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LOFT Monthly Progress Report for August 1980

Description: During August, plant modifications for small-break Test L3-5 continued. The intact-loop-break piping installation is well underway and will be completed soon. Installation of the instrument spool piece was completed and advanced testing disclosed problems which have been worked and are 90% resolved. Installation of the new small-break piping path also made it necessary to fabricate and install hangers for support purposes. Work is progressing well on this effort; however, the additional time required to completion will move the L3-5 Test from a mid-to late-September test date. Major management attention has been devoted to the successful fiscal year 1980 closeout. The actual spending rate to date is still in good agreement with the current approved budgets and authorized funding levels.
Date: September 1, 1980
Creator: Kaufman, N. C.
Partner: UNT Libraries Government Documents Department

LOFT Monthly Progress Report for April 1980

Description: During April, activities continued in preparation for Tests L6-5 and L3-7, currently scheduled for June 1 and June 23. April activities at the LOFT facility were particularly centered around the installation of new and improved instrumentation. During April, a new baseline budget was established for FY-1980, the third major change this fiscal year. This baseline plan reflects a revised test sequence and dates reflecting test needs (particularly instrumentation), and current funding. Costs to date are in good agreement with the current budgets and the authorized funding levels. During April, a revised budget was proposed for FY-1981 and a new budget was proposed for FY-1982. These budgets and their assumptions were presented to NRC in mid-year reviews and important decision elements were identified. A reorganization of the LOFT personnel was announced this month. The LOFT Experimental Program Division was replaced with the LOFT Program Division, managed by Dr. C. W. Solbrig, and with the LOFT Measurements Division, managed by D. J. Hanson.
Date: May 1, 1980
Creator: Kaufman, N. C.
Partner: UNT Libraries Government Documents Department

Summary Results of the Neptun Boil-Off Experiments to Investigate the Accuracy and Cooling Influence of LOFT Cladding-Surface Thermocouples (System 00)

Description: Nine boil-off experiments were conducted in the Swiss NEPTUN Facility primarily to obtain experimental data for assessing the perturbation effects of LOFT thermocouples during simulated small-break core uncovery conditions. The data will also be useful in assessing computer model capability to predict thermal hydraulic response data for this type of experiment. System parameters that were varied for these experiments included heater rod power, system pressure, and initial coolant subcooling. The experiments showed that the LOFT thermocouples do not cause a significant cooling influence in the rods to which they are attached. Furthermore, the accuracy of the LOFT thermocouples is within 20 K at the peak cladding temperature zone.
Date: October 1, 1981
Creator: Tolman, E. L. & Aksan, S. N.
Partner: UNT Libraries Government Documents Department

LOFT Monthly Progress Report for March 1980

Description: During March, evaluation of Test L3-2 continued and preparations began for the next tests, L6-5 and L3-7. Test L6-5 is the first test of the operational transient series and is a loss-of-feedwater incident. Test L3-7 is a small break, similar to L3-2, wherein the emergency coolant flow is adjusted to permit investigation of natural circulation modes. The controlling schedule items involve efforts to add instrumentation to the plant to better characterize system response. Specifically, a new hot-leg penetration will be installed and steam generator water level instrumentation will be improved. For March, costs to date agree very well with budget. Efforts are underway to develop a new baseline program for FY-80 and FY-81 based on a revised test plan and recent budget guidance for FY-81. These efforts are targeted for mid-year review in April.
Date: April 1, 1980
Creator: Kaufman, N. C.
Partner: UNT Libraries Government Documents Department

LOFT Monthly Progress Report for July 1980

Description: During July, the LOFT test sequence underwent careful review which determined that changes would be appropriate. Evaluation of Tests L3-4 and L6-1 indicated they would not add significantly to the information base available from other experiments; therefore, these tests were cancelled. As shown in the Management Summary Schedule included in this report, the next test to be run is L3-5, scheduled for mid-September. Test L3-5 will be a small-break test in the cold leg side of the operating loop of the plant. Work efforts during July concentrated on plant preparation for the mid-September test. Installation of a new small-break path from the cold leg to the blowdown suppression tank, together with the associated new instrumentation installations, were well underway and on schedule at month's end. The Actual spending rate to date is in agreement with current budgets and authorized funding levels.
Date: August 1, 1980
Creator: Kaufman, N. C.
Partner: UNT Libraries Government Documents Department

