Westinghouse Owners Group Irradiation Effects on Reactor Vessel Supports PDF Download

Author: Warren H. Bamford
Publisher:
ISBN:
Category : Nuclear pressure vessels
Languages : en
Pages :

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Category :
Languages : en
Pages : 202

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The purpose of this report is to present the findings from the work done in accordance with the Task Action Plan developed to resolve the Nuclear Regulatory Commission (NRC) Generic Safety Issue No. 15, (GSI-15). GSI-15 was established to evaluate the potential for low-temperature, low-flux-level neutron irradiation to embrittle reactor pressure vessel (RPV) supports to the point of compromising plant safety. An evaluation of surveillance samples from the High Flux Isotope Reactor (HFIR) at the Oak Ridge National Laboratory (ORNL) had suggested that some materials used for RPV supports in pressurized-water reactors could exhibit higher than expected embrittlement rates. However, further tests designed to evaluate the applicability of the HFIR data to reactor RPV supports under operating conditions led to the conclusion that RPV supports could be evaluated using traditional method. It was found that the unique HFIR radiation environment allowed the gamma radiation to contribute significantly to the embrittlement. The shielding provided by the thick steel RPV shell ensures that degradation of RPV supports from gamma irradiation is improbable or minimal. The findings reported herein were used, in part, as the basis for technical resolution of the issue.

Author: R. E. Johnson
Publisher:
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Category : Nuclear pressure vessels
Languages : en
Pages :

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Author: Lendell E. Steele
Publisher: ASTM International
ISBN: 9780803102293
Category : Technology & Engineering
Languages : en
Pages : 290

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Author: Lendell E. Steele
Publisher: ASTM International
ISBN: 9780803100664
Category : Freshwater microbiology
Languages : en
Pages : 269

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Author: U.S. Nuclear Regulatory Commission
Publisher:
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Category : Nuclear energy
Languages : en
Pages : 592

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Author: Lendell E. Steele
Publisher: ASTM International
ISBN: 9780803102637
Category : Technology & Engineering
Languages : en
Pages : 240

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Author: SE. Yanichko
Publisher:
ISBN:
Category : Nuclear pressure vessels
Languages : en
Pages : 38

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Westinghouse recognized that the disruption of the atomic lattice of metals by collision from energetic neutrons could alter the properties of the metals to such an extent that the changes could be of engineering significance. Furthermore, it was recognized that a physical-metallurgical phenomenon such as aging, both thermal and mechanical, also could alter the properties of a metal over its service life. Because of the potential changes in properties, reactor vessel radiation surveillance programs to monitor the effect of neutron radiation and other environmental factors on the reactor vessel materials during operational conditions over the life of the plant were initiated for Westinghouse plants with the insertion of reactor vessel material radiation surveillance capsules into the Yankee Atomic Company's Yankee-Rowe plant in 1961 [1-3].

Author: MA. Sokolov
Publisher:
ISBN:
Category : Annealing
Languages : en
Pages : 20

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One of the options to mitigate the effects of irradiation on reactor pressure vessels (RPVs) is to thermally anneal them to restore the toughness properties that have been degraded by neutron irradiation. Even though a postirradiation anneal may be deemed successful, a critical aspect of continued RPV operation is the rate of embrittlement upon reirradiation. There are insufficient data available to allow for verification of available models of reirradiation embrittlement or for the development of a reliable predictive methodology. This is especially true in the case of fracture toughness data. Under the U.S.-Russia Joint Coordinating Committee for Civilian Nuclear Reactor Safety (JCCCNRS), Working Group 3 on Radiation Embrittlement, Structural Integrity, and Life Extension of Reactor Vessels and Supports agreed to conduct a comparative study of annealing and reirradiation effects on RPV steels. The Working Group agreed that each side would irradiate, anneal, reirradiate (if feasible), and test two materials of the other. Charpy V-notch (CVN) and tensile specimens were included. Oak Ridge National Laboratory (ORNL) conducted such a program (irradiation and annealing, including static fracture toughness) with two weld metals representative of VVER-440 and VVER-1000 RPVs, while the Russian Research Center-Kurchatov Institute (RRC-KI) conducted a program (irradiation, annealing, reirradiation, and reannealing) with Heavy-Section Steel Technology (HSST) Program Plate 02 and Heavy-Section Steel Irradiation (HSSI) Program Weld 73W. The results for each material from each laboratory are compared with those from the other laboratory. The ORNL experiments with the VVER welds included irradiation to about 1 x 1019 n/cm2 (>1 MeV), while the RRC-KI experiments with the U.S. materials included irradiations from about 2 to 18 x 1019 n/cm2 (>1 MeV). In both cases, irradiations were conducted at ~290 °C and annealing treatments were conducted at ~454 °C. The ORNL and RRC-KI experiments have shown generally good agreement for both the Russian and U.S. steels. While recoveries of the Charpy 41-J transition temperatures were substantial in all cases, significantly less recovery of the lateral expansion and shear fracture in some cases (no recovery in one case) deserves further attention. The RRC-KI results for the U.S. steels showed reirradiation embrittlement rates which are conservative relative to the lateral shift prediction based on Charpy impact energy.

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Languages : en
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