ML20206B576
| ML20206B576 | |
| Person / Time | |
|---|---|
| Issue date: | 03/27/1987 |
| From: | Rubin S NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD) |
| To: | Mike Williams NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD) |
| Shared Package | |
| ML20206B554 | List: |
| References | |
| AEOD-E705, NUDOCS 8704090241 | |
| Download: ML20206B576 (2) | |
Text
,
March 27, 1987 i
AE0D/E705 MEMORANDUM FOR: Mark Williams, Chief Program Technology Branch
.0ffice for Analysis and Evaluation of Operational Data FROM: Stuart Rubin, Chief Reactor Operations Analysis Branch Office for Analysis and Evaluation of Operational Data
SUBJECT:
REVIEW 0F THE LER REPORTING REQUIREMENTS FOR THE BWR REACTOR WATER CLEANUP SYSTEM Enclosed is an engineering evaluation report that addresses the causes for the frequent automatic isolations of the BWR reactor water cleanup (RWCU) system and the safety significance of the events. The scope of the study encompassed the events reported in Licensee Event Peports (LERs)~and NRC Daily Reports, between January 1984 and October 1986. The study was initiated following the significant RWCU leakage events which occurred at Dresden 2 and Millstone 1 in the sumer of 1986.
As a consequence of the study, we have suggested that the guidance for the LER reporting requirerents for this system be modified. Our suggestion is based on our review of over 270 RWCU system events in which no significant safety problems were identified. None of these events resulted in significant radiological releases offsite, significant radiation exposures to personnel, or indications of actual or potential adverse effects on safety systems. Of the 21 events
- involving leakage outside the RWCU system pressure boundary, only two involved
! a significant quantity of fluid (e.g., greater than 2000 gallons). It is interesting to note that neither of these events were reported under the LER rule because the plants (which are of older design) did not have a RWCU system leakage detection system (LDS) that would automatically actuate the containment isolation system (ESF actuation) in the event of a system leak.
In contrast to older EWRs, new plant designs incorporate an LDS which automatically isolates the RWCU system by closure of the primary containment isolationsystem(PCIS)valvesintheRWCUsystem. Since the PCIS is an ESF, all actuations are reportable under the LER rule. In our study approxi-mately 74% of all reported events involved spurious isolations of-the PWCU system by the PCIS due to signals from the RWCU system LDS. A majority of these events could be classified as nuisance ESF actuations with no identifiable safety significance. Thus, the two most significant events were not reportable 8704090241 870327 PDR DRO NEXD PDR
. Mark Williams ,
{
while a large majority of reportable events were insignificant. It is this finding that prompts the suggested change in the LER reporting guidance for-this system.
A modification to the LER reporting guidance relative to the RWCU system 1
isolations and abnormal operational events should be considered to: (1) eliminate the reporting of PCIS actuations by the LDS involving spurious isolations of no safety significance caused by human errors and (2) require
, reporting of all significant (e.g., greater than 1,000 gals) radioactive i fluid leaks from the RWCU system pressure boundary caused by human errors or equipment failures. Events of interest for reporting would be those involvin systeme.g.,(g significant the Dresden cuantities of radioactive 2 and Millstone 1 eventsfluid discharges discussed in this from report)the RWCU
- and events involving significant occupational radiation exposures or offsite
! releases of radioactivity. This would eliminate the current reporting of inconsequential RWCU system events (e.g., actuation of the system isolation i valves by the LDS), while assuring the reporting of actual leakage events of potential safety significance.
l We would be available to discuss this suggestion in a meeting after you have j had an opportunity to review the enclosed report. If you have any specific l questions regarding the report, please contact Dr. Neill Thomasson of my staff on extension 24431.
- /r/
Stuart D. Rubin, Chief
{
Reactor Operations Analysis Branch i Office for Analysis and Evalu'ation of Operational Data
Enclosure:
! As Stated i
! cc w/o enclosure:
i C. Heltemes, Jr.
j F. Hebdon j
i DISTRIBUTION:
j PDR
- AE0D SF I ROAB SF j' ROAB CF i NThomasson PBaranowsky 1
SRubin MWilliams
! WLanning i KBlack
! FHebdon CHeltemes
! 0FC :ROAB :SC: : BC:ROAB : :AEOD : : :
- NAME
- NTjoyson :PBa sky : SRubin : FHe n : : :
lDATE : 3/ 4 /87
- 3/h/87
- 3/%I/87 . 3/ /87 : : :
0FFICIAL RECORD COPY