09/12/2016

REQUEST FOR EXPRESSION OF INTEREST: DOUBLE-SHELL TANK INTEGRITY PROJECT

PRIMARY TANK BOTTOM NON-DESTRUCTIVE EXAMINATION SYSTEM

IntroductionWashington River Protection Solutions, LLC (WRPS) as a prime contractor to the U.S. Department of Energy is issuing this Request for Expression of Interest (EOI) as a means of conducting market research to identify parties having an interest in and the resources to demonstrate a non-destructive examination system to meet a current inspection challenge within Double-Shell Tanks (DST) to support WRPS’ mission.

BackgroundTwenty-eight carbon steel, double-shell, million gallon waste storage tanks located at the Hanford site in Washington State store both radioactive and hazardous waste (as defined by The Resource Conservation and Recovery Act), which is regulated as dangerous waste under Washington State regulations. To monitor their condition and ensure continued viability, these tanks are inspected periodically through a comprehensive integrity program. Tank configuration variations and construction conditions present several access challenges that will need to be overcome in the future. Hanford’s double-shell tanks were built in groups, commonly referred to as Farms. As a summary, Table 1 provides the number of tanks in each farm and construction timeframe.

Table 1. Hanford Double-Shell Tank Overview

Tank Farm # Tanks Construction Period

241-AY 2 1968-1970241-AZ 2 1970-1974241-SY 3 1974-1976241-AW 6 1976-1979241-AN 7 1977-1980241-AP 8 1982-1986

In 2012, the first leak in a double-shell tank at Hanford was discovered in the 241-AY tank farm (Tank AY-102) and the failure was observed to be from the primary tank bottom. The exact failure location and damage mechanism are both still undetermined. Further reviews of original construction records assessed the extent to which the other double-shell tanks in the system had similar as-built characteristics. Up to this point, ultrasonic inspection has only been performed to provide information to engineers about the condition of the primary tank sidewalls, which does not provide indication of the condition of the tank bottom and thus cannot yield early warnings of potential primary tank bottom failure. As a result of this discovered integrity monitoring weakness, primary tank bottom failure, and follow-up construction research, a key improvement needs to be made to the integrity program that would add the capability to inspect the primary tank bottom of double-shell tanks. Direct inspection access to the primary tank bottom is limited to channels in an insulating concrete pad (refractory pad) that the primary tank rests on. Prior attempts have been made to utilize the air slots as a point of access to the primary bottom plate for inspection which are discussed in report RPP-RPT-25844.

Access through these refractory channels would provide data about the bottom of the primary tank from the exterior surface. Regarding access to the annulus space and air slot layout, the configuration does vary slightly among the twenty eight tanks. Each double-shell tank has risers of various diameters that provide access to the annulus space from grade (see Figure 1), the largest of which are 24-in. The ability

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to be deployed through 12-in. risers, expanding deployment flexibility, will be viewed as a benefit regarding selection for further development. The annulus space is 30-in between the primary tank and secondary liner sidewalls. Figure 2 depicts a basic double-shell tank design. Figures 3 and 4 highlight the two different refractory pad air slot configurations inherent to the double-shell tanks.

24” Annulus Access Riser

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32

Secondary Liner

Primary Tank

Annulus Floor

Refractory Pad

Primary Tank

Refractory Pad

Secondary Liner

Primary Tank

Access Riser

Air Slot

Figure 1. Double-Shell Tank Annulus Riser Access

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Secondary Liner

Primary Tank

Annulus Floor

Concrete Foundation

Refractory Pad

Concrete Shell

Figure 2. Hanford Double-Shell Tank Basic Design Detail

Historic Construction Photo

Figure 3. AY Farm Refractory Pad Air Slot Pattern and Cross Sections

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Historic Construction Photo

Figure 4. AZ, SY, AW, AN, and AP Farm Refractory Pad Air Slot Pattern and Cross Sections

The two tanks in the 241-AY tank farm share a different refractory pattern from the remaining twenty-six. As depicted, the cross-sectional dimensions for these slots vary within each pattern. The smallest and most limiting case is 1.5” x 1.5” on the outer most perimeter air slots of the AY Tank Farm.

Description of OpportunityWRPS intends to select one or more promising non-destructive examination (NDE) technologies that can perform inspection of the DST primary tank bottom from the outside surface of the primary tank. The selection of the NDE technology for primary tank bottom inspection will be based on two assessments: an initial NDE assessment (December 2016 – January 2017) followed by a prototypic NDE demonstration (July – August 2017). The initial NDE assessment will focus on flaw detection and characterization ability using simple mock-ups while the prototypic NDE demonstration will focus on the ability to detect and characterize flaws compounded by access limitations that will be presented by a more challenging mock-up with a riser and a refractory pad with air slots access limitations, as previously described.