LOFT Monthly Progress Report for January 1980

Description: During January, the LOFT Project focused on preparing for the next small-break experiment. That test, L3-2, is scheduled for February 6. The test will simulate a break size corresponding to a failure in a one-inch pipe for a 1000 MW(e) commercial power plant. It will be the second small break experiment in LOFT to use nuclear heat. Overall costs for January are very close to budget (greater than 1%). The costing rate will require continued close monitoring. The manpower rate is higher than budgeted and the material rate is less than budgeted. Detailed investigation has shown that these are intentional resource changes, reflecting decisions on the most effective method of work conduct. Thus, they do not indicate a future budget problem.
Date: February 1, 1980
Creator: Kaufman, N. C.
Partner: UNT Libraries Government Documents Department

LOFT Monthly Progress Report for February 1980

Description: The significant event of February was the on-schedule conduct of Test L3-2 on February 7. This was the second LOFT small break test with nuclear heat. It simulated a break of a one-inch pipe in a large commercial plant, whereas Test L3-1 had simulated a break of a four-inch pipe. For Test L3-2, the reactor plant and emergency core cooling system appeared to function as expected, although preliminary data evaluation indicates a higher break flow than expected, with a correspondingly greater depressurization. As the month ended, data evaluation was continuing. During February, Nuclear Regulatory Commission guidance was received that would require Tests L3-5 and L3-6 to use nuclear heat. Previously these tests, the next planned tests, had been designed as nonnuclear tests with and without operating coolant pumps. This revised guidance will require a replanning of the entire program schedule for better facility use. At the end of the month, replanning was underway. Costs for February are right on budget, although manpower levels are somewhat greater than budget. This latter variance results from an intentional manpower-material interchange.
Date: March 1, 1980
Creator: Kaufman, N. C.
Partner: UNT Libraries Government Documents Department

LOFT LTSF Thermocouple Thermal Analysis to Detemrine Transient Temperature Response

Description: A two-dimensional finite element model of the LOFT LTSF thermocouple assembly was developed to study the thermal response of the thermocouples to the expected temperature transient in the L3-4, 5 and 6 experiments. Subjecting the thermocouple model to a 10 F fluid temperature step change resulted in a .10 second delay before 95% of the step change was observed in the thermocouple temperature response. A thermal analysis was performed on the Loft Test Support Facility (LTSF) small-break thermocouple assembly to evaluate the thermal response of the thermocouples during the upcoming L3-4, 5 and 6 small-break experiments. The thermocouple assembly (see Figure 1) consists of 3 Type K thermocouples placed radially through an 8 inch diameter section on the pressurizer relief line in the LTSF. In support of the upcoming L3-4, 5 and 6 experiments the LTSF will be used to define thermal conditions expected during these tests. The temperature transients these thermocouples are required to follow are very rapid step changes. Therefore, it is necessary that these thermocouples have a short response time in order to follow the temperature transient in this line. A two-dimensional finite element model of the thermocouple assembly was constructed using COUPLE, a finite element heat conduction code. The model was subjected to a step change in fluid temperature expected to be 'seen' by the actual thermocouple and its thermal response observed. Details pertinent to this analysis are contained in appropriate sections of this report.
Date: June 23, 1980
Creator: Howell, S. K.
Partner: UNT Libraries Government Documents Department

LOFT Small Break Test Themocouple Installation

Description: The subject thermocouple design has been analyzed for maximum expected hydraulic loading and found to be adequate. The natural frequency of the thermocouple was found to be between the vortex shedding frequencies for the gas and liquid phase so that a tendency for resonance will exist. However, since the thermocouple support will have a restricted displacement, stresses found are below the endurance limit and, thus, are acceptable in respect to fatigue life as well as primary stress due to pressure loading.
Date: May 28, 1980
Creator: Fors, R. M.
Partner: UNT Libraries Government Documents Department

LOFT Monthly Progress Report for October 1980

Description: During the month of October, several significant events occurred. Three tests, L6-1, L6-2, and L6-3, in the anticipated transient series were completed. These tests were conducted to provide information on plant control systems and operator responses to transients in which the initiating event was not a loss of primary coolant. These transient tests and others scheduled for the future will add greatly to predicting responses for such transient conditions. On the 16th and 17th of October, LOFT hosted a technology transfer meeting in which representatives from more than sixty power utilities in the United States and several foreign countries participated. The purpose of this LOFT/Utility Technology Transfer meeting was to provide an open forum through which utility personnel could become better informed about the LOFT project, its past, present, and future experimental program, and how this program could serve industry needs. Several recommendations for LOFT were made by the utility community; these suggestons are being looked at very closely and correspondence with the utility representatives continues. Members of the ACRS committee met in Idaho Falls during October to review the scope of the LOFT program. General approval of the LOFT program was expressed by the ACRS, and several recommendations were made. Requests were also made for additional briefings when LOFT has further scoped the potentially more severe large break transients. Plant preparations were underway during October for the next LOFT test scheduled for mid-December. This test, designated L3-6, will be another in the small break series, with the break occurring in the intact loop of the cold leg. Budget and actuals are showing good agreement for the first month of FY-81, except for a small underrun in the manpower level which is expected to be corrected in the near future.
Date: November 1, 1980
Creator: Kaufman, N. C.
Partner: UNT Libraries Government Documents Department

