B11011, Application for Amend to License DPR-65,revising Tech Specs Re Power Distribution Limit Total Planar Radial Peaking Factor

Application for Amend to License DPR-65,revising Tech Specs Re Power Distribution Limit Total Planar Radial Peaking Factor

ML20080K672
Person / Time
Site:	Millstone
Issue date:	01/20/1984
From:	Counsil W NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES
To:	John Miller Office of Nuclear Reactor Regulation
Shared Package
ML20080K674	List: B11011, Application for Amend to License DPR-65,revising Tech Specs Re Power Distribution Limit Total Planar Radial Peaking Factor ML20080K696
References
B11011, TAC-53462, NUDOCS 8402160100
Download: ML20080K672 (4)

Text

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' NORTHEAST tfTIEJTIES ' " " ' ' " 'c '" S* '* " S ""' " * " ' " Co " "'c c "'

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P.O. box 270

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(203) ses-em January 20,1984 Docket No. 50-336 B11011 Director of Nuclear Reactor Regulation Attn: Mr. James R. Miller, Chief Operating Reactors Branch //3 U. S. Nuclear Regulatory Commission Washington, D. C. 20555

References:

(1) J. R. Miller letter to W. G. Cotnsil, dated December 30, 1983.

(2) W. G. Counsil letter to R. A. Clark, dated April 13,1983.

(3) W. G. Counsil letter to J. R. Miller, dated November 17, 1983.

Gentlemen:

Millstone Nuclear Power Station, Unit No. 2 Proposed Revisions to Technical Specifications Power Distribution Limits Pursuant to 10 CFR 50.90, Northeast Nuclear Energy Company (NNECO) hereby proposes to amend its operating license, DPR-65 for Millstone Unit No. 2, by incorporating the attached proposed changes into the plant Technical Specifications. The changes revise the total planar peaking f actor limits between 92.5 and 100% power specified in Figtre 3,2-3 of the Technical Specifications. The curve has also been extended to include operation to 65%

power. Figure 3.2-2, Axial Shape Index vs. Fraction of Allowable Power Level, has also been revised to accommodate the peaking f actor change.

NNECO applied for and recently received a license amendment in P.eference (1) authorizing Cycle 6 operation of Millstone Unit No. 2. The plant was made critical on January 5.1934 and startup physics testing was initiated. At the completion of startup physics testing, core power level was increased but, due to steam generator chemistry controls, did not achieve levels at which power peaking iactors could be measured until January 13,1984.

Extrapolatmg meastrements of the total planar peaking factor, FxyT , taken at approximately 50% power, it is expected that f ull power operation will not be achievable due to the restrictions imposed by the current limits of Technical Specification Figure 3.2-3. The ctrrent figure was generated based on the results of analyses of the Cycle 6 core loading pattern. The curve is designeo o bound as closely as possible actual plai operating characteristics as predicted B402160100 840120 k PDR ADOCK 05000336 -

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by the reload analyses. Meastrements of FxyT at current power levels indicate a underprediction in FxyTby the analyses and as noted above the present Figure 3.2-3 will limit the plant to less than f ull power.

To alleviate this derate, the fuel vendor has provided a revised total planar peaking factor curve as a f tnction of allowable fraction of rated power. NNECO has evaluated the impact of this change in peaking f actor limits and provides the following justification. The technical approach utilized involved a re-distribution of available margins using previously approved methodology to envelope the situation predicted to occur at levels approaching 100% power.

The total planar peaking f actor (FxyT) is utilizb in the determination of the local power density (kw/f t). The local power density is monitored to ensure that fuel centerline melting will not occur due to axial power maldistributions.

Additionally, the local power density limit of 15.6 kw/f t is required to be maintained ta ensure continued applicability of the large break loss-of-coolant accident analysis results.

There ctrrently exists conservatism in the local power density trip setpHnt to accommodate the increased Fxy T limit curves. As such, no setpoint changes are required as a result of the proposed changes and the margin to the specified acceptable fuci design limits is maintained for the transients and accidents which this trip protects against.

The incore monitoring system is not impacted by these proposed changes since the incore monitoring program will continue to utilize the actual meastred Fxy T when performing surveillance monitoring for linear heat rate. The revision to the FxyT curve will impact the linear heat rate surveillance when the excore monitoring system is utilized. Typically, the excore monitoring system is utilized when the incore system is inoperable; historically this is most frequently attributable to a temporary computer f ailure. To compensate f or the increase in allowable FxyT above 92.5% power, NNECO has revised the axial shape index (ASI) limits oI Figure 3.2-2. Specifically, the 4.3% increase in allowable FxyT at full power has been more than offset by a 5% decrease in the ASI limits of Figure 3.2-2. The more restrictive ASI limits are imposed when the excore monitoring system is utilized to perform the linear heat rate surveillance requirements.

