ML19260C448
| ML19260C448 | |
| Person / Time | |
|---|---|
| Issue date: | 11/16/1979 |
| From: | Burger C NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| To: | Shao L NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| References | |
| REF-GTECI-A-01, REF-GTECI-PI, TASK-A-01, TASK-A-1, TASK-OR NUDOCS 8001030424 | |
| Download: ML19260C448 (3) | |
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UNITED STATES NUCL, EAR REGULATORY COMMISSION y
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-E WASHINGTON, D. C. 20555
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NOV 10 979 NOTE TO: 1.arry Shao FR0fi:
Chatles Burger
SUBJECT:
MEETING WITH HEISSDAMPFREAKTOP (HDR) STAFF ON WATER HAMMER The HDR staff presented a brief overview of the HDR Program with particular emphasis on valve testing capabilities during blowdown and the resulting water hammer effects.
The HDR power plant was out of service for several years befort.,eing converted to a test facility for blowdown experiments.
An experimental program concerned with valves and their dynamic behavior under blowdown conditions was performed. Quick closing valves, pressure waves and the loading of the discharge pipe were observed during the blowdown conditions. The valves tested to date were a steam isolation valve and two feedwater check valves.
In addtion, analytical studies were performed using computer codes in an attempt to interpret the test results. The codes were able to handle pressure wave phenomena as well as the dynamic behavior of the quick closing valves. The analytical results were compared with the experi-mental results for the purpose of verification of the codes.
The code used to determine the effects of fluid and valve dynamics is known as "DAPSY" and the correspondence with the experimental data for this code was tenned fairly accurate.
However, the structural portion of the code was unable to agree with test results and, therefore, further work will have to be initiated to handle such problems as pipe dynamics combined with fluid-structure interaction in order to achieve better agreement between calculations and experiments.
The HDR staff requested help, from the NRC, with developing a code capable of doing this.
The HDR staff has t.een successful in damping the feedwater check valve slowly during initial closure so that the mass flow rate cannot increase to the steady state values. Then, increasing the damping during the latter part of closure, to diminish the mass flow rate very slowly, has resulted in eliminating the water haniner pressure pulse when the valve closed totally.
1700 00 UP 8001 030 i
Larry Shao 2
The NRC staff presented our water hanrner program and described what had been accomplished and what was planned for the' future.
We indicated that a large portion of our futura efforts would be directed toward resolving the steam bubble collapse problem.
After describing the problem as we saw it, the HDR staff indicated that they were not aware of the problem.
In a follow up meeting the next day, between T. Grillenberger and C. W.
Burger, T. Grillenberger expressed great interest in steam bubble collapse and that he had thought about it overnight.
He was concerned about the second pressure pulse that was observed during blowdown valve closure.
The second pressure pulse was nearly as great as the first.
We discussed the probability that the second pulse was caused by column separation. That is, after the initial pressure pulse resulting from valve closure, the water column began to reverse flow causing a pressure decrease at the valve which in turn, caused the water to flush to steam causing a steam pocket.
The water column again reversed, collapsing the steam pocket which resulted in a second pressure pulse of nearly 6,000 psi.
Dr. T. Grillenberger stated that he was concerned enough to run some laboratory tests of his own.
A list of attendees is enclosed for your review.
es W. Burger
Enclosure:
as stated cc:
T. E. Murley, RSR S. Hanauer, NRR M. Aycock, NRR V. Benaroya, DSS V. Noonan, NRR G. Bagchi, RSR C. Burger, RSR R. Colmar, D0R J. Fair, D0R R. LaGrange, D0R J. Martore, D0R C. Tan, DSS J. Zwolinski, DSS D. Fisher, DSS F. Cherny, DSS 1700 014
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Enclosure ATTENDEES G. Bagchi RSR C. Burger RSR R. Colmar DDR J. Fair D0R W. Muller-Diestsche HDR T. Grillenberger HDR R. LaGrange DDR J. Martore DOR C. Tan DSS J. Zwolinski DSS 9
v 1700 015
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