Recognizing the need for better and more reliable radiation protection Rad/Comm has designed a highly sensitive radiation detection system that fits directly on the grapple.

DEVELOPMENT OF THE CRICKET RADIATION DETECTION SYSTEM
In the vast majority of cases conventional systems that are installed in scrap processing and steel making facilities utilize large volumes of solid plastic scintillation material (typically polyvinyl toluene (PVT), Polystyrene or Sodium Iodide). The systems utilizing this material are large stationary radiation detection systems installed at truck scales, rail scales, conveyor belts and charge bucket loading areas. These systems provide a relatively high level of sensitivity for low intensity radioactive sources.

When monitoring for LOW LEVEL radiation, there are two major factors to consider when designing a radiation detection system:

1. Proximity to the material being monitored: When monitoring radioactive material that is emitting LOW LEVEL radiation it is extremely critical that the radiation detector be located as close as possible to the radioactive source or the material being scanned. This is due to the fact that radiation intensity decreases significantly as the distance from the source increases (the inverse square law).
2. Scrap density: When radioactive material is shielded by material (e.g. scrap metal) the radiation emissions can be heavily attenuated, just as they would be when a radioactive source is inside a LEAD housing. This makes detection of the radioactive source extremely difficult. However, when
the LEAD SEALED radioactive source is removed from the scrap material and is directly exposed to the face of the detector, reliable detection can be achieved relatively easily.

Based on these two factors, Rad/Comm Systems began looking at various applications and locations in order to establish what would be the ideal detection system for monitoring scrap material for low level radiation intensities.

Rad/Comm is a world leader in the design and manufacture of sensitive and innovative radiation detection systems. Rad/Comm system designers were one of the first to design and manufacture the conventional vehicle radiation detection systems currently used as a standard in the Metals industry. In addition, we were the first company to successfully design and install a system for monitoring large barges of scrap metal. Further to the success of the Barge System, we realized the need for a user-friendly, affordable detection system that would operate on contact with scrap material and continuously monitor with no interruption in production.

The result of our deliberations is the CRICKET radiation detection system, designed to meet the needs of every scrap material handler worldwide. This revolutionary, but simple, design can be fitted to any grapple - in any application. In fact, the CRICKET system will provide an optimum level of detection capability for low intensity radioactive sources on a continuous basis in applications where radiation detection systems have never existed before. The level of detection capability will far exceed any conventional radiation detection system, including detection systems that are mounted on the boom of a crane, regardless of the detector size.

THE FOLLOWING INFORMATION CONTAINS DETAILS ABOUT THE APPLICATION AND DESIGN OF THE CRICKET DETECTION SYSTEM

Mounting the CRICKET in the grapple allows direct exposure to all the material being handled. There are three different opportunities to measure ALL of the material during the handling process. Because the CRICKET system scans on a continuous basis, material is scanned on the surface before the grab even picks up the load. Secondly, the grapple load is scanned for up to 10 seconds while in the grapple. Finally, the material is scanned as it falls from the grapple. These scanning conditions allow the CRICKET to provide a very high degree of detection capability for EXTREMELY LOW LEVEL radioactive material. In addition, the CRICKET’s robust design provides greater impact-resistance then any manufactured grapple.

Many of the companies processing and melting scrap metal have installed expensive large scale radiation detection systems for scanning all recycled materials in vehicles and charge bucket loading operations. Unfortunately there have been numerous situations where these detection systems failed to detect SEALED radioactive sources in the scrap metal. These went on to be processed and/or melted, often resulting in multi-million dollar accidents. Why did these accidents occur? There are a number of reasons, but primarily, it was because one or more of the following principles associated with reliable detection of radiation were not met.

When it comes to detecting radioactive material in any situation these four principles MUST be taken into account:

a) Proximity of the radioactive source to the detection system: THE CLOSER THE BETTER.

b) The amount of time a radioactive source is exposed to the detection system: THE LONGER THE BETTER.

c) Material density between the radioactivity and the detector: THE LOWER THE DENSITY THE BETTER.

d) The surrounding ambient background radiation: THE LOWER THE BACKGROUND THE BETTER.

These four principles appear to be fairly straight forward but inactual field applications they are extremely difficult to control. The significant number of serious accidents, which have occurred after companies installed detection systems, unfortunately, has demonstrated this.
Keeping the above in mind, Rad/Comm began a research project that included potential site studies, several prototype designs, and extensive field-testing. As a result of this research, Rad/Comm has developed the CRICKET radiation detection system exclusively for grapple applications. The design of the CRICKET detection system incorporates all four of the principles in order to achieve maximum scrap monitoring efficiency.

