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MONTE-CARLO BURNUP CALCULATION UNCERTAINTY QUANTIFICATION AND PROPAGATION DETERMINATION

Description: MONTEBURNS is a Monte-Carlo depletion routine utilizing MCNP and ORIGEN 2.2. Uncertainties exist in the MCNP transport calculation, but this information is not passed to the depletion calculation in ORIGEN or saved. To quantify this transport uncertainty and determine how it propagates between burnup steps, a statistical analysis of a multiple repeated depletion runs is performed. The reactor model chosen is the Oak Ridge Research Reactor (ORR) in a single assembly, infinite lattice configuration. This model was burned for a 25.5 day cycle broken down into three steps. The output isotopics as well as effective multiplication factor (k-effective) were tabulated and histograms were created at each burnup step using the Scott Method to determine the bin width. It was expected that the gram quantities and k-effective histograms would produce normally distributed results since they were produced from a Monte-Carlo routine, but some of results do not. The standard deviation at each burnup step was consistent between fission product isotopes as expected, while the uranium isotopes created some unique results. The variation in the quantity of uranium was small enough that, from the reaction rate MCNP tally, round off error occurred producing a set of repeated results with slight variation. Statistical analyses were performed using the {chi}{sup 2} test against a normal distribution for several isotopes and the k-effective results. While the isotopes failed to reject the null hypothesis of being normally distributed, the {chi}{sup 2} statistic grew through the steps in the k-effective test. The null hypothesis was rejected in the later steps. These results suggest, for a high accuracy solution, MCNP cell material quantities less than 100 grams and greater kcode parameters are needed to minimize uncertainty propagation and minimize round off effects.
Date: May 8, 2011
Creator: Nichols, T.; Sternat, M. & Charlton, W.
Partner: UNT Libraries Government Documents Department

MONTE-CARLO BURNUP CALCULATION UNCERTAINTY QUANTIFICATION AND PROPAGATION DETERMINATION

Description: Reactor burnup or depletion codes are used thoroughly in the fields of nuclear forensics and nuclear safeguards. Two common codes include MONTEBURNS and MCNPX/CINDER. These are Monte-Carlo depletion routines utilizing MCNP for neutron transport calculations and either ORIGEN or CINDER for burnup calculations. Uncertainties exist in the MCNP steps, but this information is not passed to the depletion calculations or saved. To quantify this transport uncertainty and determine how it propagates between burnup steps, a statistical analysis of multiple repeated depletion runs is performed. The reactor model chosen is the Oak Ridge Research Reactor (ORR) in a single assembly, infinite lattice configuration. This model was burned for a 150 day cycle broken down into three steps. The output isotopics as well as effective multiplication factor (k-effective) were tabulated and histograms were created at each burnup step using the Scott Method to determine the bin width. The distributions for each code are a statistical benchmark and comparisons made. It was expected that the gram quantities and k-effective histograms would produce normally distributed results since they were produced from a Monte-Carlo routine, but some of the results appear to not. Statistical analyses are performed using the {chi}{sup 2} test against a normal distribution for the k-effective results and several isotopes including {sup 134}Cs, {sup 137}Cs, {sup 235}U, {sup 238}U, {sup 237}Np, {sup 238}Pu, {sup 239}Pu, and {sup 240}Pu.
Date: June 9, 2011
Creator: Sternat, M. & Nichols, T.
Partner: UNT Libraries Government Documents Department