An Evaluation of the PBF LOFT Lead Rod Test Results Concerning Surface Thermocouple Perturbation Effects

Description: The purpose of the Power Burst Facility Loss of Fluid Test (PBF LOFT) Lead Rod (LLR) Test program was to provide experimental data to characterize the mechanical behavior of LOFT type nuclear fuel rods under loss of coolant accident (LOCA) conditions, simulating the test conditions expected for the LOFT Power Ascension (L2) Test series. Although the LLR tests were not explicitly designed to evaluate cladding surface thermocouple perturbation effects, comparison of the Linear Variable Differential Transformer (LVDT) data for rods instrumented with and without cladding thermocouples provided pertinent information concerning the effects of cladding thermocouples on the time to DNB and time to quench data. Documentation and review of this data is presented in the following report. It will be shown that most of the LLR data indicate that the cladding surface thermocouples did not enhance the rewetting characteristics of the rods they are attached to, even though other evidence shows that the surface clad thermocouples did quench early. Finally, in order to accurately interpret and understand the limitations of the LVDT instrumentation, upon which thermocouple perturbation effects were evaluated, an analysis of the LVDT data as well as a review of the atypical response events that occurred during the LLR tests are presented in appendices to this document.
Date: February 8, 1980
Creator: Carboneau, M. L. & Tolman, E. L.
Partner: UNT Libraries Government Documents Department

LOFT Monthly Progress Report for May 1980

Description: On May 29, 1980, the fifth in a series of nuclear experiments was conducted. The experiment, designated L6-5, simulated events which would follow a loss-of-feedwater to all of the steam generators of a large commercial nuclear powered reactor system. Initial results from the experiment indicate that all significant events occurred as expected. Analysis of experimental results is continuing. In addition to conducting Test L6-5, preparations continued for the next small-break test, L3-7. Currently, efforts for that test are ahead of schedule and targeted for 6/19/80. This test is designed to investigate natural circulation modes and their stability. Of particular interest is two-phase cooling modes with water levels significantly reduced. Costs to date are in good agreement with current budgets and authorized funding levels. However, overall actual expenditures are overstated due to an accrual problem of $250,000, an electrical facility overcharge of approximately $125,000, and a cost transfer of $57,000 related to the two-phase flow loop task. Corrections for this overstatement have been filed.
Date: June 1, 1980
Creator: Kaufman, N. C.
Partner: UNT Libraries Government Documents Department

LOFT Monthly Progress Report for December 1980

Description: On December 10, 1980, LOFT conducted its fifth nuclear test in the L3 Series (small break) as well as the first in the L8 Series (core uncovery). The tests, designated L3-6/L8-1, were run in series with each experiment designated to address specific safety questions. Test L3-6 simulated a four-inch break in a commercial pressurized water reactor. The purpose of this experiment was to investigate the influence of main coolant pump operation on the quantity of fluid which leaves the system and the quantity of fluid in the reactor core region during the experiment. The results of L3-6 are being compared with the results of a previous LOFT test, designated L3-5, which was performed on September 29, 1980. On December 9 and 10, a special review group committee, commissioned by the NRC, visited LOFT. The purpose of the committee's presence here was to study and evaluate the LOFT project, and then report recommendations to the NRC. The NRC would then use this information to help determine how the resources of the project could best be utilized, and which kind and how many tests should be conducted over how long a time period. Recommendations of this committee are expected to be announced early in February. The Quick Look Report on experiment L3-6/L8-1, reviewing initial conditions and limited experimental results, was published during the month. More extensive data analysis will continue for the next several months. The current planned LOFT test schedule and target dates were rescheduled in December which resulted in a major budget revision to the baseline. Successful completion and approval is anticapted by mid-January 1981. Overall current costs are in good agreement with budgets and authorized funding levels.
Date: January 1, 1981
Creator: Leach, L. P.
Partner: UNT Libraries Government Documents Department

