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At least 685 records · Page 38

Poster — Thur Eve — 36: Implementation of constant dose rate and gantry speed arc therapy(CDR-CAS-IMAT) for thoracic esophageal carcinoma on Varian 23EX

Objective: The purpose of this study is to propose an alternative planning approach for VMAT using constant dose rate and gantry speed arc therapy(CDR-CAS-IMAT) implementation on conventional Linac Varian 23EX and used IMRT as a benchmark to evaluate the performance. Methods and materials: Eighteen patients with thoracic esophageal carcinoma who were previously treated with IMRT on Varian 23EX were retrospectively planned for CDR-CAS-IMAT plans. Dose prescription was set to 60 Gy to PTVs in 30 fractions. The planning objectives for PTVs and OAR were corresponding with the IMRT plans. Dose to the PTVs and OAR were compared to IMRT with respect to plan quality, MU, treatment time and delivery accuracy. Results: CDR-CAS-IMAT plans led to equivalent or superior plan quality as compared to IMRT, PTV's CI relative increased 16.2%, while small deviations were observed on minimum dose for PTV. Volumes in the cord receiving 40Gy were increased from 3.6% with IMRT to 7.0%. Treatment times were reduced significantly with CDR-CAS-IMAT(mean 85.7s vs. 232.1s, p < .05), however, MU increased by a factor of 1.3 and lung V10/5/3.5/aver were relative increase 6.7%,12%,17.9%,4.2%, respectively. And increased the E-P low dose area volume decreased the hight dose area. There were no significant difference in Delta4 measurements results between both planning techniques. Conclusion: CDR-CAS-IMAT plans can be implemented smoothly and quickly into a busy cancer center, which improved PTV CI and reduces treatment time but increased the MU and low dose irradiated area. An evaluation of weight loss must be performed during treatment for CDR-CAS-IMAT patients.

60 APPLIED LIFE SCIENCES↗

SU-F-T-248: FMEA Risk Analysis Implementation (AAPM TG-100) in Total Skin Electron Irradiation Technique

Purpose: Total Skin Electron Irradiation (TSEI) is a radiotherapy treatment which involves irradiating the entire body surface as homogeneously as possible. It is composed of an extensive multi-step technique in which quality management requires high consumption of resources and a fluid communication between the involved staff, necessary to improve the safety of treatment. The TG-100 proposes a new perspective of quality management in radiotherapy, presenting a systematic method of risk analysis throughout the global flow of the stages through the patient. The purpose of this work has been to apply TG-100 approach to the TSEI procedure in our institution. Methods: A multidisciplinary team specifically targeting TSEI procedure was formed, that met regularly and jointly developed the process map (PM), following TG-100 guidelines of the AAPM. This PM is a visual representation of the temporal flow of steps through the patient since start until the end of his stay in the radiotherapy service. Results: This is the first stage of the full risk analysis, which is being carried out in the center. The PM provides an overview of the process and facilitates the understanding of the team members who will participate in the subsequent analysis. Currently, the team is implementing the analysis of failure modes and effects (FMEA). The failure modes of each of the steps have been identified and assessors are assigning a value of severity (S), frequency of occurrence (O) and lack of detection (D) individually. To our knowledge, this is the first PM made for the TSEI. The developed PM can be useful for those centers that intend to implement the TSEI technique. Conclusion: The PM of TSEI technique has been established, as the first stage of full risk analysis, performed in a reference center in this treatment.

60 APPLIED LIFE SCIENCES↗

TH-AB-202-12: The First Clinical Implementation of a Real-Time Six Degree of Freedom Tracking System During Radiation Therapy

