Hanford Tank Farm Health Process Plan (HPP)
In September 2016, Pacific Northwest National Laboratory (PNNL) evaluated a recommendation made by the Tank Vapor Assessment Team (TVAT) that WRPS establish a team to evaluate tank farm vapors occupational exposure limits (OELs), develop strategies for evaluating chemicals of potential concern (COPCs) with no current industrial hygiene or toxicological data, and communicate those findings to the workforce.
To that end, PNNL recommended that WRPS and the Department of Energy (DOE) form a Health Process Plan (HPP) assessment team of subject matter experts from WRPS, DOE, and academic, medical and private institutions. The HPP team would serve as a central resource for the WRPS and be responsible for the integration of all information about tank farm emissions, exposure guidelines, and critical data or research needs to enable risk management decisions and stakeholder communication.
PNNL also recommended that a second committee be formed to provide oversight and review of proposed processes and recommendations put forth by the assessment team. This an External Advisory Committee (EAC), also be made up of nationally recognized experts in chemistry, toxicology, industrial hygiene, risk assessment and communication, and other stakeholders, would serve appointments lasting a minimum of three years.
These two teams would begin the process of developing a thorough and robust exposure assessment plan for the Hanford tank farms. This process would include the development of a database containing all relevant existing and new research documentation, modeling and simulation data, sampling data, and exposure limit guidelines. Once the proposed plan was reviewed, evaluated and refined, the team would be responsible for developing a detailed and transparent implementation plan to leverage data are being used to drive the process and justify the science behind it. For the full text, please visit this link. PNNL-25791, Rev 1 (click here).
Hanford Tank Farm Health Process Plan (HPP) provides the Tank Operations Contractor (TOC), Washington River Protection Solutions (WRPS), and the U.S. Department of Energy (DOE) a plan for a transparent, peer-reviewed process of assessing potential health risks associated with worker exposures to chemical emissions from the Hanford tank farms. WRPS has established a formal review process and chartered an Internal Review Panel and External Review Panel for evaluation of Health Process Plan recommendations.
The HPP approach builds from the strategy and processes based in the current industrial-hygiene technical basis. It defines the strategy and plan for regularly, and rigorously, reviewing and updating the Chemicals of Potential Concern (COPC) in the Hanford tanks. The HPP is used to review the corresponding Occupational Exposure Limits, and it is the strategy used when proposing exposure action levels for those COPCs or mixtures of COPCs where no acceptable limits exist. The HPP approach extends the assessments to include chronic exposure limits, acute transient exposure concentrations, and COPC mixtures.
The chartered review panels evaluate HPP recommendations, including the economic and feasibility impacts of implementation, and provides recommendations to the Office of River Protection (ORP) regarding the implementation of proposed changes. The formal, chartered review process using of the Internal and External review panels is the process WRPS uses to evaluate the following reports from Pacific Northwest National Laboratory (PNNL), listed below. As the reports are completed the report will be linked to the list.
Pacific Northwest National Laboratory (PNNL) reviewed the regulatory guidelines available for chemicals of potential concern (COPCs) related to Hanford Tank Farm operations. Regulatory guidelines for 34 of the 61 current COPCs were identified in databases developed by private or government agencies, including the American Conference of Governmental Industrial Hygienists (ACGIH) and the Occupational Safety and Health Administration (OSHA). Updated information for four COPCs (3-methyl-3-buten-2-one, 6-methyl-2-heptanone, dibutyl butylphosphonate, and tributylphosphate) was applied to propose updates for their respective Hanford Tank Farm Occupational Exposure Limits (HTFOELs). No changes for the remaining 30 COPCs with regulatory information were identified. Dimethyl mercury and 2-propenal are new additions to the COPC list. Both compounds had available regulatory guidelines. The remaining COPCs are undergoing further review and will be discussed in separate reports. For additional information, please visit this link.
Proposed Risk-Based Approach for Nitrosamine Chemicals of Potential Concern documents the re-evaluation of Hanford Tank Farm OEL for five N-nitrosamines identified as chemicals of potential concern (COPC), and two other N-nitrosamines being considered as COPCs. Pacific Northwest National Laboratory proposes a risk-based approach to establish risk-specific doses for occupational exposures to N-nitrosamine COPCs. This approach establishes a range of N-nitrosamine inhalation exposures associated with risk levels that can be used as a tool for protecting HTF workers. (Full Report Link).
