Protecting People and the EnvironmentUNITED STATES NUCLEAR REGULATORY COMMISSION
GL80041
UNITED STATES
NUCLEAR REGULATORY COMMISSION
WASHINGTON, D.C. 20555
MAY 9 1980
Generic Task No. A-7
DOCKET NOS.: 50-219, 50-220, 50-237, 50-245, 50-249, 50-254, 50-259,
50-260, 50-263, 50-265, 50-271, 50-277, 50-278, 50-293,
50-296, 50-298, 50-321, 50-324, 50-325, 50-331, 50-333,
50-341, 50-354, 50-355, and 50-366.
LICENSEES: Boston Edison Company, Carolina Power & Light Company,
Commonwealth Edison Company, Detroit Edison Company, Georgia
Power Company, Iowa Electric Light & Power Company, Jersey
Central Power & Light Company, Nebraska Public Power
District,
Niagara Mohawk Power Corporation, Northeast Nuclear Energy
Company, Northern States Power Company, Philadelphia Electric
Company, Power Authority of the State of New York, Public
Service Electric and Gas, Tennessee Valley Authority, Vermont
Yankee Nuclear Power Corporation.
FACILITIES: Oyster Creek Nuclear Generating Station, Nine Mile Point Unit
No. 1, Pilgrim Unit No. 1, Dresden Units Nos. 2 and 3,
Millstone Unit No. 1, Quad Cities Units Nos. 1 and 2,
Monticello, Peach Bottom Units Nos. 2 and 3, Browns Ferry
Units Nos. 1, 2 and 3, Vermont Yankee, Hatch Units Nos. 1 and
2, Brunswick Units Nos. 1 and 2, Duane Arnold Energy Center,
Cooper, Fitzpatrick, Enrico Fermi Unit No. 2, and Hope Creek
Units Nos. 1 and 2.
SUBJECT: SUMMARY OF MEETINGS HELD ON APRIL 22 AND 23, 1980 WITH
REPRESENTATIVES OF THE MARK I OWNERS GROUP
On April 22 and 23, 1980, the staff met with representatives of the Mark I
Owners Group in San Jose, California to discuss confirmatory analysis and
testing programs relating to the Mark I Containment Long Term Program. The
specific agenda items (i.e., downcomer "condensation oscillation" loads,
pool swell compressibility effects analyses, and the supplementary
full-scale condensation test series) are those ongoing issues for which
resolution is necessary to complete the generic aspects of the program. The
purpose of this meeting was to identify the information that would be needed
to conclude on these issues. The meeting attendees are listed in Enclosures
1 and 2.
Tuesday, April 22
R. Palaniswamy, Bechtel, presented the proposed downcomer load specification
for the "condensation oscillation" regime. A refined analytical model of the
Full Scale Test Facility (FSTF) vent system has been calibrated
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with static ("jack" test) and dynamic ("snap" test) downcomer - vent header
response data The analytical model and response data comparisons are
described in Enclosure 3.
The load specification was derived by assuming an oscillatory (i.e.,
sinusoidal) pressure load within the vent system and comparing the
calculated structural response to the response data from FSTF. From the
analyses, a design load has been derived equivalent to a 1.5 psi static
differential pressure, + - 2.5 psi at 5.5 Hz* oscillatory vent header
pressure and + - 5.0 psi at 5.5 Hz* oscillatory downcomer pressure. The load
would be applied in-phase with a damping value of 6% (lowest damping
observed in the applicable "snap" tests). Comparisons of the calculated
response to the proposed design load with the FSTF response data indicates
that the proposed design load is between 35% and 95% conservative. A report
to document the bases for this load specification will be completed about
May 1980.
The staff considered the approach presented to be viable. However, the
analyses suggest that the downcomer response mode is near resonance,
evidenced by significant amplification. Thus the vent system analytical
model may be responding to a mode of response other than the "wishbone"
mode. Therefore, the staff indicated that the assumed 6% damping must be
justified (e.g., compare displacement in the pool) and the range specified
for the driving frequency must consider the proximity of the response mode
frequency. These considerations will be addressed in the forthcoming report
and the load specification will be confirmed by data from the supplement
FSTF tests.