REACTOR PHYSICS MODELING OF SPENT RESEARCH REACTOR FUEL FOR TECHNICAL NUCLEAR FORENSICS

Description: Technical nuclear forensics (TNF) refers to the collection, analysis and evaluation of pre- and post-detonation radiological or nuclear materials, devices, and/or debris. TNF is an integral component, complementing traditional forensics and investigative work, to help enable the attribution of discovered radiological or nuclear material. Research is needed to improve the capabilities of TNF. One research area of interest is determining the isotopic signatures of research reactors. Research reactors are a potential source of both radiological and nuclear material. Research reactors are often the least safeguarded type of reactor; they vary greatly in size, fuel type, enrichment, power, and burn-up. Many research reactors are fueled with highly-enriched uranium (HEU), up to {approx}93% {sup 235}U, which could potentially be used as weapons material. All of them have significant amounts of radiological material with which a radioactive dispersal device (RDD) could be built. Therefore, the ability to attribute if material originated from or was produced in a specific research reactor is an important tool in providing for the security of the United States. Currently there are approximately 237 operating research reactors worldwide, another 12 are in temporary shutdown and 224 research reactors are reported as shut down. Little is currently known about the isotopic signatures of spent research reactor fuel. An effort is underway at Savannah River National Laboratory (SRNL) to analyze spent research reactor fuel to determine these signatures. Computer models, using reactor physics codes, are being compared to the measured analytes in the spent fuel. This allows for improving the reactor physics codes in modeling research reactors for the purpose of nuclear forensics. Currently the Oak Ridge Research reactor (ORR) is being modeled and fuel samples are being analyzed for comparison. Samples of an ORR spent fuel assembly were taken by SRNL for analytical and radiochemical analysis. The fuel assembly was ...
Date: July 18, 2011
Creator: Nichols, T.; Beals, D. & Sternat, M.
Partner: UNT Libraries Government Documents Department

QA Verification of Computer Codes Used in ORNL/TM-1999/159

Description: This report describes QA verification exercises carried out for the computer codes applied in the analyses summarized ''Stress Intensity Factors for HFIR HB-2 Nozzle Corner'' (ORNL/TM-1999/159). Several benchmark problems are presented that establish the following: (1) The version of the finite-element mesh generator code ORNOZL used in the subject analyses reproduces the results of the two sample problems given in its previously published user's guide. (2) The ABAQUS code reproduces, independently of ORNOZL, the results of a benchmark verification problem given in its Example Problems Manual that compares linear-elastic stress intensity factors for semi-elliptical surface flaws to solutions published in the literature. (3) The ORNOZL/ABAQUS code combination was benchmarked against an approximate method for estimating linear-elastic stress-intensity factors for corner flaws in pressure vessel nozzles. In addition, all input and output files produced during the analyses described in ORNL/TM-1999/159 have been archived on an electronic medium (CD-R74-ORNL/TM-1999/159) and transmitted with this report to ORNL Research Reactors Division personnel for archival storage.
Date: April 7, 2000
Creator: Williams, P.T.
Partner: UNT Libraries Government Documents Department

Decontamination and decommissioning preparation of Oak Ridge National Laboratory research reactors

Description: During the past seven years, four research reactors at Oak Ridge National Laboratory (ORNL) have been shut down by the US Department of Energy (DOE) because of a lack of funding and mission. Before the reactors are eligible to receive DOE funding for decontamination and decommissioning (D and D), certain preparations are required, including resolution of significant environmental concerns. This paper describes the results of the D and D preparations for one of these four reactors, the Oak Ridge Research Reactor (ORR), with the emphasis on the environmental aspects. The three tasks that must be completed before a facility can be transferred to the D and D program are: Completion of environmental compliance, industrial safety, and radiological reviews; Removal of all spent fuel and nuclear material; and Assurance that buildings and support systems are structurally sound so as to permit deferred final decommissioning for up to five years.
Date: December 31, 1994
Creator: Stover, R.L.; Anderson, G.E.; Finger, J.M. & Skipper, D.D.
Partner: UNT Libraries Government Documents Department

Management of spent nuclear fuel on the Oak Ridge Reservation, Oak Ridge, Tennessee: Environmental assessment

Description: On June 1, 1995, DOE issued a Record of Decision [60 Federal Register 28680] for the Department-wide management of spent nuclear fuel (SNF); regionalized storage of SNF by fuel type was selected as the preferred alternative. The proposed action evaluated in this environmental assessment is the management of SNF on the Oak Ridge Reservation (ORR) to implement this preferred alternative of regional storage. SNF would be retrieved from storage, transferred to a hot cell if segregation by fuel type and/or repackaging is required, loaded into casks, and shipped to off-site storage. The proposed action would also include construction and operation of a dry cask SNF storage facility on ORR, in case of inadequate SNF storage. Action is needed to enable DOE to continue operation of the High Flux Isotope Reactor, which generates SNF. This report addresses environmental impacts.
Date: February 1, 1996
Partner: UNT Libraries Government Documents Department

