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Elimination of TOA corrosion limits

Description: In 1958, planned large scale use of the new I & E slug geometry at more severe operating conditions than had been generally experienced suggested a possible compromise in reactor life and safety if a reasonable degree of rupture control with the new type of element was not maintained. The formalized slug corrosion limit (Top-of-Annulus limit) was issued as a Process Standard at the time of the full-scale loading of I & E geometry fuel elements to provide this limit for reactor operation. The loading of I & E slugs at all reactors has been accomplished and initial power level increases have been made. To date, 67 I & E ruptures have been sustained including both `hole` and `annulus` failures. The type and behavior of ruptures to be expected with I & E geometry are now characterized. Recent studies have indicated that the I & E failure experience is consistent with the general mathematical rupture model formulated from analysis of solid slug experience. Increased confidence in the use of this model in combination with Optimization Studies permits greater emphasis to be placed on the rupture model as a guide for reactor operation. It is the purpose of this report to present the basis for substituting the rupture model for the TOA corrosion limits for rupture control purposes.
Date: May 12, 1959
Creator: Graves, S.M.
Partner: UNT Libraries Government Documents Department

FFTF transient overpower accident: a perspective

Description: This paper is a reflection on the current understanding of the unprotected transient overpower (TOP) accident, in order to place it in perspective with regard to FFTF core energetics. The experimental data base is addressed, wtih particular emphasis on the E and H-series data, and its relevance to axial failure location and hydraulic fuel sweepout is considered. It is shown that the only way in which TOP could lead to a sizeable energy release is if either total plugging takes place or a plug at the radial center of the subassemblies propagates to the hex can walls prior to neutronics shutdown. (DLC)
Date: February 1, 1975
Creator: Waltar, A.E.
Partner: UNT Libraries Government Documents Department

Effects of burnup on fuel failure. Power burst tests on fuel rods with 13,000 and 32,000 MWd/MTU burnup

Description: Results are presented from preliminary tests designed to investigate the behavior of preirradiated fuel rods under reactivity initiated accident (RIA) conditions. The tests were conducted in 1970 as part of the SPERT/Capsule Driver Core (CDC) program. The report was intended to be published in a series of Idaho Nuclear Corporation Interim Technical Reports (IN-ITRs); however, the CDC program was terminated before the report could be released. In September 1975, the Nuclear Regulatory Commission concluded that the data contained in the report could be a valuable reference in planning future water reactor safety program tests and requested its release.
Date: January 1, 1976
Creator: Miller, R.W.
Partner: UNT Libraries Government Documents Department

Quarterly progress report on the creepdown and collapse of Zircaloy fuel cladding program sponsored by the NRC Division of Reactor Safety Research for October--December 1975

Description: The creepdown and collapse study on Zircaloy fuel cladding is concerned with the deformation behavior of cladding under normal and near-normal reactor operating conditions. Progress is reported on two phases of the program: (1) collapse testing and (2) development and fabrication of deformation-monitoring equipment. Sufficient collapse testing has been done to begin the analysis of the test data. It is apparent that all three of the independent variables used in this study (pellet-to-pellet gap, pellet-to-cladding gap, and temperature) play major roles in the collapse phenomenon. Tentative trends are presented but they constitute an insufficient basis for the quantitative formulation of a collapse model at this time. The instrumentation for deformation monitoring has been developed and provision has been made for automatic control of the data gathering system and for protection of the monitoring coils from damage caused by collapse of the specimen tube.
Date: February 1, 1976
Creator: Hobson, D. O.
Partner: UNT Libraries Government Documents Department

Computation of initial stage of RBMK reactor fuel channel vessel rupture

Description: Objective of this work is estimation of temperature and time characteristics for rupture of the zirconium pipe which is the RBMK reactor fuel channel (FC) vessel under emergencies. As an emergency the zirconium pipe temperature rise process is considered which results in loss of pipe material strength properties and pipe rupture under the action of internal pressure P=80MPa. The work was carried out under Task Order 007 of University of California - VNIIEF Subcontract No. 0002P0004-95. The problem formulation is stated in Protocol (Task 3, Appendix 3) of the Russian-American Workshop which was held in December, 1994 in Los Alamos. Physical-mechanical and geometry characteristics of structure elements (FC vessel with graphite ring and graphite slug) are presented by NIKIET. The temperature mode of the structure is taken in conformity with the NIKIET data obtained with the RELAP5/MOD3 code. Numerical simulation of structure element behavior in an emergency is performed using the DRAKON program comlex oriented to solving strength problems for complex spatial structures at intense dynamic loading. The {open_quotes}DRAKON{close_quotes} program complex is described and compared with similar western codes in its capabilities.
Date: December 31, 1995
Creator: Pevnitsky, A.V.; Solovyev, V.P. & Abakumov, A.I.
Partner: UNT Libraries Government Documents Department

