Protecting People and the EnvironmentUNITED STATES NUCLEAR REGULATORY COMMISSION
GL79048
UNITED STATES
NUCLEAR REGULATORY COMMISSION
WASHINGTON, D. C. 20555
October 2, 1979
ALL BOILING WATER REACTOR LICENSEES (Except: Dresden 1, Humboldt Bay, Big
Rock and LaCrosse)
SUBJECT: CONFIRMATORY REQUIREMENTS RELATING TO CONDENSATION OSCILLATION
LOADS FOR THE MARK I CONTAINMENT LONG TERM PROGRAM
On August 15, 1979, the staff met with representatives of the Mark I Owners
Group to discuss the acceptance criteria being developed by the staff to
begin implementation of the Mark I Long Term Program (LTP). One of the
staff's criteria requires confirmatory condensation tests in the Full-Scale
Test Facility (FSTF). The Mark I Owners Group representatives stated that
they consider additional FSTF tests unnecessary.
As a result of our review of the proposed load definition procedures for the
design basis accident "condensation oscillation" loads (i.e., high vent flow
rate with low air content), we have concluded that there are insufficient
data to establish a reasonable measure of the uncertainty in the load
magnitudes for this regime. Although we believe that the condensation
oscillation loads proposed in the Mark I Containment Program Load Definition
Report (LDR), NEDO-21888, are sufficiently conservative with respect to the
results of FSTF test run M8, we have not found sufficient applicable data to
give an adequate estimate of the uncertainty in the load magnitude so
defined, such that we can assure that the uncertainty is smaller than the
conservatism in the load definition technique. In making this assessment, we
have considered the use of the other full-scale data sources and small-scale
phenomenological studies. The questions that have been raised regarding the
applicability of these data to this issue have not been resolved and will
not be resolved in the near future.
We believe that the LDR condensation oscillation load specifications, as
modified by the staff's acceptance criteria, form a sufficient basis to
proceed with implementation of the LTP, since FSTF test M8 is prototypical
for Mark I and the load definition technique has conservatively assessed
that test data. Consequently, we intend to issue the acceptance criteria to
unit initiate the LTP plant-unique analyses. We will require in these
criteria that the conservatism in the condensation oscillation loads be
confirmed by performing a sufficient number of additional large break,
liquid blowdown tests in FSTF to establish the uncertainty in the load
magnitudes.
In addition, the staff has recently raised concerns relating to the
phenomena associated with downcomer condensation oscillation loads. These
concerns evolved from insufficient downcomer-vent header response data. The
additional FSTF test should provide improved instrumentation for the
downcomer-vent header system, particularly for the "tied" downcomers.
7911200331
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We will require that each licensee commit, on behalf of the Mark I Owners
Group as a whole, to perform these tests and provide the associated test and
plan schedule by October 31, 1979.
Sincerely,
D. G. Eisenhut, Acting Director
Division of Operating Reactors
.
Mr. William J. Cahill, Jr. 50-3
Consolidated Edison Company of New York, Inc. 50-247
cc: White Plains Public Library
100 Martine Avenue
White Plains, New York 10601
Joseph D. Block, Esquire
Executive Vice President
Administrative
Consolidated Edison Company
of New York, Inc.
4 Irving Place
New York, New York 10003
Edward J. Sack, Esquire
Law Department
Consolidated Edison Company
of New York, Inc.
4 Irving Place
New York, New York 10003
Anthony Z. Roisman
Natural Resources Defense Council
917 15th Street, N.W.
Washington, D. C. 20005
Dr. Lawrence R. Quarles
Apartment 51
Kendal at Longwood
Kennett Square, Pennsylvania 19348
Theodore A. Rebelowski
U. S. Nuclear Regulatory Commission
P. O. Box 38
Buchanan, New York 10511
