ML20127N740

Forwards Order Changing DPR-22 TS & SE

ML20127N740
Person / Time
Site:	Monticello
Issue date:	08/24/1973
From:	Anthony Giambusso US ATOMIC ENERGY COMMISSION (AEC)
To:	Mayer L NORTHERN STATES POWER CO.
Shared Package
ML20127N742	List: ML20127N740 ML20127N760
References
NUDOCS 9212010401
Download: ML20127N740 (2)

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Docket File R0 (3)

AEC PDR OGC DR Reading DLZiemann a

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Docket No. 50-263 0P 73 Branch Reading RWReid JRBuchanan, ORNL SVarga TBAbernathy, DTIE RMDiggs EPA (3)

Jtulendrie L}Nuntzing RHVollmer Northern States Power Company JF0' Leary SKari ATTN:

Mr. L. O. Mayer, Director AGiambusso NDube of Nuclear Support Services VStello MJinks (4) 414 Eiu llet Mall DJSkovholt WOM111er Atenmapolis, Minnamota 55401 ACRS (16)

Subject:

FUEL DEMSITICATION I

Gentlemen:

Transmitted herewith are (1) an Order by the Director of Regulation changing the Tech =ie=1 Specifications of License No. DPR-22; and (2) copies of empporting documentatiN.

It is requested that by 12:00 p.m. (noon EST) Aust.et 27, 1973, you inform the t h fasion by telephone and telegraph of the actions you have takaa to comply with the Order for Modification of License and the mari%n reactor power level that can be attainasi consistent with the Order.

Sincerely.

Oricinal si"ned by A. Gianum A. Giambusso, Deputy Director for Raaetor Projects Directorate of Licensing

Enclosures:

1.

Order for Modification of License 2.

Technical Report on Densification af General Electric Feactor Fuels 3.

Safety Evaluation of the Fuel Den-aification Effects on the Monticello Nuclear Power Plant

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cc w/ enclosures see next page omer >.L.:0RB #2

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9212010401 730824 PDR ADOCK 05000263.

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!..h Northern States Power Company AUG,,,,1973 cc w/ enclosures:

Gerald Charnoff Shaw, Pittman, Potts, Trowbridge and Madden 910 - 17th Street, N. W.

Washington, D. C.

20006 Donald E. Nelson, Esquire VP and GC Northern States Power Company 414 Nicollet Mall Minneapolis, Minnesota 55401 Howard J. Vogel, Esquire Knittle 6 Vogel 814 Flour Exchange Building Minneapolis, Minnesota 55415 Steve Gadler, P. E.

2120 Carter Avenue St. Paul, Minnesota 55108 Harriett Lansing Esquire Assistant City Attorney City of St. Paul 638 City Hall St. Paul, Minnesota 55102 Ken Dzugan Minnesota Pollution Control Agency 717 Delaware Street, S. W.

Minneapolis, Minnesota 55440 Warren R. Lawson, M.D.

Secretary & Executive Officer State Department of Health 717 Delaware Street, S. E.

Minneapolis, Minnesota 55440 Environmental Library of Minnesota 1222 S. E. 4th Street Minneapolis, Minnesota 55414 4

UNITED STATES OF AMERICA ATOMIC ENERGY COMMISSION t

In the t'atter of

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NORTHERN STATES POWER CO.

) Docket No. 50-263

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(Monticello Nuclear Power Station,

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ORDER FOR ' MODIFICATION OF LICENSE I.

The Northern States Power Co. ("the licensee") is the holder of Facility License DPR-22. License DPR-22 authorizes operation of the Monticello Nuclear Power Station, ("the plant") in Wright County, Minnesota. This license expressly provides, inter alia, that it is subject to all rules, regu-lations and orders of the Commission now or hereinafter in effect.

II.

On November 14, 1972, the AEC Regulatory Staff ("the Staff") issued a report entitled " Technical Report on Densification of Light Water Reactor Fuels" ("the Report"). By letter of November 20, 1972, the Staff requested the licensee to submit analyses and data specified in the report related to determining the consequences of fuel densification for normal operation of the plant, for operation of the plant during various maneuvers and transients, and under postulated accident situations, including the design basis loss--

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L of-coolant accidents. On December 29, 1972, the licensee provided the requested information including, by reference, the General Electric Company Report NEDM-10735, "Densification Considerations in BWR Fuel Design and Performance" dated December,1972. The Staff reviewed the licensee's sub-mission as well as five additional supplements to NEDM-10735 which were submitted by the General Electric Company in response to requests for

. additional information from the Staff. The latest of these supplements was dated July,1973. By letter of July 16, 1973, the Staff requested the licensee, inter alia, to furnish additional analyses regarding the calculated peak a

cladding temperatures during a postulated loss-of-coolant accident. On August 15, 1973, the licensee submitted the requested information including Supplement 6 to NEDM-10735.

