ML18153A688

Application for Amends to Licenses DPR-32 & DPR-37, Clarifying Applicability of Quadrant Power Tilt Ratio Requirements

ML18153A688
Person / Time
Site:	Surry
Issue date:	04/15/1996
From:	Ohanlon J VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML18153A689	List: ML18153A688 ML18153A690
References
96-159, NUDOCS 9604180174
Download: ML18153A688 (7)

Text

r-e e VIRGINIA ELECTRIC AND POWER COMPANY RICHMOND, VIRGINIA 23261 April 15, 1996 United States Nuclear Regulatory Commission Serial No.96-159 Attention: Document Control Desk NS&UBCB/RPC: R2 Washington, DC. 20555 Docket Nos. 50-280 50-281 License Nos. DPR-32 DPR-37 Gentlemen:

VIRGINIA ELECTRIC AND POWER COMPANY SURRY POWER STATION UNITS 1 AND 2 PROPOSED TECHNICAL SPECIFICATIONS CHANGE QUADRANT POWER TILT RATIO Pursuant to 10 CFR 50.90, the Virginia Electric and Power Company requests amendments, in the form of a change to the Technical Specifications, to Facility Operating License Nos. DPR-32 and DPR-37 for Surry Power Station Units 1 and 2.

The proposed changes will clarify the applicability of the Quadrant Power Tilt Ratio requirements.

A discussion of the proposed Technical Specifications change for Surry is provided in Attachment 1. The proposed Technical Specifications change is provided in Attachment 2. It has been determined that the proposed Technical Specifications change does not involve an unreviewed safety question as defined in 10 CFR 50.59 or a significant hazards consideration as defined in 10 CFR 50.92. The basis for our determination that the change does not involve a significant hazards consideration is provided in Attachment 3. The proposed Technical Specifications change has been reviewed and approved by the Station Nuclear Safety and Operating Committee and the Management Safety Review Committee.

Should you have any questions or require additional information, please contact us.

Very truly yours,

~V.cpj~

James P. O'Hanlon Senior Vice President - Nuclear Attachments

( 9604180174 960415 PDR ADOCK 05000280

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cc: U.S. Nuclear Regulatory Commission Region II 101 Marietta Street, N.W.

Suite 2900 Atlanta, Georgia 30323 Mr. M. W. Branch NRC Senior Resident Inspector Surry Power Station Commissioner Bureau of Radiological Health Room 104A 1500 East Main Street Richmond, Virginia 23219

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e COMMONWEALTH OF VIRGINIA )

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COUNTY OF HENRICO )

The foregoing document was acknowledged before me, in .and for the County and Commonwealth aforesaid, today by J. P. O'Hanlon, who is Senior Vice President -

Nuclear, of Virginia Electric and Power Company. He is duly authorized to execute and file the foregoing document in behalf of that Company, and the statements in the document are true to the best of his knowledge ahd belief.

Acknowledged before me this !5'1fctay of - ~ , 19_.'lt..

My Commission Expires: '-~ 31 , 19:li...

(SEAL)

- .. e e ATTACHMENT 1 DISCUSSION OF CHANGES SURRY POWER STATION

e DISCUSSION OF CHANGES INTRODUCTION Surry's Technical Specifications related to Quadrant Power Tilt Ratio (QPTR) do not explicitly define the power level at which the requirements are applicable. Although these requirements are pertinent during operations above 50% rated thermal power, we have established administrative controls and procedures to assure that verbatim compliance is maintained. Maintaining compliance with these specifications at power levels~ 50% does not enhance nuclear safety and imposes unnecessary operational constraints. In addition, measurement at low power levels is not practical within the 2% criterion due to the inherent inaccuracy of the measurement system. Therefore, we are proposing a change to the Technical Specifications to clarify the power levels at which the QPTR limit is applicable. Surry's current design basis relative to QPTR limits is consistent with the Standard Technical Specifications (STS) with regard to fuel design criteria and core radial power distribution.

Our review performed in accordance with 10 CFR 50.59 has determined that the proposed changes do not constitute an unreviewed safety question and that a significant hazards consideration in accordance with 10 CFR 50.92 is not created by the proposed Technical Specifications changes.

BACKGROUND Amendments No. 26 to Facility Operating Licenses Nos. DPR-32 and DPR-37 were issued on November 26, 1976 to address the Surry Unit 2 steam generator repair and the resulting revision of the emergency core cooling system evaluation and power distribution monitoring requirements. The QPTR requirement currently reflected by Technical Specification 3.12.B.5 was established by these amendments.

CURRENT LICENSING BASIS Currently, Technical Specification 3.12.B.5 establishes the allowable QPTR at 2.0%,

consistent with the STS. However, the current specification does not explicitly define the power levels at which the requirement is applicable. Therefore, Surry is currently conservatively applying this requirement to ensure verbatim compliance with the Technical Specifications.

