Presentation on theme: "James T. (Tom) Voss Los Alamos National Laboratory Health Physics Measurements Group (RP-2) Radiation Instrumentation and Calibration Team Stationary Contamination."— Presentation transcript:
James T. (Tom) Voss Los Alamos National Laboratory Health Physics Measurements Group (RP-2) Radiation Instrumentation and Calibration Team Stationary Contamination Monitors LA-UR
LANL currently uses more than 400 Hand and Foot Monitors (HFMs) in 5 different configurations. 32 Eberline HFM-7s, 89 HFM-8s, 180 TA-55HFs (alpha only), 30 TA-HFs (beta pancake), 80 Ludlum Model 214s used as HFMs. Eberline HFM-7s are alpha + beta HFMs TA-HFs with the beta pancake are used as beta hand monitors More than 300 of the HFMs are alpha-only using air- proportional alpha detectors, this includes the HFM- 8s, TA-55 HFs (alpha only), and Ludlum Model 214s.
Approximately 1,000 Ludlum Model 214s and Model 215s are used as glove box monitors (GBMs). The available HFM technologies are; P-10 gas-flow proportional, dual alpha + beta scintillator, GM pancake and sealed gas proportional (beta only), and air-proportional (alpha only). ZnS alpha + beta has been applied to hand-held detectors but has not yet been available in HFMs.
This comparison covers the P-10 gas-flow proportional, dual scintillator, and air-proportional alpha HFMs. The HFMs in this comparsion are; Berthold LB146-2, Bladwerx cHFM, Canberra Sirius-5AB, Thermo HFM11, Fuji NHP, and Ludlum The LB146-2, cHFM, Sirius-5AB, and HFM11 are P-10 gas-flow proportional, the Fuji NHP is a dual scintillator, and the 4906 is an air-proportional.
The PCMs (Personnel Contamination Monitors) in this comparison are; Canberra Argos 5AB and Thermo Scientific iPCM12.
The evaluation criteria include; overall size, weight, durability, ease of use, detection capability, alarm capability, ease of maintenance and calibration, response to environmental affects, and response to interfering radiations.
Berthold LB Foot print is approximately 31 by 34 inches Weight is approximately 180 pounds
Bladewerx - cHFM Compact Hand and Foot Monitor Foot print is approximately 18 x 17.6 inches Weight is approximately 75 lbs (34 kg) Uses 2.5 sq. feet of floor space
Canberra Sirius-5AB Foot print is approximately 30 by 37 inches. Weight is approximately 290 pounds.
Thermo HFM11 Foot print is approximately 32 by 37 inches. Weight is approximately 270 pounds.
Fuji NHP Foot print is approximately 29 by 30 inches. Weight is approximately 220 pounds.
Ludlum 4906 Foot print is approximately 36 by 31 inches Weight is approximately 150 pounds
Canberra - Argos 5AB Personnel Contamination Monitor Footprint is approximately 36 x 40.2 inches. Weight is approximately 321 kg (706 pounds).
Thermo Fisher Scientific - iPCM12 Installed Personnel Contamination Monitor Footprint is approximately 28.6 x 37 inches. Weight is approximately 400 kg (880 pounds).
THE EVALUATION OVERALL SIZE The LANL HFM requirement of no more than a 36 by 36 inch footprint was met by 4 of the 6 HFMs evaluated. Two of the HFMs that did not meet the size requirement because one measurement was 37 inches. WEIGHT ALL of the HFMs met the LANL requirement of no more than 300 pounds. Both PCMs were much heavier than the HFMs but there was no limit on the weight of PCMs.
DURABILITY NONE of the HFMs fully met the LANL requirement of durability. ALL of the HFMs and PCMs have vulnerable detector windows. EASE OF USE NONE of the HFMs fully met the LANL requirement of ease of use. Most of the problems regarding ease of use are related to the positioning of the hands of the user.
DETECTION CAPABILITY ALL of the HFMs meet the LANL requirement of detecting 500 DPM Alpha and 5,000 DPM Beta within 16 seconds. The alpha detection efficiencies of the HFMs were from 10 to 14% and the beta detection efficiencies were from 19 to 24%. The alpha background count rates in the low background area were from 1 to 18 CPM and the beta background count rates were from 1,000 to 2,400 CPM. Note that the Ludlum 4906 is an alpha-only HFM and obviously does not detect beta radiations.
ALARM CAPABILITY NONE of the HFMs fully met the LANL requirement of alarm annunciation. Problems were noted for both sound level on some of the HFMs and the lack of sound indication on some of the HFMs. EASE OF MAINTENANCE AND CALIBRATION NONE of the HFMs fully met the LANL requirements for ease of maintenance and calibration. Problems were noted with the awkwardness of using the calibration software and with replacing the hand detectors.
RESPONSE TO ENVIRONMENTAL AFFECTS The HFMs’ response to environmental affects was not directly evaluated. According to the manufacturers’ literature ALL of the HFMs will operate with temperatures from 0 to 40 C and RH from 0 to 95%. With the small amount of radon data collected it appears that ALL of the HFMs would meet the LANL requirement of being able to operate with radon/thoron concentrations up to 0.1 pCi/L.
