ML20236R479

Application for Amend to License DPR-61,modifying Calibr Requirements for Power Range Nuclear Instrumentation When Plant Operated at steady-state Reduced Power & Channels Adjusted to Provide Enhanced Overpower Protection.Fee Paid

ML20236R479
Person / Time
Site:	Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png
Issue date:	11/19/1987
From:	Mroczka E CONNECTICUT YANKEE ATOMIC POWER CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
Shared Package
ML20236R481	List: B12605, Proposed Tech Specs,Modifying Calibr Requirements for Power Range Nuclear Instrumentation When Plant Operated at steady- State Reduced Power & Channels Adjusted to Provide Enhanced Overpower Protection ML20236R479
References
B12605, NUDOCS 8711230307
Download: ML20236R479 (4)

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CONNECTICUT YANKEE ATOMIC POWER COMPANY B E R L I N. CONNECTICUT P.o. box 270

• HARTFoRO, CONNECTICUT 061410270 TELEPHONE monoco November 19,1987 Docket No. 50-213 B12605 Re: 10CFR50.90 s

U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555 Gentlemen:

Haddam Neck Plant Proposed Revision to Technical Specifications Operational Safety items Pursuant to 10CFR50.90, Connecticut Yankee A tomic Power Company (CYAPCO) hereby proposes to amend Operating License No. DPR-61 for the Haddam Neck Plant by incorporating the attached proposed change into the plant technical specifications.

Specifically, the proposed change will modify the calibration requirements for the power range nuclear instrumentation whenever the plant is operated at steady-state reduced power and these channels have been adjusted to provide enhanced overpower protection, j

Discussion j l

Haddam Neck Technical Specification - Table 4.2-1, " Minimum Frequencies for i Testing, Calibrating and/or Checking Instrument Channels," requires that the power range nuclear instruments be calibrated with a heat balance calculation daily, except when the plant is shut down. This practice ensures that the power range nuclear instruments provide an accurate indication of reactor power. This ,

requirement is implemented by Surveillance Procedure SUR 5.1-75, " Power i Range Channel Calibrations." j The power range nuclear instrumentation channels provide the overpower trip function of the reactor protection system (RPS). The nuclear overpower trip has three setpoints, at 25 percent, 74 percent, and 109 percent power that 'are manually selected by the operator. As a result, at intermediate power levels, there may be a large margin between actual core power and the overpower.

protective trip. In order to provide enhanced protection against positive reactivity transients when the plant is operated at steady-state reduced power, the power range nuclear instruments will be adjusted such that a 9 percent margin to an overpower trip setpoint is maintained. For example, if the plant 8711230307 871119 PDR ADOCK 05000213 Ql & geol

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U'. S. Nuclear Regulatory Commission B12605/Page _2 November 19,1987 were operated at 50 percent steady-state power, the overpower trip selector switch would be set to the mid position (74 percent trip setpoint) and the power range nuclear instruments adjusted to indicate a power level of 65 percent. This reduces the margin to trip from 24 percent to 9 percent. This practice ensures that operation at intermediate power levels will be bounded by the analyzed accident scenarios which are terminated by the overpower trip. This practice has been implemented by Operating Procedure NOP 2.2-2, " Steady State Operation and Surveillance."

The intent of the Technical Specification change is to revise Table 4.2-1 such that the heat balance calibration of the nuclear instruments is not required when the power range channels have been adjusted to maintain a 9 percent margin to the overpower trip setpoint during steady-state reduced power operation. This practice improves the overpower protection of the RPS and provides for safer plant operation. The disadvantage of having incorrect indication on the nuclear instruments is not significant in that the primary indication of reactor power during Mode 1 operation is a process computer on line calorimetric calculation.

Additionally, other indications of reactor power are available which are not affected by the proposed calibration practice. Further, adjusting the power range channels as described above has no adverse impact on the functioning of the RPS.

