Passive heat removal impact on AREVA HTR design

Lommers, Lewis; Mays, Brian; Shahrokhi, F.

doi:10.1016/j.nucengdes.2013.12.034

Cited by 14 publications

(3 citation statements)

References 1 publication

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“…Additionally, the test facility retained aspects common to fundamental natural circulation thermosiphons and may be of interest to R&D efforts of crosscutting technologies. ANL/NSE-21/3 Lommers et al, 2014 [22] investigated the viability of the water-based RCCS concept for the Framatome SC-HTGR design, under the most challenging heat removal scenario, namely, a depressurized loss of forced circulation, or a depressurized conduction cooldown (DCC). Initial scoping analysis of the DCC scenario included a nominal or best estimate prediction of the anticipated system performance, followed by three conservative cases for peak fuel temperature, core barrel temperature, and RPV temperature.…”

Section: Air-cooled Rccsmentioning

confidence: 99%

An Overview of Non-LWR Vessel Cooling Systems for Passive Decay Heat Removal (Technical Letter Final Report)

Lisowski¹,

Lv²,

Alexandreanu³

et al. 2021

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The following report provides a technical review of various reactor vessel cooling system (VCS) concepts under consideration for decay heat removal (DHR) in non-light water advanced reactor designs. This review focuses on ex-vessel designs, including the Reactor Cavity Cooling System (RCCS), the Reactor Vessel Auxiliary Cooling System (RVACS), and hybrid iterations, using both air and water cooling to achieve their heat removal function. Based on a literature review of publicly available sources published between 1979 and 2021, a technical summary is presented detailing existing and planned VCS design options, their applicability to specific reactor type, and review of authored research and development studies. Following an assessment of the availability of data and modeling tools, an evaluation was performed analyzing their likely performance during normal, degraded, and accident conditions, including reliability, stability, and longevity.With renewed consideration of air-based DHR systems by some US vendors, there is a need to fully understand the complexities inherent to natural circulation systems, and more importantly, how they may influence safety-related heat removal functions and system performance. For DHR systems that rely on air-based mode of cooling, this entails quantification of the impacts of low flow conditions during start-up, relative elevations of inlet and outlet ducts for below-grade installations, effects of the use of multiple parallel chimneys for redundancy, and impact of weather conditions at the plant site. For systems relying on water-based mode cooling, reliance on limited coolant inventory in an event of pipe break or extended duration accident scenarios, sensitivities related to stability of boiling flow and heat transfer conditions, and quantification of full-scale structural vibrations on balance of plant structures are among the complicating factors. Paperwork Reduction Act StatementThis report does not contain information collection requirements and, therefore, is not subject to the requirements of the Paperwork Reduction Act of 1995 (44 United States Code [U.S.C.] 3501 et seq.). Public Protection NotificationThe U.S. Nuclear Regulatory Commission (NRC) may not conduct or sponsor, and a person is not required to respond to, a request for information or an information collection requirement unless the requesting document displays a current valid Office of Management and Budget (OMB) control number.

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Section: Air-cooled Rccsmentioning

confidence: 99%

An Overview of Non-LWR Vessel Cooling Systems for Passive Decay Heat Removal (Technical Letter Final Report)

Lisowski¹,

Lv²,

Alexandreanu³

et al. 2021

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“…The reactor is sized to achieve the maximum power level possible for a prismatic block modular HTGR with fully passive cooling capability. 13 This minimizes the cost of heat from the unit.…”

Section: Iic Sc-htgr Heat Removalmentioning

confidence: 99%

Sensitivity of SC-HTGR Conduction Cooldown to Reactor Cavity Cooling System Failure

et al. 2021

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The inherent passive heat removal characteristics of modular High Temperature Gas-Cooled Reactors (HTGRs) are well known. Modular HTGRs use a combination of coated-particle fuel, ceramic core materials, core geometry, and power level to maintain acceptable fuel temperatures for all credible operating and accident conditions. Heat from the reactor vessel is radiated to a passive reactor cavity cooling system (RCCS), which removes excess heat from the reactor cavity. The RCCS for Framatome's Steam Cycle-High Temperature Gas-Cooled Reactor (SC-HTGR) is a highly reliable, redundant system. Similar to most other modular HTGR concepts, RCCS failure is not considered credible for any accident scenario. Nonetheless, reactor module performance with a compromised RCCS is still of interest. Evaluation of such beyond-designbasis scenarios supports safety assessment of extremely low probability beyond-design-basis events (BDBEs) as well as the development of RCCS design requirements and plant emergency procedures. This study evaluates the performance of the SC-HTGR during a long-term depressurized loss of forced circulation event without RCCS operation. Boundary conditions are varied to determine their effect on reactor temperatures. Safety and investment risk considerations are addressed. The results of this study indicate that the safety impact is modest since fuel temperatures remain within their limits. However, the investment risk is more significant since vessel temperatures could significantly exceed design limits for these hypothetical BDBEs.

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“…The full scale concept is housed entirely within the reactor containment building, Figure 1, and intended to operate continuously during normal operation with active cooling off the water tanks to maintain nominal inventory temperatures of 30°C. During accident transients, where active cooling is no longer available, the inventory begins a gradual rise in temperature, eventually reaching saturation conditions with loss of inventory through boil-off to the atmosphere [14]. The inputs and observations details of this full scale design were provided by a technical report released to the DOE [15].…”

Section: Design and Review Basismentioning

confidence: 99%