R. Torak, Accurex, described the analyses which were used to investigate the
effects of compressibility on scaled pool swell loads (report NEDE-24778-P).
The analyses consisted of a finite element, compressible, one-dimensional
vent flow model coupled to a semi-empirical bubble/poolswell model. The
bubble model was calibrated with quarter Scale Test Facility (QSTF) data.
The coupled analytical model was then applied to ideal QSTF test conditions
and equivalent full-scale conditions. The results of these analyses indicate
that compressibility tends to mitigate the pool swell loads by a net
reduction in the mass and energy into the bubble. For water leg lengths less
than about four inches, the download or the torus tends to be higher at
full-scale conditions; however, the Mark I Owners indicated that all plants
intended to operate with water legs greater than six inches.
Following the discussion of the compressibility analyses and conclusions,
the Mark I Owners representatives addressed the comments submitted by our
consultants at BNL in a letter dated March 12, 1980 (J. D. Ranlet,
* GE will specify a frequent range to assure conservative plant-specific
loads.
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BNL, to C. Grimes, NRC). The principal comment concerned the relative
accuracy of the analyses with respect to the number of nodes and timestep
size. R. Torak presented the results of error studies (Enclosure 4) which
indicate that the total error in load magnitude is less than about 5%,
compared to a mitigation effect of approximately 20% for the net upload. The
net downloads were affected less by error. The principal reason for the
relatively low error was the prototypically low Mach numbers for the vent
flow rate (approximately 0.31.) Additional information concerning node and
time-step sensitivity and model descriptions were presented in response to
questions raised in the BNL report.
The staff and consultants concluded that two additional analyses (i.e.,
full-scale and equivalent 1/4-scale) should be performed which would model
the drywell with a constant mass inflow and use the same scaled vent system
models. The comparison of the integrated mass flow up to the time of peak
upload for these two analyses would be sufficient to demonstrate the "mass
defect" between the scaled QSTF and full-scale equivalent vent flow. The
Mark I Owners Group agreed to provide such analyses in a letter report. The
staff concluded that this comparison would provide a sufficient basis to
demonstrate whether compressibility would constitute a mitigating effect for
the Mark I vent flow conditions.
The Mark I Owners Group inquired about the additional efforts that would be
needed to take quantitative credit for the mitigating effects of
compressibility on the torus pool swell loads. The staff responded that
considerable justification would have to be presented for the assumptions
and judgements inherent to the vent flow model and extrapolation of the
empirical bubble formation parameters. The staff indicated that quantitative
credit would be unlikely, because the analyses would have to be good enough
to quantify pool swell loads, in which case a three-dimensional flow model
may be necessary.
Wednesday, April 23
C. Collins, GE, described the FSTF supplemental tests that are to be
performed in May and June 1980 (Enclosure 5). These tests will duplicate
test M8 (design-basis liquid break) and will be designated M11 and M12. The
only difference in the facility from the M8 configuration will be that all
of the downcomer pairs will be "tied" and additional instrumentation has
been installed on the downcomer-vent header system. The Mark I Owners Group
indicated that examination of the vent system welds was performed before the
"snap" tests and no evidence of damage due to the previous test series was
found.
The Mark I Owners Group suggested a meeting with the staff in July 1980 to
review the "quick-look" data from tests M11 and M12 and data comparisons to
test M8 The "quick-look" data would include (1) test initial conditions, (2)
bottom-center wall pressure transients, (3) pressure transients from the
extreme downcomer pairs, and (4) downcomer - vent header and downcomer - tie
strain measurements. The staff requested
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that, in order to provide an expeditious resolution to that issue, the Mark
I Owners should plan to submit an interim report following the July 1980
meeting which would provide sufficient information for the BNL consultants
to develop a supplement to the Mark I SER. Specifically, this report should
include comparisons of the pressure - frequency spectra from tests M8, M11,
and M12 and the Load Definition Report (LDR) to establish the conservatism
in the torus shell pressure load specification, and a phasing evaluation of
the pressure transients in the two extreme downcomer pairs. A complete
report of the test results could then be issued in December 1980, as
planned, without affecting the overall schedule for the resolution of the
Mark I program.
