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in creator/contributor: "Pratt, W. T."

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Containment response to postulated ex-vessel core meltdown accidents in the fast flux test facility

An evaluation of the containment response to ex-vessel core meltdown accidents in the Fast Flux Test Facility is discussed. Particular attention is given to the possibility of the molten fuel/steel mixture remaining in a molten form after entering the reactor cavity. For the molten pool configurations considered, significant H/sub 2/ concentrations were reached in the RCB before the reactor cavity floor was penetrated. The melt-front impacts the pressure transient, not through gas generation, b… more

Date: January 1, 1979

Creator: Pratt, W. T.; Gasser, R. D. & Marchese, A. R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Containment performance for the core melt accidents in BWRs with Mark I and Mark II containments

Most previous risk assessment studies have assumed catastrophic failure of containments for severe accidents which are predicted to exceed the containment yield stress. This investigation analyzes the progression of a severe accident in order to develop realistic containment temperature and pressure loading, utilizes models for containment leakage estimates for the various loading histories, and assesses the expected failure modes and timing of releases for core melt accidents in Boiling Water … more

Date: January 1, 1985

Creator: Perkins, K. R.; Yang, J. W.; Greene, G. A.; Pratt, W. T. & Hofmayer, C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Evaluation of containment failure modes and fission product releases during core meltdown accidents in a BWR with a Mark III containment

An assessment is described of potential failure modes and fission product releases for a large number of postulated core meltdown accidents in a BWR with a Mark III containment. For this containment design, the most important failure mode was found to be due to hydrogen related phenomena. A one-dimensional lumped parameter computer code has been developed and used to determine the probability of various hydrogen phenomena for a range of postulated core meltdown sequences. Potential containment … more

Date: January 1, 1985

Creator: Ludewig, H.; Yu, W. S.; Jaung, R. & Pratt, W. T.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Mitigation of internally initiated severe accidents for a BWR Mark-II power plant

A probabilistic risk assessment and consequence analysis for a BWR with a Mark-II containment design has shown that overpressurization is the dominant containment failure mode for a wide range of potential core meltdown accidents. This failure mode is a major contributor to the predicted off-site health consequences. Mitigation of this failure mode is aimed at maintaining the containment integrity by using a wetwell venting system and a drywell spray system. Detailed analyses with the MARCH 2 c… more

Date: January 1, 1985

Creator: Yang, J. W. & Pratt, W. T.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Analysis of hydrogen production during a BWR6 core heatup transient

An extensive study was performed for the prediction of hydrogen production during a BWR6 core heatup transient. Hydrogen production was found to be strongly affected by the transient core heat transfer and vessel hydrodynamics. Various sources important for steam generation and hydrogen production were identified. The results of the study were used by the NRC staff in their evaluation of the adequacy of the H/sub 2/ release histories suggested by the Hydrogen Control Owner's Group (HCOG). The o… more

Date: January 1, 1986

Creator: Yang, J. W. & Pratt, W. T.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Risk contribution from low power, shutdown, and other operational modes beyond full power

During 1989 the Nuclear Regulatory Commission (NRC) initiated an extensive program to carefully examine the potential risks during low power and shutdown operations. Two plants, Surry (a pressurized water reactor) and Grand Gulf (a boiling water reactor), were selected for study by Brookhaven National Laboratory and Sandia National Laboratories, respectively. The program objectives included assessing the risks of severe accidents initiated during plant operational states other than full power a… more

Date: January 1, 1995

Creator: Whitehead, D. W.; Brown, T. D.; Chu, T. L. & Pratt, W. T.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

QUASAR: A methodology for quantification of uncertainties in severe accident source terms

The purpose of the present paper is to describe a methodology which was developed as part of the QUASAR (Quantification and Uncertainty Analysis of Source Terms for Severe Accidents in Light Water Reactors) program at BNL. QUASAR is a large program which will apply the methodology described in this paper to severe accident sequences in LWRs using the STCP.

Date: January 1, 1986

Creator: Khatib-Rahbar, M.; Park, C.; Pratt, W. T.; Bari, R. A.; Ryder, C. & Marino, G.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Evaluation of potential severe accidents during low power and shutdown operations at Surry: Unit 1, Volume 1

This document contains a summarization of the results and insights from the Level 1 accident sequence analyses of internally initiated events, internally initiated fire and flood events, seismically initiated events, and the Level 2/3 risk analysis of internally initiated events (excluding fire and flood) for Surry, Unit 1. The analysis was confined to mid-loop operation, which can occur during three plant operational states (identified as POSs R6 and R10 during a refueling outage, and POS D6 d… more

Date: October 1995

Creator: Chu, T. L.; Pratt, W. T. & Musicki, Z.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Assessment of Uncertainties in Core Melt Phenomenology and Their Impact on Risk at the Z/Ip Facilities

An evaluation of core meltdown accidents in the Z/IP facilities has been performed. Containment event trees have been developed to relate the progression of a given accident to various potential containment building failure modes. An extensive uncertainty analysis related to core melt phenomenology has been performed. A major conclusion of the study is that large variations in parameters associated with major phenomenological uncertainties have a relatively minor impact on risk when external in… more

Date: January 1, 1983

Creator: Pratt, W. T.; Ludewig, H.; Bari, R. A. & Meyer, J. F.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Accident Management for Severe Accidents

The management of severe accidents in light water reactors is receiving much attention in several countries. The reduction of risk by measures and/or actions that would affect the behavior of a severe accident is discussed. The research program that is being conducted by the US Nuclear Regulatory Commission focuses on both in-vessel accident management and containment and release accident management. The key issues and approaches taken in this program are summarized. 6 refs.

