ML20127P346
| ML20127P346 | |
| Person / Time | |
|---|---|
| Issue date: | 01/27/1993 |
| From: | Amy Cubbage Office of Nuclear Reactor Regulation |
| To: | Rosalyn Jones Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 9302010261 | |
| Download: ML20127P346 (3) | |
Text
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i January 27, 1993 l
HEMORANDUM FOR:
Robert C. Jones, Chief Rea:. tor Systems Branch Division cf Systems Safety and Analysis THRU-Timothy E. Collins, Chief BWR Reactor Systems Section Reactor Systems Branch Divi:lon of Systems Safety and Analysis FROM:
Amy E. Cuobage, Reactor Systems Engineer BWR Reactor Systems Section Reactor Systems Branch Division of Systems Safety and Analysis
SUBJECT:
MEETING
SUMMARY
FROM BWRGG MEETING ON POTENTIAL BWR WATER LEVEL INSTRUMENT ERRORS A meeting was held with the BWR Owners' group (BWROG) on January 15, 1993 to update the staff on current BWROG activitles to assers and address potential inaccuracies of BWR f
water level instrumentation caused by the evolution of dissolved non condensible gas during and after rapid depressurization events.
The list of attendees is provideti in the enclosure, and a summary of the issues discussed is provided below.
The BWROG -informed the staff that -there was a transfer of responsibility for this issue from the Regulatory Response Group (RRG) to a full committee. The CWROG then proceeded to-discuss the BWROG program for resolution of this issue.
They emphasized that the objective of the program is to address and resolve the issue by determining the validity of the postulated phenomenon, determining the effectiveness of potential hardware modifications, and by performing analyses and testing. The purpose of the program, not to prove that modifications are not necessary.
The Owners' group provided an update to the status of all aspects of the program.
Gathering of plant specific data and development of the analytical model are-proceeding-as scheduled, and are nearing completion. The reference leg de-gas test is proceeding within one week of the schedule.. Testing is scheduled to begin mid-February at the EPRI facility-in Charlotte, North Carolina. The staff was invited to-travel to Charlotte during the week of February 8 to tour and inspect the test facility. 'The BWROG has selected-a facility and is making preliminary prepacations for the condensate chamber test.
At this time, however, they stated that they are waiting-for the results of the de-gas test prior to moving forward with the condensate chamber test. The Owners' nroup is also working on acceptance criteria for level indication errors. The NRC staff requested a separate meeting to discuss the BWROG acceptance crite'ria when they are established.
The BWROG discussed that when certain factors are taken into account, such as the bubble r-rise velocity, the hydrostatic head of the column of water, and the relaxation time or de-gas rate, that calculated errors may be less than those initially predicted. They are clso finding _ that the de-gas rate may be independent of the rate of depressurization. The g;
BWROG perfnrn.ed a demonstration of these effects during the meeting.
The BWROG noted that REIDEIU R303 TORY ETR 923 g%d p?Ng//./ Q / ^;-
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I these results were strictly preliminary and that the testing program and analyses must be ncrformed tafore coning to any conclusions.
They have, however, come to the conclusion that the potential errors are well bounJod by inittai calculations presented ia July of 1992.
The staf f not.ed that a representative of the B5W Ovme r c ' Group (B&WOG) said that BLW had perrormed some testinc, of reference legs for the non-condensible gas problem in the mid 1970's. Tre BWROG said that they would pursue this with the B&WOG.
There is a separate raodification subcommittee that is moving forward independently of the testing and analyses programs to identify and evaluate potential hardware modifications.
The subcommittet is evaluating potential modifications such as backfill of the reference legs or venting the condensate chansber.
lhe staf f reiterated the position that the schedule for completion of the test program
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must not be deleyed, and that it will be dif ficult to convince the staff that hardware modifications are not required to resolve this problern. Whil< the staff was interested in the BWP0G demnnstration, they remained skeptical and are waiting for the results of the detailed test and analyses program.
Due to the short time schedule of the program, the staff requested that the BWR03 naintein frequent communicatter., with the staff so that we can remain involved, and observe testing.
The staff requested another update meeting via telecon on February 1.
The staff also requested a meeting to discuss the condensate chamber test when the decision is made whether or not to proceed with this test, in addittun to a meeting on acceptance criteria as discussed above.
The staff expressed interest in traveling to Charlotte, NC to tour the de-gas test facility.
The plans for the meeting on acceptance criteria and the tour of the test facility will be finalized durina the february 1 telecon.
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Amy E. Cubbage, Reactor Systems Engineer BWR Reactor Systems Section Reactor Systems branch e
Division of Systems Safety and Analysis
Enclosures:
As stated cc w/ enclosure:
A. Thadani P. Blanch DISTRIBUTION:
Central Fi'les PDR SRXB R/F RJones ICellins TQuay (13E-16)
JClifford (13E-16)
WButler (14DR)
REaton (14D-1)
GKelly (Region I)
JLee (9A-2)
ACubbage Cubbago R/F SRXB:DSSA)(C.
XUBBAGE:j i 1j)v/03 0FFICI AL RECURE C()PY Docarmr.t Name: G:mtgsum01.16
l EELMBE lilfll[{G ATTENQEf,ji
[LA3E afF1LIATION J.LLLPEQ!!I A. Thadani NRC 301-504-2884 R. Jones NRC 301-504-2895 T. Collins NRC 301-504-2897 A. Cubbage NRC 301-504-2375 T. Quay HRC 301-504-1371 G. Beck PEC0/BWROG 215-640-6450 P. Harriott GENE /BWROG 403-925-6948 L. Gifford GENE /BWROC 301-770-9650 J. Beard NUS 301-858 86(4 H. Yasui Tol.yr Electric Power Co.
202-457-0790 K. Graney Serch licensing 301-417-3299
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