Purpose: In current practice, imaging is typically performed prior to treatment; the cancer target motion during treatment is unknown. We present the first clinical implementation of real time Kilovoltage Intrafraction Monitoring (KIM) system which tracks the cancer target translational and rotational motions during treatment. Methods: KIM technology: KIM estimates the 3D position of the target tumour based on segmented 2D positions of the three implanted fiducials in each of the kV images (125 kV, 10 mA at 11 fps) taken continuously during the treatment arc. The 2D-3D target estimation is based on a probability distribution function, obtained during pre-treatment CBCT. Rotations about each axis with the centroid of the markers as the pivot were calculated using the iterative closest point algorithm in real time. Patient: A patient with prostate adenocarcinoma undergoing stereotactic body radiotherapy (SBRT) with 36.25 Gy delivered in 5 fractions (Varian TrueBeam, 6X, VMAT) was enrolled in the study. The trial complies with Australian ethical and regulatory standards. Results: Of the 5 fractions of treatment the patient received, KIM was utilised successfully in 4 fractions with 3 couch shifts due to large persistent prostate movements (>2mm for more than 5 seconds). KIM translational accuracy and precision in comparison with post treatment kV-MV triangulation are 0.28±0.59 mm, −0.19±0.25 mm and 0.23±0.69 mm in the Left-Right, Superior-Inferior and Anterior-Posterior directions, respectively. KIM rotational accuracy as compared with triangulation is: 0.429°±2.22°, −0.44°±4.7° and 0.06°±1.08° in the roll, pitch and yaw direction, respectively. Conclusion: The first six degree of freedom KIM system was successfully implemented clinically. The presented KIM system has sub-millimeters accuracy and precision in all three translational axes, and less than 1° of mean error in all three rotational axes. Acknowledgement: This work is supported by Cancer Australia grants APPXXX, APPYYY.

60 APPLIED LIFE SCIENCES↗

National Energy Efficiency Evaluation, Measurement and Verification (EM&V) Standard: Scoping Study of Issues and Implementation Requirements

This report is a scoping study that identifies issues associated with developing a national evaluation, measurement and verification (EM&V) standard for end-use, non-transportation, energy efficiency activities. The objectives of this study are to identify the scope of such a standard and define EM&V requirements and issues that will need to be addressed in a standard. To explore these issues, we provide and discuss: (1) a set of definitions applicable to an EM&V standard; (2) a literature review of existing guidelines, standards, and 'initiatives' relating to EM&V standards as well as a review of 'bottom-up' versus 'top-down' evaluation approaches; (3) a summary of EM&V related provisions of two recent federal legislative proposals (Congressman Waxman's and Markey's American Clean Energy and Security Act of 2009 and Senator Bingaman's American Clean Energy Leadership Act of 2009) that include national efficiency resource requirements; (4) an annotated list of issues that that are likely to be central to, and need to be considered when, developing a national EM&V standard; and (5) a discussion of the implications of such issues. There are three primary reasons for developing a national efficiency EM&V standard. First, some policy makers, regulators and practitioners believe that a national standard would streamline EM&V implementation, reduce costs and complexity, and improve comparability of results across jurisdictions; although there are benefits associated with each jurisdiction setting its own EM&V requirements based on their specific portfolio and evaluation budgets and objectives. Secondly, if energy efficiency is determined by the US Environmental Protection Agency to be a Best Available Control Technology (BACT) for avoiding criteria pollutant and/or greenhouse gas emissions, then a standard can be required for documenting the emission reductions resulting from efficiency actions. The third reason for a national EM&V standard is that such a standard is likely to be required as a result of future federal energy legislation that includes end-use energy efficiency, either as a stand-alone energy-efficiency resource standard (EERS) or as part of a clean energy or renewable energy standard. This study is focused primarily on this third reason and thus explores issues associated with a national EM&V standard if energy efficiency is a qualifying resource in federal clean energy legislation. Developing a national EM&V standard is likely to be a lengthy process; this study focuses on the critical first step of identifying the issues that must be addressed in a future standard. Perhaps the most fundamental of these issues is 'how good is good enough?' This has always been the fundamental issue of EM&V for energy efficiency and is a result of the counter-factual nature of efficiency. Counter-factual in that savings are not measured, but estimated to varying degrees of accuracy by comparing energy consumption after a project (program) is implemented with what is assumed to have been the consumption of energy in the absence of the project (program). Therefore, the how good is good enough question is a short version of asking how certain does one have to be of the energy savings estimate that results from EM&V activities and is that level of certainty properly balanced against the amount of effort (resources, time, money) that is utilized to obtain that level of certainty. The implication is that not only should energy efficiency investments be cost-effective, but EM&V investments should consider risk management principles and thus also balance the costs and value of information derived from EM&V (EM&V should also be cost-effective).

