IR 05000271/1998080

Corrected Page 23 for Insp Rept 50-271/98-80 Issued on 980716.Section E8.2 Was Amended in Order to Be More Consistent W/Findings Documented in Other Sections of Rept & to More Clearly Reflect NRC Conclusion Re LER 98-005

ML20236V196
Person / Time
Site:	Vermont Yankee File:NorthStar Vermont Yankee icon.png
Issue date:	07/24/1998
From:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
To:
Shared Package
ML20236V192	List: IR 05000271/1998080 ML20236V190
References
50-271-98-80, NUDOCS 9807310357
Download: ML20236V196 (1)

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E8.2 Mcensee Event Reoorts (92700)

(Closed) LER 98-005: HPCl/RCIC Exhaust Lines Susceptible to Water Hamme This LER, issued on April 9,1998, documented a discrepancy, identified by the licensee on January 15,1998 as a result of its design basis initiatives, wherein the installation of the vacuum breakers could result in water harnmer in those lines -

(deportability is discussed in Section E5.1). The inspector reviewed the following:

(1) the installation of EDCR 98-402;(2) design document revisions to maintein configuration control; and, (3) the associated safety evaluatio Regarding item (1), the recentiy installed design change modified the existin turbine exhaust lines vacuum breaker arrangement to equalize with the torus air space, rath . than the reactor building atmosphere . This change resolved the water hammer concern and installed a design consistent with General Electric

. Service Information Letter (SIL) No. 30, which had first highlighted this problem in 197 Regarding item (2), the inspector observed that draft revisions to the FSAR, the training module, and the DBDs did not fully describe the design basis for the vacuum breakers. However, the inspector noted that the licensee had not finalized the revisions and had agreed to consider enhanced description Regarding item (3), it appeared that the safety evaluation did not address the direct path created between the torus air space and the turbine exhaust line. Upon further evaluation, the inspector.found that the licensee had appropriately considered the pathway in question by virtue of the fact that the check valves now receive Type C leak testing and were successfully tested during the recent refueling outage. The penetration must, therefore, still meet 10CFR53, Appendix J limits and thus no new I leakage pathway was created, nor would accident consequences be increase Further, the inspector independently noted additional considerations which bolster the pathway argument: (1) the torus air has already been " scrubbed" by the suppression pool water, removing radiciodine; (2) the torus air pressure will, by design, be about 40% lower than the drywell peak accident pressure (Pa) at which containment isolation valves are tested; (3) the exhaust line check valves were provided with new disks and seats, leak tested with air at Pa, and left relatively leak tight; and, (4) the primary containment leakage rate used in the FSAR accident analysis is twice the allowable Appendix J limi (Ooen) LER 98-010: Potential challenge to containment systems in the event of a LOCA. The emergency operating procedures (EOPs) regarding Torus Rupture Disc l: Burst Pressure were inadequate in that they did not prevent or caution the operators about the possibility of prematurely bursting the rupture disc which causes a loss of I'

9807310357'980724 PDR ADOCK 05000271 i G PDH E I

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