skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Prometheus Hot Leg Piping Concept

Abstract

The Naval Reactors Prime Contractor Team (NRPCT) recommended the development of a gas cooled reactor directly coupled to a Brayton energy conversion system as the Space Nuclear Power Plant (SNPP) for NASA's Project Prometheus. The section of piping between the reactor outlet and turbine inlet, designated as the hot leg piping, required unique design features to allow the use of a nickel superalloy rather than a refractory metal as the pressure boundary. The NRPCT evaluated a variety of hot leg piping concepts for performance relative to SNPP system parameters, manufacturability, material considerations, and comparison to past high temperature gas reactor (HTGR) practice. Manufacturability challenges and the impact of pressure drop and turbine entrance temperature reduction on cycle efficiency were discriminators between the piping concepts. This paper summarizes the NRPCT hot leg piping evaluation, presents the concept recommended, and summarizes developmental issues for the recommended concept.

Authors:
 [1];  [2]
  1. Bechtel Bettis, Inc., Bettis Atomic Power Laboratory, West Mifflin, PA 15122 (United States)
  2. KAPL, Inc., Knolls Atomic Power Laboratory, Schenectady, NY 12301 (United States)
Publication Date:
OSTI Identifier:
21054553
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 880; Journal Issue: 1; Conference: International forum-STAIF 2007: 11. conference on thermophysics applications in microgravity; 24. symposium on space nuclear power and propulsion; 5. conference on human/robotic technology and the vision for space exploration; 5. symposium on space colonization; 4. symposium on new frontiers and future concepts, Albuquerque, NM (United States), 11-15 Feb 2007; Other Information: DOI: 10.1063/1.2437489; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
22 GENERAL STUDIES OF NUCLEAR REACTORS; COMPARATIVE EVALUATIONS; DESIGN; EFFICIENCY; ENERGY CONVERSION; HEAT ENGINES; HEAT RESISTING ALLOYS; HTGR TYPE REACTORS; NICKEL; NUCLEAR POWER PLANTS; PERFORMANCE; PRESSURE DROP; REACTOR MATERIALS; REFRACTORY METALS; SPACE PROPULSION REACTORS; TURBINES; NESDPS Office of Nuclear Energy Space and Defense Power Systems

Citation Formats

Gribik, Anastasia M., and DiLorenzo, Peter A. Prometheus Hot Leg Piping Concept. United States: N. p., 2007. Web. doi:10.1063/1.2437489.
Gribik, Anastasia M., & DiLorenzo, Peter A. Prometheus Hot Leg Piping Concept. United States. doi:10.1063/1.2437489.
Gribik, Anastasia M., and DiLorenzo, Peter A. Tue . "Prometheus Hot Leg Piping Concept". United States. doi:10.1063/1.2437489.
@article{osti_21054553,
title = {Prometheus Hot Leg Piping Concept},
author = {Gribik, Anastasia M. and DiLorenzo, Peter A.},
abstractNote = {The Naval Reactors Prime Contractor Team (NRPCT) recommended the development of a gas cooled reactor directly coupled to a Brayton energy conversion system as the Space Nuclear Power Plant (SNPP) for NASA's Project Prometheus. The section of piping between the reactor outlet and turbine inlet, designated as the hot leg piping, required unique design features to allow the use of a nickel superalloy rather than a refractory metal as the pressure boundary. The NRPCT evaluated a variety of hot leg piping concepts for performance relative to SNPP system parameters, manufacturability, material considerations, and comparison to past high temperature gas reactor (HTGR) practice. Manufacturability challenges and the impact of pressure drop and turbine entrance temperature reduction on cycle efficiency were discriminators between the piping concepts. This paper summarizes the NRPCT hot leg piping evaluation, presents the concept recommended, and summarizes developmental issues for the recommended concept.},
doi = {10.1063/1.2437489},
journal = {AIP Conference Proceedings},
number = 1,
volume = 880,
place = {United States},
year = {Tue Jan 30 00:00:00 EST 2007},
month = {Tue Jan 30 00:00:00 EST 2007}
}
  • The Naval Reactors Prime Contractor Team (NRPCT) recommended the development of a gas cooled reactor directly coupled to a Brayton energy conversion system as the Space Nuclear Power Plant (SNPP) for NASA's Project Prometheus. The section of piping between the reactor outlet and turbine inlet, designated as the hot leg piping, required unique design features to allow the use of a nickel superalloy rather than a refractory metal as the pressure boundary. The NRPCT evaluated a variety of hot leg piping concepts for performance relative to SNPP system parameters, manufacturability, material considerations, and comparison to past high temperature gas reactormore » (HTGR) practice. Manufacturability challenges and the impact of pressure drop and turbine entrance temperature reduction on cycle efficiency were discriminators between the piping concepts. This paper summarizes the NRPCT hot leg piping evaluation, presents the concept recommended, and summarizes developmental issues for the recommended concept.« less
  • This paper reports on three 0.5% hot-leg small-break loss-of-coolant accident experiments that are conducted at the ROSA-IV Large-Scale Test Facility (LSTF), a 1/48 volumetrically scaled full-height model of a pressurized water reactor. Three experiments simulate breaks located at the side, bottom, and top of the horizontal hot-leg piping to investigate the effect of break orientation on system thermal-hydraulic responses. Although the overall system responses in the three experiments are qualitatively the same, the break flow rate is affected significantly by the break orientation for most of the time preceding the initiation of core uncovering: The break flow rate is largestmore » for the bottom break and smallest for the top break. The RELAP5/MOD2 code fails to predict the differences in break flow rate observed in the experiments. However, several modifications, based on separate-effect experiments, made particularly to the break flow calculation models enable this code to simulate the experimental results well.« less
  • Countercurrent reflux core cooling is one of the possible mechanisms for heat removal during small-break loss-of-coolant accidents (LOCAs) in pressurized water reactors (PWRs) with U-tube steam generators. The objective of this analysis is to obtain an algebraic correlation for flooding and unflooding in a pressurized water reactor (PWR) hot leg during reflux core cooling. This correlation may be used in loss-of-coolant accident analysis codes such as RELAP5. The one-dimensional two-fluid model equations are solved to obtain a void fraction profile along the pipe. A jump condition is included in the model to account for the possibility of a hydraulic jump.more » The flooding correlation by Mishima and Ishii is used to determine the flooding point. The model is validated against the scaled-down data of Krolewski and the full-scale data of Ohnuki, Adachi, and Murao. Reducing the coefficient of the flooding correlation to match the full-scale data is necessary to account for the effect of diameter size. Based on the validated model, a flooding correlation is obtained along the lines of the Wallis flooding criterion. It is further shown that under the conditions prevalent during PWR refluxing, the hysteresis between flooding and unflooding is not relevant, so the same correlation is valid for both.« less
  • The RETRAN-02 computer code was used to perform a best-estimate analysis of a 7.52-cm-diam hotleg break in a three-loop Westinghouse pressurized water reactor. This break size produced a net primary coolant mass depletion through the early portion of the transient. The primary system started to refill only after the accumulator valves opened. As the primary system refilled, there were extreme temperature differentials around the system with cold, denser fluid collecting at the lower elevations and two-phase fluid at higher elevations.