Processing facilities detection systems

The Instrumentation and Control Fundamentals Handbook was developed to assist nuclear facility operating contractors provide operators, maintenance personnel, and the technical staff with the necessary fundamentals training to ensure a basic understanding of instrumentation and control systems. The handbook includes information on temperature, pressure, flow, and level detection systems position indication systems process control systems and radiation detection principles. This information will provide personnel with an understanding of the basic operation of various types of DOE nuclear facility instrumentation and control systems. 

Alarms should be initialed by the local or main control facility for the location. Manual activation means should be provided for all emergency, fire, and toxic vapor alarm signals. Activation of fire suppression systems by automatic means should also indicate a facility alarm. Most fire and gas detection systems are also set to automatically activate alarms after confirmation and set points have been reached. Manual activation of field or plant alarm stations should activate the process or facility alarms. 

Halon systems were the ideal fire suppression agent before their implications of environmental impact due to ozone depletion. The industry is gradually phasing out usage of halon systems for this reason. A flowchart to analyze mechanisms to supplement or eliminate Halon systems for electrical or computer processing areas is shown in Figure 11. Some of the prime reasons to eliminate the use of Halon systems is that the facility may be constantly manned with a relatively low fire risk. Other facilities may have a very low combustible load and can be supplemented by highly sensitive fire detection means, such as a VESDA fire detection system. 

It is not the intent of this Guideline to deal in depth with facility security issues. However, effective fire prevention in a processing facility depends on people in addition to systems to detect developing fires and other incidents and to detect unauthorized intrusion into the facility. Intruder-caused vandalism, damage, spills, releases, or fires are not common, but are a credible threat. The potential fire prevention and protection requirements to manage the risk of security events from terrorism need to be considered in the overall fire protection system design. 

Photochromic dithienylethenes have been considered as extremely promising systems to store information. The success of optical information processing requires the facile detection method which can read the stored information in a non-invasive manner. It is to say that the non-destructive readout capability is indispensable. On the basis of the ability to fine-tune the excitation wavelengths of porphyrins and the fact that they exhibit strong luminescence and attractive coordination properties, Branda covalently attached two porphyrins to the dithienylethene backbone, and synthesized a hybrid for non-destructive information processing [29], as shown in Scheme 1. It was the first example of photochromic porphyrinic dithienylethene. 

Therefore, if a leak-detection system has been installed to warn of releases of toxic or flammable materials from a plant, the implementation of a process safety management system should include the detection system as part of the process (CCPS 1989 CCPS 1988). In this manner the leak-detection system will be subject to the facility s management-of-change procedures, and changes to the leak-detection system, will be carefully evaluated before being implemented. 

The 1S-2S transition in muonium has also been measured by laser spectroscopy. The transition is induced by a two-photon Doppler-free process and detected through the subsequent photoionization of the 2S state in the laser field. The key to success in this experiment was the production of muonium into vacuum from the surface of heated W or of Si02 powder. The discovery experiment(33) was done at the KEK facility in Japan with a pulsed muon beam and an intense pulsed laser system. A subsequent experiment(34) done with the pulsed beam at RAL and a similar pulsed laser has improved the signal substantially and has achieved a a precision of about lO" in the 1S- 2S interval, thus determining the Lamb shift in the IS state to about 1% accuracy (Fig. 22). The precision of this experiment should be greatly improved in a new experiment now underway at RAL. This experiment will provide a precise... 

Gas turbines should be installed with automatic fuel shutoff valves. Locate cooling towers far away from process units. Whenever possible, maintain cooling water pressure more than process stream pressure, at the coolers. Install gas detectors at the top of cooling towers, and an automatic shutdown system for cooling tower fans, in case of gas detection. Boiler and other utilities should be located far away from process facilities so that they will not be exposed to fires and explosions originating in the process plants. Install deflagration or detonation arrestors in low-pressure fuel gas systems connected to atmosphere or fired systems. 

The basic detection process uses the neutron-alpha reaction in Li. The 4.78-MeV reaction energy produces an easily detected alpha particle with low sensitivity to gamma radiation and good electrical noise immunity. A prototype neutron detection system using a 20-mm gold window surface barrier detector coupled to a LiF foil was tested at the Los Alamos National Laboratory (LANL) Critical Test Facility in the fall of 1968. The detector unit produced an alarm when placed 580 m from a metal assembly producing 5 X 10 fissions in 33 ps. This detector is presently installed in tlie 11 neutron criticality alarm systems at Rocky Flats. 

Atmospheric vapor, gas, or liquid releases or spills within a process facility occur every day. They are a major cause of catastrophic incidents. In order to provide an inherently safer facility the common release of vapors or gases to the atmosphere or liquids should be prevented or eliminated wherever practical. Not only does this improve the safety of a facility, it also decreases the amount of fugitive emissions or liquids that occur therefore decreasing any potential harm to the environment. Containment of waste gases, vapors, and liquids, human surveillance, increased testing, inspection and maintenance, gas detection (fixed systems and portable devices), and adequate vapor dispersion features are all measures to lessen the probability of an incident occurring. 

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