• The bipartisan proposal secured by Senators Crapo, Risch, and Whitehouse would fund a program to reuse spent naval fuel for advanced reactor technologies.
• A pilot plant is planned to be built at the Idaho National Laboratory.

Sen. Mike Crapo (R-ID)

The Idaho National Laboratory (INL) nuclear research effort will benefit from a $15 million pilot program secured by Idaho Senators Mike Crapo (R-ID) and James Risch (R-ID), and Rhode Island Senator Sheldon Whitehouse (D-RI) to recycle spent naval fuel via down blending for use in advanced nuclear reactors.

The proposal by the senators was adopted this week by the full Senate on a 87-9 vote. The Senate is currently debating the Fiscal Year 2019 Energy and Water Appropriations bill.

The demonstration project would down blend high-enriched uranium (HEU) fuel to a level where it could be used in advanced nuclear reactors.  These reactors require a fuel known as high-assay low enriched uranium (HALEU), enriched to less than 20% of fissile content (U235).  The Idaho Falls Post Register reported that the HALEU could be used in advanced reactors which are also small modular reactors (SMRs) that are not based on light water (LWR) technologies.

The Senators explained their intent in a joint press release;

“Reusing higher-enriched spent HEU naval fuel produces reusable HALEU. The recycled fuel has the potential to reduce waste that would otherwise be disposed at taxpayers’ expense or require long-term repository disposal.”

There is no plan for a deep geologic repository and political battles over the fate of the Yucca Mountain site in Nevada may continue for a long time.

Pilot Program to Produce HALEU

The United States currently lacks a supply of the HALEU fuel needed to power advanced nuclear reactors.  This recycling program would, if approved and fully funded by Congress, supply fuel necessary for these reactors.

The pilot program would likely test the feasibility of the process and also serve as a basis for the eventual design of a full scale facility to be built at the Naval Reactors site at the Idaho lab.

Because the HEU fuel coming into the facility will be highly radioactive, it will have to be remote handled as it is broken up and down blended with ordinary uranium (U238) to make the HALEU. Fabrication of fuel assemblies for each unique advanced reactor design will likely be custom jobs at least for the first of a kind (FOAK) units.  Examples might include pebble bed TRISO fuel as well as fuel for MSR type designs.

Organizational and Environmental Issues

If the future unfolds this way, it will be the first major collaboration between the Naval Reactors program and DOE’s support for development of advanced commercial reactor designs.

Note that the various entities involved in the project at the Idaho site all operate under separate authorizations from Congress and with different contractors carrying out the work.  They include the R&D programs at the Idaho National Laboratory (INL)  (DOE_NE), the Naval Reactors Facility (NRF)(DOD), and the Idaho Cleanup Project (DOE-EM).  Getting the pilot project up and running will take collaboration from all of them.

In October 2016 the Associated Press reported that the Navy and U.S. Department of Energy announced plans to build a $1.6 billion facility at at the Idaho lab that would handle spent fuel from the nation’s fleet of nuclear-powered warships through at least 2060. (fact sheet). Readers can refer to a full report on Neutron Bytes here

Some of the facilities at the Naval Reactors site date back to the the Cold War era which is one reason why the government thinks that an upgrade is in order. The State of Idaho, which wants all of the spent fuel gone from the site by 2035, seemed to recognize that business as usual is the more likely scenario. A spokesman for the lab told the the AP;

“We would prefer to see a state-of-the-art facility if they’re going to continue to bring in spent fuel,” said Susan Burke, Idaho National Laboratory oversight coordinator for the state Department of Environmental Quality.

A final environmental impact statement (EIS) issued June 2015 explains the rationale for the plant. Work started with a groundbreaking for the plant in August 2017. The facility is expected to begin operation in 2024.

History of Navy Spent Fuel at Idaho

From the beginnings of the nuclear navy and until 1990 spent nuclear fuel from naval reactors was shipped to Idaho for reprocessing. The chemical plant that did that work ceased operations, but the spent fuel kept coming. Under the terms of a Federal District Court consent decree, almost all of the spent fuel must be removed from Idaho by 2035.

According to a report by the Department of Energy, the Idaho site is home to at least 14 metric tonnes of heavy metal (MTHM) fuel elements sent there by the U.S. Navy. DOE also reports other inventories of Navy fuel, but does not report the volume of fuel assemblies nor their mass nor their level of enrichment. It is likely to be a good deal more than 14 tonnes.