Date: January 1, 1988

Creator: Bari, R. A.; Pratt, W. T.; Lehner, J.; Leonard, M.; Disalvo, R. & Sheron, B.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Markov Model of Severe Accident Progression and Management

The earthquake and tsunami that hit the nuclear power plants at the Fukushima Daiichi site in March 2011 led to extensive fuel damage, including possible fuel melting, slumping, and relocation at the affected reactors. A so-called feed-and-bleed mode of reactor cooling was initially established to remove decay heat. The plan was to eventually switch over to a recirculation cooling system. Failure of feed and bleed was a possibility during the interim period. Furthermore, even if recirculation w… more

Date: June 25, 2012

Creator: Bari, R. A.; Cheng, L.; Cuadra, A.; Ginsberg, T.; Lehner, J.; Martinez-Guridi, G. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Insights Gained From in-Depth Reviews of Several Industry Generated Pras

During the last several years BNL staff have performed in-depth reviews of the containment failure modes and fission product release analyses of all the ''industry'' PRAs submitted to the Office of Nuclear Reactor Regulation, NRC. This program started with a reevaluation of the risks reported in the Zion and Indian Point Probabilistic Safety Studies (PWRs with large dry containments) and was followed by reviews of the Limerick (BWR with Mark II containment) and Big Rock Point (early BWR design)… more

Date: January 1, 1985

Creator: Pratt, W. T.; Khatib-Rahbar, M.; Bari, R. A. & Rosenthal, J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Issues in risk analysis of passive LWR designs

This paper discusses issues which bear on the question of how safety is to be demonstrated for ``simplified passive`` light water reactor (LWR) designs. First, a very simplified comparison is made between certain systems in today`s plants. comparable systems in evolutionary designs, and comparable systems in the simplified passives. in order to introduce the issues. This discussion is not intended to describe the designs comprehensively, but is offered only to show why certain issues seem to be… more

Date: December 31, 1992

Creator: Youngblood, R. W.; Pratt, W. T.; Amico, P. J. & Gallagher, D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Review of APR+ Level 2 PSA

Brookhaven National Laboratory (BNL) assisted the Korea Institute of Nuclear Safety (KINS) in reviewing the Level 2 Probabilistic Safety Assessment (PSA) of the APR+ Advanced Pressurized Water Reactor (PWR) prepared by the Korea Hydro & Nuclear Power Co., Ltd (KHNP) and KEPCO Engineering & Construction Co., Inc. (KEPCO-E&C). The work described in this report involves a review of the APR+ Level 2 PSA submittal [Ref. 1]. The PSA and, therefore, the review is limited to consideration of accide… more

Date: February 17, 2012

Creator: Lehner, J.R.; Mubayi, V. & Pratt, W. T.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Issues in risk analysis of passive LWR designs

This paper discusses issues which bear on the question of how safety is to be demonstrated for simplified passive'' light water reactor (LWR) designs. First, a very simplified comparison is made between certain systems in today's plants. comparable systems in evolutionary designs, and comparable systems in the simplified passives. in order to introduce the issues. This discussion is not intended to describe the designs comprehensively, but is offered only to show why certain issues seem to be i… more

Date: January 1, 1992

Creator: Youngblood, R. W.; Pratt, W. T.; Amico, P. J. & Gallagher, D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

NRC support for the Kalinin (VVER) probabilistic risk assessment

The US Nuclear Regulatory Commission (NRC) and the Federal Nuclear and Radiation Safety Authority of the Russian Federation have been working together since 1994 to carry out a probabilistic risk assessment (PRA) of a VVER-1000 in the Russian Federation. This was a recognition by both parties that this technology has had a profound effect on the discipline of nuclear reactor safety in the West and that the technology should be transferred to others so that it can be applied to Soviet-designed p… more

Date: December 31, 1998

Creator: Bley, D.; Diamond, D. J.; Chu, T. L.; Azarm, A.; Pratt, W. T.; Johnson, D. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Risk contribution from low power and shutdown of a pressurized water reactor

Date: April 1997

Creator: Chu, T. L. & Pratt, W. T.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Containment performance perspectives based on IPE results

Perspectives on Containment Performance were obtained from the accident progression analyses, i.e. level 2 PRA analyses, found in the IPE submittals. Insights related to the containment failure modes, the releases associated with those failure modes, and the factors responsible for the types of containment failures and release sizes reported were gathered. The results summarized here are discussed in detail in volumes 1 and 2 of NUREG 1560. 3 refs., 4 figs.

Date: 1997

Creator: Lehner, J. R.; Lin, C. C. & Pratt, W. T.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Prioritization of Environmental, Safety, and Health Issues at Brookhaven National Laboratory

This paper describes short-term and long-term enhancements to the existing prioritization system at BNL which are being carried out under the Management Systems Improvement Program in response to DOE`s Integrated Safety Management System Evaluation of BNL. The enhancements focus on: inclusion of stakeholder (public, elected officials, and media) perceptions; achievement and maintenance of full compliance with all applicable federal, state, and local laws, ordinances regulations, and codes; devo… more

Date: April 1, 1998

Creator: Mubayi, V.; Lehner, J.; Lin, C. C.; Conrad, C. & Pratt, W. T.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

NRC Support for the Kalinin (Vver) Probabilistic Risk Assessment

Date: October 26, 1998

Creator: Bley, D.; Diamond, D. J.; Chu, T. L.; Azarm, A.; Pratt, W. T.; Johnson, D. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department