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PROBABILISTIC HAZARD ASSESSMENT FOR TORNADOES, STRAIGHT-LINE WIND, AND EXTREME PRECIPITATION AT THE SAVANNAH RIVER SITE

Description: Recent data sets for three meteorological phenomena with the potential to inflict damage on SRS facilities - tornadoes, straight winds, and heavy precipitation - are analyzed using appropriate statistical techniques to estimate occurrence probabilities for these events in the future. Summaries of the results for DOE-mandated return periods and comparisons to similar calculations performed in 1998 by Weber, et al., are given. Using tornado statistics for the states of Georgia and South Carolina, we calculated the probability per year of any location within a 2⁰ square area surrounding SRS being struck by a tornado (the ‘strike’ probability) and the probability that any point will experience winds above set thresholds. The strike probability was calculated to be 1.15E-3 (1 chance in 870) per year and wind speeds for DOE mandated return periods of 50,000 years, 125,000 years, and 1E+7 years (USDOE, 2012) were estimated to be 136 mph, 151 mph and 221 mph, respectively. In 1998 the strike probability for SRS was estimated to be 3.53 E-4 and the return period wind speeds were 148 mph every 50,000 years and 180 mph every 125,000 years. A 1E+7 year tornado wind speed was not calculated in 1998; however a 3E+6 year wind speed was 260 mph. The lower wind speeds resulting from this most recent analysis are largely due to new data since 1998, and to a lesser degree differences in the models used. By contrast, default tornado wind speeds taken from ANSI/ANS-2.3-2011 are somewhat higher: 161 mph for return periods of 50,000 years, 173 mph every 125,000 years, and 230 mph every 1E+7 years (ANS, 2011). Although the ANS model and the SRS models are very similar, the region defined in ANS 2.3 that encompasses the SRS also includes areas of the Great Plains and lower Midwest, regions with much higher ...
Date: December 4, 2013
Creator: Werth, D.; Weber, A. & Shine, G.
Partner: UNT Libraries Government Documents Department

A probabilistic tornado wind hazard model for the continental United States

Description: A probabilistic tornado wind hazard model for the continental United States (CONUS) is described. The model incorporates both aleatory (random) and epistemic uncertainties associated with quantifying the tornado wind hazard parameters. The temporal occurrences of tornadoes within the continental United States (CONUS) is assumed to be a Poisson process. A spatial distribution of tornado touchdown locations is developed empirically based on the observed historical events within the CONUS. The hazard model is an aerial probability model that takes into consideration the size and orientation of the facility, the length and width of the tornado damage area (idealized as a rectangle and dependent on the tornado intensity scale), wind speed variation within the damage area, tornado intensity classification errors (i.e.,errors in assigning a Fujita intensity scale based on surveyed damage), and the tornado path direction. Epistemic uncertainties in describing the distributions of the aleatory variables are accounted for by using more than one distribution model to describe aleatory variations. The epistemic uncertainties are based on inputs from a panel of experts. A computer program, TORNADO, has been developed incorporating this model; features of this program are also presented.
Date: April 19, 1999
Creator: Hossain, Q; Kimball, J; Mensing, R & Savy, J
Partner: UNT Libraries Government Documents Department

Exploring Spontaneous Planning During the North Texas April 3, 2012, Tornadoes: an Assessment of Decision-making Processes

