United States Nuclear Regulatory Commission - Protecting People and the Environment

Description and RELAP5 Assessment of the PMK-2 CAMP-CLB Experiment: 2% Cold Leg Break Without HPIS With Secondary Bleed (NUREG/IA-0201)

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Publication Information

Date Published: March 2001

Prepared by:
L. Perneczky, G. Baranyai, A. Guba, Gy. Ézsöl, I. Tóth
KFKI Atomic Energy Research Institute
P.O. Box 49
H-1525 Budapest, Hungary

Prepared as part of:
The Agreement on Research Participation and Technical Exchange
under the International Code Application and Maintenance Program (CAMP)

Office of Nuclear Regulatory Research
U.S. Nuclear Regulatory Commission
Washington, DC 20555-0001

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Abstract

There is a general interest to validate best estimate (BE) reactor safety system codes for VVER-type reactors. The OECD-VVER code validation matrix is Used for the selection of tests in support of accident management (AM) and to eliminate "white spots" in the matrix. Based on this matrix - test types not yet covered - a proposal was made at the 12th (Spring '98) CAMP meeting in Ankara:

  • perform VVER-440/213 related experiment on the Hungarian PMK-2 test facility
  • validate RELAP5/mod 3.2 code.

The CAMP-CLB test is an AM-type experiment with small leak in the primary coolant system needing secondary side heat removal. The break size is 2 %, heat removed by break is insufficient to depressurise primary circuit below secondary pressure. Steam dump valve to atmosphere regulates secondary pressure until - as an AM action - secondary bleed is started following core fuel rod simulator overheating which is a consequence of unavailability of the high pressure injection systems.

Report presents a short description of the PMK-2 facility, the initial and boundary conditions of the test followed by an evaluation of the results by measured parameters. After reviewing modelling aspects and results of post-test calculations by RELAP5/mod3.2.2Gamma a sensitivity study is described. The "bifurcation type" behaviour encountered in parametric studies could be the result of the code calculating by different constitutional models depending on the time step or secondary heat losses. This behaviour needs further investigation and it is reported as a new RELAP5 User Problem.

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