Low-activity waste feed delivery -- Minimum duration between successive batches [report]

B.B. Peters
1998 unpublished
The purpose of this study is to develop a defensible basis for establishing what "minimum duration" will provide acceptable risk mitigation for low-activity waste feed delivery to the privatization vendors. staging of low-activity waste feed batches. durations with current feed delivery plans and potential privatization vendor facility throughput rates. The study establishes a probabil istic-based duration for A comparison i s made of the TRADEMARK DISCLAIMER. Reference herein t o any s p e c i
more » ... f i c comnercial product, process, o r service by trade name, trademark, manufacturer, or otherwise, does not necessarily c o n s t i t u t e o r imply i t s endorsement, recomndation, o r favoring by the United States Goverment or any agency thereof or i t s contractors or subcontractors. P r i n t e d i n the United States of America. To obtain copies of t h i s docunent, contact: Docunent Control Services, EX%CUTIVE SUMMARY The US. D e p a m n t of Energy-Richland Operations Ofsice (RLJ is in the first stages of contracting with private companies for the treatment and immobilization of tank wastes. The tank waste retrieval, treatment, and immobilization mission has been conceived to occur in two phases. In Phase 1, the Project Hanford Management Contractor (PHMC) team will deliver tank waste to two private contractors on behalf of E. The private contractors will demonstrate the capability to treat (separate and immobilize) the waste. Three envelopes of low-activity waste (LAW (Envelopes A, B and C) will be processed during Phase 1. During Phase 2 the private contractors will retrieve, treat, and immobilize the waste. One of the primary risks that the PHMC team has identified that must be managed to successfrclly meet the feed delivery requirements for the Phase 1 feed delivery is the following: The final contracts for Phase 1B with the private contractors may be for a higher feed rate than the Tank Waste Remediation System (TWRS) Project Contractor can initially deliver. In addition, private contractor contracts for Phase 1B may deviate from specifications in the Phase 1A contracts or from planning assumptions made by the TWRS Project Contractor. A key recommendation to mitigate this risk and increase the robustness of the feed delivery system is to 7mpose a minimum time duration between the completion of the delivery of one feed batch and the waste transfer date for the following batch. ' I A study to develop a basis for establishing this minimum duration was completed which had the following key conclusions: At a 95 percent probability, the minimum duration was determined to be 260 days for Envelope A and 190 days for Envelope's B and C. It was concluded that the Waste Feed Delivery system had a high probability of supporting delivery of waste iii HNF-2540 Revision 0 feed for a privatization contractor processing rate of 2 MT Na/day per contractor. Even i f all activities were completed within an optimistic time frame there would be only a small (approximately 2Opercent) overall improvement in the total time required to retrieve, qualify, and deliver a batch of LAW. Waste feed djustment to meet an envelope requirement can increase substantially the time required to retrieve, qualifi, and deliver a batch of LAW. Chemical shimming can add 10 to 20 days, blending waste from another tank can add 50 to 90 days, and side-pocketing a feed batch and restaging the next feed batch can add 100 to I40 days. The purpose of this study is to develop a basis for establishing what 'fninimum duration" will provide acceptable risk mitigation for LA Wfeed delivery to the privatization vendors. The study establishes a probabilistic-based duration for staging of LAWfeed batches. A comparison is made of the durations with current feed delivery plans and potential privatization vendor facility throughput rates. These durations are expressed in terms of the minimum duration between successive LAW batches. That is the time required to retrieve, tranger, aajmt (if necessary), and qualify a LAW feed batch. The study scope was the operational phase of waste retrieval, staging, and feed qualijkation only. It did not address risk from project delays or the ability to accelerate projects to support higher vendor processing rates. A key assumption is that all necessary equipment is in place and initially functional to support waste feed delivery. Two retrieval and four waste feed adjustment scenarios were modeled. Laboratory sample analysis was identified as a key schedule risk element so a sensitivity analysis was completed to assess three alternative laboratory enabling assumptions. Detailed activity schedules were developed for each case based on the schedule developed in support of the Readiness-To-Proceed effort. Information regarding specific activity durations was obtained iv V Duration (d) Comparing these durations with the currently planned waste feed batches, it can be concluded that Waste Feed Delivery (WFD) can successfully support privatization vendor processing rates of 2 MT Na/day per vendor but probably not 3 MT Na/day. 2 MT Na/day: WFD %stem has > 90 percent Probability of Success except for Batches 4 and 9 (40 to 75 percent) 3 MT Na/day: WFD System has > 70percent Probability of Success except for Batches 3, 4, and 9 which have little chance (< 15 percent, assumes Projects can be accelerated to support). vi HNF-2540 Revision 0 The three types of waste feed adjustments have different impacts to the feed delivery schedules. Shimming can extend the delivery schedule 10 to 20 days, blending waste from another tank can ahd 50 to 90 days, and side-pocketing the feed batch and staging the next batch (restaging) can add 100 to 140 days. The relative impacts of the most significant activities are shown graphically as a tornado diagram in Figure ES-2. The vertical center line of the tornado is placed at the median duration for the full retrieval scenario modeled. Each of the bars represents a significant activity with the median duration for the activity aligned with that for the full retrieval. The le8 side of each bar represents the 'bptimistic"duration for the activity while the right side represents the Pessimistic"va1ue. These three values are shown along with the title for each activity. As can be seen, analysis of waste samples and issuing the Feed Qualiscation report are the primary contributors to the retrieval/staging/qualification time. The position of the bars also shows that even if all activities were completed within the optimistic time there would be a small improvement (approximately 20 percent) in the total time required. Alternatively, the pessimistic values, which represent various types of failures during the activity, can signijicantly extend the total time required. The key sample analysis risk is a laboratory shutdown resulting from audithon-compliance findings. The other primary contributor to schedule risk is adjustment of the waste feed composition if it doesn't meet the envelope specification. The key risk associated with feed adjustment is developing options for completing the adjustment and getting a decision and approval to proceed. Based on areas of risk identijied by this study and previous ones, there are several changes to DOE guidance and to PHMCplans which could reduce the risks associated with supporting waste feed delivery to the privatization vendors. These include the following: vii HNF-2540 Revision 0 Figure ES-2. Tornado Diagram--Waste Feed Delivery.
doi:10.2172/362496 fatcat:s4hqv7oxwbe2hmedunytmvqry4