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Production of Tritium in a Commercial Light Water Reactor—Supplemental Environmental Impact Statement

On April 3, 2017, TVA issued a Record of Decision (ROD) to implement the preferred alternative identified in the Final Supplemental Environmental Impact Statement (SEIS) on the Production of Tritium in a Commercial Light Water Reactor (CLWR), issued by the Nuclear National Security Administration (NNSA) and adopted by TVA in early 2016. TVA amended its ROD on May 30, 2024, to clarify its final decision.

The NNSA is a semi-autonomous agency within the Department of Energy (DOE). DOE issued an EIS in 1999 on the CLWR program, which addressed the production of tritium in TVA reactors using Tritium Producing Burnable Absorber Rods (TPBARs). In the ROD for the CLWR EIS, DOE selected TVA’s Watts Bar Nuclear Plant Unit 1 and Sequoyah Nuclear Plant Units 1 and 2, located in Spring City and Soddy-Daisy, Tenn., respectively, for tritium production. TVA was a cooperating agency in the development of the CLWR EIS and issued its ROD on the CLWR program in 2000. TVA has been producing tritium for NNSA at Watts Bar Unit 1 since 2004.

At the time of preparation of the 1999 EIS, it was estimated that tritium permeated through the wall of the TPBARs into the reactant coolant at a rate of 1 curie per TPBAR per year (there are approximately 10,000 curies of tritium produced by a TPBAR). After 1999, irradiation experience at Watts Bar showed that the actual permeation rate is 3-4 curies per TPBAR per year. Therefore, DOE/NNSA developed supplemental analysis to the 1999 EIS in order to analyze the potential impacts from TPBAR irradiation at TVA sites on a conservative (e.g., bounding) estimate of the tritium permeation rate, as well as a conservative interpretation of DOE/NNSA’s revised estimate of the maximum number of TPBARs necessary to support current tritium supply requirements.

During their supplemental review, DOE/NNSA published a draft SEIS for public comment in August 2014 and held two public hearings in September 2014 in Athens and Chattanooga, Tennessee. Based on public and stakeholder input, the 2016 Final SEIS was revised to reflect the most current information on several issues, including TPBAR irradiation quantities, the status of related NEPA documents, and updated accident analyses based on 2014 seismic information. The Final SEIS also includes responses to the public comments. In the Final SEIS, DOE/NNSA identified Alternative 6, which would enable irradiating a total of up to 5,000 TPBARs at the Watts Bar and Sequoyah sites, as the preferred alternative because it best met the estimate of tritium needs for national security. In June 2016, the DOE/NNSA published its decision to implement Alternative 6.

TVA was a cooperating agency in the development of the SEIS and adopted the Final SEIS in March 2016. On April 3, 2017, TVA published its ROD in the Federal Register, stating its intent to implement Alternative 6 as well.

Subsequent to the 2016 SEIS, TVA received license amendments from the Nuclear Regulatory Commission (NRC) to increase TPBAR irradiation in Watts Bar Unit 1 and to begin TPBAR irradiation in Watts Bar Unit 2. TVA currently irradiates TPBARs in both Watts Bar units.

In early 2023, TVA submitted license amendment requests to the NRC to increase TBPAR irradiation at Watts Bar (up to 2,496 TPBARs at each Watts Bar unit, or 4,992 in total). To support the requests, TVA reviewed the 2016 SEIS to determine whether the analysis remains adequate for the proposal. After consultation with the DOE/NNSA, TVA issued a Determination of NEPA Adequacy memorandum in February 2023 to document its conclusion that the SEIS adequately addresses the potential impacts associated with increasing TBPAR irradiation at Watts Bar and that the 2016 SEIS does not require additional supplementation. In April 2024, the NRC approved license amendments, allowing up to 2,496 TPBARs at each Watts Bar unit.

TVA issued its amended ROD in May 2024, to clarify that Alternative 4 of the 2016 SEIS aligns more closely with its decision than the alternative identified in its 2017 ROD (Alternative 6).

External Contact

For general information on the CLWR program and the SEIS, contact:

CLWR SEIS Document Manager
P.O. Box 5400
Albuquerque, NM 87185-5400
E-mail: [email protected]

External Document

The Final SEIS and the NNSA’s Record of Decision are available on the NNSA website.

Related Documents

Amended TVA Record of Decision (May 2024)

Determination of NEPA Adequacy (2023)

TVA Record of Decision (April 2017)


More information on this environmental review can be obtained from:

Matthew Higdon
NEPA Specialist
[email protected]
400 West Summit Hill Drive, WT 11B
Knoxville, TN 37902