ML19321A821
| ML19321A821 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 07/01/1980 |
| From: | Novak T Office of Nuclear Reactor Regulation |
| To: | Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| References | |
| NUDOCS 8007240244 | |
| Download: ML19321A821 (5) | |
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NUCLEAR REGULATORY COMMISSION o
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July 1,1980 I^l*
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T Docket No. 50-312 8
i Mr. J. J. Mattimae Assistant General Mana pr and Chief Engineer S.acramento Municipal Utility District 6201 S Street P. O. Box 15830 Sacramento, California 95813
Dear Mr. Mattimoe:
Recently we have been notified by the Toledo Edison Conpany that a number of fuel assembly holddown spring failures have been observed at the Davis-Besse. 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 assenblies 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, b&f-YQ Thomas M. N:vak, Assistant Director
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for Operating Reactors Division of Licensing
Enclosure:
Holddown Spring Questions i
cc w/ enclosure-See next page i
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80072404 W.
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Eacramento Municipal Utility District cc w/ enclosure (s):
Christopher Ellison, Esq.
David S. Kaplan, Secretary and Dian Grueuich, Esq.
General Counsel California Energy Commission 6201 S Street lill Howe Avenue P. O. Box 15830 Sacramento, California 95825 Sacramento, California 95813 Ms. Eleanor Schwartz Sacramento County California State Office Board of Supervisors 600 Pennsylvania Avenue, S.E., Rm. 201 827 7th Stre'et, Room 424 Washington, D.C.
20003 Sacramento, California 95814 Docketing and Service Section Office of the Secretary
-usiness and Municipal Department U. S. Nuclear Regulatory Commission rmn ity-County Library Washington, D.C.
20555 Sacramento, California 95814 Resident Inspector Di ect
, Technical Assessment 0
s, alifornia 95628 Office of Radiation Programs Dr. Richard F. Cole U.S.Env)ronmentalProtectionAgency Atomic Safety and Licensing Board (AW-59 i
Panel vystal Mall #2 U. S. Muciear Regulatory Commission Arlington, "irginia 20460 Washington, D.C.
20555 U. S. Environmental Protection Agency Mr. Frederick J. Shon Region IX Office Atomic Safety and Licensing Board ATTN:
EIS COORDINATOR Panel 215 Fremont Street U. S. Nuclear Regulatory Commission San Francisco, California 94111 Washington, D.C.
20555 Mr. Robert S. Borsum Elizabeth S. Bowers, Esq.
Sabcock & Wilcox Chairman, Atomic Safety and Nclear Foveer Generation Division Licensing Board Panel uite 420, 7735 Old Georgetown Road U. S. Nuclear Regulatory Commission c
Lothesda, Maryland 20014 Washington, DC 20555 Thomas Baxter, Esq.
Shaw, Pittran, Potts' a Tr,wbridge 1800 M Street,"?M i
ziashington, D. C. -2003G -
Herbert H. Brown, Esq.
Mr. Michael R. Eaton Lawrence Coe Lanpher, Esq.
Energy Is'ues Coordinator Hill, Christopher and Phillips, P. C.
Sierra Club Legislative Office 1900 M St., NW 1107 9th St., Room 1020 Washington, D. C.
20036 Sacramento, CA 95814 Helen Hubbard P. O. Box 63 Sunol, California 94586
Sacramento Municipal Utility District cc w/ enclosure (s):
Atomic 55fety and Licensing Board Panel U. S. Nuclear Regulatory Commission Washington, D.C.
20555 Atomic Safety and Licensing A'ppeal Board Panel U. S. Nuclear Regulatory Commission Washington, D.C.
20555 California Department of Health ATTN: Chief, Environmental Radiation Control Unit Radiological Health Section 714 P Street, Room 498 Sacramento, California e
Encicsura HOLD-DOWN SPRING QUESTIONS TO LICENSEES 1
(If the reactor is down for refueling and the reactor vessel head is off) Examine all fuel assembly holddown springs in the core and in the shent 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.
Report the number and extent of damage on the springs and affected assedly components.
2.
Provide a discussion of the safety signifi ce of operating with one or more broken springs in the core. i / discussion should include, but not necessarily be limited to the following:
Assume the holddown spring is broken, provide an estimate nf the(Provide 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 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.) Contra,*ily, demonstrate the margin between the assembly weight and the calculated maximum applied lift-off force, if there is such margin.
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 detection. Are there installed noise detectors capable of detection of broken springs, pieces of cladding, or vibrating assemblies?
c.
Hase there been any excore or in-core neutron detector indications of levitated assemblies? Describe the expected reactivity effects that would result fran lift-off or re3 eating 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 asser51ias?. 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 e.
( i) 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.
'(ii) 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).
- Enclosure l
3.
Provide a bescription of the cause of the failures and corrective action to raduce the likelihood of future failures at your facility.
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