Martin Pilch - Academia.edu (original) (raw)

Papers by Martin Pilch

The purpose of the Sandia National Laboratories (SNL) Advanced Simulation and Computing (ASC) Sof... more The purpose of the Sandia National Laboratories (SNL) Advanced Simulation and Computing (ASC) Software Quality Plan is to clearly identify the practices that are the basis for continually improving the quality of ASC software products. This plan defines the SNL ASC Program software quality engineering practices and provides a mapping of these practices to the SNL Corporate Process Requirement (CPR)001.3.6: "Corporate Software Engineering Excellence." This plan also identifies ASC management's and the software project teams' responsibilities in implementing the software quality practices and in assessing progress towards achieving their software quality goals.

Adiabatic equilibrium models for direct containment heating

Measuring and communicating progress in predictive capability

Verification: a physics-based procedure with applications to CTF and BISON

Proposed for presentation at the CASL Technical Symposium (Virtual) held November 15-19, 2020 in N/A, N/A, US., 2020

Development and implementation of a CTF code verification suite

Nuclear Engineering and Design, 2020

Abstract CTF is a thermal hydraulic subchannel code developed to predict light water reactor (LWR... more Abstract CTF is a thermal hydraulic subchannel code developed to predict light water reactor (LWR) core behavior. It is a version of Coolant Boiling in Rod Arrays (COBRA) developed by Oak Ridge National Laboratory (ORNL) and North Carolina State University (NCSU) and used in the Consortium for the Advanced Simulation of LWRs (CASL). In this work, the existing CTF code verification matrix is expanded, which ensures that the code is a faithful representation of the underlying mathematical model. The suite of code verification tests are mapped to the underlying conservation equations of CTF and significant gaps are addressed. As such, five new problems are incorporated: isokinetic advection, conduction, pressure drop, convection, and pipe boiling. Convergence behavior and numerical errors are quantified for each of the tests and all tests converge at the correct rate to their corresponding analytic solution. A new verification utility that generalizes the code verification process is used to incorporate these problems into the CTF automated test suite.

Code Verification and Solution Verification framework in pin-resolved neutron transport code MPACT

Annals of Nuclear Energy

Ctf: A Modernized, Production-Level, Thermal Hydraulic Solver for the Solution of Industry-Relevant Challenge Problems in Pressurized Water Reactors

SSRN Electronic Journal

Verification and Validation

Systems Engineering for Commercial Aircraft, Apr 1, 2016

We explore choices of boundary conditions within pressure convection-diffusion preconditioners fo... more We explore choices of boundary conditions within pressure convection-diffusion preconditioners for the incompressible Navier-Stokes equations. While these methods have been shown to be efficient, choosing the proper boundary conditions for the preconditioning operator is not well understood. In this paper, we first explore the effect of having "ideal" boundary conditions within the preconditioner. While not computationally feasible, the ideal boundary condition results highlight the importance of suitable boundary conditions. The remainder of the paper explores somewhat more practical approximations to the ideal conditions based on ILU factorizations and probing [5].

This report presents a perspective on the role of code comparison activities in verification and ... more This report presents a perspective on the role of code comparison activities in verification and validation. We formally define the act of code comparison as the Code Comparison Principle (CCP) and investigate its application in both verification and validation. One of our primary conclusions is that the use of code comparisons for validation is improper and dangerous. We also conclude that while code comparisons may be argued to provide a beneficial component in code verification activities, there are higher quality code verification tasks that should take precedence. Finally, we provide a process for application of the CCP that we believe is minimal for achieving benefit in verification processes. Figure 5.2 The multiplicity of challenges in using the CCP.

V and V principles and challenges

An Integral Effects Test to investigate the effects of condensate levels of water and preexisting hydrogen on direct containment heating in the Surtsey Test Facility. The IET-7 experiment

This report discusses the seventh experiment of the Integral Effects Test (IET-7) series. The exp... more This report discusses the seventh experiment of the Integral Effects Test (IET-7) series. The experiment was conducted to investigate the effects of preexisting hydrogen in the Surtsey vessel on direct containment heating. Scale models of the Zion reactor pressure vessel (RPV), cavity, instrument tunnel, and subcompartment structures were constructed in the Surtsey Test Facility at Sandia National Laboratories. The RPV was modeled with a melt generator that consisted of a steel pressure barrier, a cast MgO crucible, and a thin steel inner liner. The melt generator/crucible had a hemispherical bottom head containing a graphite limitor plate with a 4-cm exit hole to simulate the ablated hole in the RPV bottom head that would be formed by ejection of an instrument guide tube in a severe nuclear power plant accident. The cavity contained 3.48 kg of water, and the containment basement floor inside the cranewall contained 71 kg of water, which corresponds to scaled condensate levels in th...

