ML20206B555

Forwards AEOD Engineering Evaluation Rept on Operational Experience Re BWR RWCU Sys.Study Based on LERs Submitted During Jan 1984 - Oct 1986 & NRC Daily Repts.Reevaluation of Daily Surveillance Testing Suggested

ML20206B555
Person / Time
Issue date:	03/31/1987
From:	Hebdon F NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD)
To:	Sniezek J Office of Nuclear Reactor Regulation
Shared Package
ML20206B554	List: ML20206B547 ML20206B555 ML20206B558 ML20206B576 ML20206B597
References
AEOD-E705, TAC-62757, TAC-62758, NUDOCS 8704090214
Download: ML20206B555 (3)

Text

. . . __ __ ._ _ __

.l f -8 4' March 31,-1987 n ~

AE0D/E705-MEMORANDUM FOR: James H. Sniezek, Deputy Director

. Office of Nuclear Reactor Regulation l

i. FROM: Frederick J. Hebdon, Deputy Director Office for Analysis of Operational Dataand Evaluation %

)

SUBJECT:

SURVEILLANCE TESTING REQUIREMENTS'FOR RWCU SYSTEM

' AUTOMATIC ISOLATION LEAKAGE DETECTION SYSTEMS f Enclosed for your information and use is an AEOD engineering ' evaluation report ,

2 on operational experience associated with the BWR reactor water cleanup (RWCU) system. The study was based on Licensee Event Reports (LERs) submitted between '

!- January 1984 and October 1986 and selected NRC Daily Reports.

J

! The study found that over 15% of the BWR LERs submitted during the study period i were associated with RWCU' system events. Of these approximately 75%' involved

} spurious isolation events. About half of the spurious isolation events were

initiated by the leak detection system (LDS) temperature detector' modules, mostly during daily surveillance testing of the temperature modules. Most of the other spurious isolation events were due to a lack of temperature-(density) i compensation of the LDS differential flow monitors.

i

About 90% of the 21 actual system leakage events involved minor leakage from l the RWCU system pressure boundary. The two most significant events occurred at

! Dresden 2, which involved a leak of 140,000 gallons of low energy coolant from

a filter-demineralizer valve, and at Millstone 1, involving' discharge of 2,200 l gallons of high energy coolant to the RWCU system equipment area. The operating-l data revealed no significant safety-related implications associated with the

RWCU system operational problems. The principal impact of these events is

{ operational in that licensee resources are utilized to investigate, correct and report RWCU system events diverting attention from other more important activi-i ties that have true safety significance. The only significant regulatory factor j identified in the study was the undesirable increased occupational exposure

that occurs as a result of each automatic isolation of the RWCU system. Such j exposure results from investigations'and possible' cleanup activities associated ,

with actual leakage events.

i j In view of the absence of any safety significant consequences from actual leakage events, of no resulting failures in safety-related systems, and of no

significant degradations of the RWCU system isolation system, coupled with the i high frequency of nuisance-type spurious isolations, we have suggested that NRR L reevaluate the need for daily surveillance testing of the LDS~ temperature i monitors. A decreased frequency of testing would, we believe, result in a i

8704090214 870327 i PDR ORG bEXD

PDR i

James H. Sniczek -2_ )

proportional decrease in spurious isolations with little adverse impact on isolation system reliability. By separate letter, we have suggested that INP0' consider following up on this study, to characterize design and operational improvements, including procedural improvements, that provide additional means for reducing the frequency of RWCU system spurious. isolation events.

1 We 'are available to discuss our suggestion to NRR with you after you have had an opportunity to review the enclosed report. It'is noted that these sugges-tions may relate to a wider range of systems than.the RWCU system. This might be something to address in a preliminary manner at the meeting.

If you or your staff have any questions concerning the enclosed engineering evaluation report, please contact Dr. Neill Thomasson of my staff on extension x24431.

moussessay

c. J. Ham ,;,,

v Frederick J. Hebdon, De uty Director Office for Analysis and Evaluation of Operational Data

Enclosure:

As Stated cc w/ enclosure:

T. Gwynn, OCM E. Jordan, IE J. Partlow, IE BWR Resident Inspectors Regional Offices Chattanooga Training Center BWR Project Directors DISTRIBUTION:

PDR AE00 SF l AE00 CF ROAB CF ROAB SF NThomasson PBaranowsky SRubin MWilliams KBlack WLanning

FHebdon CPeltemes

• See next sheet for previous concurrenc 0FC :ROAB:AEOD :SC:ROAB  : BC:POAB  : DD:AE  : D: D  :  :

...._:.___.._____:............:..._________:_p __:_ ______:.__ ....___.:_....__ ...

NAME :NThomasson :PBaranowsky : SRubin  : N on  : 0 temes :  :

, DATE :3/27/87* :3/27/87*  : 3/27/87*  : 3/4.X87  : 3/sT/87  :  :

0FFICIAL RECORD COP'Y

a q

** James H. Snitzak proportional decrease in spurious isolations with little adverse impact on isolation system reliability. By separate letter, we have suggested that INP0 j initiateadetailedstudy,basedonthecommariesintheenclosedreport,tg characterize design and operational improvements, including procedural improve-ments, that provide additional means for reducing the frequency of RWClVsystem spurious isolation events.

We are available to discuss this suggestion with you after you ha e had an oppor-tunity to review the enclosed report. Itisnotedthatthesesv@gestionsmay relate to a wider range of systems than the RWCU system. Thi/mightbesomething to address in a preliminary manner at the meeting.

If you or your staff have any questions concerning the entiosed engineering evaluation report, please contact Dr. Neill Thomasson ,of my staff on extension x24431.

/

/

/

Frederick J'.' Hebdon, Deputy Director Office for' Analysis and Evaluation of Operational Data

Enclosure:

As Stated cc w/ enclosure:

D. Humenansky, OCM E. Jordan, IE J. Partlow, IE BWR Resident Inspectors Regional Offices Chattanooga Training Cente BWR Project Directors DISTRIBUTION:

PDR AEOD SF AE0D CF ROAB CF ROAB SF NThomasson PBaranowsky SRubin NWilliams KBlack WLanning FHebdon CHeltemos

^

0FC :ROAB E00 :SC:]  : BC:ROAB  : DD:AEOD  : D:AEOD  :  :

..... : .. g .

9._:... /

NAME :NTHs Sh :PBad n wsky

....:___________.:............:..k.f.....:___.........:.......__

SRubin  : EHebdon :C emes :  :

'DATE:3/I)/87'

3 87  : 3/51/87  : 3/ /87  : 3/ 87  :  :

OFFICIAL RECORD COPY