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

Feedbacks from Focus Group Meeting on Training and Implementation of Building Energy Codes in China

A focus group meeting is a very effective quality research approach to collect information on a specific project. Through focus group meetings at both Changchun and Ningbo in August 2010, the project team gained a more complete understandings of key stakeholders (such as their education level), their training needs and expectations, key factors influencing their decision making, and incurred implementation difficulties. In addition, the meeting helped the project team (especially PNNL) improve its understanding of the implementation status of building energy codes in other regions (such as small cities and counties neighboring to urban areas, small townships and rural areas distant from urban areas). The collected feedbacks will serve as important input not only for better design of training materials and the development of an on-line training website, but also for development of follow-up projects to promote building energy codes in China.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

An Exploration of Impacts of Wide-Scale Implementation of Net Zero-Energy Homes on the Western Grid

Pacific Northwest National Laboratory conducted a study on the impact of wide-scale implementation of net zero-energy homes (ZEHs) in the western grid. Although minimized via utilization of advanced building technologies, ZEHs still consume energy that must be balanced on an annual basis via self-generation of electricity, which is commonly assumed to be from rooftop photovoltaics (PV). This results in a ZEH having a significantly different electricity demand profile than a conventional home. Widespread implementation of ZEHs will cause absolute demand levels to fall compared to continued use of more conventional facilities; however, the shape of the demand profile will also change significantly. Demand profile changes will lead to changes in the hourly value of electric generation. With significant penetration of ZEHs, it can be expected that ZEHs will face time-of-day rates or real-time pricing that reflect the value of generation and use. This will impact the economics of ZEHs and the optimal design of PV systems for subsequent ZEHs.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

A Linac Simulation Code for Macro-Particles Tracking and Steering Algorithm Implementation

In this paper, a linac simulation code written in Fortran90 is presented and several simulation examples are given. This code is optimized to implement linac alignment and steering algorithms, and evaluate the accelerator errors such as RF phase and acceleration gradient, quadrupole and BPM misalignment. It can track a single particle or a bunch of particles through normal linear accelerator elements such as quadrupole, RF cavity, dipole corrector and drift space. One-to-one steering algorithm and a global alignment (steering) algorithm are implemented in this code.

43 PARTICLE ACCELERATORS↗

Used Fuel Disposition Campaign International Activities Implementation Plan

The management of used nuclear fuel and nuclear waste is required for any country using nuclear energy. This includes the storage, transportation, and disposal of low and intermediate level waste (LILW), used nuclear fuel (UNF), and high level waste (HLW). The Used Fuel Disposition Campaign (UFDC), within the U.S. Department of Energy (DOE), Office of Nuclear Energy (NE), Office of Fuel Cycle Technology (FCT), is responsible for conducting research and development pertaining to the management of these materials in the U.S. Cooperation and collaboration with other countries would be beneficial to both the U.S. and other countries through information exchange and a broader participation of experts in the field. U.S. participation in international UNF and HLW exchanges leads to safe management of nuclear materials, increased security through global oversight, and protection of the environment worldwide. Such interactions offer the opportunity to develop consensus on policy, scientific, and technical approaches. Dialogue to address common technical issues helps develop an internationally recognized foundation of sound science, benefiting the U.S. and participating countries. The UNF and HLW management programs in nuclear countries are at different levels of maturity. All countries utilizing nuclear power must store UNF, mostly in wet storage, and HLW for those countries that reprocess UNF. Several countries either utilize or plan to utilize dry storage systems for UNF, perhaps for long periods of time (several decades). Geologic disposal programs are at various different states, ranging from essentially 'no progress' to selected sites and pending license applications to regulators. The table below summarizes the status of UNF and HLW management programs in several countriesa. Thus, the opportunity exists to collaborate at different levels ranging from providing expertise to those countries 'behind' the U.S. to obtaining access to information and expertise from those countries with more mature programs. The U.S. fuel cycle is a once through fuel cycle involving the direct disposal of UNF, as spent nuclear fuel, in a geologic repository (previously identified at Yucca Mountain, Nevada), following at most a few decades of storage (wet and dry). The geology at Yucca Mountain, unsaturated tuff, is unique among all countries investigating the disposal of UNF and HLW. The decision by the U.S. Department of Energy to no longer pursue the disposal of UNF at Yucca Mountain and possibly utilize very long term storage (approaching 100 years or more) while evaluating future fuel cycle alternatives for managing UNF, presents a different UNF and HLW management R&D portfolio that has been pursued in the U.S. In addition, the research and development activities managed by OCRWM have been transferred to DOE-NE. This requires a reconsideration of how the UFDC will engage in cooperative and collaborative activities with other countries. This report presents the UFDC implementation plan for international activities. The DOE Office of Civilian Radioactive Waste Management (OCRWM) has cooperated and collaborated with other countries in many different 'arenas' including the Nuclear Energy Agency (NEA) within the Organization for Economic Co-operation and Development (OECD), the International Atomic Energy Agency (IAEA), and through bilateral agreements with other countries. These international activities benefited OCRWM through the acquisition and exchange of information, database development, and peer reviews by experts from other countries. DOE-NE cooperates and collaborates with other countries in similar 'arenas' with similar objectives and realizing similar benefits. However the DOE-NE focus has not typically been in the area of UNF and HLW management. This report will first summarize these recent cooperative and collaborative activities. The manner that the UFDC will cooperate and collaborate in the future is expected to change as R&D is conducted regarding long-term storage and the potential disposal of UNF and HLW in different geologic environments. While some continuation of on-going or recent cooperative and collaborative activities are expected to continue, the approach taken in these activities may be different than past activities given the changes in the U.S. waste management program. In addition, new cooperative and collaborative activities with different scope than in the past may be undertaken. Such potential future cooperative and collaborative activities will be discussed. The last part of the plan includes the implementation of the UFDC international activities.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

