OECD LOFT-T-3804, 'OECD LOFT Project, Quick-Look Report on ... OECD LOFT-T--3804 "WW OECD LOFT...

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Transcript of OECD LOFT-T-3804, 'OECD LOFT Project, Quick-Look Report on ... OECD LOFT-T--3804 "WW OECD LOFT...

  • OECD LOFT-T--3804

    "WW

    OECD LOFT Project

    Quick-Look Report on OECD LOFT

    Experiment LP-FP-2

    September 1985

    NOTICE

    This report is for the benefit of OECD LOFT participants and their designees only

    This report has been prepared pursuant to the "Agreement on an OECD Project of the LOFT Experimental Programme." It is the policy of the Management Board that the Information contained in this report be used only for the benefit of the participants and the participants' designees. The contents of this report should not be disclosed to others or reproduced wholly or partially unless authorized in accordance with the laws, regulations, policies, or written permission of the appropriate project participant.

    Prepared by EG&G Idaho, Inc. under the direction of the U.S. Department of Energy, Idaho National Engineering Laboratory

  • 0

    E 0•

    -ri 0

    QUICK-LOOK REPORT ON OECD LOFT EXPERIMENT LP-FP-2

    Authors: - .

    J. P. Adams 0 J. C. Birchley z

    N. Newman N

    E. W. Coryell ) Mi M. L. Carboneau x ( -<

    S. Guntay L. J. Siefken M O

    Contributors: X (.

    Y. Anoda C) J. Bagues

    V. T. Berta E. Borioli 0. Briney

    J. Esteban D. L. Hagrman

    R. Hesbol K. J. McKenna D. C. Mecham

    S. M. Modro

    D. L. Batt, Supervisor FP-2 Experiment Section

    D. W. Croucher, Manager LOFT Experiment Planning and Analysis Branch

    P. North, Manager OECD LOFT Project

  • QUICK-LOOK REPORT ON OECD LOFT EXPERIMENT LP-FP-2

    Authors:

    J. P. Adams J. C. Birchley

    N. Newman E. W. Coryell

    M. L. Carboneau S. Guntay

    L. J. Siefken

    Contributors:

    Y. Anoda J. Bagues

    V. T. Berta E. Borioli 0. Briney

    J. Esteban 0. L. Hagrman

    R. Hesbol K. J. McKenna D. C. Mecham

    S. M. Modro

    Published September 1985

    EG&G Idaho, Inc. Idaho Falls, Idaho 83415

    Prepared for the U. S. Department of Energy

    Idaho Operations Office Under DOE Contract No. OE-ACO7-761DO1570

  • ABSTRACT

    Experiment LP-FP-2 was conducted on July 9, 1985, in the Loss-of-Fluid

    Test (LOFT) facility at the Idaho National Engineering Laboratory under the

    auspices of the Organization for Economic Cooperation and Development

    (OECD). The objectives of this experiment were to obtain information on

    the release of fission products from the fuel and transport of these

    fission products in a vapor and aerosol environment from the primary coolant system. The thermal/hydraulic boundary conditions during the

    release and transport of fission products were based on a V-Sequence

    accident. The emergency core cooling (ECC) injection was delayed until

    specified temperature limits on the thermal shroud were reached, by which

    time the desired time and conditions for fission product release and

    transport were achieved. The plant was then brought to a safe condition

    with full ECC injection. Specially designed fission product measurements

    were made in the primary coolant system and blowdown suppression system during the transient and also up to 44 days thereafter, during which time

    the plant was maintained in a quiescent state and the two systems were

    individually isolated. This document provides an initial assessment of the

    experiment that covers the initial conditions, sequence of events,

    preliminary results of the fission product behavior within the

    thermal/hydraulic boundary conditions, and comparisons of the results with

    preexperiment calculations.

    ii

  • SUMMARY

    Experiment LP-FP-2, conducted on July 9, 1985, was the second fission

    product release and transport experiment and the eighth (and last)

    experiment conducted in the Loss-of-Fluid Test (LOFT) facility at the Idaho

    National Engineering Laboratory under the auspices of the Organization for

    Economic Cooperation and Development. The principal objectives for this

    experiment were to determine the fission product release from the fuel and

    the subsequent transport of those fission products (in a predominantly

    vapor/aerosol environment) from the primary coolant system. The initial

    conditions were representative of commercial pressurized water reactor

    (PWR) operations. The thermal/hydraulic boundary conditions during fission

    product release and transport were based on a V-Sequence accident wherein a

    low-pressure injection system (LPIS) line ruptures and the emergency core

    cooling (ECC) injection is delayed until fuel rod cladding and control rod

    melting and material relocation occurs. The transient was initiated by

    scramming the reactor, inserting the center fuel module control rods, and,

    after a specific delay, opening a break in the intact loop cold leg. A

    second break (simulated LPIS line) was opened 222 s after reactor scram.

