SECY-08-0147, Response to Utah'S September 13,2018,Letter on NRC Recommendation for Site-Specific Performance Assessment for Depleted Uranium Penetrators

Response to Utah'S September 13,2018,Letter on NRC Recommendation for Site-Specific Performance Assessment for Depleted Uranium Penetrators

ML18267A309
Person / Time
Issue date:	09/28/2018
From:	John Tappert NRC/NMSS/DDUWP/LLWB
To:	Shaun Anderson State of UT, Dept of Environmental Quality, Utah Citizens
Dembek S
References
SECY-08-0147
Download: ML18267A309 (3)

Text

September 28, 2018 Mr. Scott T. Anderson, Director Division of Waste Management and Radiation Control Department of Environmental Quality 195 North 2950 West Salt Lake City, UT 84116

SUBJECT:

U.S. NUCLEAR REGULATORY COMMISSION SECY-08-0147 INTERPRETATION

Dear Mr. Anderson:

This letter is in reply to your letter of September 13, 2018, where you requested guidance from the U.S. Nuclear Regulatory Commission (NRC) regarding the NRCs Response to Commission Order CLI-05-20 Regarding Depleted Uranium, designated as SECY-08-0147 (Agencywide Documents Access and Management System Accession No. ML081820814).

Your letter referenced the recommendation in SECY-08-0147 that a site-specific performance assessment should be conducted to evaluate proposed disposal of significant quantities of depleted uranium (DU) and asked whether that recommendation applied to forms of DU other than DU oxides, which was the form of DU assumed in the analysis supporting SECY-08-0147.

You noted, in your letter, metallic DU penetrators (i.e., ammunition) as an example of one potential alternative form of DU.

During a follow-up call with you and your staff on September 20, 2018, you clarified that your specific concern was whether the NRCs analytical framework was applicable only to DU oxides or to other forms of DU as well. The answer to that question is that this framework can be applied to all chemical forms of DU. During that phone call, you also indicated that, in one case under consideration, the material quantity for disposal would be above 10 metric tons.

As described in SECY-08-0147, the quantity of DU proposed for disposal is a critical factor in developing a sufficient analysis under 10 CFR 61.13. SECY-08-0147 characterizes 1 to 10 metric tons of DU as small quantities that could be suitable for shallow disposal. The SECY paper also describes large quantities of DU as quantities similar to those being generated at uranium enrichment facilities, and provides that a site-specific analysis can determine whether specific disposal conditions will ensure the safe disposal of those quantities, consistent with 10 CFR 61.13 and Part 61, Subpart C. For example, the analysis underlying SECY-08-0147 considered the disposal of 1.4 million metric tons of DU.

The site-specific performance assessment described in SECY-08-0147 was based on an analysis of DU oxides because that is the form of DU that was considered most likely to be disposed of in significant quantities. However, the approach described in SECY-08-0147 to evaluate disposal of significant quantities of DU with a site-specific analysis was not limited to DU oxides.

S.T. Anderson 2 SECY-08-0147 indicates that, for disposal under arid conditions, the most significant anticipated risk due to disposal of significant quantities of DU oxides results from exposure to radon gas.

Therefore, for disposal at an arid site, factors affecting the flux of radon from the site, such as the depth of disposal, design of radon barriers, and radon emanation rate from the waste would impact disposal cell performance and potential dose. The rate of radon emanation from metallic DU, such as DU penetrators, is expected to be lower than the rate of radon emanation from DU oxides because of the lower porosity of metallic DU as compared to DU oxides. Whether the rate of radon emanation from metallic DU would be sufficiently lower than the rate of radon emanation from DU oxides, such that a site-specific analysis would not be necessary, would depend on other features of the site that affect potential exposure to radon gas, as well as the quantity of the DU being considered for disposal. Any consideration of the characteristics of the waste form would also be affected by alterations of the waste form during disposal. For example, metallic DU is susceptible to oxidation when in contact with atmospheric oxygen.

Alternative forms of DU could also have characteristics not directly considered in the technical analysis underlying SECY-08-0147. For example, pyrophoricity is a concern for finely-divided metallic DU and larger pieces (i.e., not finely-divided) DU at elevated temperatures. Similarly, hydrogen generation can be a concern for metallic DU in unvented storage in some circumstances. The NRC published draft final guidance on the conduct of technical analyses for low-level waste disposal facilities, NUREG-2175, in 2016 (available at ADAMS Accession No.

ML14357A072).

If you have any additional questions, please contact either Stephen Dembek at 301-415-2342 or Dr. Christianne Ridge at 301-415-5673.

Sincerely,

/RA AKock for/

John R. Tappert, Director Division of Decommissioning, Uranium Recovery and Waste Programs Office of Nuclear Material Safety and Safeguards

ML18267A338 *via email DUWP DUWP DUWP DUWP OGC DUWP OFFICE PYadav for CRidge RChang CMcKenney AGendelman JTappert NAME SDembek DATE 9/25/18* 9/25/18* 9/25/18 9/25/18 9/26/18* 9/28/18