LOFT Monthly Progress Report for November 1980

Description: During November major work efforts were directed towards preparation for Test L3-6/L8-1. These tests, to be run in sequence, will evalute the system effects of primary coolant pump operation during a small break LOCA (L3-6), and are to obtain a partial core uncovery to aid in the planning and conduct of future core uncovery experiments (L8-1). Plant modifications in preparation for the December test included installation of a new PC-3 gamma densitometer to measure the density of fluid coming from the steam generator and the installation of the EPRI Liquid Level Detector system to measure levels of fluid during the core uncovery experiment. Other key efforts concerned planning for test conduct and safety analysis. On November 6 and 7 the LOFT Review Group met in Idaho Falls to evaluate the activities on LOFT since its last meeting in February. Future test plans, budgets, the man-machine (AOC) program, and various other topics presented by LOFT personnel and consultants were discussed. Several suggestions were presented by those in attendance. These comments were directed to the areas of test scheduling and the kinds of tests to be run as well as how LOFT could better communicate with utilities and vendors to transmit information to the general nuclear power industry. Overall costs are in good agreement with current budgets and authorized funding levels. In the areas of fuel design and analysis, a temporary overrun will be shown for the first few months of the fiscal year. This overrun is due to an Exxon billing received ahead of schedule. A recovery plan has been implemented and actuals are expected to be in agreement with budget by January 1981.
Date: December 1, 1980
Creator: Kaufman, N. C.
Partner: UNT Libraries Government Documents Department

LOFT Monthly Progress Report for September 1980

Description: The fourth nuclear powered small break test (L3-5/5A) was conducted on September 29, 1980. The test was initiated from a steady state operating condition wherein the core was generating heat at a maximum rate of approximately 52 kW/m. The test consisted of two parts: L3-5 simulated a 4-in. pipe break in a commerical pressurized water reactor; the second part, L3-5A, was intended to investigate natural circulation and steam generator heat transfer modes and also plan recovery using secondary system control in a situation where the pipe break and the ECCS accumulator are isolated from the primary coolant system. Initial test data indicated that all systems functioned as expected. The several hundred measurements of system coolant and reactor core conditions made during the three hour duration of the test will continue to be analyzed over the next several months. Preparations were also underway for conduting three tests in the Anticipated Transient Series. These tests, designated L6-1, L6-2, and L6-3 will provide information on plant control systems and operator response to transients in which the initiating event is not a loss-of-primary coolant. The transient tests to be conducted during September and others scheduled in the future will add greatly to understanding responses necessary to a transient condition. September 1980 marked the successful completion of FY-1980. Final closing values for each of the funding sources are included as part of this report. NRC and foreign funded tasks closed FY-1980 with underruns documented by identifying committed and uncommitted carryovers.
Date: October 1, 1980
Creator: Kaufman, N. C.
Partner: UNT Libraries Government Documents Department

A New Assessment of the LOFT-Wyle Blowdown Test WSB03R Using RELAP5-3D

Description: The RELAP-3D (version bt03) computer program was used to assess the LOFT-Wyle blowdown test (WSB03R). The primary goal of this new assessment is to represent faithfully the experimental facility and instrumentation using the latest three-dimensional fluid flow modeling capability available in RELAP5-3D. In addition, since RELAP5-3D represents a relatively new and significant upgrade to the capabilities of the RELAP5 series of computer programs, this study serves to add to its growing assessment base. The LOFT-Wyle Transient Fluid Calibration test facility consisted of an approximately 5.4m3 pressure vessel with a flow skirt which created an annulus that acted as a downcomer. An instrumented blowdown loop with an orfice was connected to the downcomer. This facility, built to calibrate the orfices used in several of the LOFT experiments, simulated the LOFT reactor vessel and broken loop cold leg. For the present assessment an existing RELAP5 model developed at INEEL was corrected and upgraded. The model corrections included: (1) employing the proper measured downcomer thickness, (2) positioning the experimental instrumentation in its correct location, and (3) setting the fluid conditions to their measured initial values. Model upgrades included: (1) use of a more finely-detailed fluid component nodalization, (2) explicit modeling of the experimental facility beyond the blowdown orifice, (3) addition of heat structure components to represent the heat capacity of structural material, and (4) use of three-dimensional fluid components to model asymmetrical portions of the facility. The new assessment highlights the need to model explicitly the effects of heat storage in structural materials for slowly evolving transients. The assessment also highlights the sensitivity of choked-flow limited calculations to: (1) the model employed, (2) input discharge coefficient values and/or (3) input nonequilibrium values. In addition, the present assessment demonstrates that an instability in the calculated liquid fraction at the base of the downcomer obtained ...
Date: April 16, 2002
Creator: Bandini, B.R.; Aumiller, D.L. & Tomlinson, E.T.
Partner: UNT Libraries Government Documents Department