INL/EXT-13-28526 - Final Report - Assessment of Testing Options for the NTR at the INL - Executive Summary

Aug 28, 2026

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NTR development hinges on verifying a flight-ready engine while maintaining safe containment of radioactive materials. The report evaluates three validation approaches, including full-power above-ground testing, SAFE subsurface exhaust filtering, and driver-reactor fuel testing followed by an integrated first space test. A reexamination for implementation at the Idaho National Laboratory analyzes site geology, gas transport, and cost for non-nuclear sub-scale model validation and for a potential nuclear-furnace-equivalent facility.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages41

Reading Time1 h 43 min

AccessFree to download

Executive Summary

Testing Options for NTR Verification

Reexamination at the INL Site

SAFE Method Advantages and Cost Assessment

Introduction

Purpose and Background

INL/EXT-13-28526 Final Report – Assessment of Testing Options for the NTR atthe INL Steven D. Howe Travis McLing Michael McCurry Mitchell Plummer February 2013 The INL is a U.S. Department of Energy National Laboratory operated by Battelle Energy Alliance INL/EXT-13-28526 Final Report – Assessment of Testing Options for the NTR at the INL Steven D. Howe Travis McLing Michael McCurry Mitchell Plummer February 2013 Idaho National Laboratory Idaho Falls, Idaho 83415 [http://www.inl.gov](http://www.inl.gov) Prepared for the U.S. Department of Energy Office of Nuclear Energy Under DOE Idaho Operations Office Contract DE-AC07-05ID14517 Final Report-Assessment of Testing Options for the NTR at the INL Steven D. Howe, Travis Mc Ling, Michael McCurry, Mitchell Plummer Executive Summary One of the main technologies that can be developed to dramatically enhance the human exploration of space is the nuclear thermal rocket (NTR) . Several studies over the past thirty years have shown that the NTR can reduce the cost of a lunar outpost, reduce the risk of a human mission to Mars, enable fast transits for most missions throughout the solar system, and reduce the cost and time for robotic probes to deep space. Three separate committees of the National Research Council of the National Academy of Sciences have recommended that NASA develop the NTR. One of the primary issues in development of the NTR is the ability to verify a flight ready unit. Three main methods can be used to validate safe operation of a NTR, after which a fully complete engine could be launched into orbit for the first full power test. The NTR testing options include 1) Full power, full duration test in an above ground facility that scrubs the rocket exhaust clean of any fission products; 2) Full power , full duration test using the Subsurface Active Filtering of Exhaust (SAFE) technique to capture the exhaust in subsurface strata; 3) Test of the reactor fuel at temperature and power density in a driver reactor with subsequent first test of the fully integrated NTR in space. The first method, the above ground facility, has been studied in the past [Rocketdyne, INL, MSFC] . The second method, SAFE, has been examined for application at the Nevada Test Site. The third method relies on the fact that the Nuclear Furnace series of tests in 1971 showed that the radioactive exhaust coming from graphite based fuel for the NTR could be completely scrubbed of fission products and the clean hydrogen flared into the atmosphere. Under funding from the MSFC, the Center for Space Nuclear Research (CSNR) at the Idaho National laboratory (INL) has completed a reexamination of Methods 2 and 3 for implementation at the INL site. In short, the effort performed the following: x Assess the geology ofthe INL site and determine a location suitable SAFE testing; x Perform calculations of gas transport throughout the geology; x Produce a cost estimate of a non-nuclear , sub-scale test using gas injection to validate the computational models; x Produce a preliminary cost estimate to build a nuclear furnace equivalent facility to test NTR fuel on a green field location on the INL site. Reexamination of Method 3, involving test of the reactor fuel in a driver reactor indicated that anew Category I facility would be required, which would cost in excess of $250M. Reexamination of Method 2, showed that the INL geology is substantially better suited to the SAFE testing method than the NTS site. The existence of impermeable interbeds just above the sub-surface aquifer ensure that no material from the test, radioactive or not, can enter the water table. Similar beds located just below the surface will prevent any gaseous products from reaching the surface for dispersion. The extremely high permeability of the basalt strata between the interbeds should allow rapid dispersion of the rocket exhaust. In addition, the high permeability suggests t

FAQs

What problem does the report focus on for nuclear thermal rockets (NTR)?

The report addresses how to verify a flight-ready NTR unit while ensuring safe operation and effective handling of radioactive exhaust and fission products.

What are the three main NTR testing options compared in the report?

The options are: (1) full-power, full-duration above-ground testing with scrubbed exhaust; (2) full-power, full-duration SAFE subsurface exhaust filtering; and (3) reactor fuel testing in a driver reactor, followed by a first integrated NTR test in space.

Why does the report favor the SAFE testing option at the INL site?

The INL geology is described as better suited for SAFE testing due to impermeable interbeds that protect the water table, high permeability basalt strata that support rapid dispersion, and an overall cost advantage including a non-nuclear sub-scale validation approach.

Aug 28, 2026

Upload by Himbo