ML19320D213

Requests Response to Encl Questions Re Fuel Assembly Holddown Spring Failures.Initial Holddown Spring Failure Was Identified During Underwater Insps of Fuel in Reactor Vessel During Current Refueling Outage

ML19320D213
Person / Time
Site:	Davis Besse
Issue date:	07/01/1980
From:	Novak T Office of Nuclear Reactor Regulation
To:	Crouse R TOLEDO EDISON CO.
References
NUDOCS 8007210115
Download: ML19320D213 (3)

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• July 1, 1980 Docket No. 50-346

1. . Richard P. Crouse

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Toledo Edison Corrpany Edison Plaza 300 Madison Avenue Toledo, Ohio 43652

Dear Mr. Crouse:

On May 13,1980 you informed us of the failare of a holddown spring on a fuel assembly which was observed during underwater inspections of the fuel in the reactor vessel during the current refueling outage. Based upon your subsequent inspections, additional holddown spring failures were identified and reported.

On June 10, 1980, a meeting was held in Bethesda with members of your staff and B&W to discuss the status of the inspections. The presentation of the meeting was organized to address a set of questions that we had informally transmitted to your staff prior to the meeting. Although these questions were addressed on June 10, we would like to formally document your responses.

It is requested that you provide responses to the enclosed questions in time for us to include an evaluation of this issue in the Safety Evaluation Report for your reload.

Sir:cerely.

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Thomas M. Novak, Assistant Director for Operating Reactors Division of Licensing

Enclosure:

Holddewn Spring Questions cc w/ enclosure:

See next page 8007210//6 p

Toledo Edison Company cc w/ enclosure (s):

U. S. Nuclear Regulatory ranission Mr. Donald H. Hauser, Esq.

Resident Inspector s.0ffice The Cleveland Electric O

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EIS COORDINATOR 230 South Dearborn Street Mr. Robert B. Borsum Babcock & Wilcox Chicago, Illinois 60604 Nuclear Power Generation Division Suite 420, 7735 Old Georgetown Road Bethesda, Maryland 20014 Ohio Department of Health ATTN: Director of Health Ida Rupp Public Library 310 Madison Street 450 East Town Street Columbus, Ohio 43216 Port Clinton,0hio 43452 President, Board of County Coninissioners of Ottawa County Port Clinton, Ohio 43452 Attorney General Department of Attorney General 30 East Broad Street Columbus, Ohio 43215 Harold Kahn, Staff Scientist Power Siting Comission 361 East Broad Street Columbus, Ohio 43216 l'

Mr. Rick Jagger Industrial Comission State of Ohio 2323 West 5th Avenue Columbus, Ohio 43216 Mr. Ted Myers Licensing Engineer Toledo Edison Company Edison Plaza 300 Madison Avenue Toledo, Ohio 43652

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b Enclosure HOLD-DOWN SPRING OUESTIONS 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 s1 pent 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 assembly 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.

i Assume the holddown spring is broken, provide an estimate of the(Provide a.

flow conditions under which the asserslies 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 ptsnps 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.

I 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?

I c.

Have there been any excore or in-core neutron detector indications of levitated i

assemblies? Describe the expected reactivity effects that would result from lift-off or reseating of assemblies with broken hold-down springs. What i

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.

C,. scribe 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.

'(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.

.