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SHORT COMMUNICATION
Year : 2012  |  Volume : 35  |  Issue : 1  |  Page : 52-54  

Bulk laundry monitoring system


1 Radiation Safety System Division, Bhabha Atomic Research Centre, Trombay, Mumbai, Maharashtra, India
2 Waste Management Division, Bhabha Atomic Research Centre, Trombay, Mumbai, Maharashtra, India

Date of Web Publication6-May-2013

Correspondence Address:
Vaishali M Thakur
RSSD, Modular Lab., BARC, Trombay, Mumbai-400085
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0972-0464.111410

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  Abstract 

Protective wear (like boiler suits, hand gloves etc.) is necessary while handling radioactive material in plants/laboratories. During the course of work, it is quite possible that protective wear may get contaminated. These protective wear are packed in laundry bags and send to Decontamination Centre (DC) for washing. There is a need for monitoring the laundry bags at the time of receipt, as well as before dispatch to respective locations to comply with AERB guidelines. To avoid cross contamination during wash cycle, contaminated bags (>0.5 mR/h on surface) need to be segregated. Present paper describes the development of such system for monitoring surface dose rate on bags at the time of receipt.

Keywords: Dose rate, geiger mueller detectors, laundry monitor


How to cite this article:
Thakur VM, Jain A, Verma A, Rande N R, Anilkumar S, Babu D, Sharma D N. Bulk laundry monitoring system. Radiat Prot Environ 2012;35:52-4

How to cite this URL:
Thakur VM, Jain A, Verma A, Rande N R, Anilkumar S, Babu D, Sharma D N. Bulk laundry monitoring system. Radiat Prot Environ [serial online] 2012 [cited 2021 Apr 13];35:52-4. Available from: https://www.rpe.org.in/text.asp?2012/35/1/52/111410


  Introduction Top


Protective wears (such as boiler suits, hand gloves, etc.) are necessary while handling radioactive material in plants/laboratories. During the course of work, it is quite possible that protective wear may get contaminated. These protective wears are packed in laundry bags and send to Decontamination Centre for washing. There is a need for monitoring the laundry bags [1] at the time of receipt, as well as before dispatch to respective locations to comply with Atomic Energy Regulatory Board (AERB) guidelines. To avoid cross-contamination during wash cycle, contaminated bags (>5 μSv/h on surface) need to be segregated. This paper describes the development of such system for monitoring surface dose rate on bags at the time of receipt.


  System Description Top


Present system consists of (i) Monitoring unit, (ii) Microcontroller processing unit (MPU), and (iii) Data logger. Monitoring unit consists of six Geiger Mueller (GM) detectors (LND 719) arranged inside three poles separated by 120° apart along the curved surface of cylindrical plastic drum of 65 cm diameter and 75 cm height as shown in [Figure 1]. These detectors were covered with lead shield (~8 mm thick) from three sides to reduce the background. Plastic drum is mounted over a weighing platform which is used to measure the weight of laundry bags. Weight information will be utilized for gamma attenuation correction. Each bag is attached with Radio-Frequency Identification (RFID) tag to monitor its details such as bag origin, monitoring operator details, chemicals required for decontamination, radiological status, etc., These data will be stored in data logger for further analysis. MPU is developed around Philips 80C552 microcontroller embedded with the user friendly software. This unit is interfaced with 8-counter card, liquid crystal display, and RS-485 communication link as shown in [Figure 2]. This MPU receives RFID tag information, weight of bag (in kg) from monitoring unit through MODBUS protocol. The embedded software is developed in Keil environment. The radiological status of bag along with weight and RFID tag number are stored in MPU unit memory as well as transfer to remote PC for data storage and further analysis.
Figure 1: Monitoring and tracking station

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Figure 2: Schematic sketch of bulk laundry monitor

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  System Operation Top


On switching system power ON, micro-controller will reset all counters, checks the system functioning and loads the preset/default parameters. Then system acquires background data for a period of 30 min to make necessary background subtraction during measure cycle. After reading RFID tag attached to laundry bag, bag will be kept inside plastic drum for 30 s monitoring. If any one of the six GM detectors exceeds the preset dose rate (i.e., >5 μSv/h on surface of the bag), audio-visual alarm will be triggered. This bag will be sent for separate washing. Processing unit can store 100 bags data and transfer to remote PC through RS-485 interface for further analysis.


  Results Top


A 100 MBq Cs-137 source was used to check the sensitivity, dose rate linearity of six GM (LND 719) detectors. Sensitivity of all the GM detectors [2] was found to be ~10 Counts Per Second (CPS) per μSv/h. To study the system response to non-uniform distributed source geometries, data were collected over the 2 months, by keeping source at (i) three different locations in two planes (P1 and P2) and (ii) at geometrical center of the drum as shown in [Figure 3] (locations L1, L2, L3, L4, L5, L6, and L7). [Figure 4] shows the variation of dose rate seen by each detector with respect to point source (37 MBq Cs-137) kept at different locations inside the drum. It was found that each detector counts vary within 1s statistical limit. While taking the each detector's counts, the rough position of any strong source present in the waste bag can be predicted. This information can be used to calculate the content of activity present in the waste bag. [3] The data from the processing unit can be transferred to PC by RS-485 communication and report can be generated.
Figure 3: Source locations to study system response to non-uniformly distributed sources

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Figure 4: Data variation with the source kept at different locations

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  Conclusions Top


The system installed at ETP after calibration was effectively segregated the contaminated bags from the rest and thus prevents from cross-contamination during wash cycle. Present system will help to reduce man-rem consumption due to semi-automatic monitoring. It improves sensitivity due to good geometry, background subtraction and attenuation corrections. Long/user selectable counting time improves statistics. System generated data base helps to improve and optimize the decontamination agent's inventory.


  Acknowledgments Top


Authors gratefully acknowledge the guidance and encouragement of Dr. A. K. Ghosh. We thank our colleagues, Shri. Pravin Sawant and Shri Satish Joshi for their support and cooperation during the course of this development work. Services provided by our colleagues at RSSD workshop in the fabrication of the mechanical assembly are thankfully acknowledged.

 
  References Top

1.Ranade NR, Prakash S, Deshpande VK. Laundry Contamination Monitor Using Large Area Gas Flow Proportional Counters. In: Babu DA, Ashok Kumar, Raman N, Sharma DN, editors. Waste Management Division. Paper presented at CNIRD; 2005.  Back to cited text no. 1
    
2.Knoll GF. Text book of Radiation Detection and Measurement, 3 rd ed., John Wiley & sons Inc., United States of America; 2000. p. 208-9.  Back to cited text no. 2
    
3.Singh VP, Managanvi SS, Shah TN. Development of a laundry monitor for contamination control. Radiation Protection Environment 2010;33:123-7.  Back to cited text no. 3
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4]



 

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  In this article
Abstract
Introduction
System Description
System Operation
Results
Conclusions
Acknowledgments
References
Article Figures

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