ML20151Z175

Application for Amend to License DPR-3,modifying Tech Specs to Remove Ref to Specific Value of 2,200 Ppm & Provide Generalized Boron Concentration Value & Remove Requirement for Inverse Count Rate Multiplication Measurement.Fee Paid

ML20151Z175
Person / Time
Site:	Yankee Rowe
Issue date:	08/11/1988
From:	Devincentis J YANKEE ATOMIC ELECTRIC CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
Shared Package
ML20151Z179	List: ML20151Z175 ML20151Z187
References
FYR-88-108, PC-223, NUDOCS 8808290223
Download: ML20151Z175 (4)

Text

e . 4 TeWone (6171872-8100 1&X 1103W7619 YANKEE ATOMIC ELECTRIC COMPANY

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r .. +sg 1671 Worcester Road, framrngham, Massachusetts 01701 August 11, 1988 FYR 88-108 PC-223 United States Nuclear Regulatory Comi::sion Document Control Desk Washington, DC 20555

References:

(a) License No. DPR-3 (Docket No. 50-29)

(b) Yankee Nuclear Power Station Core 19 Performance Analysis, January 1987

Subject:

Yankee Nuclear Power Station Refueling Operations

Dear Sir:

Pursuant to Section 50.90 of the Commission's Rules and Regulations, the Yankee Atomic Electric Company (YAEC) hereby requests the authorization to make the following changes.

Proposed Change Reference is made to the Technical Cpecifications of License No. DPR-3 of the Yankee Nuclear Power Station (YNPS). We propose to modify the Technical Specifications as described below:

1. Modify Page 3/4 9-1 Action Statement 3.9.1.a. to remove reference to the specific value of 2,200 ppm and provide a generalized boron concentration value which ensures that sufficient shutdown margin requirements are met.

2. Modify Page 3/4 9-2 to remove Surveillance Requirement 4.9.1.1.c which requires an inverse count rate multiplication measurement to be performed at least aftor the instetton of each five fuel assemblies in order to verify shutdowr margin.

Description of Change current Technical Specification 3.9.1 governing refueling operations, Mode 6, requires that a k-effective of 0.93 or less be maintained to ensure sufficient shutdown margin to criticality. In order for the YNPS to meet that requirement, it is necessary to maintain a refueling boron concentration in excess of 2.200 pptu. This proposed change deletes the reference to the 2,200 ppm value and replaces it with a boron concentration value needed to satisfy shutdown margin requirements, goo /

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United States Nuclear Regulatory Commission August 11, 1988 page 2 The inverse count rate multiplication measurement surveillance is an outdated and unnecessary esquirement. Sufficient control for monitoring shutdown margin and to preclude inadvertent criticality is maintained via other means. Surveillance of the boron concentration of all filled portions of the Main Coolant System snd shield tank cavity during refueling operations to verify shutdown margin is a practice consistent with the Standard Technical Specification (STS) surveillance for shutdown margin in Mode 6. This is also consistent with shutdown margin verification in other operating modes.

Reason and Basis for Change The reason for removal of the 2,200 ppm value to a generalized boron concentration value sufficient to meet the shutdown margin requirement in Mode 6 is administrative. The boron concentration value needed to maintain sufficient shutdown margin during refueling is in excess of 2,200 ppm. The wording change in Action Statement 3.9.1.a to a boron concentration value sufficient to ensure a k-effective of 10 93 provides consistent terminology with the Limiting Condition for Operation (LCO) as specified in Technical Specification 3.9.1.

The removal of Surveillance Requirement 4.9.1.1.c is proposed to eliminate an unnecessary surveillance when other surveillance requirements are present to ensure sufficient shutdown margin is available, and inadvertent criticality is precloded.