On the basis of the Staff's review of the above identified submittals and its evaluation of fuel densification effects upon the operation of boiling water reactors which are reflected in a safety evaluation report relating to the plant dated August 24, 1973, the Staff has determined that changes in the operating conditions for the plant are necessary in order to assure that the calculated peak cladding temperature of the core of the plant following a postulated loss-of-coolant accident will not exceed 2300oF taking into account fuel densification effects as described in the Staff's safety _ evaluation identified above, and, therefore, that the Technical Specifications of License DPR-22

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3-l should be amended to require: (1) the immediate control of steady-state l

power operation so that the average linear heat generation rate of all the rods in any fuel aosmebly, as a function of planar exposure, at any axial location, shall not exceed the maximum average planar linear heat generation rate of 11.5 kw/ft; and (2) that during steady state power operation,.the i

linear heat generation rate (LHGR) of any rod in any fuel assembly at any i

axiallocation shall not exceed the maximum allowable LHGR as calculated

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using the equation for maximum LHGR provided in Limiting Condition for f

Operation, section'3.5.K of the attached Appendix 1.

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In view of the foregoing, the Director of Regulation finds that the public 4

i health, safety, and interest require that the following Order be made effective l

immediately. Pursuant to the Atomic Energy Act of 1954, as amended, the l

l Commission's regulations in 10 CFR-SS 2.204 and 50.100 and the license i

condition noted in Part I above t

IT IS ORDERED THAT:

f The Technical Specifications of License DPR-22 are hereby l

changed, to include Limiting Conditions for Operation, sections 3.5.J. and 3.5.K., and Surveillance Requirements.

sections 4.5.J. and 4.5.K. attached hereto as Appendix I i

and the p' ant shall be operated immediately in accordance therewith.

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t Within thirty (30) days from the date of publication of this notice in the k

Federal Register the licensee may file a request for a hearing with respect to this Order. Within the same thirty (30) day period any other person whose interest may be affected may file a request for a hearing with respect to this Order in accordance with the provisions of 10 CFR S 2.714 of the Commission's

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Rules of Practice. If a request for a hearing is filed within the time prescribed herein, the Commission willissue a notice of hearing or an appropriate order.

For further details pertinent to this Order see: the Staff Technical Report on Densification of Light Wster Reactor Fuels, November 14, 1972; letter to A. V. Dienhart feom A. Giambusso, November 20, 1972; letter to A. Giambusso from L. O. Mayer, December 29, 1972, with enclosure General Electric topical report, Densification Considerations in BRW Fuel Design and Performance; letter to A. V. Dienhart, with enclosure the Staff's GE Model for Fuel Densifi-cation, July 16, ~ 1973; letter to D. Zieman from L. O. Mayer, August 15, 1973; the Staff Technical Report on Densification of General Electric Reactor Fuels, August 23, 1973; the Staff Safe 6y Evaluation of the Fuel Densification Effects on the Monticello Nuclear Power Station, August 24, 1973; all of which are available for public inspection at the Commission's PucPc Document Room, 1717 H Street, N. W., Washington, D. C.

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Copies of these documents may be obtained upon request addressed to the Deputy Director for Reactor Projects Directorate of Licensing, U. S. Atomic Energy Commission, Washington, D, C.

20545, FOR THE ATOMIC ENERGY COMMISSION 4

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l Dated at Bethesda, Maryland this 24th day of August,19T i

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1-1 APPENDIX 1 TO AEC ORDER 1

CllANGE NO. ' 9 TO Tile TEC11NICAL SPE6fFICATIONS i

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LICENSE NO. DPR-22 l

NORTHERN STATES POWER COMPANY DOCKET NO. 50-263 l

l AUGUST 24, 1973 i

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are based on experimental data and predict with a 95% confidence that 90% of the population exceed t

i the predictions.

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3. 5. K Local LHGR This specification assures that the linear heat generation rate in any rod is less than the design Ilockr hest generation even if fuel pellet densification is postulated. The power spike penalty specified isLbased on the analysis presented in Section 3.2.1 of the GE topical report NEDM-10735 Supplement 6, and assumes.a lineatly increasing variation in axial gaps between' core bottom and top,

.and assures with a 95T' confidence, that no more than one fuel rod exceeds the design. linear heat I

l generation' rate due to power spiking.