LANL PDMLink Product Structure Implementation [Slides]

Over the past 2 and a half years LANL has done both functionality exploration as well as production implementations of PDMLink Product Structure to control the configuration of many of the LANL Design Agency Products. Based on this experience LANL has been recommending for over a year that future product structure implementation in PDMLink do not use the two digit suffix in the number field of enterprise parts (or WTParts). The suffix will be part of one of the attributes for Part Number. Per the TBP's the two digit suffix represents a change in form, fit, or function in a part or a change in the production agency or a number of other conditions. It also denotes backward compatibility with earlier suffixed parts (see TBP 402 section 3.1).

42 ENGINEERING↗

Including Alternative Resources in State Renewable Portfolio Standards: Current Design and Implementation Experience

Currently, 29 states, the District of Columbia, and Puerto Rico have instituted a renewable portfolio standard (RPS). An RPS sets a minimum threshold for how much renewable energy must be generated in a given year. Each state policy is unique, varying in percentage targets, timetables, and eligible resources. This paper examines state experience with implementing renewable portfolio standards that include energy efficiency, thermal resources, and non-renewable energy and explores compliance experience, costs, and how states evaluate, measure, and verify energy efficiency and convert thermal energy. It aims to gain insights from the experience of states for possible federal clean energy policy as well as to share experience and lessons for state RPS implementation.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

FASTGRASS implementation in BISON and Fission gas behavior characterization in UO 2 and connection to validating MARMOT

This activity is supported by the US Nuclear Energy Advanced Modeling and Simulation (NEAMS) Fuels Product Line (FPL). Two major accomplishments in FY 15 are summarized in this report: (1) implementation of the FASTGRASS module in the BISON code; and (2) a Xe implantation experiment for large-grained UO 2 . Both BISON AND MARMOT codes have been developed by Idaho National Laboratory (INL) to enable next generation fuel performance modeling capability as part of the NEAMS Program FPL. To contribute to the development of the Moose-Bison-Marmot (MBM) code suite, we have implemented the FASTGRASS fission gas model as a module in the BISON code. Based on rate theory formulations, the coupled FASTGRASS module in BISON is capable of modeling LWR oxide fuel fission gas behavior and fission gas release. In addition, we conducted a Xe implantation experiment at the Argonne Tandem Linac Accelerator System (ATLAS) in order to produce the needed UO 2 samples with desired bubble morphology. With these samples, further experiments to study the fission gas diffusivity are planned to provide validation data for the Fission Gas Release Model in MARMOT codes.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

Implementation Plan for Qualification of Sodium-Cooled Fast Reactor Technology Information

This document identifies and discusses implementation elements that can be used to facilitate consistent and systematic evaluation processes relating to quality attributes of technical information (with focus on SFR technology) that will be used to support licensing of advanced reactor designs. Information may include, but is not limited to, design documents for SFRs, research-and-development (R&D) data and associated documents, test plans and associated protocols, operations and test data, international research data, technical reports, and information associated with past U.S. Nuclear Regulatory Commission (NRC) reviews of SFR designs. The approach for determining acceptability of test data, analysis, and/or other technical information is based on guidance provided in INL/EXT-15-35805, “Guidance on Evaluating Historic Technology Information for Use in Advanced Reactor Licensing.” The implementation plan can be adopted into a working procedure at each of the national laboratories performing data qualification, or by applicants seeking future license application for advanced reactor technology.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

