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| 1 |
ID:
080448
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| Publication |
2007.
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| Summary/Abstract |
Radiation portal monitors are starting to be deployed at overseas ports to prevent nuclear weapons from entering the U.S. in a shipping container. Current designs have containers on trucks passing through a portal monitor at approximately 10 mph, before being routed to one of several lanes at the port's front gate for a driver identification check. For a fixed cost of testing, which consists of the costs of radiation portal monitors plus offsite x-ray and possibly manual testing of containers generating a false radiation alarm that cannot be resolved by gamma-ray imaging, the neutron detection limits of the current design are compared with those of two other designs that do not affect truck congestion at the front gate. For a wide range of budgets, it is optimal to have six monitors in each lane that simultaneously test a truck while it is being processed at the front gate. This design is robust against the location (within the container) of the weapon and reduces the detection limit (relative to the current design) by approximately a factor of three (although the accuracy of this value is limited by the lack of publicly available data) for practical budgets, which is enough to offset some shielding for a plutonium weapon, but insufficient to detect an uranium weapon
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| 2 |
ID:
080446
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| Publication |
2007.
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| Summary/Abstract |
Progress in monitoring the Comprehensive Nuclear Test Ban Treaty (CTBT) is examined, beginning with the 2002 National Academy of Sciences CTBT study, followed by recent findings on regional seismology, array-monitoring, correlation-detection, seismic modeling, and non-seismic technologies. The NAS-CTBT study concluded that the fully completed International Monitoring System (IMS) will reliably detect and identify underground nuclear explosions with a threshold of 0.1 kt in hard rock, if conducted anywhere in Europe, Asia, North Africa, and North America. In some locations the threshold is 0.01 kt or lower, using arrays or regional seismic stations, but with an increase in background events. As an example, the 0.6-kiloton North Korean test of October 9, 2006 was promptly detected by seismometers in Australia, Europe, North America, and Asia. The P/S ratio between 1-15 Hz clearly showed that the event was an explosion and not an earthquake. The advances in seismic monitoring, described in this article, strengthen the conclusions of the NAS study. Interferometric synthetic aperture radar can, in some cases, identify and locate 1-kt tests at 500 m depth by measuring subsidence to 2-5 mm. InSAR can discriminate between earthquakes and explosions from the subsidence pattern. InSAR will not give a rapid response, but InSAR can locate nuclear tests to within 100 meters, excellent for on-site inspections. Cooperative monitoring can detect yields of 10 kg next to a test site and less than a gram when two meters from experiments without revealing nuclear secrets.
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| 3 |
ID:
080447
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| Publication |
2007.
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| Summary/Abstract |
Effective treaty monitoring requires that nuclear monitoring data be safe from tampering. Tamper-indicating seals and standard data encryption/integrity techniques, however, do not provide sufficient security, especially against electronic and physical attacks in the context of international nuclear safeguards. This article presents an alternative approach for assuring the integrity of monitoring data called the "One-Time Pad of Digits Substitutions" (OPODS). This cipher is a combination of the unbreakable one-time keypad, and the traditional substitution cipher. OPODS provides unbreakable security prior to an adversary trespassing inside nuclear monitoring hardware (even if the trespassing goes undetected), and good security after
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