Dr. Hak-Soo Kim Letter

Dr. Hak-Soo Kim                                                                    November 1999

Supervisor of Pressurized Water Reactor Safety Analysis

Commonwealth Edison Company

1400 Opus Drive

Downers Grove, IL.

To Whom It May Concern:

This letter is provided to discuss the activities and performance of Joseph S. Miller from October 1996 to September 1999.  Mr. Miller worked as a contractor for Commonwealth Edison in several different areas during this time.  I will only discuss the areas relevant to my responsibilities.

Mr. Miller began his work on evaluating a long standing problem of the Auxiliary Feedwater Pumps (AFWPs) for Byron Units 1 & 2 and Braidwood Units 1 & 2.  Both of these plants are Westinghouse Pressurized Water Reactors (PWRs) with large dry containments.  Since the beginning of plant operation, a very low-pressure signal in the pump suction during the start of the AFWPs would cause spurious alarms and/or trips to occur.  Mr. Miller modeled the AFW system from the Condensate Storage Tank (CST) to the Steam Generators using the computer program RELAP5.  With this model he was able to assess the root cause of the problem and propose a modification to correct it.  Once the modification was implemented, the problem was eliminated.  This effort required Mr. Miller to walk down the systems and coordinate information from the site System Engineers.  Mr. Miller attended several meeting with plant staff to discuss results and to evaluate alternatives.  Overall Mr. Miller performed in an Outstanding manner in successfully completing this project.

Another project that Mr. Miller completed was the evaluation of three-dimensional effects on the steam generator internals due to pipeline break depressurization wave.  As part of the evaluation of steam generator structural integrity, Commonwealth Edison performed a one-dimensional analysis of the steam generator internal structure during the rupture of the steam line.  During the review of licensing amendments for the Steam Generator replacement project for Byron and Braidwood, the NRC question the impact that three dimensional flow effects would have on the Steam Generator structure.  Using a multi stream tubes calculation with two-phase flow characteristics modeled, Mr. Miller evaluation the three-dimensional effects of the flow stream and provided a response to the NRC.

Mr. Miller participated in the first reload evaluation using the Replacement Steam Generators provided by Babcock & Wilcox for Braidwood and Byron Nuclear Power Stations.  Since an expedited schedule was required to successfully complete the reload safety analysis, Mr. Miller was sent to Westinghouse in Pittsburgh to support the Vendor in completing the reload safety analyses on schedule.  Mr. Miller developed input for use in the thermal hydraulic computer program, NOTHRUMP, and evaluated the feedwater transient for the reload safety analysis.  To complete this project Mr. Miller worked with other members of the Westinghouse safety analysis team and used Westinghouse software.  All analyses were completed on schedule and in an outstanding manner.

Mr. Miller completed an evaluation of local leak rate testing requirements to determine if Commonwealth Edition could request an exemption to some of the testing.  A steam leak model was developed that match the test data within 10 per cent.  The computer program, RELAP5, was used to predict the depressurization rate of the steam generator after it was isolated.  RELAP5 was also used to model a spectrum of small breaks to determine the break flow into the containment for different size breaks and GOTHIC was used to predict the pressure and temperature response due to these small breaks.  Mr. Miller completed all these analyses and developed a response matrix for leak detection requirements.

Mr. Miller successfully completed the technical specification changes for Condensate Storage Tank level requirements and AFWP actuation set point levels.  Mr. Miller also performed an evaluation for the adequacy of vortex correlations.  A correlation was developed and proposed that provided adequate protection from the formation of air ingestion vortices.

Mr. Miller provided technical guidance to many of the engineers at Commonwealth Edison and all his work was performed well.  I would recommend Mr. Miller for any Senior Level Position that required technical knowledge and guidance.

Sincerely,

Hak-Soo Kim

Supervisor of PWR Safety Analysis

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Last revised: October 30, 2000

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