Abstract

Analyses were performed using MELCOR and RADTRAD to investigate main steam isolation valve (MSIV) leakage behavior under design basis accident (DBA) loss-of-coolant (LOCA) conditions that are presumed to have led to a significant core melt accident. Dose to the control room, site boundary and LPZ are examined using both approaches described in current regulatory guidelines as well as analyses based on best estimate source term and system response. At issue is the current practice of using containment airborne aerosol concentrations as a surrogate for the in-vessel aerosol concentration that exists in the near vicinity of the MSIVs. This study finds current practice using the AST-based containment aerosol concentrations for assessing MSIV leakage is non-conservative and conceptually in error. A methodology is proposed that scales the containment aerosol concentration to the expected vessel concentration in order to preserve the simplified use of the AST in assessing containment performance under assumed DBA conditions. This correction is required during the first two hours of the accident while the gap and early in-vessel source terms are present. It is general practice to assume that at {approx}2hrs, recovery actions to reflood the core will have been successful and that further core damage can be avoided. more » The analyses performed in this study determine that, after two hours, assuming vessel reflooding has taken place, the containment aerosol concentration can then conservatively be used as the effective source to the leaking MSIV's. Recommendations are provided concerning typical aerosol removal coefficients that can be used in the RADTRAD code to predict source attenuation in the steam lines, and on robust methods of predicting MSIV leakage flows based on measured MSIV leakage performance. « le Document type: Report

Abstract

Due to the need of maintaining and providing high purity argon for the D0 experiment. it is necessary to have a purity verifying device readUy aVailable. The testing eqUipment used by the D0 cryo group is called the Argon Test Cell (ATC). It operates by taking a sample of the argon to be tested and running it through a test cell for purity determination. LiqUid nitrogen cooling loops are used to to keep the argon cold during the testing. The initial placement of the ATC was outside of the D0 Cryo Control Room. This was not a favorable place. mainly because of exposure to the elements on the operators and the device. A plan was made to move the ATe from outside to inside the control room. This would allow security. favorable environment conditions. and general overall improved access and operability. Havtng the ATC inside causes some concern over some issues. It is true that the ATC employs cryogenic piping components. so there is an ODH possibility ifthose components were to faU and leak. However. there are ways by which we can determine the ODH class fairly easily. Using the methods outlined in D0 EN-229. the components of the cryogenic pipelines are summed and grouped according to failure possibility and likely leakage upon failure. (Note that this is the reason that one type of component may be listed a multiple number of times in the appendix spreadsheet, as the different components have different possible leak rates. depending on position or size. etc.). The result is an ODH class 0. since the fatality rate has to be above 10{sup -7} for a hazard condition to be present. The fatality rates in this analysis only come within an order of magnitude of this safety limit due to using conservative estimates. Note that the 130 scfm fan must be active for the ODH status to remain O. The control room ventilation is on emergency power. An alarm attached to the fan will notify the operators of fan failure. but both the fan and the alarm can be turned off when they are not needed. The fan need not be active as long as there are no cryogens in the ATC, and the argon and nitrogen supply line valves have been secured closed. For ODH detection purposes, an ODH head has already been installed in the control room as a result of the DAB southSide ODH plan. Document type: Report

Abstract

The development of two external waste tank and pipeline leak detection systems based on the electrical potential fields is reviewed. The Boeing system measured the distortion of an imposed ac potential field. The Battelle--Northwest system measured the change in the magnitude of the existing dc potential field generated by the cathodic protection system and the local electrochemical potential near the electrodes in the sediment. It was found that in a dry area the systems can detect as low as 200 liters of leakage. The engineering assistance to the tank farm management in assessing the suspected leakers is also presented. Document type: Report

Abstract

Author(s): Oldenburg, Curtis M.; Birkholzer, Jens T. | Abstract: The Cap-and-Trade and Low Carbon Fuel Standard (LCFS) programs being administered by the California Air Resources Board (CARB) include Carbon Dioxide Capture and Storage (CCS) as a potential means to reduce greenhouse gas (GHG) emissions. However, there is currently no universal standard approach that quantifies GHG emissions reductions for CCS and that is suitable for the quantitative needs of the Cap-and-Trade and LCFS programs. CCS involves emissions related to the capture (e.g., arising from increased energy needed to separate carbon dioxide (CO2) from a flue gas and compress it for transport), transport (e.g., by pipeline), and storage of CO2 (e.g., due to leakage to the atmosphere from geologic CO2 storage sites). In this project, we reviewed and compared monitoring, verification, and accounting (MVA) protocols for CCS from around the world by focusing on protocols specific to the geologic storage part of CCS. In addition to presenting the review of these protocols, we highlight in this report those storage-related MVA protocols that we believe are particularly appropriate for CCS in California. We find that none of the existing protocols is completely appropriate for California, but various elements of all of them could be adopted and/or augmented to develop a rigorous, defensible, and practical surface leakage MVA protocol for California. The key features of a suitable surface leakage MVA plan for California are that it: (1) informs and validates the leakage risk assessment, (2) specifies use of the most effective monitoring strategies while still being flexible enough to accommodate special or site-specific conditions, (3) allow quantification of stored CO2, and (4) offer defensible estimates of uncertainty in monitored properties. California’s surface leakage MVA protocol needs to be applicable to the main CO2 storage opportunities (in California and in other states with entities participating in California’s Cap-and-Trade or LCFS programs), specifically CO2-enhanced oil recovery (CO2-EOR), CO2 injection into depleted gas reservoirs (with or without CO2-enhanced gas recovery (CO2-EGR)), as well as deep saline storage. Regarding the elements of an effective surface leakage MVA protocol, our recommendations for California are that: (1) both CO2 and methane (CH4) surface leakage should be monitored, especially for enhanced recovery scenarios, (2) emissions from all sources not directly related to injection and geologic storage (e.g., from capture, pipeline transport, etc.) should be monitored and reported under a plan separate from the surface leakage MVA plan that is included as another component of the quantification methodology (QM), (3) the primary objective of the surface leakage MVA plan should be to quantify surface leakage of CO2 and CH4 and its uncertainty, with consideration of best-practices and state-of-the-art approaches to monitoring including attribution assessment, (4) effort should be made to monitor CO2 storage and migration in the subsurface to anticipate future surface leakage monitoring needs, (5) detailed descriptions of specific monitoring technologies and approaches should be provided in the MVA plan, (6) the main purpose of the CO2 injection project (CO2-EOR, CO2-EGR, or pure geologic carbon sequestration (GCS)) needs to be stated up front, (7) approaches to dealing with missing data and quantifying uncertainty need to be described, and (8) post-injection monitoring should go on for a period consistent with or longer than that prescribed by the U.S. EPA. Document type: Report