ML19257A606

Forwards Request for Addl Info Needed for OL Application Review.Response Should Be Submitted Prior to 800131

ML19257A606
Person / Time
Site:	Zimmer
Issue date:	12/11/1979
From:	Stolz J Office of Nuclear Reactor Regulation
To:	Borgmann E CINCINNATI GAS & ELECTRIC CO.
References
NUDOCS 8001040734
Download: ML19257A606 (4)

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UNITED STATES 8 "f ) v - 'j NUCLEAR REGULATORY COMMISSION W

C WASHINGTON, D. C. 20555

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DEC 1 1 1979 Docket No. 50-358 Mr. Earl A. Borgmann Vice President - Engineering Cincinnati Gas & Electric Ccmpany P. O. Box 960 Cincinnati, Ohio 45201

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION (Wm. H. Zimmer, Unit No. 1)

In order that we may continue our review of your application for a license to operate the Zimmer Nuclear Power Station, Unit No.1, your response to the enclosed request for additional information is needed.

The request is based uoan information contained in your application as amended through Revision 62 and your responses to our previous requests. We will need your response to this request prior to January 31, 1980.

Please contact us if ycu desire infomation or clarification regarding the enclosure.

Sincerely, j<i J,h Jo n F. Stolz, Chief

'L4ght Water Reactors Branch No.1 Division of Project Management

Enclosure:

Request for Additional Information cc: See next page 1851 120

-7 8001040 /

DEC 11 1979 cc: Troy B. Conner, Jr., Esq.

David B. Fanknauser, ?-3 Conner, Moor.e & Corber 3569 Nine Mile Road 1747 Pennsylvania Avenue, N. W.

Cincinnati, Ohio 45230 Washington, D. C.

20006 Dr. Frank F. Hooner Mr. William J. Moran School of Natural Resources General Counsel University of "ichigan The Cincinnati Gas and Electric Ann Arcor, Michigan 4S109 Company P. O. Box 960 Mr. Stepnen Schumacher Cincinnati, Ohio 45201 Miami Valley Pcwer Proiect P. O. Box 252 Mr. William G. Porter, Jr.

Dayton, Ohio 45401 Porter, Stanley, Arthur and Platt

!!s. Augusta Prince, Chairperson 37 West Broad Street 601 Stanley Avenue Columbus, Ohio 43215 Cincinnati, Ohio 45225 Mr. Steven G. Smith, Mananer Charles Secancefer, Esc., Chairman Engineering & Project Control Atomic Safety & Licensing Board The Dayton Power and Light Panel Comoany U. S. Nuclear Regulatory Commission P. O. Box 1247 Wasnington, 3. C.

20555 Dayton, Ohio 45401 Mr. Glenn 0. Bright J. Robert Newlin, Counsel Atomic Safety and Licensing The Dayton Power and Light Board Par.el Ccmpany V. S. Nuclear Regulatorv Commission P. O. Box 1247 Washington, 3. C.

205 5 Dayton, Ohio 45401 Leah S. Kosik, Esq.

Mr. James D. Flynn 3454 Correll Place Manager, Licensing Cincinnati, Ohio 45220 Environmental Affairs The Cincinnati Gas and N. Peter Heile, Esq.

Electric Company Assistant City Solicitor P. O. Box 960 Rcom 214, City Hall Cincinnati, Ohio 45201 Cincinnati, Ohio 45220 Mr. J. P. Fenstermaker Atcmic Safety and Licensing Scarc Senior Vice President-Cperations Panel Columbus and Southern Ohio U. S. Nuclear Regulatorv Commission Electric Comoany Washington, D. C.

20555 215 North Frcnt Street Columbus, Ohio 43215 Atcmic Safety and Licensing Appeal Board U. S. Nuc! ear Regulatorv Commission Washington, D. C.

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1851 121' m

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ENCLOSURE REOUEST FOR ADDITIONAL INFORMATION WM. H. ZIMMER ROUND-TWO OUESTIONS Introduction This enclosure consists of the twenty-ninth in a series of positions (and requests for additional information). We will need your response in order to complete our safety evaluation of your Zimmer OL application. The request is in the area of:

231.0 Fuel Section, Core Performance It will be helpful to us if your responses are in a " Position and Response" format using the same number designation as the position. The first r. umber designated the review area and the second (in parentheses) designated the associated section of the FSAR. Of course, your responses should include revision to the FSAR wherever appropriate.

NOTE: Your response involves only the commitment to perform the same actions as recuired in IE Bulletin No. 79-26.

1851 122

Request For Zimmer 1 Reactor Fuels Section

.'31.12 A cecy of IE Sulletin No. 79-26 concerning a recently analyzed failure mode for BWR control rod blades is attached. As a result of observed cracks in the control rod claddina, some B C 4

is leached out of the tubes which results in decreased reactivity worth. The bulletin lists actions to be taken by licensees of all operating BWR alants.

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To pecceed toward an coerating license for your plant, we need to have your commit. Tent to perform the same actions as recuired in the Sulletin.

UNITID STATES 551NS:

6320 NUCLEAR REGULATORY COMMISSION Accession No.:

OFFICE OF INSPECTION AND ENFORCEMENT 7910250475 WASHINGTON, D.C.

20555 November 20, 1979 IE Bulletin No. 79-26 EORON LOSS FROM SWR CONTROL BLADES Description of Circumstances:

The General Electric Company (GE) has informed us of a f ailure mode for control blades wnich can cause a loss of bcron poison material.

Hot cell examinations of both foreign and domestic blades have revealed cracks naar the uppe

.nd of stainless steel tubing and loss of baron from the tubes.

The cracks coron loss have so far been confined to locations in the poiscn tubes with more than 50 percent Baron-10 (310) local depletion. Observed crack sizes range from a cuarter to a half inch in length and from one to two mils in width.

GE has postulated that the cracking is due to stress corrosion induced by solidification of boron carbide (8 C) particles and swelling of the compacted 4

3 C as helium and lithium concentrations grow. Once primary ccolant penetrates 4

the clad::ing (i.e., the cracking has progressed through the cladding wall and the helium-lithium pressures are sufficient to open the crack), baron is leached out 10 of the tube at locations with more than 50 percent B local depletion (local depletion is considered to be twice the average depletion).

It was further found with similar cracking but with less than 50 percent local depletion of BIO, that leaching did not occur even though primary coolant hac penetrated the cladding.

The cracking and boren loss shorten the design life of the control blade.

According to the GE criteria the end of design life is reached when the reactivity worth of the blade is reduced by 10 percent, which corresponds to 42 percent 310 depletion averaged over the top quarter of the control blade.

Because of the leaching mechanism, GE has reduced 1

the top cuarter of the control blad DUPLICATE DOCUMENT The safety significance of boron los

• Y scram reactivity. Although shutdown entered into system under:

ANO No. of pages:

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