NUREG-1431, Revision 1, Standard Technical Specifications for Westinghouse Plants indicates that the QPTR requirements are applicable at reactor thermal power levels

> 50%. This requirement is appropriate above 50% power since it precludes core power distributions from exceeding design limits. This is done by ensuring that no significant changes in gross core power distribution occur between normal peaking factor measurements.

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"cuRRENT DESIGN Isis e The QPTR limit ensures that the gross core radial power distribution remains consistent with the design values used in the safety analyses. Precise radial power distribution measurements are made during startup testing, after refueling, and periodically during power operation.

The purpose of surveillance of core power distributions is to preclude distributions that violate the following fuel design criteria:

a. During a large break loss of coolant accident, the peak cladding temperature must not exceed a limit of 2200 °F [1 O CFR 50.46];

b. During a loss of forced reactor coolant flow accident, there must be at least 95%

probability at the 95% confidence level (the 95/95 departure from nucleate boiling (DNB) criterion) that the hot fuel rod in the core does not experience a DNB condition;

c. During an ejected rod accident, the energy deposition to the fuel must not exceed 280 cal/gm [Regulatory Guide 1.77]; and

d. The control rods must be capable of shutting down the reactor with a minimum required [SHUTDOWN MARGIN] SOM with the highest worth control rod stuck fully withdrawn [GDC 26].

Generally, these criteria can be met by ensuring that the core peaking factor design basis is met. QPTR is a means of ensuring that the peaking factors do not exceed the limits between surveillances. In other words, the QPTR limits ensure that FN ~H and F0 (Z) remain below their limiting values by preventing an undetected change in the gross radial power distributi.on. During power operation, the FN ~H and Fa(Z) limits must be maintained to preclude core power distributions from exceeding design limits assumed in the safety analyses.

Applicability ::;; 50% power is not required because there is either insufficient stored energy in the fuel or insufficient energy being transferred to the reactor coolant to require the implementation of a QPTR limit on the distribution of core power. Note that the FN ~H and F0 (Z) LCOs still apply, but allow progressively higher peaking factors at 50% power or lower. At or below 50% power the additional surveillance on QPTR is not necessary.

Generally speaking, there are continuously increasing thermal margins as power decreases, even with the allowed increase in peaking factors. Also, reload design experience for Surry shows that there are increasing margins between predicted peaking factors and the limits as power decreases.

Because of these phenomena, the normal surveillance of these peaking factors is adequate and does not need to be supplemented with an additional surveillance of QPTR for power levels ::;; 50%. Therefore, from a design basis standpoint, it is acceptable to limit the application of the QPTR requirements established by Surry's Technical Specification 3.12.B.5 for only power levels > 50%.

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DISCUSSION Surry's Technical Specifications related to QPTR do not explicitly define the power level limits at which the requirements are applicable. Complying with these specifications at power levels :::; 50% does not enhance nuclear safety and imposes unnecessary operational constraints, as discussed in the preceding section.

Therefore, the proposed change to Technical Specification 3.12.B.5 would explicitly limit the applicability of the QPTR related requirements to power levels > 50%.

Surry's current design basis relative to QPTR limits is consistent with the STS with regard to fuel design criteria and core radial power distribution.

SPECIFIC CHANGES Technical Specifications 3.12.B.5, 3.12.B.6, and 3.12.B.7 are being revised to indicate that the QPTR requirements are applicable only at power levels > 50%.

The Section 3.12 Basis is being revised to describe the basis for the changes to Technical Specifications 3.12.B.5, 3.12.B.6, and 3.12.B.7.

SAFETY SIGNIFICANCE The proposed Technical Specifications changes do not involve any hardware modifications or changes in system configuration or plant operations. The changes have been reviewed against the criteria of 10 CFR 50.59 and it has been determined that an unreviewed safety question does not exist for the reasons described below.

QPTR limits assure that the gross core radial power distribution remains consistent with design limits above 50% power. At or below 50% rated thermal power, there is insufficient stored energy in the fuel or insufficient energy being transferred to the reactor coolant to require implementation of a QPTR limit on the distribution of core power. Therefore, the probability of occurrence or the consequences of an accident or malfunction of equipment important to safety and previously evaluated in the Updated Final Safety Analysis Report is not increased.

The proposed change would limit the application of QPTR limits to operation at powe'r levels > 50% to preclude core power distributions from occurring which would violate fuel design criteria previously analyzed. At or below 50% rated thermal power, there is sufficient thermal margin in the core such that normal monthly surveillance on power peaking factors is considered to be adequate to ensure compliance with the fuel design limits. The plant is not being operated in a different manner that would create any new or different accident precursors. Therefore, the possibility for an accident or malfunction of a different type than that previously evaluated in the safety analysis report has not been created.

The proposed change only affects the applicability of the QPTR limits. The QPTR limits remain unchanged to preclude any violation of previously analyzed fuel design criteria. Adherence to the QPTR limits, hot channel factors, and applicable Limiting Conditions for Operation will continue. Therefore, the margin of safety as described in the Bases Section of any part of the Technical Specifications is not reduced.

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