ML19320D210
| ML19320D210 | |
| Person / Time | |
|---|---|
| Site: | Crystal River  |
| Issue date: | 07/01/1980 |
| From: | Novak T Office of Nuclear Reactor Regulation |
| To: | Hancock J FLORIDA POWER CORP. |
| References | |
| NUDOCS 8007210110 | |
| Download: ML19320D210 (3) | |
Text
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UNITED STATES i
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g NUCLEAR REGULATORY COMMISSION 3
5 WASHINGTON. o. c. 2 ossa E
July 1, 1980
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Docket No. 50-302 Mr. J. A. Hancock
, Director, Nuclear Operations Florida Power Corporation P. O. Box 14042, Mail Stop C-4 St. Petersburg, Florida 33733
Dear Mr. Hancock:
Recently we have been notified by the Toledo Edison Comany that a number of fuel assembly holddown spring failures have been observed at the Davis-Besse Unit No. I plant which is currently undergoing its first refueling outage. We understand that as a result of these failures, Babcock & Wilcox has requested that you conduct examinations of fuel assemblies at your facility to determine if any failures have occurred. We are interested in knowing the results of holddown spring inspections at your facility as well as the safety significance of operating with broken springs in the core.
Enclosed is a set of questions regarding this subject.
It is requested that you provide responses to these questions within 60 days of receipt of this letter.
Sincerely, Q. 6/. '
]
Thomas M. Novak, Assistant Director for Operating Reactors Division of Licensing
Enclosure:
Holddown Spring Questions cc w/ enclosure:
See rnxt page 80 07210 W
Crystal River-3 50-302 Florida Power Corporation cc -/ enclosure (s):
Mr. S. A. Brandimore Mr. Robert B. Borsum Vice President and General Counsel Babcock & Wilcox P. O. Box 14042 Nuclear Power Generation Division St. Petersburg, Florida 33733 Suite 420, 7735 Old Georgetown Road Bethesda, Maryland 20014 Mr. Wilbur Langely, Chairman Board of County Commissioners Citrus County Iverness, Florida 36250 Bureau of Intergovernmental Relations U. S. Environmental Protection Agency 660 Apalachee Parkway Region IV Office Tallahassee, Florida 32304 ATTN: EIS C00RDINATCR 345 Courtland Street, N.E.
Mr. Barry Smith, Resident Inspector Atlanta, Georgia 30308 U. S. Nuclear Regulatory Comission Di o
Technical Assessment P.
o C
River Florida 32629 Office of Radiation Programs (AW-459)
U. S. Environmental Protection Agency Crystal Mall #2 Arlington, Virginia 20460 Crystal River Public Library Crystal River, Florida 32629 Mr J, Shreve The Public Counsel Room 4 Holland Bldg.
Tallahassee, Florida 32304 Administrator Department of Environmental Regulation Power Plant Siting Section State of Florida 2600 Blair Stone Road Tallahassee, Florida 32301 Attorney General Department of Legal Affairs The~ Capitol Tallahassee, Florida 32304 i
Dr. W!111am R. Stratton Los Alamos Scientific Lab Box 503 Los Alamos, New Mexico B7544 w
Enclosure HOLD-DOWN SPRING VUESTIONS TO LICENSEES 1
(If the reactor is down for refueling and the reactor vessel head is nff) Examine all fuel assembly holddown springs in the core and in the stent fuel pool and report the number and extent'of damage on the' springs and affected assembly components.
or (Alt.) (If the reactor is operating.) Review video tapes of the core from the.last refueling and examine all assemblies in the spent fuel pools.
i Report the number and extent of damage on the springs and affected asser21y components.
2.
Provide a discussion of the safety significance of operating with one oc more broken springs in the core. Your discussion should include, but not necessarily be limited to the following:
Assume the holddown spring is broken, provide an estimate nf the i
a.
flow conditions under which the asser211es would be levitated.
(Provide the value of the force required to lift the assembly, the flow conditions under which that force would be supplied, the number of coolant pumps that would be in operation under such conditions, and the schedule of reactor operations under which such conditions might have been achieved.) Contrarily, demonstrate the margin between the assembly weight and-the calculated maximum t
applied lift-off force, if there is such margin.
t b.
Have any loose assembly parts (i.e., broken springs, pieces of cladding) been observed anywhere in the primary system? Describe your methods for loose part i
detection. Are there installed noise detectors capable of detection of broken springs, pieces of cladding, or vibrating assemblies?
i Have there been any excore or in-core neutron detector indications of levitated c.
assemblies? Describe the expected reactivity effects that would result from lift-off or reseating of assembifes with broken hold-down springs. What efforts are being utilized to detect loose assemblies by either nuclear or mechanical monitoring devices?
d.
Have there been any observed indications of lateral repositioning of loose assemblies?. Describe the methods used to detect lateral assembly motion.
Describe the degree of lateral repositioning that is physically (dimensionally) possible after lift-off. What are the postulated worst-case effects of a laterally displaced assembly?
e.
(1) Describe the degree of " worst-case" mechanical damage that would be expected as a result of movement of a " loose" assembly (one with a broken spring) against adjacent assemblies, core baffle, or other core components.
'(11) Discuss the results of flow tests or other experiments that have provided measurements of axial or lateral vibratory motion of an assembly after lift-off or that would otherwise support the response to Q 2.e(i).
3.
Provide a Uescription of the cause of the failures and corrective action to reduce the likelihood of future failures at your facility.
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