# Panel Closure Redesign: Update August 2011 Thomas Klein - URS, Regulatory and Environmental Services, Carlsbad, NM 88220

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# Introduction This presentation will cover operational and long term design aspects: • Major Design Criteria • Research Activities • Interim Closure •Gas Monitoring •Current Research Activities • Planned Change Request • Regulatory Schedule

2EPA Certification (long -term) • Option D design represented in Performance Assessment • Salado Mass Concrete NMED Hazardous Waste Facility Permit (operational period) • Limit migration of volatile organics at the point of compliance for 35 years. • Maintain functionality under loads generated by salt creep. • Maintain functionality under loads generated by internal pressures. • Maintain functionality under loads generated by a postulated methane - based explosion. • Limit migration of Volatile Organic Compounds (VOCs).

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# Major Design Criteria• 2001 - DOE identified several changes needed to the panel closure design after initial investigations. These changes were: 1. Replace Salado Mass Concrete with generic salt - based concrete. (EPA/NMED) 2. Replace isolation wall with construction wall. (NMED) 3. Replace freshwater grouting with salt - based grouting. (EPA/NMED) 4. Allow option of implementation of panel closure completion within a year instead of 180 days. (NMED)

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# Research Activities

# Interim Closure

• 2003 - To comply with the requirements of the Hazardous Waste Facility Permit, the DOE constructed the block wall portion of the Panel Closure Option D design for Panels 1 and 2. This allowed DOE to study the effects of salt creep on the block wall and verify previously identified changes.

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# Gas Monitoring
• 2007 - DOE - Hydrogen and Methane monitoring is being performed in waste filled panels and the results have shown that methane and hydrogen levels are below regulatory limits (NMED).

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### • Continue to collect Hydrogen, Methane and VOC data. (NMED) • Review and evaluate Hydrogen, Methane and VOC data. (NMED) • Run Performance Assessment with the new panel closure design represented in the models. (EPA) • Integrate with new Hazardous Waste Facility Permit requirements. (NMED) 

# Combining Research Activities and the Planned Change Request

## • Evaluates monitoring data from panels with emplaced waste and evaluates potential for explosive gas (NMED). • Performance assessment that incorporates updated design (PC3R) (EPA). • Ensure long -term porosities and permeability of the new design are comparable to the Option D design (EPA).

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# Planned Change Request9 

# Planned Change Request Cont.

## EPA- Planned submittal September 2011.

- 18 to 24 month review (Rulemaking)

- Projected approval 2013 NMED - Planned submittal January 2012.

- 12 to 18 month review and comment period.

- Projected approval 2013.

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# Regulatory Schedule

# Conclusion

19 • As a result of increased understanding of the repository and the stored waste obtained over 12 years of operation, the DOE has determined that a revision of the approved Option D panel closure design should be made. • The revised design described in this PCR will reduce the risk of injury to construction workers, enhance constructability, reduce construction cost, and reduce the impacts on on -going repository operations . • A change to the design specified in Condition 1 of the Certification Decision is required because of the problems in manufacturing SMC to the specifications in the CCA. * An analysis of the results of earlier PAs suggests that this revised design will have a long -term performance essentially the same as with Option D.