    The first break was closed prior to fuel rod failure to provide a well

    defined path for fission product transport. The transient continued until

    control rod and fuel rod cladding melting and fission product release from the fuel occurred. The experiment was terminated by injection from both

    ECC lines into the reactor vessel downcomer and lower plenum.

    The initial assessment of data from instruments monitoring the upper

    plenum (Fl) and the reactor vessel outlet (F2) sampling lines indicates

    that fission products were sampled and the lines operated as expected.

    Since the gamma spectrometer located on the Fl line (G6) failed prior to

    the experiment, a gross gamma detector (remote area monitor) was placed on

    the top of the reactor vessel and detected fission products from both the

    fuel/cladding gap and the fuel as they were transported through the Fl

    line. The spectrometer (G2) that monitored the combined effluent from the

    Fl and F2 lines during the transient measured several isotopes of xenon and

    krypton.

    iii

  • Radiation scans of the simulated LPIS line at the time of the first

    postexperiment containment entry indicate that fission products were

    collected by the deposition coupons in this line. Metal temperatures at

    the deposition coupon locations in both the reactor vessel and simulated

    LPIS line were approximately 100 K (180'F) higher than saturation, which

    was sufficiently high to ensure fission product deposition in steam.

    The gamma spectrometer in the simulated LPIS line (G5) sampled various

    isotopes. In order of volatility, these were xenon, iodine, cesium,

    tellurium, and rubidium.

    The G5 gamma spectrometer, the F2 and F3 aerosol sampling systems, and

    the D2 and D3 deposition spool pieces appear to have operated as designed.

    High background may limit the applicability of the GI (primary system),

    G2 [blowdown suppression tank (BST) vapor], and G3 (BST liquid) gamma

    spectrometers during the early part of the posttransient phase, and one or

    more of the Dl protected coupons may have been exposed to reflood. There

    was a loss of data from the G6 gamma spectrometer, which was partially

    recovered with data from a remote area monitor. Also, significant data

    were obtained from grab samples and Health and Safety instrumentation.

    Experiment predictions indicated that, in order to produce the desired

    fission product release and transport boundary conditions, the thermal

    transient should produce cladding temperatures of 2100 K (3320°F) or higher

    for a minimum of three minutes. During the experiment, cladding

    temperatures exceeded 2100 K (3320*F) for at least 4-1/2 min, which was 50%

    longer than the minimum 3 min identified prior to the experiment. As a

    result, the final fission product concentrations in the primary coolant

    system and blowdown suppression tank are expected to be higher than those

    which were predicted, thus enhancing the detectability of low-yield fission

    products.

    Comparison with the measured thermal/hydraulic response showed that

    the predictions were very adequate as a planning tool for this experiment.

    The timing and extent of the core thermal response was closely predicted

    iv

  • with the exception of the lack of steam starvation in the upper parts of

    the center fuel module. This discrepancy resulted from a

    larger-than-predicted center fuel module steam flow which, in turn, is

    judged to have been caused by greater-than-calculated depressurization rate

    during the high temperature period of the transient. The resistance in the

    simulated LPIS line was much greater than modeled. This led to a higher

    primary system pressure at the start of the high temperature period and a

    continued depressurization during the high temperature period as opposed to

    the nearly flat pressure response that was predicted. Inability to

    accurately predict the flow resistance in this line was recognized prior to

    the experiment as an area of experimental uncertainty, and adequate

    contingency measures were included in the Experiment Operating Procedure.

    Based on the preliminary information presented herein, the data

    obtained from this experiment are considered adequate to meet the fission

    product measurement objectives and, ultimately, the overall experiment

    objectives,