Since the Navy intends to use the facility through 2060, it is plausible to assume that the available inventory of HEU spent fuel will likely meet future needs of advanced reactors over the next few decades. Just add the inventory of spent fuel already at the site to the future returns from nuclear power naval vessels over the next 40 years to complete the picture.

Down blending the highly enriched (80%+ U235) uranium (HEU) fuel to just under 20% U235, or lower, but greater than 5%, would make it available for use in advanced reactors being designed by various startups in the U.S. TRISO fuel has been tested at the Idaho lab at 9% U235.

DOE has been moving the Navy fuel from wet to dry storage for the past decade.  It takes about six years according to the final EIS for the project, for the fuel to cool down enough to be moved from wet storage to dry casks. This means that there will be a six year delay between the time the spent fuel arrives at the Naval Reactors facility and the time it can be used for a down blending process. However, given the existing inventories of various kinds of spent fuel from naval; vessels, once the facility is built, it could start operations right away.

Advantages of the HALEU Program

In any case, once the spent fuel was down blended and fabricated into new new at less than 20% U235 three things would be accomplished.

• First, the material would no longer be considered to be spent fuel since its composition had been changed, and,
• Second, because it was now below the HEU threshold of 20%U235, it could be handled more easily in different ways including making it available for use by developers of advanced reactor designs.
• Third, if the fuel fabrication facility is set up properly, it could produce multiple lines of nuclear fuel types, depending on markets and customer ability/willingness to pay. It would keep nuclear fuel supply chain for advanced reactors in US. Developers of advanced reactors in the US would not have to go to Russia, or China, for their fuel.

Conceivably, the HALEU would be shipped off site to where these reactors are to be built and operated.  However, some developers, like Terrestrial Energy and Transatomic Power, are considering options for locating their first of a kind reactors (FOAK) at the Idaho site.

These developers are thinking of following in the footsteps of NuScale, which has a DOE site permit at INL, to build a first of a kind light water reactor, one that uses fuel enriched to below 5% U235, for its customer UAMPS, at the Idaho lab.

If these developers locate at the INL, some of the new HALEU might never actually leave the boundaries of the federal facility and, if used in these new reactors, would eventually become a new form of spent nuclear fuel. The timeline for this process easily stretches into the next several decades and may require a modification to the consent decree.

Note this plan does not affect other forms of spent nuclear fuel also stored at the Idaho lab.

The long-term management of spent nuclear fuel at INL is constrained to a large extent by a 1995 agreement between the State of Idaho, DOE, and the U.S. Navy. The agreement and an addendum signed in 2008 specify, among other things, that;

• DOE shall complete the transfer of all spent fuel from wet storage facilities at Idaho National Engineering Laboratory by December 31, 2023.
• DOE shall remove all SNF, including naval spent fuel and Three Mile Island spent fuel from Idaho by January 1, 2035 and that no more than 9 MTHM of naval SNF may be kept at INL after that date.

History of Efforts to Make HALEU Available

Last January the Nuclear Energy Institute issued a white paper calling for policy changes to allow developers of advanced reactors to use HALEU.

The report tackles the lack of a pathway to high-assay low-enriched uranium (high-assay LEU) (that is, uranium enriched between 5% to 20% with fissile elements).  While there is no prohibition to commercial access to high-assay LEU, there is also no domestic source for this fuel type.

Current fuel cycle facilities are capped legally (and sometimes physically) to work with 5% or less U235 enriched LEU.  This is a bottleneck to realizing the promise of advanced reactors, as developing the infrastructure for this industry will require “a minimum of seven to nine years.”  The report recommends that DOE and NRC collaboratively take the following actions:

• Support development of new shipping packages capable of holding high-assay LEU;
• Develop “criticality benchmark data needed” to enable the private sector to license high-assay LEU “facilities and transport packages”;
• Directly support the design of high-assay LEU facilities and fuel types; and
• Issue final guidance documents on Material Control and Accountability and physical security for “Category II” facilities that contain high-assay LEU.

Also, in May 2017 Rod Adams wrote a blog post about these issues at Atomic Insights. The article includes a good summary of congressional testimony by Ashley Finan, of the Nuclear Innovation Alliance, on the need for HALEU. Note the article posted on his blog first appeared in Fuel Cycle Week published by International Nuclear Associates, Inc., Washington, DC.

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