A Qualitative Assessment of Current CCF Guidance Based on a Review of Safety System Digital Implementation Changes with Evolving Technology

The US Nuclear Regulatory Commission (NRC) is initiating a new rulemaking project to develop a digital system common-cause failure (CCF) rule. This rulemaking will review and modify or affirm the NRC's current digital system CCF policy as discussed in the Staff Requirements Memorandum to the Secretary of the Commission, Office of the NRC (SECY) 93-087, Policy, Technical, and Licensing Issues Pertaining to Evolutionary and Advanced Light Water Reactor (ALWR) Designs, and Branch Technical Position (BTP) 7-19, Guidance on Evaluation of Defense-in-Depth and Diversity in Digital Computer-Based Instrumentation and Control Systems, as well as Chapter 7, Instrumentation and Controls, in NRC Regulatory Guide (NUREG)-0800, Standard Review Plan for Review of Safety Analysis Reports for Nuclear Power Plants (ML033580677). The Oak Ridge National Laboratory (ORNL) is providing technical support to the NRC staff on the CCF rulemaking, and this report is one of several providing the technical basis to inform NRC staff members. For the task described in this report, ORNL examined instrumentation and controls (I&C) technology implementations in nuclear power plants in the light of current CCF guidance. The intent was to assess whether the current position on CCF is adequate given the evolutions in digital safety system implementations and, if gaps in the guidance were found, to provide recommendations as to how these gaps could be closed.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

Implementation of flowsheet change to minimize hydrogen and ammonia generation during chemical processing of high level waste in the Defense Waste Processing Facility

Testing was completed to develop a chemical processing flowsheet for the Defense Waste Processing Facility (DWPF), designed to vitrify and stabilize high level radioactive waste. DWPF processing uses a reducing acid (formic acid) and an oxidizing acid (nitric acid) to rheologically thin the slurry and complete the necessary acid base and reduction reactions (primarily mercury and manganese). Formic acid reduces mercuric oxide to elemental mercury, allowing the mercury to be removed during the boiling phase of processing through steam stripping. In runs with active catalysts, formic acid can decompose to hydrogen and nitrate can be reduced to ammonia, both flammable gases, due to rhodium and ruthenium catalysis. Replacement of formic acid with glycolic acid eliminates the generation of rhodium- and ruthenium-catalyzed hydrogen and ammonia. In addition, mercury reduction is still effective with glycolic acid. Hydrogen, ammonia and mercury are discussed in the body of the report. Ten abbreviated tests were completed to develop the operating window for implementation of the flowsheet and determine the impact of changes in acid stoichiometry and the blend of nitric and glycolic acid as it impacts various processing variables over a wide processing region. Three full-length 4-L lab-scale simulations demonstrated the viability of the flowsheet under planned operating conditions. The flowsheet is planned for implementation in early 2017.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Implementation of Software Tools for Hybrid Control Rooms in the Human Systems Simulation Laboratory

The Institute for Energy Technology (IFE) and Idaho National Laboratory have designed, implemented, tested and installed a functioning prototype of a set of large screen overview and procedure support displays for the Generic Pressurized Water Reactor (GPWR) simulator in the U.S. Department of Energy’s Human Systems Simulation Laboratory. The overview display is based on IFE’s extensive experiences with large screen overview displays in the Halden Man-Machine Laboratory (HAMMLAB), and presents the main control room indicators on a combined three-screen display. The procedure support displays are designed and implemented to provide a compact but still comprehensive overview of the relevant process measurements and indicators to support operators' good situational awareness during the performance of various types of procedures and plant conditions.

97 MATHEMATICS AND COMPUTING↗

DRAFT: Accident Tolerant Fuels Draft Implementation Plan

The ATF Implementation Plan integrates DOE’s objectives and goals with the national laboratory’s expertise and infrastructure in support of the technology development by three industry partners. DOE’s plan is to develop advanced LWR fuels with enhanced accident tolerance in response to the Congressional request and to install a lead fuel assembly containing accident tolerant fuel technology in a U.S. commercial nuclear power plant by 2022. DOE has three contracts in place with each of the principle US commercial nuclear fuel vendors in support of ATF research and development, AREVA Services LLC, General Electric, and Westinghouse LLC. The purpose of the ATF Implementation Plan is to describe the technology development and progress required to insert one (or possible two) concepts as a LFR or LFA in a commercial LWR by 2022. In particular, this document shows the integration between the functional documents guiding ATF development and provides a rough order of magnitude estimate of the required budget from FY2016 through FY2022. It is expected that after FY2022, the needed budget request would significantly decrease as works transitions from Phase 2 to Phase 3, corresponding to a decrease in DOE project responsibility and an increase in industry responsibility and associated funding support.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