W. Kennedy, Structural Mechanics Associates, described the results of
analyses which were performed to investigate the effects of the relative
phasing of the harmonic components of the "condensation oscillation" torus
shell pressure - frequency spectra (Enclosure 6). The results of this
analysis indicated that neither the assumed pressure amplitude, 2% damping,
for steady-state loading contributed much to the conservatism in the design
load. Cumulative Distribution Functions (CDFs) were developed for the
Bechtel model of FSTF (i.e., Monticello) and the NUTECH model of Oyster
Creek. From an assessment of these CDFs, the following design rule was
developed:
1. Use LDR pressure - amplitude spectra and 2% damping.
2. Absolute sum the responses of the three (3) highest amplitude
harmonics.
3. Square-root-the-sum-of-the-squares (SRSS) the responses of the
remaining 27 harmonics (up to 30 Hz).
This design rule results in calculated structural responses which
essentially match the peak responses observed in FSTF test M8.
The staff noted that the load specification proposed in the LDR was
considered acceptable because the conservatisms provided by the coupled load
- structure analysis techniques (i.e., absolute sum of all of the hormonics)
would offset the uncertainties associated with the stochastic nature of the
phenomena (i.e., uncertainty in the load magnitude). Therefore, further
consideration of the proposed design rule must be deferred until the load
magnitude uncertainty can be quantified from the supplemental FSTF tests.
Once adequate documentation of these tasks has been submitted to the NRC, as
described above, and providing there are favorable results from
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the supplementary FSTF test series, the staff will conclude the generic
aspects of the Mark I Containment Long Term Program with a supplement to the
Safety Evaluation Report.
C. I. Grimes
A-7 Task Manager
Generic Issues Branch
Division of Safety Technology
Enclosure: As stated
cc: See Distribution Sheet
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ENCLOSURE 1
MARK I OWNERS GROUP MEETING
APRIL 22, 1980
Name Organization
C. I. Grimes NRC/DOR
J. R. Fair NRC/DOR
D. B. Fetters PECo
D. F. Lehnert Detroit Edison
J. C. Carter TVA
A. A. Sonin BNL/MIT
J. D. Ranles BNL
R. Kosson BNL/Grumman
R. J. Mulford GE
L. D. Steinert GE
G. Wade GE
S. A. Hucik GE
U. C. Saxena GE
A. Mukherjee GE
L. J. Sobon NUTECH
P. D. Hedgecock NUTECH
G. Uram NUTECH
B. Whiteway NUTECH
T. Ballard NUTECH
R. Torak Accurex
W. S. Kennedy Accurex
R. Kendal Accurex
R. Palaniswamy Bechtel
J. J. Bhatt Bechtel
S. A. White SCSI
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ENCLOSURE 2
MARK I OWNERS GROUP MEETING
APRIL 23, 1980
Name Organization
C. I. Grimes NRC/DOR
J. R. Fair NRC/DOR
D. B. Fetters PECo
D. F. Lehnert Detroit Edison
J. D. Ranlet BNL
R. Kosson BNL/Grumman
C. Brennen BNL/CIT
T. J. Mulford GE
R. H. Moen GE
L. D. Steinert GE
S. A . Hucik GE
G. Wade GE
U. Saxena GE
C. E. Collins GE
R. L. Mapes GE
J. L. Baskin NUTECH
R. A. Malte NUTECH
T. A. Ballard NUTECH
A. F. Deardorff NUTECH
G. Uram NUTECH
B. Whiteway NUTECH
W. S. Kennedy Accurex
L. M. Broderick Wyle
W. Kennedy SMA