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The possible effects of fuel pellet densification were:

(1) creep collapse of the cladding due l

i to. axial gap formation; (2) increase in the LilGR becausa of pellet calumn shortening; (3) power spikes l

r due to axial gap formation; and (4) changes in stored energy due to increased -radial gap size. : Calculations L

show that clad collapse s conservatively predicted not to occur currently or prior to September 1974.

Therefore, clad collapse-is not considered in the analyses. Since axial thermal expansion of the fuel 4'

pellets is greater than axial shrinkage due to densification, the analyses of peak clad temperature do not' consider any change in LIICR due to pellet column shortening. Although, the formation of axial gaps might produce a local power spike at one location on any one rod in a fuel assembly, the increase in lL local power density would be on the order of only 2% at the axial midplane. Since small local variations in power distribution have a small effect on peak clad temperature, power spikes were not considered in l

i the analysis of loss-of-coolant accidents.

Changes in g1p size affect the peak clad' temperature by their-effect on pellet clad thermal conductance and fuel pellet stored energy. The pellet-clad thermal i

conductance assumed for each rod is dependent on the steady state operating linear heat generation rate t'

and gap size. As specified in the AEC Fuel Densification Model for BWR's,: the gap size was calculated i.

assuming that.the pellet densified from the measured pellet density to 96.5%.of theoretical density.

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For the most critical rod, the-tuo standard deviation lower bound on initial pellet density was assumed.

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i For the other 48 rods the two standard deviation lower bound on the initial mean " boat" pellet density a

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was assumed.

I The curves used to. determine pellet-clad thermal conductance as a function of linear heat generation I

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i 3.5.J Averane Planar LHGR

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1 the peak cladding temperature following the postulated design basis l

This specificatica assures that loss-of-coolant acci<ient will not exceed the 2300"F limit specified in the Interim Acceptance Criteria

j (LAC) issued in June.1971 considering the postulated effects of fuel pellet densification.

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The peak cladding temperature following a postulated loss-of-coolant accident is primarily a' function I

i generation rate of all the rods of a fuel assembly at any axial location and is a

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.of the' average heat Since expected only dependent secondarily on the. rod to rod power distribution within an assembly.

i local variations in-power distribution-within a fuel assembly affect the calculated peak clad temperature

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f by less than 120*F relative. to the peak temperature 'for a typical fuel design, the limit on the average the 1AC limit.

i linear heat generation rate ic sufficient to assure that calculated temperatures are belas I

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= The maximum average planar IJIGR of 11.5 kW/f t is the same es that shown on the curves labeled I

(gamna) on-Figures 4-9C1 and 4-9C2 of the GE topical report " Fuel Dcnsification Effects on General

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Electric Boiling Water Reactor Fuel," UEDMH10735, Supplement 6, August 1973 and is the result of the t

These calculations were made to determine calculations presented in Section'4.3.4 of the same report.

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r the effect of.densification on peak clad temperature and were performed in accordance uith the AEC Fuel i

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l Densification Model for BUR's.which is attached to NEDM-10735, Supplement 6 as. Appendix B.,

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3.5 LIMITING CONDITIONS FOR OPERATION 4.5 SURVEILLANCE REQUIREXENTS

.T. Average Planar LHGR J.

Average Planar LHGR During steady state pouer operation, the, average linear. heat generation rate (LEGR) of all the Daily during reactor power operation, the rods. in any' fuel assembly, as a function of average planar LHGR shall be checked.

i average planar exposure, at any axial location, shall not exceed = the r.aximus average P anar LHGR l

of 11.5 kW/ft.

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Local LHGR K.

Local LHGR c

During steady state power operation, the linear Daily during reactor power operation, the heat generation rate (LHGR) of any rod in any local LEGR shall be checked.

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fuel asser_bly at any.arial ' location shall not exceed t'.c maximum allowable LHGR as calculated by the following equation:

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~f LHGR LHGR AP )

L max

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(P / max 1-LT

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1 LHGR F

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Design LHGR = 17.5 KW/ft i

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/. P max = Maximum power spiking' penalty = 0.038 j

LT = Total core length = 12'ft 2

j L = Axial position above bottom of core

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1 4.5.J6K Average and Local LHGR

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.The LHCR shall be' checked daily to... determine if fuel burnup, or control rod movement J are slow, and only a few control-rods changes in pouar distribution. ' Since changes due to burnu1 are coved. daily, a daily check of' power distribution is adequate.

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