Significant Hazards Consideration in accordance with 10CFR50.92, CYAPCO has reviewed the attached proposed l change and has concluded that it does not involve a significant hazards l consideration. The basis for this conclusion is that the three criteria of j 10CFR50.92(c) are not compromised; a conclusion which is supported by our '

determinations discussed below. The proposed change does not involve a significant hazards consideration because the change would not:

1. Involve a significant increase in the probability or consequences of an accident previously evaluated. The probability of occurrence or the consequences of an accident or malfunction of equipment important to safety previously evaluated in the Safety Analysis Report is not increased since the proposed change would require that the 9 percent margin be verified at the same frequency at which the calibration would have been performed.

The net effect of maintaining the 9 percent margin during reduced power operation is the same or more conservative as calibrating the power range channels with respect to the protective function.

2. Create the possibility of a new or different kind of accident from any previously evaluated. The possibility for an accident or malfunction of a different type than any evaluated previously in the Safety Analysis Report is not created since the change and/or failure modes associated with the change do not modify the plant response to the point where it can be considered a new accident.

s U2 S. Nuclear Regulatory Commission B12605/Page 3 November 19,1987 l

Since no physical plant changes are planned and since the RPS performance will not.be adversely affected, there is no adverse j effect on plant response. The proposed change, in fact, is intended to ensure that the plant can adequately mitigate reactivity transients initiated at intermediate power levels.

1 There are no failure modes associated with the proposed change j which could represent a new unanalyzed accident. The proposed change does not adversely impact the probability of any accident.

The only effect of the proposed change is to improve the capability of the RPS to mitigate reactivity transients initiated from intermediate power levels.

3. Involve a significant reduction in a margin of safety. The margin of safety, as defined in the basis for any Technical Specifications is not reduced since the proposed change does not have any adverse impact on the protective boundaries for any design basis i accident. 1 Additionally, as discussed earlier, the proposed change does not i adversely affect the RPS overpower trip. Therefore, there is no f adverse impact on the RPS and there can be no adverse impact on the consequences of any accident. Therefore, it does not adversely impact the basis of the Technical Specifications.

The Commission has provided guidance concerning the application of standards in 10CFR50.92 by providing certain examples (51 FR 7750, March 6,1986). While none of the examples provided by the Commission are .directly applicable to the proposed change, example (ii) most closely reflects the intent of the change.

Example (ii) is a change that constitutes an additional limitation, restriction, or j control not presently included in the Technical Specifications. Although the proposed change itself is not an additional limitation, it is a necessary change in order to implement the practice of calibrating the nuclear instrumentation to provide enhanced overpower protection. This re-calibration is considered to be an additional limitation. Thus, while the change itself is not an additional limitation,it does not decrease the effectiveness of the current surveillance and it is necessary in order to implement an additional operation restriction. This is supported by the conclusion discussed above that the only effect of the proposed change is to improve the capability of the RPS to mitigate reactivity trandents initiated from intermediate power levels.

The Haddam Neck Nuclear Review Board has reviewed and approved the I attached proposed revision and concurs with the above determinations.

In accordance with 10CFR50.91(b), CYAPCO will provide the State of I Connecticut with a copy of this proposed amendment. i l

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' U.S'. Nuclear Regulatory Commission B12605/Page.4

. November 19,1987

p Pursuant to the requirements.of 10CFR170.12(c), enclosed with this amendment ~

request is the application fee of $150.-

Very truly.yours, CONNECTICUT YANKEE ATOMIC POWER COMPANY.'

E. 3 f czka'. J s

Seni Vice President cc: Mr. Kevin McCarthy Director, Radiation Control Unit Department of Environmental Protection

. Hartford, Connecticut 06116 '

W. T. Russell, Region I Administrator

3. T. Shediosky, Resident inspector, Haddam Neck Plant'.

A. Wang, NRC Project Manager, Haddam Neck Plant

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STATE OF CONNECTICUT )

) ss. Berlin -

COUNTY OF HARTFORD )

Then personally appeared before me, E. 3. Mroczka,'who being duly sworn,' did state that he is Senior Vice President of Connecticut Yankee.' Atomic Power Company, a Licensee herein, that he is authorized to execute and . file the ,

foregoing information in the name and on behalf of the Licensee herein, and that '

the statements contained in said information are true and correct to_the best of his knowledge and belief.

AllhMM5  ;

Kiotsry Publ

& Commiseion Expires March 31,1988 i

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