Headquarters Daily Report
JULY 19, 2001
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REPORT NEGATIVE NO INPUT
ATTACHED INPUT RECEIVED RECEIVED
HEADQUARTERS X
REGION I X
REGION II X
REGION III X
REGION IV X
PRIORITY ATTENTION REQUIRED MORNING REPORT - HEADQUARTERS JULY 19, 2001
Licensee/Facility: Notification:
Northern States Power Co. MR Number: H-01-0047
Monticello 1 Date: 07/19/01
Monticello,Minnesota
Dockets: 50-263
BWR/GE-3
Subject: Drywell-To-Torus Vent Pipe Bellows Shipping Restraints
Left In Place
Reportable Event Number: 38130
Discussion:
The licensee for the Monticello nuclear power plant has reported that it
found that shipping fasteners had not been removed properly from the
protective covers of the drywell-to-torus piping bellows when the bellows
were installed during original plant construction. These bellows are on
the eight vent pipes that connect the drywell to the torus on BWR Mark 1
containments. The fasteners were to be removed so that the bellows could
accommodate the axial expansion or contraction of the piping when
subjected to large temperature changes that might occur during a
design-basis accident. If the fasteners were to remain in place, they
might restrict the bellows' movement, degrading the operability of the
bellows. Upon discovery of this condition, the licensee declared the
containment inoperable. The licensee subsequently unbolted the fasteners
from each of the eight pipe bellows, and declared the containment
operable once again.
The discovery at Monticello followed a similar discovery at another BWR
Mark 1 reactor, Duane Arnold. However, the manufacturer, design of the
covers, and locations of the shipping bolts were different at each unit.
Subsequently, a Region I plant, Pilgrim, identified a similar condition.
The NRC is evaluating the significance and generic applicability of this
information.
Contacts: Bruce Burgess, Region III
630-829-9629
E-mail: blb@nrc.gov
Robert Benedict, NRR
301-415-1157
E-mail: rab1@nrc.gov
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