Description: The primary purpose of this research program is to confirm the spontaneous planning behavior in post-disaster operations while at the same time contribute to the development of the concept in a tornado type disaster. An additional goal also includes examining how the process takes place in resolving unanticipated problems as a disaster unfolds. This study uses qualitative methodology which is case study to probe the concept of spontaneous planning behavior to solve unexpected challenges as a disaster develops. Specifically, semi-structured, open-ended questions were utilized to collect data from stakeholders in eleven functional organizations in three impacted cities during the North Texas April 3, 2012, tornadoes. Findings indicate that debris removal and ensuring public safety, search and rescue, securing damaged neighborhoods, activation of emergency operations centers, damage assessment, restoration of communication system, public relations and media, and volunteer and donation management activities appear to have benefited from spontaneous planning behavior. Further findings suggest that the driving forces behind the phenomenon were gathering valuable new information, learning opportunity within the disaster, relative freedom and significant high degree of discretion, response was innovative with flexibility, and solutions waiting for problems features proposed in the integrated decision-making model (IDMM). However, it was uncovered that interview respondents’ answers tend to indicate that mixed organizational structures helped in problem resolutions rather than just flat organizational structure as some decision making literature may suggest. Analysis of this decision-making model expanded the understanding of how spontaneous planning behavior took place in resolving unforeseen problems in post-disaster operations. This research project confirmed the concept of spontaneous planning in the North Texas tornadoes as well as suggesting how it occurred. The research program validates spontaneous planning behavior in tornadoes; advances and develops the concept of spontaneous planning; increases understanding, description, and management of post-disaster operations; improves emergency management operations; promotes ...
Date: August 2014
Creator: Peters, Ekong Johnson
Partner: UNT Libraries

Evaluation of natural phenomena hazards as part of safety assessments for nuclear facilities

Description: The continued operation of existing US Department of Energy (DOE) nuclear facilities and laboratories requires a safety reassessment based on current criteria and guidelines. This also includes evaluations for the effects of Natural Phenomena Hazards (NPH), for which these facilities may not have been designed. The NPH evaluations follow the requirements of DOE Order 5480.28, Natural Phenomena Hazards Mitigation (1993) which establishes NPH Performance Categories (PCs) for DOE facilities and associated target probabilistic performance goals. These goals are expressed as the mean annual probability of exceedance of acceptable behavior for structures, systems and components (SSCs) subjected to NPH effects. The assignment of an NPH Performance Category is based on the overall hazard categorization (low, moderate, high) of a facility and on the function of an SSC under evaluation (DOE-STD-1021, 1992). Detailed guidance for the NPH analysis and evaluation criteria are also provided (DOE-STD-1020, 1994). These analyses can be very resource intensive, and may not be necessary for the evaluation of all SSCs in existing facilities, in particular for low hazard category facilities. An approach relying heavily on screening inspections, engineering judgment and use of NPH experience data (S. J. Eder et al., 1993), can minimize the analytical effort, give reasonable estimates of the NPH susceptibilities, and yield adequate information for an overall safety evaluation of the facility. In the following sections this approach is described in more detail and is illustrated by an application to a nuclear laboratory complex.
Date: February 1, 1995
Creator: Kot, C.A.; Hsieh, B.J.; Srinivasan, M.G. & Shin, Y.W.
Partner: UNT Libraries Government Documents Department

Rationale for wind-borne missile criteria for DOE facilities

Description: High winds tend to pick up and transport various objects and debris, which are referred to as wind-borne missiles or tornado missiles, depending on the type of storm. Missiles cause damage by perforating the building envelope or by collapsing structural elements such as walls, columns or frames. The primary objectives of this study are as follows: (1) to provide a basis for wind-borne or tornado missile criteria for the design and evaluation of DOE facilities, and (2) to provide guidelines for the design and evaluation of impact-resistant missile barriers for DOE facilities The first objective is accomplished through a synthesis of information from windstorm damage documentation experience and computer simulation of missile trajectories. The second objective is accomplished by reviewing the literature, which describes various missile impact tests, and by conducting a series of impact tests at a Texas Tech University facility to fill in missing information.
Date: September 1, 1999
Creator: McDonald, J R & Murray, R
Partner: UNT Libraries Government Documents Department

[News Clip: AL tornado]

Description: B-roll video footage from the KXAS-TV/NBC station in Fort Worth, Texas covering a news story about storm damage featuring people inspecting and cleaning up storm damage in a residential area. This footage was broadcast at 6pm.
Date: October 9, 1999, 6:00 p.m.
Creator: KXAS-TV (Television station : Fort Worth, Tex.)
Partner: UNT Libraries Special Collections

[News Clip: Water spout]

