The quantity of the visible light emitted (TL output) is found to be proportional to the energy absorbed by the TL material.

The TLD personnel monitoring system essentially consists of two major parts: TLD badge and the TLD badge reader.

The TLD Badge comprises of a plastic cassette containing Two or Three Teflon TLD discs (13.3mm and 0.8mm thick) that are mechanically push fitted on to circular holes (12.0mm) punched in an aluminium card. The Badge has 2 or 3 row punched ID code as per user requirement.

The TLD Badge Reader is designed to measure X, Gamma and Beta radiation dose. The metal filter combination (1mm Al + 0.9mm Cu) is provided to reduce the photon energy dependence of the TL discs. The TL badge reader is calibrated such that the TL output of the disc under the metallic filter reads directly the gamma radiation dose.

Features

• All DC motors are replaced by low power & low noise stepper motors for precise motion.
• Proven Nichrome Heater assembly, is used in the design.
• Ni63 based light source card is used for PMT gain stability check as & when required.
• Digital Flow rate measurement instead of rotameter based design to ensure flow rate is within limits during entire readoutcycle. This prevents readout when gas flow is beyond limits
• Improved heat dissipation to prevent temperature rise within the PMT assembly resulting in better stability of readings.
• SMPS based power supplies for operating over wide voltage ranges.
• Mother board based design for easy maintenance of electronic sub-assemblies.
• Uses compact imported HV module for high stability and low ripple & drift.
• Automatic magazine home recognition & positioning.
• Reads 2 disc & 3 disc TLD cards with 2D bar code as per Nucleonix design.

A. HARDWARE SPECIFICATIONS

Dosimeter :	Three-element BARC CaSO4 (Dy) PTFE disc dosimeter badge with personnel ID marked on the TLD card.
Light Measurement System :	Photo-multiplier tube (R6095 or its equivalent) bialkali Light measuring system (LMS).
Dark current :	Dark current is 1µSv (CaSO4) equivalent with software-based sampling & subtraction.
Heater Element :	Nichrome wire heater assembly.
Heating Method :	Once temperature reads 280oC TL disc of the TLD cards are positioned in front of the heater for readout and acquisition cycle goes ON for 30 sec for each disc.
Nitrogen flow rate measurement :	Digital flow rate meter
Heating Cycle :	The temperature is raised to 280°C in 8 sec and clamped at 280°C
Dose Range :	Reader is capable of reading badges from 50 µSv to 2.0Sv automatically and the dose response is linear over the entire range.50µSv – 1.0Sv (Gamma) and 100µSv – 10Sv (Beta).
Dose Threshold :	<50 µSv.
Readout time :	100 sec. per badge.
Residual Signal :	8 to 12% of initial TL in the linear dose range specified
Light source :	LED light source is provided for PMT check & gain adjust
Flow Rate Measurement :	A digital flow measurement system is provided for flow rate measurement & failure check.
Facilities Available :	Entry of personnel details for badges, editing of calibration factor etc. Storage of dose and glow curve data of badges in database. Stepper motor based drive assembly is provided for magazine & TLD card transport in a magazine. Digital linear actuators are used for TLD card raise & shutter control.
Software :	Win 7 compatible software developed on .net platform for storage of readings in a database and display of glow curves, computations of dose & generation of dose reports.
Temperature Monitoring :	Chromel Alumel thermocouple in hot gas stream. External temperature monitoring output at the back panel.
Range Selection :	Automatic from 9.999mSv to 5.000Sv
Calibration :	Coarse adjustment by varying the EHT through a potentiometer in the EHT circuit; fine through software.
Safeguards :	Heater/Gas flow failure: The heater and gas flow are checked for failure in every dosimeter readout cycle. In the event of failure of heater or gas flow the readout is terminated and a message indicating heater / gas flow failure is flashed on the PC monitor. Mechanical Failure : Any mechanical failure during readout cycle is sensed by the programme and the cycle is terminated with an option for the user to restart the cycle. EHT & input circuit (I-F converter) are also sensed and reading cycle is terminated in case of failure.
Nominal Power Supply :	Power supply : 230V, 50Hz : +/-10% Power requirements: 500 VA (max including PC).
PC Requirements:	Suitable latest PC configuration with win 7 Operating system or as requested.
Applications:	Personnel Monitoring of radiation workers in Nuclear power stations, Isotope laboratories, Industrial radiography installations, diagnostic & therapeutic radiology centres, etc.

