ML20044E322

Forwards Summary of 930317 Meeting Re BWROG Test Program Per .Suppl to 920828 Rept Expected

ML20044E322
Person / Time
Issue date:	04/06/1993
From:	Thadani A Office of Nuclear Reactor Regulation
To:	Beck G BWR OWNERS GROUP, SOUTHERN NUCLEAR OPERATING CO.
References
NUDOCS 9305240188
Download: ML20044E322 (1)

Text

l April 6, 1993 8(

Mr. George J. Beck, Chairman BWROG Water Level Committee Boiling Water Reactor Owners' Group c/o Southern Nuclear Operating Company P.O. Box 1295, Bin B052 Birmingham, AL 35201

SUBJECT:

3/17/93 MEETING CONCERNING THE BWROG TEST PROGRAM.

i Your letter to W. T. Russell, NRC, dated March 31, 1993, discussed a meeting between the NRC and the BWROG that was held in Charlotte, North Carolina on March 17, 1993, tc discuss the BWROG program to resolve the reactor water level issue. While the staff agrees that the topics of our March 4, 1993 letter were discussed at this meeting, we do not believe that all of these issues are resolved. The enclosed meeting summary, dated March 30, 1993, prasents the staff position on the BWROG program.

Please note, as indicated ii +9e enclosed meeting summary, that the staff expects the BWROG to supplement, as necessary, their August 28, 1992 report to include events that initiate at law reactor preswre.

QiGINAL SIGNED BY A. C.EAUNO Ashok C. Thadani, Director Division of Systems Safety and Analysis

, Office of Nuclear Reactor Regulation

Enclosure:

As stated cc:

P. Blanch E. Hadley DISTRIBUTION SRXB R/F RJones REaton (140-1)

TCollins TQuay (13E-16)

ACubbage JClifford (13E-16)

ACubbage R/F GKelly (Region I)

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MEMORANDUM FOR:

Robert C. Jones, Chief Reactor Systems Branch Division of Systems Safety and Analysis THRU:

Timothy E. Collins, Chief BWR Reactor Systems Section Reactor Systems Branch Division of Systems Safety and Analysis FROM:

Amy E. Cubbage, Reactor Systems Engineer BWR Reactor Systems Section Reactor Systems Branch Division of Systems Safety and Analysis

SUBJECT:

MEETING

SUMMARY

FROM BWROG MEETING A meeting was held with the BWR Owners' Group (BWROG) on March 17, 1993, at the EPRI NDE facility in Charlotte, North Carolina. The BWROG is conducting a reference leg de-gas test at this facility. The purpose of the meeting was to observe the ongoing testing and to discuss staff concerns about the test program which were forwarded to the BWROG by letter dated March 4,1993 from W. T. Russell, NRC, to ' George Beck, BWROG. The list of attendees is provided in Enclosure 1, a copy of the slides used by the BWROG during the meeting is provided in Enclosure 2, and a summary of the issues discussed is provided below.

The BWROG provided a brief overview of the BWROG program, and reviewed the actions that have been taken to date to address the issue of potential errors in water level t

instrumentation due to non-condensible gases. They proceeded to describe the test program, including the full-scale reference leg de-gas test and bench top testing.

The purpose of the benchtop testing is to evaluate the effect of the following parameters on de-gassing: (1) reference leg material; (2) reference leg diameter; (3) reference leg slope; (4) temperature; and (5) vibration.

The reference leg de-gas test procedure and test matrix were described to the staff.

At a meeting on February, 17, 1993, the BWROG discussed their test plan and the 6 reference leg In a letter dated March 4,1993 to the BWROG, the configurations that were to be tested.

staff expressed concerns that the test program should include configurations more similar The BWROG'is in geometry and reference leg diameter to those found in actual plants.

considering including reference leg configurations more indicative of actual plant At this time tne test matrix includes two depressurization rates, one configuratior.s.

simulates the large break LOCA depressurization rate, and the other simulates the rate of depressurization for ADS actuation. After this discussion, the staff wis given a tour of the reference leg de-gas test facility. During this tour, the staff observed the ongoing testing.

Next, the BWROG discussed the activities of the reactor water level measurement modifications and procedures committee to evaluate potential modifications to the reactor water level instrumentation system. Three potential _ modifications were identified by the

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t committee which do not require the condensing chamber test for verification or validation, these are: (1) condensing chamber vent; (2) backfill systems; and (3) core range monitoring (a design in which the variable leg of the narrow range is used for the r

3 reference leg of the fuel zone range). Five other modifications were also discussed which I

would require the condensing chamber test for verification and validation. All of these potential modifications involved different designs of the condensing chamber.

At the end of their formal-presentation, the BWROG addressed staff concerns discussed in j

the March 4, 1993 letter. The staff re-emphasized its position that 1/2 inch tubing, and more complex configurations need to be included in the full-scale reference leg de-gas test plan.

The staff noted that level instrumentation is important for BWRs, and enough evidence exists today to say_that the reliability of the instrumentation needs to be improved.

i Further, an event occurred recently at WNP-2, during a slow plant depressurization,.

involving both level indication " notching" and a sustained level indication error of significant magnitude. While the staff believes that the test program is good scientific t

work that will lead to a better understanding of the phenomenon, the objective of the program is not sufficiently oriented toward testing the effectiveness of hardware i

modifications. Therefore the staff re-iterated its belief that modifications will be needed to improve the functional reliability of the water level instrumentation.

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t' in addition, as a result of the WNP-2 event, the staff discussed the need for the BWROG program to include potential level errors during slow depressurization. -The st&ff 28, 1992 report, which evaluated the j

requested that the BWROG supplement their August safety implications of potential level indication errors, to include events that initiate at a low reactor pressure. Finally, the staff expressed its expectation that all BWR i

utilities will provide a response, by July 30, 1993, informing the NRC of their plans and j

schedule for hardware modifications.

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Amy. Cubbage, Reactor Systems Engineer BWR eactor Systems Section Reactor Systems Branch Division of Systems Safety and Analysis

Enclosures:

As stated 1

cc w/ enclosure:

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ENCLOSURE 1 MEETING ATTENDEES NAME AFFILIATION TELEPH0t(E 301-504-2884 A. Thadani NRC/DSSA 301-504-2895 R. Jones NRC/SRXB 301-504-2897 T. Collins NRC 301-504-2875 l

A. Cubbage NRC 215-640-6450 G. Beck PEC0/BWROG 408-925-1913 G. Stramback GE 215-327-1200 ext. 3551 G. Sealy PEC0/BWROG B. McKillip Continuum Dynamics 609-734-9282 A. Kaufman Continuum Dynamics 609-734-9282 215-892-3918 D. Weber PEC0/BWROG 708-663-7447 T. Best CEC 0/BWROG 205-877-7408 J. Wade SNC/BWROG 504-381-4228 J. Morgan GSU/BWROG 704-547-6058 i

J. Menthausen EPRI 704-547-6087 T. Mulford EPRI/PSE 509-377-4797

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5. Wood WPPSS/BWROG 408-925-1308 T. Green GE 509-337-4632 T. Miles WPPSS/BWROG 509-377-4536' l

M. Monson WPPSS/BWROG 215-774-7717 t

J. Refling 77al/BWROG

~201-316-7057 J. Moore GPUN/BWROG-f 1

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