Description: B-roll video footage from the KXAS-TV/NBC station in Fort Worth, Texas covering an unknown news story featuring a funnel cloud in the background of an unidentified city and a group of unidentified people discussing the storm on the beach. This footage was broadcast at 10pm.
Date: October 5, 1999, 10:00 p.m.
Creator: KXAS-TV (Television station : Fort Worth, Tex.)
Partner: UNT Libraries Special Collections

[News Script: Rescue school]

Description: Script from the WBAP-TV station in Fort Worth, Texas, covering a news story about members of the Dallas county sheriff's department fire marshal holding a rescue school in light of a recent tornado.
Date: April 23, 1957
Creator: WBAP-TV (Television station : Fort Worth, Tex.)
Partner: UNT Libraries Special Collections

[News Script: Storm]

Description: Script from the WBAP-TV/NBC station in Fort Worth, Texas, covering a news story about a tornado hitting Somerset.
Date: May 2, 1959
Creator: WBAP-TV (Television station : Fort Worth, Tex.)
Partner: UNT Libraries Special Collections

[News Script: Pilot Point]

Description: Script from the WBAP-TV/NBC station in Fort Worth, Texas, covering a news story about Pilot Point holding a tornado drill.
Date: April 1, 1959
Creator: WBAP-TV (Television station : Fort Worth, Tex.)
Partner: UNT Libraries Special Collections

[News Script: Everman tornado]

Description: Script from the WBAP-TV/NBC station in Fort Worth, Texas, covering a news story about a tornado that hit Everman, south of Fort worth. This tornado caused great damage totaling at about 50-thousand dollars.
Date: October 4, 1959
Creator: WBAP-TV (Television station : Fort Worth, Tex.)
Partner: UNT Libraries Special Collections

[News Script: Silverton tornado]

Description: Script from the WBAP-TV station in Fort Worth, Texas, covering a news story about a deadly tornado that struck the Panhandle town of Silverton.
Date: May 16, 1957
Creator: WBAP-TV (Television station : Fort Worth, Tex.)
Partner: UNT Libraries Special Collections

[News Script: Tornado]

Description: Script from the WBAP-TV/NBC station in Fort Worth, Texas, covering a news story about a tornado hitting Hill county.
Date: April 1, 1959
Creator: WBAP-TV (Television station : Fort Worth, Tex.)
Partner: UNT Libraries Special Collections

Level 1 Tornado PRA for the High Flux Beam Reactor

Description: This report describes a risk analysis primarily directed at providing an estimate for the frequency of tornado induced damage to the core of the High Flux Beam Reactor (HFBR), and thus it constitutes a Level 1 Probabilistic Risk Assessment (PRA) covering tornado induced accident sequences. The basic methodology of the risk analysis was to develop a ``tornado specific`` plant logic model that integrates the internal random hardware failures with failures caused externally by the tornado strike and includes operator errors worsened by the tornado modified environment. The tornado hazard frequency, as well as earlier prepared structural and equipment fragility data, were used as input data to the model. To keep modeling/calculational complexity as simple as reasonable a ``bounding`` type, slightly conservative, approach was applied. By a thorough screening process a single dominant initiating event was selected as a representative initiator, defined as: ``Tornado Induced Loss of Offsite Power.`` The frequency of this initiator was determined to be 6.37E-5/year. The safety response of the HFBR facility resulted in a total Conditional Core Damage Probability of .621. Thus, the point estimate of the HFBR`s Tornado Induced Core Damage Frequency (CDF) was found to be: (CDF){sub Tornado} = 3.96E-5/year. This value represents only 7.8% of the internal CDF and thus is considered to be a small contribution to the overall facility risk expressed in terms of total Core Damage Frequency. In addition to providing the estimate of (CDF){sub Tornado}, the report documents, the relative importance of various tornado induced system, component, and operator failures that contribute most to (CDF){sub Tornado}.
Date: May 1, 1994
Creator: Bozoki, G.E. & Conrad, C.S.
Partner: UNT Libraries Government Documents Department