Fuel element performance

Description: For some time, it has been considered that cycling natural uranium fuel elements through the {alpha}-{beta} transformation point (approx. 662 C) is a contributing factor in split type ruptures. This hypothesis is based upon the fact that the transition temperature, a one percent increase in volume occurs. It is reasoned that as the uranium hardens under irradiation, it becomes progressively less able to adjust to the severe stresses imposed by the volume change as the material cycles through the {alpha}-{beta} transformation point. Failure finally occurs by a splitting of the core. The IPD is now interested in evaluating some of the effects of reactor operation upon fuel performance. It appears that the life of solid fuel elements may be prolonged if sudden changes in reactor operation can be minimized. It is the purpose of this report to bring to the attention of FPD management the new ideas being developed in the IPD on split type failures and to point out the effect such thinking may have on future fuel element development activities. Based on a discussion with personnel in PID, there is reasonable hope that the performance of solid fuel elements will not be limited by the {alpha}-{beta} transformation, and that the solid geometry can be used to advantage in all HAPO production reactors.
Date: December 31, 1957
Creator: Hagie, L. T.
Partner: UNT Libraries Government Documents Department

Slug jacket failures, January 1952

Description: There were twenty slug jacket failures during the month of January 1952. Of these, fourteen were end cap failures, five were split slugs and one has not been removed. A total of 311.4 hours of outage time was required for removal of these ruptured slugs from the reactors. The detection, removal and radiation aspects, along with the slug data, are shown on the attached sheets.
Date: February 13, 1952
Creator: Lewis, C. G.
Partner: UNT Libraries Government Documents Department

Design of production test IP-423-A-FP evaluation of uranium fuel cores having virus heat treatments

Description: Fuel element warp occurring during the irradiation period is considered to be one of the major fuel element dimensional stability problems. Warp has been shown to correlate with accelerated corrosion attack. and also can contribute to stuck fuel charges, particularly in bumpered or self-supported charges where the annular clearances are reduced due to the presence of the projection rails. Thus, any process which offers a potential for reducing the average warp should be evaluated. Preliminary tests offsite have indicated that the use of a commercially available oil for a quench medium following beta heat treatment produces a fuel core with less residual stresses and a slightly finer and more uniform grain size than that produced by the present HAPO method of water quench. Thus, adoption of an oil quench nay offer a means whereby warp can be reduced without incurring costly revisions to equipment or fabrication processes. This report presents an irradiation testing program to evaluate the performance of oil quenched cores and to determine the optimum core heat treatment.
Date: January 5, 1962
Creator: Hodgson, W. H. & Clinton, M. A.
Partner: UNT Libraries Government Documents Department

C reactor overbore fuel examination

Description: On April 16, 1962, the fuel charge in overbore tube 3062-C sustained a failure, and upon examination after discharge was found to contain three split failures and three ``worm tracked`` elements (depression in the aluminum cladding apparently the result of uranium cleavage and subsequent yielding of the cladding). These failures occurred approximately ten days following a period of reactor neutron flux cycling, and during a second cycle at C Reactor. In addition to the failures, a total of 17 elements, from nine separate fuel charges, contained worm tracks. Four of these elements were sent to Radiometallurgy Laboratory for destructive examination, to determine the mechanism of the suspected uranium cleavage.
Date: April 18, 1963
Creator: Hladek, K. L.; Teats, R. & Weakley, E. A.
Partner: UNT Libraries Government Documents Department

Examination of enriched ruptured element from 2955C (RM 452)

Description: A CIIIE (enriched) element, one of two elements which failed April 5, 1962 in tube 2955C, was shipped to the Radiometallurgy Laboratory for detailed examination. The element was 21st from the downsteam end. A more severe rupture which occurred in the 19th piece from the downsteam end was believed to have caused the initial rupture indication. After a hot startup a heat cycle developed in the part of the reactor containing tube 2955 increasing the bulk water temperature about 20 per cent. At about the same time the temperature rise was noted, the first rupture indication was seen. The reactor was shutdown 40--45 minutes later, tube 2955 was pushed, and the two ruptures were found. The element was classed as a ``hot spot`` failure. Detailed examination was requested to determine the cause of failure and characterize the nature of any observed corrosion.
Date: August 21, 1962
Creator: Gruber, W. J.
Partner: UNT Libraries Government Documents Department

Interim goal exposure plans for O-III-NB and O-III-EB material for B, D, DR and F reactors

Description: The purpose of this report is to recommend variable goal plans for natural and enriched bumper fuel elements, specifically for 0-III-NB and 0-III-EB materials, to be irradiated at the B, D, DR, and F Reactors. The average goal exposure for all bumper fuel elements at D Reactor was specified to be 900 MWD/T, with provisions being made for revision by normal procedures. Exposures for enriched bumper material at the B, M. and F Reactors were not specified in the PITA supplement authorizing charging of this material.
Date: February 13, 1961
Creator: Bloomstrand, R. R.
Partner: UNT Libraries Government Documents Department

Production test IP-394-I: Use of PT-216 fuel columns for routine axial flux determination

Description: It is the objective of this production test to authorize the use of PT IP-216-A (Quality Certification) fuel columns and supplementary numbered columns are required for obtaining routine axial flux measurements suitable for metal performance analysis.
Date: February 13, 1961
Creator: Graves, S. M.
Partner: UNT Libraries Government Documents Department

