War activities and radioactive ionization

sources

Prof.Esad Prohić, Ambassador of Republic of Croatia to I.R. Iran and former professor of Environmental issue at the Faculty of Sciences, University of Zagreb, Croatia

War activities and radioactive ionization sources-how dangereous they could be for environment and humans?

In the very simplified manner the casualties of the war activities can be divided to:

1. Direct (human) casualties as a direct act of war activites- casualties in time on war activities or as effect of that;

2. Indirect casualties (still on humans as

well) by deleterous effect on environment- delay casualties

During the war in Croatia, some 15 years ago, residential objects, industrial plants and halls, warehouses, hospitals, schools, roads and highways and similar objects were destroyed and demolished by shelling and bombing.

These and similar objects are usually protected by radioactive lightning rods,self-luminous signs and smoke detectors, for example.

In Republic of Croatia (which is about seventeen times smaller then Iran) we found about 430 radioactive lightning rods and more then 50 thousands smoke detectors.

During the damage of the various buildings containing particular radioactive ionization sources, the protective shields or protective vesells, in which these sources have been located, could be broken. In this case the radioactive radiation could be uncontrolled spread into the environment.

Even more dangerous is if somebody finds these damaged source and, without be aware of its harmfull effects, keeps it in its vicinity.

Of course the children beeing curious by nature could be more in danger because such objects could for them look like toys.

Use of radioactive sealed sources and devices

The properties of radiation are used in a wide variety of applications. However, in all these applications, the radiaactive material is contained within the sealed source and the device allows the radiation to be used in a controlled way.

The danger appears if, for some reason, like war activities, for example, the radiation seal breaks and radiation freely goes to the environment.

The application areas for the use of radioactive devices and sources my be roken into six groups:

Medical uses; Non-medical irradiation of products; Gauging systems; Imaging systems (radiography); Materials analysis; Miscellaneous uses.

Miscellaneous uses

There are many other applications of radioactive devices and sources, like:

Power generation using a radioisotope thermoelectric generator;

Smoke detectorsSelf-luminous signs;Gun sights;Elimination of static electricity;Lightning prevention

Description of use

Small radioactive sources used to be attached to lightning conductor rods. It was thought that the sources would cause ionization of the air around the conductor rod and would increase the efficiency of the lightning conductor.

Various types of source have been reported to have been used, including 226 Ra and 241 Am alpha sources, as well as 69 Eu and 60 Co gamma sources.

The radioactive lightning conductor rod was shown not to be effective during the 1970s and most have been removed from service.

Typical environment of use

Radioactive lightning conductor rods were used mostly on lightning conductor worldwide where hazardous materials were held in the building being protected. In some countries, they were also installed on many public buildings, such as mosques and churches.

Since 1970, most countries have operated a programme to remove radioactive lightning rods from service.

Sources: 241Am : up to 1.1 GBq (30mCi) 226Ra : up to 1.1 GBq (30mCi)

Self-luminous sign

Description of use Self-luminous signs use a mixture of beta emitting 3H

(tritium) gas sealed into a glass tube that is internally coated with phosphor emits visible light when it interacts with beta particle.

The gas is sealed into a glass tube and the light can be seen at all times. No power is required, making it ideal for emergence signs which may be required in buildings in the event of a power failure.

No radiation passes out of the glass tube and, but in the event of breakage, tritium gas is dispersed in well ventilated areas.

Typical environment of use

The devices are used quite extensively in traffics, public buildings and aircrafts.

Sources: 3H : up to 740 GBq (20Ci)

Smoke detector

Description of use

Radioactive smoke detectors contain a very small 241Am alpha source which ionizes the air in a chamber. If smoke enters the chamber, the radiation is absorbed by the smoke and the air ioization is reduced. This in turn causes a reduction in current between the plates, causing and alarm to trip.

Typical operating environment

These devices are in common use in homes, offices and factories in all locations.

Smoke detectors are supplied with the radioactive source fitted. The source remains in the smoke detector for the lifetime of the device.

Sources241Am : maximum activity 37 kBq (1µCi)

Old sources used 226Ra or 239 Pu up to 2.5 Mq (70 µCi)

Limiting exposure to ionizing radiation

The level of human exposure to ionizing radiation may be controlled and limited in three ways:

1. Distance

2. Time

3. Shielding

For individuals discovering sources or devices, distance and time are the best methods for controlling and limiting exposure to radiation, especially in the situation (like we assume here) when shielding is broken.

In the event that an uncontrolled source or device is identified, the public can be protected from radiation by a combination of distance and time.

As a general rule, the intensity of the radiation field from a point source of radiation is reduced in proportion to the square of the distance.

When sources or devices are identified, it is important to leave the area immediately, in order to minimize time and thus radiation exposure.

What is about other non-ionizing building materials?

Asbestos (roof sheets, fences).

PCBs (grease in transformers and other devices and military tenks, T-54/55-Russian tenks);

And many others!!!!!!!

This is another story Maybe for next year

conference.