Safety demonstration tests using high temperature engineering test reactor

Nakagawa, Shigeaki; Takamatsu, Kuniyoshi; Tachibana, Yukio; Sakaba, Nariaki; Iyoku, Tatsuo

doi:10.1016/j.nucengdes.2004.08.016

Cited by 36 publications

(12 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…High temperature gas-cooled reactors (HTGRs) also have good ATWS characteristics without any alternative action. 25,26) But the power rating and the core dimensions of the HTGRs are limited so as not to release fission gas from the coated particle fuels at accidents. On the other hand, good ATWS characteristics of the Super LWR are achieved with a high core power rating of 1,000 MWe.…”

Section: Discussion Of the Atws Characteristicsmentioning

confidence: 99%

ATWS Characteristics of Super LWR with/without Alternative Action

Ishiwatari

Oka

Koshizuka

et al. 2007

Journal of Nuclear Science and Technology

View full text Add to dashboard Cite

Anticipated-transient-without-scram (ATWS) of the supercritical-pressure light water cooled thermal reactor with downward-flow water rods (Super LWR) is analyzed to clarify its safety characteristics. At loss-of-flow, heat-up of the fuel cladding is mitigated by the water rods removing heat from the fuel channels by heat conduction and supplying their coolant inventory to the fuel channels by volume expansion. The average coolant density is not sensitive to the pressure due to the small density difference between ''steam'' and ''water'' at supercritical-pressure. Closure of the coolant outlet of the once-through system causes flow stagnation that suppresses an increase in the coolant density due to an increase in the temperature. Therefore, the increase in power is small for pressurization events. The coolant density and Doppler feedbacks provide good self-controllability of the power against loss-of-flow and reactivity insertion. An alternative action is not needed either to satisfy the safety criteria or to achieve a high-temperature stable condition for all ATWS events. Initiating the automatic depressurization system is a good alternative action that induces a strong core coolant flow and inserts a negative reactivity. It provides an additional safety margin for the ATWS events. Even the high core power rating of the Super LWR has excellent ATWS characteristics, providing a key reactor design advantage.

show abstract

Section: Discussion Of the Atws Characteristicsmentioning

confidence: 99%

ATWS Characteristics of Super LWR with/without Alternative Action

Ishiwatari

Oka

Koshizuka

et al. 2007

Journal of Nuclear Science and Technology

View full text Add to dashboard Cite

show abstract

“…Safety demonstration tests have been conducted using the HTTR to improve the safety design and evaluation [3][4][5][6][7][8][9]. Tripping one and two out of three gas circulators without operating the reactor power control system resulted in a rapid decrease in the reactor power owing to the inherent safety features of the HTGR [1], such as the negative reactivity feedback effect of the core and slow temperature transient [10].…”

Section: Overview Of Safety Demonstration Testsmentioning

confidence: 99%

“…In fact, when there were a large number of neutrons, a negative feedback effect occurred during the CR withdrawal test [3][4][5][6][7][8][9] of the HTTR, and a reactivity of approximately 5.0 × 10 −4 ( k/k) was inserted into the core for approximately 5-10 s. The Xenon inserted reactivity of 2.3 × 10 −4 ( k/k) is close to that of 5.0 × 10 −4 ( k/k) in value approximately. After the reactor power peak occurred, it was restricted owing to the negative reactivity feedback effect, as shown in Figure 9.…”

Section: Reactivity Balancementioning

confidence: 99%

Experiments and validation analyses of HTTR on loss of forced cooling under 30% reactor power

Takamatsu

Tochio

Nakagawa

et al. 2014

Journal of Nuclear Science and Technology

Self Cite

View full text Add to dashboard Cite

In a safety demonstration test involving the loss of both reactor reactivity control and core cooling, the high-temperature engineering test reactor (HTTR) demonstrates spontaneous stabilization of the reactor power. The test and analytical results of tripping one or two out of three gas circulators without reactor scram have already been reported. Moreover, the pre-analytical result of tripping all three gas circulators without reactor scram has been presented. On the other hand, the test and analytical results of tripping all three gas circulators without reactor scram are shown in this paper. About experiments, at an initial reactor power of 30% (9 MW), when all three gas circulators were tripped without reactor scram to reduce the coolant flow rate to zero, the fuel temperature did not show a large increase because the large heat capacity of the graphite core could absorb heat from the fuel in a short period. Moreover, the decay heat could be transferred through the graphite core and the reactor pressure vessel (RPV), emitted by thermal radiation from its outer surface and removed to the active vessel cooling system; therefore, the core at 9 MW was never exposed to the danger of a core melt, and the reactor power was stabilized spontaneously. About analyses, the reactivity performance is important for predicting the converging level of reactor power that affects the fuel temperature during a loss of forced cooling (LOFC) without reactor scram. With regard to thermal hydraulics, the performances of graphite heat conduction in the reactor core and thermal radiation from the RPV surface to the reactor cavity cooling system are crucial for predicting the temperature behavior of the fuel and RPV in the LOFC condition. It was confirmed that reactor kinetics coupled with heat transfer could be applied to reactor safety and accident analysis based on the comparison between the experiments and the analyses.

show abstract

“…The safety demonstration tests are conducted to demonstrate inherent safety features of the HTGRs as well as to obtain the core and plant transient data for validation of safety analysis codes and for establishment of safety design and evaluation technologies of the HTGRs (8) .…”

Section: Httr Plantmentioning

confidence: 99%

Integrated On-line Plant Monitoring System for HTTR with Neural Networks

Nabeshima

Subekti

Matsuishi³

et al. 2008

JPES

Self Cite

View full text Add to dashboard Cite

The neural networks have been utilized in on-line monitoring-system of High Temperature Engineering Tested Reactor (HTTR) with thermal power of 30MW. In this system, several neural networks can independently model the plant dynamics with different architecture, input and output signals and learning algorithm. Monitoring task of each neural network is also different, respectively. Those parallel method applications require distributed architecture of computer network for performing real-time tasks. One of main task is real-time plant monitoring by Multi-Layer Perceptron (MLP) in auto-associative mode, which can model and estimate the whole plant dynamics by training normal operational data only. The basic principle of the anomaly detection is to monitor the difference between process signals measured from the actual plant and the corresponding values estimated by MLP. Other tasks are on-line reactivity prediction, reactivity and helium leak monitoring, respectively. From the on-line monitoring results at the safety demonstration tests, each neural network shows good prediction and reliable detection performances.

show abstract

Safety demonstration tests using high temperature engineering test reactor

Cited by 36 publications

References 2 publications

ATWS Characteristics of Super LWR with/without Alternative Action

ATWS Characteristics of Super LWR with/without Alternative Action

Experiments and validation analyses of HTTR on loss of forced cooling under 30% reactor power

Integrated On-line Plant Monitoring System for HTTR with Neural Networks

Contact Info

Product

Resources

About