CONCEPTUAL STUDY OF SPECTRAL BLANKOUT TECHNIQUE ON INSPECTING OF SOME SURROGATED NUCLEAR WARHEADS

We built up a nuclear warhead verification system based on an Intranet platform. The hardware of the system consists of an Intranet server, two personnel computers and a portable high purity gerinanium gamma-ray spectrometer. The software, Blanking-out, is made of two modules designed for the inspecting and inspected parties respectively. Both modules are interactive and communicate through the Intranet. When the system operates, any sensitive information carried by the high resolution gamma-ray spectrum collected by the detector will be meddled by the inspected module before the package of spectral data is sent to the inspecting module to prevent a disclosure of sensitive information. After receiving the spectral data, the inspecting module will display on the screen of the inspecting PC terminal the verification results in a form of blankouted spectrum (spectral blanking-out form) or a form of a piece of phrase (phrase form). The guideline to the spectral blanking-out is that: for those ranges of energy obligated to be inspected, the inspected module should ensure that the inspecting module can display truly their objective spectrum; and for the other ranges of energy, the inspected module can blankout certain parts of the spectra based on the knowledge of sensitive information. Phrase form is rather straightforward, answering the question whether the inspected warhead is a “uranium-type”, “plutonium-type” or “non-nuclear type.” We conducted a demonstration on some surrogates for nuclear warheads to see whether the nuclear warhead verification system possesses the capability of identifying the type of a warhead and blanking-out sensitive spectral information. The demonstration was carried out successfully. Phrase form is especially recommendable due to its stronger capability to prevent sensitive information from disclosure and its higher verification credibility. The demonstration also disclosed some deficiencies of the system, such as too much disintegrated hardware components lower the integration of the system, the interactive operation of the inspected module and the spectral blanking-out form decrease the verification credibility and so on.