DISPOSAL CRITICALITY ANALYSIS FOR ALUMINUM-BASED DOE FUELS

Description: This paper describes the disposal criticality analysis for canisters containing aluminum-based Department of Energy fuels from research reactors. Different canisters were designed for disposal of high enriched uranium (HEU) and medium enriched uranium (MEU) fuel. In addition to the standard criticality concerns in storage and transportation, such as flooding, the disposal criticality analysis must consider the degradation of the fuel and components within the waste package. Massachusetts Institute of Technology (MIT) U-Al fuel with 93.5% enriched uranium and Oak Ridge Research Reactor (ORR) U-Si-Al fuel with 21% enriched uranium are representative of the HEU and MEU fuel inventories, respectively. Conceptual canister designs with 64 MIT assemblies (16/layer, 4 layers) or 40 ORR assemblies (10/layer, 4 layers) were developed for these fuel types. Borated stainless steel plates were incorporated into a stainless steel internal basket structure within a 439 mm OD, 15 mm thick XM-19 canister shell. The Codisposal waste package contains 5 HLW canisters (represented by 5 Defense Waste Processing Facility canisters from the Savannah River site) with the fuel canister placed in the center. Figures 1 and 2 show the waste package after emplacement in the repository.
Date: December 1, 1997
Creator: Gottlieb, J.; Davis, Wesley & Peter, Dr.
Partner: UNT Libraries Government Documents Department

Evaluation of reactor kinetic parameters without the need for perturbation codes.

Description: The analysis of research reactor transients depends on the effective delayed neutron fraction (k{sub eff}), its family-dependent components ({beta}{sub eff,i}), the prompt neutron lifetime (l{sub p}), and the decay constants ({lambda}{sub i}) for each delayed neutron family. Beginning with ENDF/B-V data, methods are presented for accurately calculating these kinetic parameters within the framework of diffusion theory but without the need for a perturbation code. For heavy water systems these methods can be extended to include the delayed photoneutron component of {beta}{sub eff}. However, a separate calculation is needed to estimate the fractional loss of fission product gamma rays, energetic enough to dissociate the deuteron, from leakage, energy degradation and absorption in fuel and structural materials. These methods are illustrated for a light-water Oak Ridge Research Reactor (ORR) LEU core and for a heavy-water Georgia Tech Research Reactor (GTRR) HEU core where calculated and measured values of the prompt neutron decay constant ({beta}{sub eff}/l{sub p}) are compared.
Date: January 14, 1998
Creator: Bretscher, M. M.
Partner: UNT Libraries Government Documents Department

CNEA/ANL collaboration program to develop an optimized version of DART validation and assessment by means of U{sub 3}Si{sub x} and U{sub 3}O{sub 8-}Al dispersed CNEA miniplate irradiation behavior.

Description: The DART code is based upon a thermomechanical model that can predict swelling, recrystallization, fuel-meat interdiffusion and other issues related with MTR dispersed FE behavior under irradiation. As a part of a common effort to develop an optimized version of DART, a comparison between DART predictions and CNEA miniplates irradiation experimental data was made. The irradiation took place during 1981-82 for U3O8 miniplates and 1985-86 for U{sub 3}Si{sub x} at Oak Ridge Research Reactor (ORR). The microphotographs were studied by means of IMAWIN 3.0 Image Analysis Code and different fission gas bubbles distributions were obtained. Also it was possible to find and identify different morphologic zones. In both kinds of fuels, different phases were recognized, like particle peripheral zones with evidence of Al-U reaction, internal recrystallized zones and bubbles. A very good agreement between code prediction and irradiation results was found. The few discrepancies are due to local, fabrication and irradiation uncertainties, as the presence of U{sub 3}Si phase in U{sub 3}Si{sub 2} particles and effective burnup.
Date: October 16, 1998
Creator: Solis, D.
Partner: UNT Libraries Government Documents Department

Oak Ridge Research Reactor quarterly report, July, August, and September of 1977

Description: The ORR operated at an average power level of 29.5 MW for 23.4% of the time during July, August, and September of 1977. Three fuel elements were declared spent (60.7% burnup) during the quarter, while five new elements were placed in service. The reactor was shut down on seven occasions, none of which were unscheduled. Reactor downtime needed for refueling, maintenance and checks was quite low, with the reactor remaining available for operation 86.5% of the time. Maintenance activities, both mechanical and instrument were essentially routine in nature. In-service inspections completed during the quarter included inspection of the ORR primary heat exchanger No. 2.
Date: January 1, 1978
Creator: Hurt, S.S. III & Lance, E.D.
Partner: UNT Libraries Government Documents Department

