New Radiation detecting sensors and systems being developed for threat of dirty bomb attack and Nuclear accidents

There is also  growing concern that the widespread availability of radiological materials may result in a dirty bomb attack. Recently a secret group of fewer than 10 people in undercover congressional operation was easily able to buy the raw ingredients for a dirty bomb in US. This has set off alarms among some lawmakers and officials in Washington about risks that terrorists inside the United States could undertake a “dirty bomb” attack and the harmful effects of radiation from such an event. Apart from terrorists, there is also threat of accidents involving nuclear material.

Since the invention of nuclear power, there have been numerous “accidents.” From Three Mile Island and Chernobyl to the more recent problems in Fukushima, it would seem nuclear power is not fully under our control. Recently  a Chinese scientist  has warned that the single mountain under which North Korea most likely conducted its five most recent nuclear bomb tests, including the latest and most powerful on Sunday, could be at risk of collapsing. Wang Naiyan, the former chairman of the China Nuclear Society and senior researcher on China’s nuclear weapons program, said that if Wen’s findings were reliable, there was a risk of a major environmental disaster. Another test might cause the whole mountain to cave in on itself, leaving only a hole from which radiation could escape and drift across the region, including China, he said.

Radioactive materials (RM) are widely used in industry, medicine, agriculture and scientific research. When radioactive elements decay, they produce energetic emissions (alpha particles, beta particles, or gamma rays) that can cause chemical changes in tissues. High-activity RM in several physical and chemical forms can cause severe deterministic effects to individuals in a short period of the exposure time, as well as induce long-term radioactive contamination, if not managed safely and securely during their production, use, transportation, storage and disposal.

The effects of radiation exposure would be determined by: the amount of radiation absorbed by the body; the type of radiation (gamma, beta, or alpha); the distance from the radiation to an individual; the means of exposure-external or internal (absorbed by the skin, inhaled, or ingested); and the length of time exposed. The health effects of radiation tend to be directly proportional to radiation dose. In other words, the higher the radiation dose, the higher the risk of injury.

Radiation can be readily detected with equipment carried by many emergency responders, such as Geiger counters, which provide a measure of radiation dose rate. Other types of instruments are used to identify the radioactive element(s) present. But they only work within a range of a few metres. Radiation portal monitors are used to detect the invisible gamma and neutron radiation and warn security officials of unauthorized movements of nuclear materials at borders and checkpoints. Security agencies are increasingly seeking out better, smaller and less expensive detection devices  to detect and prevent this type of terrorist attack.

One of thrust areas of DARPA is to counter CBRNE threats by developing and testing networked, mobile and cost-effective nuclear- and radiological-weapons detectors that can easily be deployed to provide real-time surveillance over city-scale areas. DARPA  under their SIGMA program had designed a pocket-sized radiation detector to help foil terrorists attempting to detonate concealed dirty bombs or full-blown nuclear weapons in or around U.S. cities and crucial government and industrial infrastructure. Direct measurement of gamma and neutron emission remains one of the few definitive to detect and identify special nuclear materials and radiological sources, DARPA officials say.