SNIPER-GN a new Backpack Radiation Device for SNM

Tests and Performances of a special Identifier for Nuclear Threats and SNM in realistic scenarios

SITUATION:

Increase of concerns in global nuclear security and the current dramatic situation oblige to consider scenarios where the ability to detect and alarm in seconds and identify within 1 minute a nuclear threat is highly required. The most desiderable, but not yet available feature is the identification with a high level of efficiency of the Special Nuclear Material (SNM) also when it’s Shielded, moderated or masked. A small amount of SNM, “the size of an apple”, used with malicious intent and coupled with a conventional explosive is enough to produce a dirty bomb which is one of the worst terrorist threats.

For this reason, it is essential to secure nuclear material by having measurement systems capable to fast detect the nuclear threats and provide the most accurate identification of the smuggled nuclear material. Radioactive isotope identifiers are today commercially available. They can count and identify gamma sources and, for the most complete systems, a neutron counter is included. The performances of such devices are compliant with IEC and ANSI standards such as N42.34 or N42.53 where requirements on the capability to trigger the gamma and the neutron alarm and identify the gamma sources are specified.

CHALLENGES:

Up to now there is no standard with specifications concerning the identification of the source by means of the neutron measurement because there is no technology capable of providing this type of measurement. Neutrons are emitted mainly by SNM together with gammas. However, gammas can be easily shielded by few cm of high-density material, such as concrete or lead, thus making it impossible to reveal the presence of the smuggled source. On the other hand, neutrons do not interact with high-density material and can be detected outside of the shielding.

PRODUCT:

For this reason CAEN developed and patented an innovative algorithm capable to identify, in only 1 minute, through the neutron measurement, the neutron emitters with discrimination between fission sources (like Californium 252), alpha-n sources (like Am-Be and Am-Li), Plutonium and Uranium, thanks to innovative detectors and advanced digital electronics. In this article we are now presenting extensive test results conducted for more than 4 years towards the realization of a portable advanced system for the measurement and identification of radioactive material.

The new compact, rugged and IP67 SNIPER-GN with the included 8.1” display rugged tablet displaying a multi-peaks gamma source identification spectra and report.

The device is capable to address, in only 1-minute, complex scenarios such as Shielding and Masking and at the same time determine in real time the Threat, including the determination of SNM isotopes with an enrichment level estimation: U, Pu-239, PuWG, UWG, Am-Be, Am-Li, or a combination of Shielding and Masking scenarios. Currently, when a neutron alarm is detected the alert level becomes maximum because some SNM could be involved. It therefore becomes necessary to isolate the area, to involve a team of experts equipped with at least one high-resolution gamma measurement system and one for neutron multiplicity. Intervention and measurement times and the specializations required to obtain preliminary information are very high. With the SNIPER-GN system all this can be done in 1 minute with an even higher level of accuracy since the instrument can also indicate the presence of shielding (Lead), moderator (polyethylene) or gamma masking sources without the need of support from experts.

RESULTS:

The measurement campaign show that the performances of the devices are exceeding the actual referenced standards, especially in sensitivity and furthermore because is the only instrument that will be available for “Interdiction” in the world to execute in real time SNM identification. Typical detection time for this kind of measurement is 1s for gamma emitters, 2s for neutron emitters and 1 minute for identification including shielding.

Laboratory setup with two SNIPER-GN measuring a 5.6g Plutonium source placed at 75 cm of distance and shielded with 5 cm of Lead. The two screens show the results obtained in 1 min of identification. Pu is identified through neutrons and the shielding condition is displayed

For example, SNIPER-GN can detect and identify in only 1 minute: • 5.6g of Plutonium placed at 2.5 meters of distance (12 correct identification on 15 tries 80%) • 5.6g of Plutonium placed at 1.5 meters of distance (105 correct identification on 105 tries 100%) • 5.6g of Plutonium placed at 0.5 meters of distance with wrapped by 6 cm of polyethylene and 5 cm of lead to shield the source (10 correct identification on 10 tries 100%) • A Cf-252 source of 0.57 MBq placed at 2 meters (15 correct identification on 15 tries 100%) • A Cs-137 source of 16.17 MBq encapsulated in 6 mm of lead at 10 m of distance (< 10 nSv/h on the detector)

Laboratory setup with two SNIPER-GN measuring an Am-Be source placed at 50 cm of distance and shielded with 5 cm of Lead. The screen shows the result obtained in 1 min of identification. Am-Be is identified through neutrons and the shielding condition is displayed”

A 10g Uranium pellet enriched at 10% in U-235 placed identified in 1 minute by the SNIPER-GN”

IMPLEMENTATION:

This device is already NATO coded because it is in use in the Italian Navy. More units were sold to environmental maintenance industry and are currently in use in horizon2020 project for homeland security and border control.

CONCLUSION:

The electronics and the detectors were finally enclosed in a IP67 rugged case with an ergonomic carrying handle, it is now battery powered with more than 8 hours of autonomy. The SNIPER-GN is now 47 x 17.5 x 33.5 cm and less than 10 kg. The data are visualized on a common tablet wi-fi connected to the SNIPER-GN device placed in the backpack.

• Current identifiers can only count and sometimes identify gamma. The most complete devices can also count neutrons. In case of neutron alarm a team of experts and a lot of time are required to identify the threat. • SNIPER-GN is a breakthrough identification device designed for the homeland security and the CBRNe community • SNIPER-GN is the first and currently only device on the market capable to identify in 1 minute a neutron source by the neutron measurement with discrimination between Pu, U, Am/Be, Am/Li and Cf-252 • In 1 minute of measurement, it can also detect the presence of shielding, moderator or common gamma masking sources and it can also provide an estimation of the enrichment level of Pu and U.