|GM Pancake probe
|TBM-3S, Internal probe TBM-6SP, HP-210, HP-260, HP-360, B-20 ER
|a, b, g sources calibration, extremely low g sensitivity
|15
|-
|End window GM tube
|Automess 6150 AD / AD-17
|a, b, g sources calibration, extremely low g sensitivity
|7
|-
|External BGO LEG probe
|TBM-6SP
|high g sensitivity
|5
|-
|Xenon filled proportional counter
|LB 124B
|b, g sources calibration
|150
|-
|ZnS(Ag) scintillation counter
|LB 124 SCINT
RadEye HEC
|a, b sources calibration
|150
|-
|Large area proportional detector
|Automess 6150 AD / AD-K
|a, b, g sources calibration, extremely low g sensitivity
|170
|}
'''A.4. Reference transfer equipment'''
Reference transfer equipment which CNSC uses for periodic verification of a and b emission rates and gamma activity measurements of traceable calibration sources includes a large area planar NaI(Tl) planar detector, small diameter dual phosphor ZnS(Ag), a large area ZnS(Ag) scintillator detector for alpha and beta counting and a large area sealed gas proportional counter. Appendix on measurement traceability and secondary measurement standards provides details of the program for maintaining traceability of reference equipment.