The FxyT s not input to any of the DNB limiting conditions f or operation or DNB limiting safety system setpoints (Thermal Margin / Low Pressure Trip).

The extension of the FxyT curves to 65% power f rom the ctrrent cutof f at T peaks during approximately low power operation with non-steady state conditions. This poin Fxk was previously 80% power is required in the event of higher analyzed as part of the Cycle 6 reload analyses and is input to the safety analyses submitted in Ref erence (2) as updated in Ref erence (3).

NNECO has reviewed the attached proposed changes pursuant to 10 CFR 50.59 and has determined that they do not constitute an unreviewed saf ety question.

Specifically, the margins of sa'ety as defined in the technical specification bases t  ;

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are maintained.' ~1n addition, the probability of occurrence or the consequences

-of a previously analyzed accident have 1.ot been increased and the possibility ior a new type of accident not previously evaluated has not been created.

In accordance with 10 CFR 50.92, NNECO has reviewed the attached proposed changes and has concluded that they do not involve a significant hazards consideration. The basis for this conclusion is that the three criteria of 50.92(c) are not compromised, a conclusion which is supported by our determination made pursuant to 10 CFR 50.59.' Further, the changes f all within the envelope of Item

_ (111) on 48 FR 14870 of amendments that are considered not likely to involve a significant hazards consideration. The f uel assemblies .are identical to those

- approved by the NRC in Reference (1), no significant changes to the acceptance

. criteria for the Technical Specifications are being proposed, and the analytical

. methods utilized are identical to those approved by the NRC in Reference (1).

NNECO respectfully requests that this amendment be processed in accordance with the procedures . outlined in :10 CFR 50.91(a)(5). As previously discussed, NNECO' made Millstone Unit No. 2 critical on January 5,1984 following an extended ref ueling and maintenance outage. Revised tech,ical specifications

. Reference supporting 1).(Cycle

. These6technical operations were applied specifications for inon are based Reference (2) and issued in our fuel vendor's l predictions of core physical parameters.- The FxyT curve is typically designed to bound as closely as possible the operating characteristics predicted by the reload analyses /

After completing startup testing and steam generator cleanup, power levels of 30% and greater' were achieved .. on January 13, 1984. At that time,

. measurements of FxvT . were possible and evidence of the mderprediction in FxyTwas' identified. NNECO could not have identified this situation until power levels in excess of 20% were achieved. These f acts explain why this matter was not formally brought to the attention of the NRC previously. During the past

. week NNECO . accomplished such ~ activities as evaluation of the power distribution data, obtaining and reviewing the1 revised analyses from our fuel vendor, and processing of this amendment request through our internal review committees.

It is estimated that a power level of approximately 90% of rated thermal power

- can :be: achieved with the current technical specification limits resulting in a ~

derate on the order of 10%. .Therefore, this amendment request is governed by lthe provisions of 50.91(a)(5),in that

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" failure to act'in a timely way would result in derating .....of a

. nuclear power plant,". :

Hence,'we request that the Commission dispense with notice and comment on the determination of no significant nazards consideration and publish a notice of iscuance under 10 CFR 2.106. The emergency situation occurred due to a small

. underprediction in FxyT ni the analyses previously submitted to support cycle 6 operation.- The underprediction by our fuel vendor was of a magnitude that the margin available in the total planar peaking factor curve was not sufficient to allow 100% power operation. Reevaluations were performed on an expedited J

Od 4-a basis to accommodate the existing situation. This situation could not have been anticipated by NNECO since valid measurements of Fx T obtained prior to operation at 30% power level or higker.could not have been Hence, expedited processing of this license amendment is justified under 50.91(a)(5).

In accordance with 10 CFR 50.92(b), NNECO is providing the State of Connecticut with a copy of this preposed amendment.

The Millstone Unit No. 2 Nuclear Review Board has reviewed and approved this proposed amendment and has concurred with the above determinations.

We trust you find this information satisfactory and remain available to assist you in the expedited review of this matter. Current plant conditions indicate that the unit will be capable of escalating in power level above the authorized limit (estimated to be approximately 90%) late on Monday, January 23, 198te.

~ Therefore we request that the amendment be issued by close-of-business on January 23. We will keep the NRC Project Manager informed regarding actual plant status if conditions change.

Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY

/Tl W. G. Counsil Senior Vice President cc: Mr. Arthur Heubner Director, Radiation Control Unit Department of Environmental Protection State Office Building Hartford, CT 06116 STATE OF CONNECTICUT )

) ss. Berlin COUNTY OF HARTFORD )

Then personally appeared before me W. G. Counsil, who being duly sworn, did state that he is Senior Vice President of Northeast Nuclear Energy Company, Licensee herein, that he is authorized to execute and file the foregoing

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information in the name and on behalf of the Licensees herein and that the statements contained in said information are true and correct to the best of his knowledge and belief.

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