Personnel ID :

Using optical sensing arrangement, punched code of the TLD card is readout automatically before acquisition.

Additional Accessories / Items Required for personnel monitoring TLD Lab with punched code personnel ID

(i) Three element (BARC Developed) CaSO4 (Dy) PTFE disc dosimeter badges

(ii) Cassette holder

(iii) Annealing oven

(iv) Nitrogen cylinder / Generator with regulator

(v) Radioactive source exposure device for TLD cards calibration

Note: Manufactured by NUCLEONIX SYSTEMS based on Technology from Bhabha Atomic Research Center, Mumbai.

B. SOFTWARE FOR TLD BADGE READER

The software for TL Badge reader serves as comprehensive ‘TL Dose records management software’. It is user-friendly, reliable and feature rich. It has powerful fault diagnostics reporting capabilities.

Key features of Software:

• Provides Commands for complete fault diagnostics of the Reader that includes checking of Light Source, Dark Current, Heater, Gas flow, EHT, Mechanical movements.
• Provides screen to enter Institution, Personnel and Card details prior to acquisition.
• Acquisition of up to 50 cards can be done in one go.

• Acquisition can be paused & resumed without any loss of data.
• Fault checks are performed during acquisition and reported to user.
• Calibration factors for Reader and D1, D2, D3 positions can be set.
• Dose calculator is provided for calculation of Dose by manually entering Integral TL values for D1, D2, D3 positions.
• Glow curve data is stored in Text file and can be optionally exported to Excel.
• Glow curve data can be viewed at a later data individually for each card.
• Dose values for each card, Personnel numbers are written to a batch file.
• Dose information can be optionally written to Nucleonix Dose Records management database and User wise Cumulative Dose reports can be generated.

Specifications

Working Chamber size :	14” x 14” x 14” (Appox) ; Litres :43.
No. of trays :	Two
Heaters:	80/200 Nichrome elements.
Working Temperature :	From ambient to 350oC/400oC.
Temperture Accuracy :	+ / -1 degree , in bare oven.
Temperture Indication & Control :	Tempreture controlled by PID type digital controller cum indicator with safety alarm.
Digital timer :	Digital timer of (0-99) Hrs can be set.
Air circulation System :	For maximum uniformity of temperature inside the working chamber ,air circulating system is provided by means of a meter driven fan
Heaters :	Heaters are made out of best quality Nichrome Wire insulated with refractory runners and enclosed in stainless sheet and fitted to the sides of the Oven.

Cinstruction of Oven Body:

Interior :	Polised stainless steel 304/ Anodizwd Aluminum / SS.316 (GMP Model).
Exterior :	Heavy gauge Mild steel / SS304 (GMP model).
Chamber :	Double Walled.
Ventillation :	Air Ventilators are provided near the top of the sides for removing hot gases and fumes.
Insulation:	75mm thick Mineralwool.
Shelves :	sturedy Elegant –fabricated precisely to give minimum resistancs to air circulation.
Finish :	Finished with attractive and durable powder coated in pleasant shade.
Door:	an insulated hinged side swinging type double walled door with asbestos gasket , ball catch lock and handle provided for easy and effortless closing & opening of door.
Insulation:	High grade ceramic fibre blanket insulation is provided on all the six sides of the Oven Power Rating:2.5 K.W.
Input Supply :	Single phase AC, 230 Volts.