Improvements to CTF Code Verification and Unit Testing (FY2020)

Experimental results of tests to investigate the effects of hole diameter resulting from bottom head failure on Direct Containment Heating (DCH) in the Surtsey Test Facility. The WC-1 and WC-3 Tests

The WC-1 and WC-3 experiments were conducted using a dry, 1:10 linear scale model of the Zion rea... more The WC-1 and WC-3 experiments were conducted using a dry, 1:10 linear scale model of the Zion reactor cavity to obtain baseline data for comparison to future experiments that will have water in the cavity. WC-1 and WC-3 were performed with similar initial conditions except for the exit hole between the melt generator and the scaled model of the reactor cavity. For both experiments the molten core debris was simulated by a thermitically generated melt formed from 50 kg of iron oxide/aluminum/chromium powders. After the thermite was ignited in WC-1, the melt was forcibly ejected by 374 moles of slightly superheated steam at an initial driving pressure of 4.6 MPa through an exit hole with an actual diameter of 4.14 cm into the scaled model of the reactor cavity. In WC-3, the molten thermite was ejected by 300 moles of slightly superheated steam at an initial driving pressure of 3.8 MPa through an exit hole with an actual diameter of 10.1 cm into the scaled model of the reactor cavity. ...

Kinetic limitations to adiabatic equilibrium models for direct containment heating (DCH)

Probabilistic risk assessment studies are being extended to include a wider spectrum of reactor p... more Probabilistic risk assessment studies are being extended to include a wider spectrum of reactor plants than was considered in NUREG-1150. There is a need for computationally simple models of direct containment heating (DCH) that could be used for screening studies aimed at identifying potentially significant contributors to overall risk. The two-cell kinetic model developed here is an extension of the two-cell equilibrium model developed previously, which captured a major mitigating feature due to containment compartmentalization. This extension of the equilibrium model represents additional mitigating features resulting from two kinetic competitions: time-of-flight limitations to debris/gas heat transfer and debris oxidation, and the noncoherence or reactor coolant system blowdown with debris residence in the atmosphere. Predictions of containment pressurization and hydrogen production are compared to experiment data taken in the Surtsey facility located at Sandia National Laborato...

The Integral Effects Test (IET-1) in the Surtsey Test Facility

The first experiment of the Integral Effects Test (IET-1) series was conducted to investigate the... more The first experiment of the Integral Effects Test (IET-1) series was conducted to investigate the effects of high pressure melt ejection (HPME) on direct containment heating (DCH). A 1:10 linear scale model of the Zion reactor pressure vessel (RPV), cavity, instrument tunnel, and subcompartment structures were constructed in the Surtsey Test Facility at Sandia National Laboratories (SNL). The RPV was modelled with a melt generator that consisted of a steel pressure barrier, a cast MgO crucible, and a thin steel inner liner. The melt generator/crucible had a semi-hemispherical bottom head containing a graphite limitor plate with a 3.5 cm exit hole to simulate the ablated hole in the RPV bottom head that would be formed by tube ejection in a severe nuclear power plant (NPP) accident. The reactor cavity model contained 3.48 kg of water with a depth of 0.9 cm that corresponded to condensate levels in the Zion plant. A steam driven iron oxide/aluminum/chromium thermite was used to simula...

Nuclear Technology - NUCL TECHNOL, 1992

This paper reports that the limited flight path experiments investigate the effect of reactor sub... more This paper reports that the limited flight path experiments investigate the effect of reactor subcompartment flight path length on direct containment heating (DCH) in a severe reactor accident. The test series consists of eight experiments with nominal flight paths of 1, 2, or 8 m. A thermitically generated mixture of iron, chromium, and alumina simulates the corium melt of a severe accident in a light water reactor. After thermite ignition, superheated steam forcibly ejects the molten debris into a 1:10 linear scale model of either the Surry or Zion reactor cavity. The blowdown steam entrains the molten debris and disperses it into a 103-m[sup 3] containment model. The vessel pressure, gas temperature, debris temperature, hydrogen produced by steam/metal reactions, debris velocity, mass dispersed into the Surtsey vessel, and debris particle size are measured for each experiment. The measured peak pressure for each experiment is normalized by the total amount of energy introduced in...