ML19320D593
| ML19320D593 | |
| 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 | |
| TAC-42266, NUDOCS 8007210581 | |
| Download: ML19320D593 (3) | |
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" G CM L PDR J01shinski NRC PDR TERA RTedesco NSIC TNovak Dockat No. 50-302 ORB #4 Rdg RReid NRR Rdg PErickson DEisenhut RIngram RPurple OELD Mr. J. A. Hanced AE00 Director, Nuclear Operations IE-3 Florida Power Corporation ACRS-16 P. O. Box 14042, Mail Stop C-4 Gray File St. Petersburg, Flcrida 33733
Dear Mr. Hancock:
Recently ~we have been notified by the Toledo Edison Ccepany that a nunter of fuel assenbly holddown spring failures have been observed at the Davis-Besse. Unit Mc. I plant which is currently undergoing its first refueling We understand that as a result of these failures, Sabcock & Wilcox cutage.
has requested that ycu conduct examinaticns of fuel assent 11es at your facility to determine if any failures have occurred. We are interested in knowing the results of holddown spring inspections at ycur facility as well as the safety significance of cperating with broker, springs in the cere.
Enclosed is a set of questions regarding this subjecc. It is requested that you provide responses to these questions within 60 dan of receipt of this letter.
Sincerely.
Criginal sI9ted BY Thomas M. Novak, Assistant Director for Operating Reactors Division of Licensing
Enclosure:
Holddown Spring Questions cc w/ enclosure:
See next page 1
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TERA THovak NRC PDR NSIC RReid Occket.kcEIO-302 OR3f4 Rdg ORBH PM NRR Rdg RIngram DEisenhut AE00 RPurple OELD J01shinski IE-3 rir. J. A. Hancock o
ACTS 'i6 Directer, Nuclear Ope Florida Power Corporation
'. O. Sox 14042. Mail Stop C-4 St. Petersburg, Florida 33733
Dear Mr. Hancock:
Recently we have been notified by the Toledo Edisen Ccr@any that a number of fuel assedly holdecwn spring f ailures have been cbserved at the Davis-
- Besse. Unit No. I plant which is currently undergoing its first refueling cutase. We understand that as a result of these failures, Babccck & Wilcox has requested that you conduct examinations of fuel asse211es at your facility to detersine if any failures have cccurrred. We are interested in knowing the results of holddown spring inspections at your facility as well as the safety significance of operating with brcken springs in the core.
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Enclosed is a set of questions regarding this subject.
It is requested that you provide respcnses to these questiens within 50 days of receipt cf this letter.
Sincerely, Thesas M. Novak, Assistant Directcr for Operating Reacto*'
Division of Licensing
Enclosure:
Holddcwn Spring Questions cc w/ enclosure:
See next page o,,,ce b:m.
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0, UNITED STATES NUCLEAR REGULATORY COMMISSION 2
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WASHINGTON. D. C. 20665 t
July 1, 1980
%,, *.... y Docket No. 50-302 Mr. J. A. Hareock
, Director, Nuclear Operations Florida Power Cr.rporation P. O. Box 14042, Mail Stop C-4 St. Petersburg, Florida 33733
Dear Mr. Hancock:
Recently we have been notified by the Toledo Edison Cogany that a number of fuel assembly holddown spring failures have been observed at the Davis-Bessa, Unit No.1 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, G2. n/. '
]
Thomas M. Novak, Assistant Director
~
for Operating Reactors Division of Licensing
Enclosure:
Holddown Spring Questions cc w/ enclosure:
See next page l
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Enclosure
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HOLD-DOWN SPRING QUESTIONS TO LICENSEES 1
(If the reactor is down for refueling and the reactor vessel head isoff) Examine all fuel asserri f holddown springs in the core and in the s)ent fuel pool and report the number and extent'of damage on the' springs and affected assembly crmonents.
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.
Repor.t the number and extent of damage on the springs and affected assembly I
components.
2.
Provide a discussion of the safety significance of operating with one or more broken springs in the core. Your discussion should include, but not necessarily be limited to the following:
Assume the holddewn spring is broken, provide an estimate af the(Provid a.
flow conditions under which the assemblies would be levitated.
the value of the force required to lift the assembly, the flow conditions under which that force would be supplied, the nurrter 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 applied lift-off force, if there is such margin.
t i
b.
Have any loose assembly parts (i.e., broken springs, pieces of cla' ding) been d
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?
c.
Have there been any excore or in-care neutron detector indications of levitated assemblies? Describe the expectr.d reactivity effects that would result from lift-off or reseating of assemblies 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?
i 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, e. ore baffle, or other core components.
'(19 Discuss the results of flow tests or other experiments that have provided mearurements 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 3escription cf the cause of the failures and corrective action to reduce the likelihood of future failures at your facility.
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