Verification of the boron concentration in Mode 6 provides adequate control that sufficient shutdown margin is maintained. Surveillance of the boron concentration is the means of shutdown margin verification in STS during Mode 6 operation, as well as in the other operating modes at the YNPS.

periodic surveillance of the boron concentration during refueling operations is required by Technical Specification 4.9.1.3. Boron concentration surveillance is a more directly observable and more accurate indication of shutdown margin than the inverse count rate multiplication measurement at highly suberitical reactor conditions. There is more uncertainty in the inverse multiplicaticn measurement due to changes in the source-fuel-detector geometry during core loading which generally produces a scattering of the measured data.

Technical Specification 4.9.1.1.c is also not needed to preclude inadvertent criticality as othcr means are present for that purpose. These include the following:

1. Technical Specification 4.9.1.2 which requires equipment which would make possible inadvertent reactivity increases to be made inoperable and tagged out of service.

2. Technical Specification 4.9.1.5 which requires a record of the neutron count rate before and after any change in core geometry.

Unitcd Stotcs NuclGnr Rigulctory Commisalon August 11, 1988 page 3

3. Technical Specification 3.9.1. Action Statement b, which requires that with a significant unexpected increase in the count rate on any channel or an unexpected increase in the count rate by a factor of two after addition of a new fuel assembly or removal of a control rod to suspend core alterations until the situation is reviewed by plant technical supervisory personnel.

In addition, during fuel movement when the shleid tank cavity is filled, the assumed shutdown margin for a boron dilution event is 5.0%

(Reference (b)), when in fact the actual refueling boron concentration is calculated based on the freshly loaded core with a k-effective of 0.93 and the most worthy control rod stuck out of the core. A 1.0% reactivity uncertainty is also applied to the calculated value. Therefore, inadvertent criticality during Mode 6 due to boron dilution is extremely unlikely given the large suberitical margin during fuel movements.

Safety Consideration This change is requested in order to replace reference to a specific value with a more generalized form which nill meet the LCO requirement, and to delete a surveillance requirement in Mode 6 which is unneccesary. As such, this proposed change would not:

1. Involve a significant increase in the probability or consequences of an accident previously evaluated. This change will not increase significantly the probability or consequences of an accident, as the shutdown margin of the core will continue to be adequately monitored and sufficient control to preclude inadvertent criticality already exists.

2. Create the possibility of a new or different kind of accident from any previously analyzed. This modification only provides an administrative wording change and deletes an unnecessary surveillance requirement. Therefore, it does not create the possibility of a new or different kind of accident because it does not modify plant operation.

3. Involve a significant reduction in a margin of safety. This modification only provides an administrative wording change and deletes an unnecessary surveillance requirement which does not affect the safety margins which currently exist during Mode 6 operation. Thus, this change does not involve a reduction in a margin of safety.

Based on the considerations contained herein, it is concluded that there is reasonable assurance that operation of the Yankee plant, consistent with the proposed Technical Specifications, will not endanger the health and safety of the public. This propoted change has been reviewed by the Nuclear Safety Audit and Review Committee.

Fee An application fee of $150.00 is enclosed in accordance with 10CFR170.21.

. -o . .

United States Nuclear Regulatory Commission August 11, 1988 page 4 Schedule of chanze i These changes to the Yankee Technical Specification will be implemented upon Commission approval. We intend to shutdown the current cycle on November 11, 1988 for refueling operations; therefore, a timely review and approval of this submittal would be appreciated.

We trust that you will find this submittal satisfactory; however, should you desire additional information, please contat: us.

Very truly yours, YANKEE ATOMIC ELECTRIC COMPANY

)

J. DeVincentis "

Vice President BLD/22.875 Enclosure I

oc United States Nuclear Regulatory Commission, Region I United States Nuclear Regulatory Commission Resident Inspector YNPS COMMONWEALTH OF MASSACHUSETTS)

)ss MIDDLESEX COUNTY )

Then personally appeared before me, J. DeVincentis, who, being duly sworn, did state that he is Vice President of Yankee Atomic Electric Company, that he is duly authorized to execute and file the foregoing document in the name and on the behalf of Yankee Atomic Electric Company and that the '

statements therein are true to the best of his knoifledge and belief, r<C~ $

ifobert H. Croce Notary Public My Commission Expires August 29, 1991 l

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