ML20236T973

PN-75-002:on 750416,Region III Ofc Notified That Svc Water Pumphouse for Units 1 & 2 Has Settled 2.4 Inches at SE corner,4.3 Inches at SW corner,4.2 Inch in Nw Corner & 6.72 Inches at Ne Corner

ML20236T973
Person / Time
Site:	North Anna
Issue date:	05/01/1975
From:	Jennifer Davis, Gower G, Thornburg H NRC OFFICE OF INSPECTION & ENFORCEMENT (IE)
To:
References
PN-75-002, PN-75-2, NUDOCS 9807290211
Download: ML20236T973 (1)

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. GO PRELIMINARY NOTIFICATION - NOT FOR PUBLIC DISCLOSURE PN 75-02 Q May 1, 1975 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE

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l Facility: North Anna, Units 1, 2, 3 and 4 j Virginia Electric and Power Company i

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Subject:

SETTLDIENT OF SERVICE WATER PUMPHOUSE SERVING UNITS 1 AND 2 Our Region II (Atlanta) office was notified on April 16, 1975, that the i.

' service water pumphouse for Units 1 and 2 has settled 2.4 inches at the SE corner, 4.3 inches in the SW corner, 4.2 inches in the NW corner and '

6.72 inches in the NW corner. The plan dimensions of the pumphouse are approximately 40 feet X 60 feet.

Settlement of the structure was first identified in early 1972 when one of the wing walls separated from the l pumphouse 5/8 of an inch. Settlement of the structure has been monitored since August 1972.

The FSAR, dated January 3, 1973, states that the anticipated settlement would be 0.12 feet or 1.44 inches. In the light of what was being experienced, I the anticipated settlement was changed by amending the FSAR, December 18, l 1974, to 0.4 feet or 4.8 inches at the center of the pumphouse. Since the EM i 2 inch service water lines were velded into place the structure has settled in excess of one inch which has, according to Stone and Webster calculations, (g

introduced additional stresses into the system'at the points of fixity. It is anticipated that the structure will settle at least 3 additional inches over its service life.

Because of the public interest these facilities have experienced in the l past, our concern for safe operation of these facilities, and since the service water pumphouse for Units 3 and 4 is under construction, it is t

l. considered urgent that the design be reviewed and that remedial action be l taken to stabilize the settlement of the Units 1 and 2 pumphouse, l

l Two Region II inspectors were at the site April 29, 1975, and reviewed the problem with plant construction management.

Contact:

GGower, IE x7261, HDThornburg, IE x7353, JGDavis, IE x7541 u

Distribution. OJ -

Chairman p ers .. Commissioner Mason Secretary Commission'er Gilinsky Commissioner Rowden JCAE Commissioner Kennedy Congressional Liaison '

go R. V. Gossick, EDO D. R. Knuth, IE 9

J. A. Harris, PA B. C. Rusche, NRR H. H. Brown, ISF

! p H.. Larson, NMSS H. K. Shapar, GC e:. .

U:

b, 9907290211 7~r0501 l

PDR Ia:E PN-75-OO2 PDR I