Radiochemistry for the rupture of a Zircaloy-2 clad thermocoupled fuel element in KER Loop-1 on May 12, 1961

Description: On the 1600--2400 shift, May 12, 1961, the delayed neutron monitor on KER Loop 1 gave a high coolant activity signal indicating a possible fuel element failure in this loop. KE Reactor was shut down immediately thereafter. This report is being written to summarize the events pertinent to the KE Reactor scram and to discuss the results and significance of data from the analyses of coolant samples taken from the KER Loop-1 System.
Date: August 18, 1961
Creator: Perrigo, L. D.
Partner: UNT Libraries Government Documents Department

Post irradiation examination of transverse cracked rupture from 2986 DR (Rm 427)

Description: An O III N, I and E dingot element exhibited several transverse cracks when it failed in tube 2986 DR. Detailed examination in the Radiometallurgy Laboratory was requested to determine the cause of failure and obtain the ingot number. The element was so badly damaged that it was impossible to determine the exact cause of failure. Reaction between the coolant and fuel occurred at the internal surface around the spire over the total length of the element. Reaction was the greatest near the midpoint where the transverse cracks occurred and was least in the male end. Metallography of both longitudinal and transverse sections revealed that the metal quality of the fuel vas good. Cracks which originated from the oxide extended in both the longitudinal and transverse directions. The fuel near the core, which was insulated by oxide, was annealed but had not been heated into the uranium beta phase. One transverse crack which appeared to have water entry was observed approximately two inches from the male end. The ingot number was UZ 5751 B. After removal of the cladding at the ends, the uranium was bright dip etched and no defects were observed in the surface metal.
Date: August 28, 1961
Creator: Gruber, W. J.
Partner: UNT Libraries Government Documents Department

Radiometallury examination of three overbore split failures from 3062C (RM C-422)

Description: Three overbore elements, 75Zl2, 75Zl4, and 75Zl5 were discharged from 3062C on April 16, 1962 with longitudinal splits after an exposure of 676. The three elements, two of which had completely split apart, were received on July 5, 1963 to determine the cause of failure. All three elements had failed in the same manner with several full length longitudinal cracks in the uranium extending radially from the canwall to about midway in the core. The failure mechanism was found to be the same as that observed during the examination of worm-tracked overbore elements under RM 456 in which incipient failures had occurred from excessive core temperatures. In two out of the three worm-tracked elements the interior core temperatures had exceeded the beta transformation point as a result of severe cycling conditions. In these three ruptures from 3062C the maximum core temperature had not reached the beta phase; however, the failures were undoubtedly caused by excessive hoop stresses resulting from high internal core temperatures.
Date: October 22, 1963
Creator: Teats, R.
Partner: UNT Libraries Government Documents Department

Proposed irradiation of substandard fuel elements. Phase 2

Description: The reference letter outlined an initial proposal for irradiating limited categories of substandard fuel elements in the upstream positions of the reactor process tubes. As Phase 2 of this program, a comprehensive study has been made of all current fuel reject categories with respect to use in the upstream low rupture potential positions. This report describes additional ``reject`` fuel categories, the estimated cost savings, rupture potential, and procedures for identifying and handling pieces to fulfill the combined requirements of Phase 1 and 2 of this program. Future methods for grading fuel elements to reduce rupture potential in the downstream reactor positions are also outlined in this report.
Date: April 22, 1963
Creator: Blanton, W. A. & Weakley, E. A.
Partner: UNT Libraries Government Documents Department

Scram recovery data preceding ``C`` overbore fuel failures

Description: Considerable interest has been generated concerning the recent series of overbore fuel failures at C Reactor. It therefore is appropriate to document the operating conditions which existed prior to the failures. This report presents a chronological description of events leading up to the failures, and graphs and tables of various pertinent parameters.
Date: May 15, 1962
Creator: Wood, S. A.
Partner: UNT Libraries Government Documents Department

Production Test IP-237-A, irradiation of enriched seven-rod cluster elements for ETR testing

Description: Two Zircaloy-2 jacketed seven-rod cluster elements will be irradiated in the 3674 KE front-to-rear test hole to an exposure of 1000 MWD/T and two elements will be irradiated in the 3674 KW front-to-rear test hole to an exposure of 2000 MWD/T. After irradiation, the elements will be sent to the ETR where they will be ruptured during reactor operation to determine the failure characteristics of co-extruded Zircaloy-2 jacketed cluster elements.
Date: February 23, 1959
Creator: Kratzer, W. K.
Partner: UNT Libraries Government Documents Department

Net return course - operational severity index formuli

Description: This document presents a nomograph from which the relationship between reactor operating parameters, tube power, and outlet temperature can be correlated with rupture rate. The index indicates the severity of the reactor climate during irradiation and does not include the metal quality parameters defined in the rupture rate equation. The general form of the Operational Severity Index Equation is OSI=P{sup 3.3}/1000{times}t{sub 0}{sup 8.7}/100, where OSI, is the unitless Operational Severity Index, P is the tube power in kW, and t{sub 0} is the tube outlet temperature, in degrees C.
Date: December 28, 1959
Partner: UNT Libraries Government Documents Department