ML092020020
| ML092020020 | |
| Person / Time | |
|---|---|
| Issue date: | 10/02/1998 |
| From: | Han J Office of Nuclear Regulatory Research |
| To: | Eltawila F Office of Nuclear Reactor Regulation |
| Han, James T. | |
| References | |
| Download: ML092020020 (3) | |
Text
October 2, 1998 MEMORANDUM TO: Farouk Eltawila, Chief FROM:
SUBJECT:
Reactor and Plant Systems Branch Division of Systems Technology Office of Nuclear Regulatory Research James T. Han Reactor and Plant Systems Branch Division of Systems Technology Office of Nuclear Regulatory Research Answers to the Questions Raised by the OECD/NEA/CSNI Senior Group of Experts on Nuclear Safety Research Facilities and Programs This note addresses the questions raised by the OECD/NEA/CSNI experts. Listed below are the questions and our answers. Attached to this MEMO are the OECD/NEA/CSNI question list and a response from Prof. M. Ishii of Purdue University.
Question 1.
Which specific needs do you see for further experiments in large facilities?
Specific processes/phenomena and relation to safety issues.
Answer:
In July 1996, OECD/CSNI published a state-of-the-art review report
[NEA/CSNI/R996}17, OCDE/GD(97}12], which defined a comprehensive list of the integral test facility validation matrix for the assessment of thermal-hydraulic codes for LWR LOCAs and transients. The validation test matrix represents the best set of available test data that were produced internationally over the last 20 years prior to 1996. However, the matrix was focused only on the phenomena and processes in the reactor coolant system (RCS). Missing in the validation matrix and the OECD/CSNI report are the BWR containment phenomena and processes.
The specific needs for future experiments are the integral-effects data of the RCS and containment phenomena and processes under various LOCAs in a BWR test facility. The phenomena and processes of interest include the RCS blowdown with rapid decrease in pressure and temperature and water level, mass flow rate at the break, rise in the containment (including both drywell and wetwell) pressure and temperature, steam condensation in the suppression pool, steam condensation on the drywell wall with the presence of non-condensible, non-condensible gas and temperature distributions in the drywell, thermal stratification in the suppression pool, and the long-term pressure and temperature response in the RPV and containment.
An important point to make is that the BWR containment phenomena and processes are thermal-hydraulically coupled to the RCS phenomena and processes especially after the RCS is depressurized. As a result, integral-effects test data involving both the RCS and containment are needed.
Relevance to nuclear reactor safety The containment is the last line of defense against the release of radionuclides, and its integrity is a very important safety issue. In order to assess and understand the containment response to various LOCAs, the Integral-effects test data involving both the RCS and the containment are therefore needed.
Question 2.
Which major facilities in your country can help to satisfy these needs?
Show correspondence of your facilities' features to the needs that you have itemized above.
Answer:
The PUMA test facility at Purdue University (West Lafayette, Indiana, USA) is well suited to provide the integral-effects test data on the RCS and containment phenomena and processes in a BWR. PUMA has the key components and systems relevant to the operating BWRs, and it has the state-of-the-art instrumentation.
PUMA has a reactor pressure vessel (RPV), drywell, wetwell including a suppression pool, Automatic Depressurization System (ADS) for rapid RPV depressurization, Isolation Condenser System {ICS) for RPV cooling, feedwater system, drwyell spray, wetwell spray, and external heat exchangers for suppression pool cooling if needed.
In addition, PUMA also has two passive safety systems that are unique to an advanced BWR called the Simplified Boiling Water Reactor (SBWR), which was designed by the General Electric Company. The passive safety systems consist of the Passive Containment Cooling System (PCCS) for drywell cooling and the Gravity-Driven Cooling System (GDCS) to provide emergency core cooling water to the RPV. These two passive systems can be valved out if not needed in a test. Similar to the operating BWRs, the ADS of PUMA uses the safety/relieve valves (SRVs) to allow flow from the RPV to the suppression pool. But unlike the operating BWRs, the ADS of PUMA also has depressurization valves (DPVs) that provide blowdown paths from the RPV to the drywell. The DPVs can be valved our if not needed in a test.
PUMA is well instrumented. It has approximately 420 measurements for pressure, temperature, water level, oxygen concentration, flow rate, void fraction, and core power. It is designed to perform large-break or small-break LOCAs at three different elevations in the RPV. PUMA has a volume of 1/400 and a height of 1/4 of an advanced BWR. It is designed for low-pressure tests (no more than 150 psia), and it is well-suited to obtain data at low-pressure and low-flow conditions where the existing data are scarce.
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Question 3.
If closure of your facility is imminent within the next 5 years:
A.
What makes the PUMA facility unique, so that closure should be of concern to OECD?
Answer:
PUMA has the key BWR-relevant components and the state-of-the-art instrumentation to provide integral-effects test data on the coupled RCS and containment phenomena and processes. In addition, PUMA is operationally flexible with a number of isolation valves to valve out unneeded components. As a result, separate-effects test data of interest to the OECD members can also be obtained at PUMA. Examples of the separate-effects tests are the single-phase and two-phase natural circulation in the RPV and isolation condensers, condensation of the steam and non-condensible gas mixture in the suppression pool, non-condensible gas distribution in the drywell, condensation in the vertical-tube condensers of the ICS or the PCCS with or without the presence of non-condensible. In addition, RPV blowdown into drywell via the DPVs will provide containment data for dry containments as in the PWRs.
B.
Which investigations of common interest to OECD member countries could be performed in the PUMA facility?
Answer:
Any of the integral-effects and separate-effects tests discussed under #A above could be performed in the PUMA facility.
C.
What is the annual cost of operation of the PUMA facility?
Answer:
Attachments: As stated
$500,000 (in 1999 U.S. dollars) is the annual PUMA operational cost.
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