SYSTEM OVERVIEW

The CRICKET consists of four assemblies: the protective shield, the detection unit, the battery pack and the controller. The protective shield is made of several parts and mounts directly on the underside of the grapple base plate (see fig. 1). The shield is delivered in separate parts with installation instructions that include mounting and assembly. The detection unit is delivered as a complete tested assembly that will be mounted inside of the protective shield as is specified in the assembly instructions supplied with the system. The detection unit will be connected via a low voltage signal cable to the battery pack through the center section of the grapple. The battery pack is supplied in parts that will be assembled after the battery box is mounted to the main support tube which connects the base plate to the lifting mechanism on the tower section of the grapple (see Fig. 2.). The battery pack supplies +6volts DC to the detection unit and a wireless transmitter that communicates with the controller (see Fig. 3). The controller is mounted inside the equipment operator’s cab. The remote console provides all the necessary components that will alert the operator to a detection of radioactive material and the systems operating condition. The controller system has two parts: the controller and the power supply/battery charger. The controller can be equipped with an internal battery pack to allow remote operation outside the operators cab. The power supply requires 24Vdc from the crane and supplies power to the control console.

The typical charge time for the grapple battery is 8 hours, with a normal usage time of 72 hours. The second battery supplied with the system can be utilized for those operating conditions that require continuous use such as three shifts per day. The detection system employs an extensive self-test/diagnostic routine with operational indicators to denote correct operational status, such as grapple battery voltage level, grapple temperature and low count rate, even when there has been physical damage to the detector wear plate itself. The grapple-mounted detector utilizes a motion sensor to conserve battery life. Once the grapple is moved the unit turns on, initializes and performs a 10-second self-test routine. After the initial movement the unit will remain powered on as long as the grapple is moving. When the grapple has been stationary for 10 minutes the detector will power down to conserve battery capacity. There is no calibration required; the system does it automatically after startup. Once the self-calibration is complete the unit operates automatically with no operator interaction. The remote unit will alarm with audio/visual alarms in the event radiation is detected and will notify the operator with an audio alarm and displayed message if there is a system malfunction. The following information provides more detail for each component of the system and the modes of operation.

The following is an outline of the CRICKET detection systems mechanical design and operation.

1. DETECTOR PROTECTIVE SHIELD - The shield can be fitted to any sized grapple and is made of a special design that provides an extremely high level of impact and wear resistance. The unit also incorporates a special material that allows maximum radiation penetration through the active window area of the shield. The shield will allow the penetration of low primary gamma energy such as that given off by 241Am. The shield is welded to the bottom plate of the grapple tower section as shown in the photo and includes a removable section that is called the wear plate. The wear plate is made of extremely high wear resistant material that can be replaced or repaired if damaged. The shield also incorporates a wear plate sensor that will alert the operator to any damage that may result in damage to the detection unit inside. The internal sensor is easily repaired once the damage on the wear plate has been rectified.

2. DETECTION UNIT - The detection unit is the primary component of the detection system. The unit is mounted inside a specially designed “G” force compensation case that shunts the impact and multi-frequency ringing that is associated with grapple material handing conditions. The case is easily removed from the protective shield when the wear plate is taken off. The case resists corrosion from water and hydrocarbon products such as oil and grease. Inside the special case are the electronic and large volume detection assemblies, designed to withstand SEVERE repeated impacts and vibration associated with this application. The assemblies are mounted in such a way that they are isolated from the direct transfer of energy. The components of each assembly are also specially selected and manufactured to our PROPRIETARY specifications with the focus on rugged MIL-SPEC designs. The size of the detection medium is configured to the size of the grapple. The systems electronic components include several sensors that are used to monitor the operating conditions of the grapple such as temperature, motion and impact with the scrap material. The unit is powered by 12Vdc from the battery pack via a shielded communication cable. The cable is protected with mesh shield and mounted inside the grapple tube section where maximum protection can be maintained.

3. BATTERY PACK - The battery pack measures 8”x5”x2 ½” and incorporates a rugged steel box construction (see Photo). The box is welded in a protected area on the tube of the grapple center section. A small ½” hole is drilled in the tube to allow the communication cable access to the battery pack connections. The battery pack includes a shock-mounted standard 6Vdc 7.2A/hr dry cell battery and wireless communication system. The battery powers the detection units electronic circuits and wireless system. The wireless system utilizes a low powered digital non-licensed frequency that can transmit up to 500 ft.

4. RC2000 CONTROL CONSOLE - The remote control console (see Photo) includes a touch sensitive 6.5” graphics LCD screen with a high speed microprocessor based system utilizing state-of-the-art wireless communications. The unit measures 11”Lx6”Wx5”D and is mounted on a flexible bracket assembly inside the crane. The unit is powered by 80 to 240 AC or 24Vdc at 2 amps. The unit communicates with the detector assembly via a low powered digital non-licensed frequency that can transmit up to 1000 ft. The unit provides all the necessary components to alert the operator to a detection of radioactive material and information on the systems operating condition. There is also a specially designed non-radioactive simulated test circuit that allows complete testing of the entire system by a touch key on the graphics screen. The system is extremely easy to use and provides complete Menu driven graphics.

If you would like to print this information, download our folder. For a price request, please contact us.

Folder Cricket	Folder "Liebherr" Cricket

 

 

.