Bulk Laundry Monitoring System

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

Full text

ISSN 0972-0464
Radiation
Protection and
Environment
Vol. 35 / Number 1 / January-March 2012
Publication of INDIAN ASSOCIATION FOR RADIATION PROTECTION (IARP)
www.iarp.org.in
Radiation Protection and Environment / Volume 35 / Number 1 / January-March 2012 / Pages 1-***

52 Radiation Protection and Environment | January 2012 | Vol 35 | Issue 1 |
Short Communication
INTRODUCTION
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
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
Identication (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.
SYSTEM OPERATION
On switching system power ON, micro‑controller will
reset all counters, checks the system functioning and
Bulk laundry monitoring system
Vaishali M. Thakur, Amit Jain, Amit Verma, N.R. Rande1, S. Anilkumar, D.A.R. Babu,
D.N. Sharma
Radiation Safety System Division, 1Waste Management Division, Bhabha Atomic Research Centre, Trombay, Mumbai,
Maharashtra, India
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
Address for correspondence:
Mrs. Vaishali Thakur, RSSD, Modular Lab., BARC, Trombay, Mumbai-400085, India. E-mail: vmthakur@barc.gov.in
Access this article online
Quick Response Code:
Website:
www.rpe.org.in
DOI:
10.4103/0972-0464.111410

Thakur, et al.: Bulk laundry monitoring system
Radiation Protection and Environment | January 2012 | Vol 35 | Issue 1 | 53
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
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.
CONCLUSIONS
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
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
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.
2. Knoll GF. Text book of Radiation Detection and
Measurement, 3rd ed., John Wiley & sons Inc., United States
Figure 1: Monitoring and tracking station
Figure 2: Schematic sketch of bulk laundry monitor
Figure 3: Source locations to study system response to non-uniformly
distributed sources
Figure 4: Data variation with the source kept at different locations

Thakur, et al.: Bulk laundry monitoring system
54 Radiation Protection and Environment | January 2012 | Vol 35 | Issue 1 |
How to cite this article: Thakur VM, Jain A, Verma A, Rande NR,
Anilkumar S, Babu D, et al. Bulk laundry monitoring system. Radiat
Prot Environ 2012;35:52-5.
Source of Support: Nil. Conict of Interest: None declared.
of America; 2000. p. 208‑9.
3. Singh VP, Managanvi SS, Shah TN. Development of a
laundry monitor for contamination control. Radiation
Protection Environment 2010;33:123‑7.
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