This request for expression of interest is for the initial NDE assessment.

The purpose of the initial NDE assessment is to down-select NDE technologies before advancing one or more to the prototype stage and conducting the final NDE demonstration. The initial NDE assessment will evaluate the ability of participating NDE technologies to inspect the bottom of a primary tank mock-up to detect and characterize simulated degradation (e.g. wall thinning, pitting, or cracking) in the absence of overly challenging access limitations. Although the assessment will focus on flaw detection and characterization ability, any participating NDE technology must have a clear pathway for overcoming the previously described air slot and riser access challenges in order to be considered for the final NDE assessment. During the initial NDE assessment, candidate technologies will be scored under several categories that will assess a technology’s ability to:

detect different surrogate flaw types in the mock-up(s), e.g., pit, wall thinning, transverse crack; size surrogate flaws;

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classify surrogate flaws; distinguish between inner- and outer-surface connected surrogate flaws, i.e., flaw origination; independently navigate/traverse the outer surface of the mock-up(s) to conduct inspections of the

bottom (i.e., a hands-free delivery system such as a magnetic crawler with scanner); couple sensors to the carbon steel mock-up (small amounts of non-toxic liquid couplants are

allowed);

and the technology’s demonstrated or potential:

range of coverage along the length of the primary tank bottom; time required to inspect; ability to encode inspection data; compatibility of the delivery system with a corroded or dirty surface; surface preparation requirements for sensors; overall size and pathway for overcoming access limitations.

One or more carbon steel primary tank section mock-ups will be used to facilitate the initial NDE assessment. A drawing and a photograph of a sample mock-up is provided in Figure 5. The bottom portion of the mock-up(s) may be extended in length prior to the initial NDE assessment and will include unflawed areas as well as areas with surrogate flaws. The surface conditions of the mock-up(s) may range from clean to corroded/dirty. Examples of potential surface conditions are provided in Figure 6.

Figure 5. Left: Drawing of a DST Primary Liner Test Mock-up. Right: Photo of a Test Mock-up

Figure 6. Photos Showing Examples of Possible Mock-up Surface Conditions

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Candidate NDE technologies submitted to WRPS in response to this EOI will be selected for participation in the initial NDE assessment that 1) demonstrate the potential for inspection of the primary tank bottom mock-up(s) and 2) have a sufficient level of readiness to overcome access limitations that will be presented during the final NDE demonstration. For example, a traditional ultrasonic testing (UT) system that is manually coupled to and traversed along the outside of the primary tank bottom would be expected to detect and characterize flaws, but could require significant investment to mature to a prototype stage for the final NDE demonstration where access limitations would need to be overcome. However, the same UT system with a robotic delivery system would likely be more favorable, especially if the sensor and delivery system were configured to access restricted spaces such as refractory pad air slots.

It is anticipated that one or more promising NDE technologies will be selected for participation in the initial NDE assessment and a subset of the technologies will be selected at the conclusion of the initial NDE assessment for further development to work. WRPS would fund the further development of the initial NDE assessment finalists to the prototype phase with an anticipated 6 to 9 month timeframe to the final NDE demonstration. WRPS is in the process of developing a mock-up facility to support the final NDE demonstration. The mock-up facility will comprise a small portion of the tank walls and both refractory pad air slot patterns. This facility will facilitate functional testing of prospective systems to evaluate their capability against defined data objectives. The goal of this facility will be to provide the complex, remote inspection challenge for vendor verification prior to an in-tank field deployment. We look forward to your ideas and creativity as we work to solve this inspection challenge and improve our overall understanding of double-shell tank integrity at Hanford.

REQUESTInterested parties are invited to submit an expression of interest to include a response to the following provisions:

1. By 30 September, 2016 – Submit any questions necessary to clarify the scope and expectations of the initial NDE assessment.

2. By 21 October, 2016 (earlier submittals are encouraged) – Indicate interest in participating in the initial NDE assessment. Provide a description of the technology for inspection of primary tank bottoms. Include any other information that you believe would be useful in assisting WRPS in assessing the proposed technology.

3. By 11 November, 2016 – Interested parties responding to this EOI will be notified of acceptance for participation in the initial NDE assessment. It is WRPS’s intent to conduct the initial NDE assessment starting in December 2016. Participants are not required to have a technology that can yet overcome riser or air slot access challenges, but a clear path to a successful system in 6 months or less is imperative to being selected for further development and the final NDE demonstration.

This is not a Request for Proposal, but a request for an expression of interest. Responses with details on the recommended technology must be received by WRPS no later than close of business 21 October 2016, 5:00 pm (EDT) via email to: Brandon Black – Brandon_J_Black@rl.gov

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