Resilience Project Implementation Memo for the Town of Stowe, Vermont

This Resilience Project Implementation Process Memo was developed with and for the Town of Stowe Electric Department (SED) under the DOE C2C Expert Match Program. It is intended to outline the steps of a process, albeit nonlinear and iterative, to plan, design, and implement community resilience hubs.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

Model Predictive Control of HVAC Systems: Implementation and Testing at the University of California, Merced

A Model Predictive Control algorithm was developed for the UC Merced campus chilled water plant. Model predictive control (MPC) is an advanced control technology that has proven successful in the chemical process industry and other industries. The main goal of the research was to demonstrate the practical and commercial viability of MPC for optimization of building energy systems. The control algorithms were developed and implemented in MATLAB, allowing for rapid development, performance, and robustness assessment. The UC Merced chilled water plant includes three water-cooled chillers and a two million gallon chilled water storage tank. The tank is charged during the night to minimize on-peak electricity consumption and take advantage of the lower ambient wet bulb temperature. The control algorithms determined the optimal chilled water plant operation including chilled water supply (CHWS) temperature set-point, condenser water supply (CWS) temperature set-point and the charging start and stop times to minimize a cost function that includes energy consumption and peak electrical demand over a 3-day prediction horizon. A detailed model of the chilled water plant and simplified models of the buildings served by the plant were developed using the equation-based modeling language Modelica. Steady state models of the chillers, cooling towers and pumps were developed, based on manufacturers performance data, and calibrated using measured data collected and archived by the control system. A detailed dynamic model of the chilled water storage tank was also developed and calibrated. Simple, semi-empirical models were developed to predict the temperature and flow rate of the chilled water returning to the plant from the buildings. These models were then combined and simplified for use in a model predictive control algorithm that determines the optimal chiller start and stop times and set-points for the condenser water temperature and the chilled water supply temperature. The report describes the development and testing of the algorithm and evaluates the resulting performance, concluding with a discussion of next steps in further research. The experimental results show a small improvement in COP over the baseline policy but it is difficult to draw any strong conclusions about the energy savings potential for MPC with this system only four days of suitable experimental data were obtained once correct operation of the MPC system had been achieved. These data show an improvement in COP of 3.1% {+-} 2.2% relative to a baseline established immediately prior to the period when the MPC was run in its final form. This baseline includes control policy improvements that the plant operators learned by observing the earlier implementations of MPC, including increasing the temperature of the water supplied to the chiller condensers from the cooling towers. The process of data collection and model development, necessary for any MPC project, resulted in the team uncovering various problems with the chilled water system. Although it is difficult to quantify the energy savings resulting from these problems being remedied, they were likely on the same order as the energy savings from the MPC itself. Although the types of problems uncovered and the level of energy savings may differ significantly from other projects, some of the benefits of detecting and diagnosing problems are expected from the use of MPC for any chilled water plant. The degree of chiller loading was found to be a key factor for efficiency. It is more efficient to operate the chillers at or near full load. In order to maximize the chiller load, one would maximize the temperature difference across chillers and the chilled water flow rate through the chillers. Thus, the CHWS set-point and the chilled water flow-rate can be used to limit the chiller loading to prevent chiller surging. Since the flow rate has an upper bound and the CHWS set point has a lower bound, the chiller loading is constrained and often determined by the chilled water return temperature (CHWR). The CHWR temperature is primarily comprised of warm water from the top of the TES tank. The CHWR temperature falls substantially as the thermocline approaches the top of the tank, which reduces the chiller loading. As a result, it has been determined that overcharging the TES tank can be detrimental to the chilled water plant efficiency. The resulting MPC policy differs from the current practice of fully charging the TES tank. A heuristic rule could possible avoid this problem without using predictive control. Similarly, the COP improvements from the change in CWS set-point were largely captured by a static set-point change by the operators. Further research is required to determine how much of the MPC savings could be garnered through simplified rules (based on the MPC study), with and without prediction.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