Hanford Tank Farm Occupational Exposure Limits (HTFOELs) are currently used to protect workers from potential effects from long-term tank vapor exposures. This includes exposures to 61 chemicals of potential concern (COPCs). These COPCs, like many chemicals, may produce effects from single or short-term (acute) exposures that are different from long-term effects. Pacific Northwest National Laboratory (PNNL) released a report in July 2018 that proposed acute exposure limits for 12 of the 61 current COPCs. These exposure limits are called Transient Effect Concentrations (TECs). They are designed to reduce risk of short-term discomfort, irritation, or other temporary effects that may be experienced by a worker. The TECs in the PNNL report are based on exposure limits already established by regulatory and scientific authorities. Airborne levels of COPCs that may cause short-term health effects are usually much higher than the concentrations that cause long-term effects. The TECs proposed by PNNL may be used along with the long-term HTFOELs to protect workers from a broader range of potential effects than if HTFOELs are used alone.
In 2019, Pacific Northwest National Laboratory (PNNL) re-evaluated the current Hanford Tank Farm (HTF) occupational exposure limits (OELs) for furan and 13 associated substituted furans identified as chemicals of potential concern. Proposed Occupational Exposure Limits for Furans documents the toxicology data that were evaluated, the process used to develop the proposed OEL, and recommendations. (Full Report Link)
Pacific Northwest National Laboratory (PNNL) reviewed the Hanford tank farm occupational exposure limits (HTFOELs) for chronic exposures to nitrile-class chemicals of potential concern (COPCs) and 2,4-dimethylpyridine. PNNL concluded that no changes to these chronic HTFOELs are needed. The review of the compounds was initiated after differences between the chronic HTFOELs and short-term exposure guideline values developed by the United States Environmental Protection Agency (EPA) was identified. PNNL’s report presents a comprehensive evaluation of the technical basis for the short-term EPA exposure guidelines and the chronic HTFOELs for nitrile-class COPCs and 2,4-dimethylpyridine. For the full text, please follow this link.
PNNL 27991 – Chronic Hanford Tank Farm Occupational Exposure Limits: 2018 Update, Rev.0. This report documents the re-evaluation of new regulatory information since 2016 that could impact existing Hanford Tank Farm occupational exposure limits (OELs) for the 61 chemicals of potential concern (COPCs). The report summarizes the technical basis and the process used to derive updated chronic OELs. New regulatory information was identified for two of the 61 COPCs, formaldehyde and 2, 4-dimethylpyridine. This new information was used to update OELs for these two COPCs. The OELs for the remaining COPCs did not change from the 2016 assessment. (Full report here).
PNNL-27089 – Chemical Mixtures and Modeling Recommendations Acute TECs
Air sampling at the Hanford Tank Farms contributes to a large body of information about the identities and levels of tank vapor chemicals, and is routinely performed to measure the airborne levels of these chemicals in the workplace. Pacific Northwest National Laboratory (PNNL) reviewed the air sampling methods currently in use at the Hanford Tank Farms. The report discusses recent analytical advances that could enhance the characterization of tank vapors. The PNNL report discusses new laboratory instruments capable of detecting chemical vapors at very low concentrations, and recommends ways to improve the accuracy and reliability of current sampling methods. (Full Report Here).
Pacific Northwest National Laboratory (PNNL) released a Hanford Tank Vapor Chemicals of Potential Concern (COPC) update following a review of an updated set of tank vapor concentrations and improved estimates for Hanford Tank Farm Occupational Exposure Limits (HTFOELS). Air sampling results for tank headspace vapors and airborne emissions, including a range of operating conditions (i.e., quiescent, sluicing, tank transfers, etc.) were used to assess whether the updated HTFOELS or vapor concentration measurements changed the COPC status of any chemicals. Two new COPC-related recommendations were made following this assessment, including identification of nitrosodipropylamine as a COPC candidate, and retaining alkyl-substituted furans as COPCs. For the full text, please visit this link.