RESPONSE TO INTERFERING RADIATIONS ONLY the Ludlum 4906 can detect 500 DPM alpha in a combined 5 mR/hr gamma field and 2 mRem/hr fast neutron field. NONE of the other HFMs or PCMs can detect 500 DPM alpha and 5,000 DPM beta in a combined 5 mR/hr gamma field and 2 mRem/hr fast neutron field. The Berthold LB146-2, Bladewerx cHFM, Canberra Sirius-5AB, Thermo HFM11, and Fuji NHP have a calculated beta detection capability of approximately 14,000 DPM in a 1 mR/hr gamma field referenced to Cs-137. The response to interfering neutron radiation for these HFMs has not been adequately measured.
ADDITIONAL CONSIDERATIONS Berthold LB146-2 The LB146 is a production HFM, made in Germany. Bladewerx cHFM The cHFM is a production HFM, made in NM. Canberra Sirius-5AB The Sirius-5AB is a new product for Canberra. The position of the hand detectors is somewhat awkward. Thermo HFM11 The HFM11 is a production HFM, made in Germany. The HFM11 calibration software is awkward to use.
Fuji NHP The NHP is a production HFM, made in Japan, but Apantec promises to manufacture parts in the US. The NHP has been used successfully in Japan’s nuclear power industry but may not fare well in some LANL environments such as TA-54. The NHP is a dual scintillator so it does not use P-10 gas. The NHP mylar windows may be susceptible to being punctured. Fuji gangs the front and back of the hand into one PMT, which doubles the effective background for the hand detectors. The hand detectors (front and back of the hands) are parallel plates and the users fingertips are too far from the detector for good alpha detection. Fuji has promised to look into the detector spacing and the vulnerability of the mylar windows.
Ludlum 4906 The 4906 is a new product for Ludlum. The large area air-proportional alpha detectors may make it more susceptible to radon/thoron interference. (There is some evidence from our evaluation of the Ludlum 215 that tends to support this supposition.)
Berthold Technology - LB Hand and Foot Monitor Hand Detectors:15 x 23 cm 23.2% Am 241 ; 38.5% Cl 36 Foot Detectors: 15 x 35 cm 13.9% Am 241 :25.0% Cl 36 Physical Weight: 81 kg (178 pounds) Dimensions: 70 x 87.4 x151cm Footprint: 6.6 sq. ft. 7 detectors (feet & palm and back of hands plus a frisker)
Internal memory for 1,000 measured values. Each value contains; date and time, values exceeding thresholds, selected nuclides, personnel ID number if enabled, activity levels at all measuring points. The monitor performs the following diagnostic tasks; monitoring for probe failure, background drift, gas control, positional monitoring, external alarm signal, error and status messages. Rapid recovery from background changes with a dynamic background counting time USB and Ethernet connectivity RadNet compliant (uses Berthold protocol)
Bladewerx - cHFM Compact Hand and Foot Monitor Hand and Foot Detectors: Gas flow proportional, surface area 135 in 2 (871 cm 2 ) 9”w x 15”d hand and foot detector (26.86 x 38.1 cm) Frisker Detector:100 cm2 active area Beta Data Analysis Dual threshold (beta with alpha cutoff) gross counting board Background subtraction Typical 15% efficiency for Cl-36 Alpha Data Analysis Dual threshold (alpha with radon cutoff) gross counting board Background subtraction Typical 15% efficiency for Pu-239
Physical AC/DC power, operates for 4 hours on battery back up Weight: 75 lbs (34 kg) Dimensions: (W x D x H) 18” x 17.6” x adjustable 2.5 sq. feet of floor space 3 detectors including frisker 2 step monitoring Alarms may be set on individual detectors USB and Ethernet connectivity RadNet compliant
Thermo Scientific - iPCM12 Installed Personnel Contamination Monitor Dimensions x 0.94 x 2.22 meters (2.38 x 3.08 x 7.28 feet) Footprint7.33 sq. ft. Weight400 kg (880 pounds) Alpha & beta detection geometry, building on the PCM2 design. Coverage area greater than PCM2 with almost 17,000 cm 2 detection area. Utilizes 21 detectors in monitoring the body, hands and feet Detectors are split into four detection zones
Sum zones may be applied across all detectors All background, measurement, source checking, event log, voltage scanning is stored to an SQL database within the monitor, providing both local and remote access Alarms may be set on single detectors or sum zones Each measurement result may be stored against a personnel identifier Rapid recovery from background changes with a dynamic background counting time USB security dongle — allows supervisors access to diagnostic modes to further investigate the results; features three security levels QuickScan algorithm — allows for faster beta and gamma contamination monitoring without compromising the statistical probabilities of detection or false alarm
Changing background indication signal — highlights significant changes in background radiation Changing conditions alarm — indicates if there is a significant change in the count rate during the monitoring period, invalidating the measurement Calibration Integrity checking Windows XP operating system and Series 12 Software based upon that in SAM12 and PM12 USB and Ethernet connectivity RadNet compliant Detector Efficiency Body, hand, leg, arm, top of toe Cl 36 Am ± 3 % 14 ± 3 % Foot 15 ± 3 % 9 ± 3 %