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A comparison of two criticality accident alarm system detector locations for the X-700 building at the Portsmouth Gaseous Diffusion Plant. Final report

Description: A previous analysis of the X-700 Building Criticality Accident Alarm System (CAAS) showed that some of the building may not adequately be covered by the one building CAAS detector in its current location. This report compares the results of that analysis with a new analysis where the detector is in a different location. The new detector location (outside of the storage area in the center of the building--near column B-7) showed coverage for all points previously analyzed. The new centralized detector location reduces the distance and shielding between the source points and the detector. This explains the difference in the level of response when compared to the original (actual) detector location in the new annex west of the building.
Date: February 1, 1996
Creator: Skapik, C.W. & Lee, B.L. Jr.
Partner: UNT Libraries Government Documents Department

Analysis of criticality accident alarm system coverage in the X-700, X-705, and X-720 facilities at the Portsmouth Gaseous Diffusion plant

Description: Additional services for the uranium enrichment cascade process, such as maintenance and decontamination operations, are provided by several ancillary facilities at the PORTS site. These facilities include the X-700 Maintenance Facility, the X-705 Decontamination Facility, and the X-720 Maintenance and Stores Facility. As uranium operations are performed within these facilities, the potential for a criticality accident exists. In the event of a criticality accident within one of these facilities at PORTS, a Criticality Accident Alarm System (CAAS) is in place to detect the criticality accident and sound an alarm. In this report, an analysis was performed to provide verification that the existing CAAS at PORTS provides complete criticality accident coverage in the X-700, X-705, and X-720 facilities. The analysis has determined that the X-705 and X-720 facilities have complete CAAS coverage; the X-700 facility has not been shown to have complete CAAS coverage at this time.
Date: December 1, 1995
Creator: Skapik, C.W.; Dobelbower, M.C. & Woollard, J.E.
Partner: UNT Libraries Government Documents Department

Examination of criticality accident alarm coverage on the operating floors of the X-333, X-330, and X-326 facilities at the Portsmouth Gaseous Diffusion Plant

Description: This report summarizes the results of an evaluation of Criticality Accident Alarm System (CAAS) coverage of the operating floors (first floors) of the X-333, X-330, and X-326 buildings. CAAS coverage of the process cell floors (second floors) has been evaluated in previous reports. Coverage of the roadways around the three processing buildings by the cell floor detectors in these buildings has also been verified in a previous report. In order to evaluate coverage, the facilities were modeled using the Monte Carlo N-Particle Transport Computer Code (MCNP). MCNP was then used to simulate criticality accidents at various locations throughout the operating floors of the buildings and the associated neutron flux at the current detector locations was calculated. The neutron flux was then converted to an absorbed dose rate (in tissue) and compared with the Portsmouth criticality accident alarm set-point of 5mrad/hr. The parameters defining the simulated criticality accidents have been calculated as ``the minimum accident of concern`` as defined in ANSI Standard ANS 8.3-1986. These calculations are documented in Portsmouth report number POEF-SH-31. The results of this evaluation indicate that the X-333 Operating Floor CAAS may not alarm in response to a minimum accident of concern. This is primarily because of shielding provided by the numerous concrete columns used to support the second floor of this building and the large distances between the CAAS detectors. Conversely, the results indicate that the X-326 and the X-330 CAAS systems would alarm in response to a minimum accident of concern occurring on the operating floors of these buildings. It should be noted that the cell floors in these two buildings are supported with steel I-beams instead of the concrete columns used in the X-333 building.
Date: January 1, 1996
Creator: Lee, B.L. Jr.; Dobelbower, M.C.; Woollard, J. & Skapik, C.W.
Partner: UNT Libraries Government Documents Department

An examination of criticality accident alarm coverage of the X-710, X-760 Buildings and the north half of the X-7745-R storage pad at the Portsmouth Gaseous Diffusion Plant

Description: This report summarizes the results of an evaluation of Criticality Accident Alarm System (CAAS) coverage of the X-710 and X-760 buildings and the north half of the X-7745-R storage lot located east of the X-7725 building at the Portsmouth Gaseous Diffusion Plant. In order to evaluate coverage, the facilities were modeled using the Monte Carlo N-Particle Transport Computer Code (MCNP). MCNP was then used to simulate criticality accidents at various locations in the X-710 and X-760 buildings and the north half of the X-7745-R storage lot. The associated neutron flux at current detector locations was calculated. The neutron flux was then converted to an absorbed dose rate (in tissue) and compared with the Portsmouth criticality accident alarm set-point of 5mrad/hr. The parameters defining the simulated criticality accidents have been calculated as ``the minimum accident of concern`` as defined in ANSI Standard ANS 8.3-1986. These calculations are documented in Portsmouth report POEF-SH-31. The results of this evaluation indicate that the X-710 and X-760 buildings and surrounding roads are adequately covered by the CAAS systems that are currently in place in those buildings. The X-7745-R storage pad is also adequately covered by the CAAS in the X-7725 building.
Date: January 1, 1996
Creator: Skapik, C.W.; Dobelbower, M.C.; Woollard, J. & Lee, B.L. Jr.
Partner: UNT Libraries Government Documents Department