Oak Ridge research reactor. Quarterly report, April-June 1979

Description: The ORR operated at an average power level of 29.9 MW for 77.9% of the time during April, May, and June of 1979. The reactor was shut down on seven occasions, two of which were unscheduled. Reactor downtime needed for refueling, maintenance and checks was normal, with the reactor remaining available for operation 86.5% of the time. Maintenance activities, both mechanical and instrument, were essentially routine in nature.
Date: December 1, 1979
Creator: Hurt, S.S. III & Lance, E.D.
Partner: UNT Libraries Government Documents Department

Oak Ridge Research Reactor quarterly report October, November and December of 1978

Description: The ORR operated at an average power level of 29.0 MW for 80.9% of the time during October, November, and December of 1978. The reactor was shut down on fourteen occasions, four of which were unscheduled. Reactor downtime needed for refueling, maintenance and checks was normal, with the reactor remaining available for operation 92.2% of the time. Maintenance activities, both mechanical and instrument, were essentially routine in nature.
Date: May 1, 1979
Creator: Hurt, S.S. III & Lance, E.D.
Partner: UNT Libraries Government Documents Department

Oak Ridge Research Reactor quarterly report, January-March, 1979

Description: The ORR operated at an average power level of 28.9 MW for 84.2% of the time during January, February and March of 1979. The reactor was shut down on seventeen occasions, three of which were unscheduled. Reactor downtime needed for refueling, maintenance and checks was normal, with the reactor remaining available for operation 93.6% of the time. Maintenance activities, both mechanical and instrument, were essentially routine in nature with the exception of one mechanical design change. Special tests or measurements completed during the quarter included: (1) preliminary measurements for the LWR Pressure Vessel Irradiation Program; (2) flux mapping for Core No. 148-A; and (3) calibration of all six shim rods.
Date: October 1, 1979
Creator: Hurt, S.S. III & Lance, E.D.
Partner: UNT Libraries Government Documents Department

Oak Ridge Research Reactor quarterly report, April, May, and June 1981

Description: The ORR operated at an average power level of 29.8 MW for 90.7% of the time during April, May, and June 1981. The reactor was shut down on eight occasions, one of which was unscheduled. Reactor downtime needed for refueling, maintenance, and checks was normal, with the reactor remaining available for operation 91.6% of the time. Maintenance activities, both mechanical and instrument, were essentially routine in nature. In-service inspection completed during the quarter is described.
Date: January 1, 1982
Creator: Hurt, S.S. III & Lance, E.D.
Partner: UNT Libraries Government Documents Department

Oak Ridge research reactor. Quarterly report, January, February, and March 1981

Description: The ORR operated at an average power level of 27.9 MW for 88.9% of the time during January, February, and March of 1981. The reactor was shut down on seventeen occasions, seven of which were unscheduled. Reactor downtime needed for refueling, maintenance, and checks was normal, with the reactor remaining available for use 92.6% of the time. Maintenance activities, both mechanical and instrument, were essentially routine in nature with the exception of one Reactor Instrumentation and Controls Design Change Memo and one Mechanical Design Change Memo. Special tests or measurements completed during this quarter are reported in a summary entitled, ORR Reactivity and Flux Comparisons between a 280 g, 45 Weight Percent Enriched Texas Instrument Fuel Element and a 265 g Standard 93 Weight Percent Enriched Texas Instrument Fuel Element.
Date: January 1, 1982
Creator: Hurt, III, S. S. & Lance, E. D.
Partner: UNT Libraries Government Documents Department

Data acquisition and control system for the K/sub 1C/-HSST experiments at the ORR

Description: Major components and primary functions of the process control system for the K/sub 1C/-HSST irradiation experiments at the Oak Ridge Research (ORR) are described. Information relative to methodology for integrating unique features of the Digital Equipment Corporation's RSX-11M Operating System with analog-to-digital and digital-to-analog hardware is presented. In particular, data flow among various real-time applications programs relative to system hardware is presented. General features of the temperature control algorithm are presented, and results that illustrate the spatial temperature distribution in the capsule achieved by the control system are included.
Date: January 1, 1984
Creator: Miller, L.F. & Hobbs, R.W.
Partner: UNT Libraries Government Documents Department

Oak Ridge Research Reactor quarterly report, April, May, and June of 1978

Description: The ORR operated at an average power level of 27.8 MW for 72.6% of the time during April, May, and June of 1978. The reactor was shut down on fifteen occasions, two of which were unscheduled. Reactor downtime needed for refueling, maintenance and checks was higher than normal due to beam-hole-plug maintenance, with the reactor remaining available for operation 82.4% of the time. Maintenance activities, both mechanical and instrument, were essentially routine in nature. Special tests or measurements completed during the quarter included gamma flux (heating) measurements made in core positions E-7, E-5, E-3, and C-7 using lattice configurations as indicated in figure Nos. 5, 6, 7, 8, 9, and 10.
Date: December 1, 1978
Creator: Hurt, III, S. S. & Lance, E. D.
Partner: UNT Libraries Government Documents Department

Oak Ridge research reactor quarterly report, January, February, and March of 1980

Description: The ORR operated at an average power level of 29.9 MW for 91.3% of the time during January, February, and March of 1980. The reactor was shut down on twelve occasions, six of which were unscheduled. Reactor downtime needed for refueling, maintenance and checks was normal, with the reactor remaining available for use 93.7% of the time. Maintenance activities, both mechanical and instrument, were essentially routine in nature with the exception of one Reactor Instrument and Controls Design Change Memo.
Date: October 1, 1980
Creator: Hurt, S.S. III & Lance, E.D.
Partner: UNT Libraries Government Documents Department

Oak Ridge Research Reactor quarterly report, January, February, and March of 1978

Description: The ORR operated at an average power level of 28.7 MW for 73.4 percent of the time during January, February, and March of 1978. Eight new fuel elements were placed in service. The reactor was shut down on sixteen occasions, one of which was unscheduled. Reactor downtime needed for refueling, maintenance and checks was quite low, with the reactor remaining available for operation 88.9 percent of the time. Maintenance activities, both mechanical and instrument were essentially routine in nature. Special tests or measurements completed during the quarter included: (1) reactivity measurement of the Metals and Ceramics Division's (ORR-MFE-1) experiment in CP-C7; (2) flux mapping for core No. 143-B; and (3) calibration of all six shim rods on February 12, 1978 (Appendix A), and calibration of shim rods Nos. 2 through 6 on February 16, 1978.
Date: July 1, 1978
Creator: Hurt, S.S. III & Lance, E.D.
Partner: UNT Libraries Government Documents Department

Status of uranium nitride development program at the Oak Ridge National Laboratory. Part II

Description: From RDT/SNS meeting on materials development for space reactor power systems; Washington, D. C. (23 Apr 1968). Declassified 26 Nov 1973. Information is included on encapsulated UN irradiation testing in the Materials Testing Reactor, results of post-irradiation evaluation of UN capsules, and irradiation testing of clad UN fuel pins in the Low Intensity Test Reactor and in the Oak Ridge Research Reactor. (JRD)
Date: April 30, 1974
Creator: Weaver, S.C. & Scott, J.L. (comps.)
Partner: UNT Libraries Government Documents Department

Computerized process control system for the ORR-PSF irradiation experiment. Part 2: mathematical basis and computer implementation of the temperature control algorithm. Volume 2

Description: A brief description of the Oak Ridge Reactor Pool Side Facility (ORR-PSF) and of the associated control system is given. The ORR-PSF capsule temperatures are controlled by a digital computer which regulates the percent power delivered to electrical heaters. The total electrical power which can be input to a particular heater is determined by the setting of an associated variac. This report concentrates on the description of the ORR-PSF irradiation experiment computer control algorithm. The algorithm is an implementation of a discrete-time, state variable, optimal control approach. The Riccati equation is solved for a discretized system model to determine the control law. Experiments performed to obtain system model parameters are described. Results of performance evaluation experiments are also presented. The control algorithm maintains both capsule temperatures within a 288/sup 0/C +-10/sup 0/C band as required. The pressure vessel capsule temperatures are effectively maintained within a 288/sup 0/C +-5/sup 0/C band.
Date: November 1, 1980
Creator: Miller, L.F.
Partner: UNT Libraries Government Documents Department