ML18153C011

Discusses Mod of Startup Physics Test Program Using Rod Swap Technique for Determination of Control Rod Worths.Mods Have No Significant Impact on Adequacy of Startup Physics Testing Program & Consistent W/Ansi/Ans - 19.6.1 -1985, Reload....

ML18153C011
Person / Time
Site:	Surry, North Anna, 05000000
Issue date:	12/08/1989
From:	Stewart W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
89-541, NUDOCS 8912140120
Download: ML18153C011 (5)

Text

• 1.

RICHMOND, VIRGINIA 23261 VIRGINIA ELECTRIC AND POWER COMPANY December 8, 1989.

United States Nuclear Regulatory Commission Serial No.89-541 Attention: Document Control Desk NO/CGL:vlh R5 Washington, D. C. 20555 Docket Nos. 50-280 50-281 50-338 50-339 License Nos. DPR-32.

DPR-37 NPF-4 NPF-7 Gentlemen:

VIRGINIA ELECTRIC AND POWER COMPANY SURRY POWER STATION UNITS 1 AND 2 NORTH ANNA POWER STATION UNITS 1 AND 2 MODIFICATION OF STARTUP PHYSICS TEST PROGRAM INSPECTOR FOLLOWUP ITEM 280, 281/88-29-01 Virginia Electric and Power Company's Topical Report VEP-FRD-36A, "Control Rod Reactivity Worth Determination by the Rod Swap Technique," provides a description of the startup physics test program using the rod swap technique for determination of control rod worths. The rod swap methodology is utilized in startup physics test programs at both the Surry and North Anna Stations. As a result of a comparison of the Startup Physics Test Program presented in Topical Report VEP-FRD-36A to the actual tests performed for the Surry Unit 1 Cycle 1O startup, Inspector Follow-up Item 280, 281/88-29-01 was generated and documented in NRC Inspection Report 50-280, 281/88-29 dated August 24, 1988. This item noted the deletion of the rodded zero power flux map and the deletion of the measurement of the isothermal temperature coefficient with the reference bank inserted as deviations from Topical Report VEP-FRD-36A. The purpose of this letter is to formally document and address these modifications in our startup physics test program for Surry. Letter Serial No. 204, dated April 8, 1982, advised the N RC of these modifications in the startup physics test program for North Anna Unit 2. The modifications discussed in letter Serial No. 204, as well as in this letter, are also applicable to the North Anna Unit 1 startup physics test program. As discussed in the following paragraphs, these modifications have no significant impact on the adequacy of the startup physics testing program and are consistent with ANSI/ANS Standard, ANSI/ANS - 19.6.1 - 1985, "Reload Startup Physics Tests for Pressurized Water Reactors."

Deletion of the Rodded Zero Power Flux Map - The-startup physics test program in Topical Report VEP-FRD-36A specifies performance of flux maps at hot zero power (HZP) for both all rods out (ARO) and rodded conditions (Refer to Attachment 1). The purpose of these maps is to detect .anomalies in the core loading by measuring the degree of azimuthal symmetry of the neutron flux at as low a power as practical and to verify the power peaking limits established in the Technical Specifications. The

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rodded flux map was eliminated as a requirement of the startup physics testing since it provides little additional information concerning flux symmetry versus the ARO map.

Currently, the test programs in place require an ARO flux map to be taken at less than or equal to 30 percent power. The ARO HZP flux map was replaced with one taken at less than or equal to 30 percent power for consistency with ANSI/ANS-19.6.1-1985.

However, in order to verify compliance with Technical Specification limits for peaking factors for rodded at-power conditions, a comparison is made of parameters (a) and (b), defined as follows:

(a) the margin between the predicted rodded F-delta-H values and the Technical Specification F-delta-H limits (b) the maximum positive measured to predicted F-delta-H deviation from the ARO flux map.

If the predicted margin (a) is less than the measured to predicted deviation (b), then a rodded flux map is required.

Deletion of the Measurement of the Isothermal Temperature Coefficient with the Reference Bank Inserted - Topical Report VEP-FRD-36A also specifies the use of a measured isothermal temperature coefficient with the reference bank inserted to adjust the measured data for temperature changes from the nominal test conditions. In practice, a predicted value is used for the rodded isothermal temperature coefficient.

The use of the predicted, rather than a measured value, has very little impact on the measured rod worth since the moderator temperature is controlled to within +/-1 degree Fahrenheit of the nominal test conditions during the test. Additionally, the uncertainty for predicted versus measured isothermal temperature coefficients is +/-3 pcm/degree Fahrenheit as indicated in Topical Report VEP-FRD-20A, "The PDQ07 One Zone Model." The ARO isothermal temperature coefficient at HZP is measured and the acceptance criteria are verified. This provides a check on the predicted values. If the measured value does not meet the acceptance criteria, an evaluation is performed to determine the reason. provides a table describing the minimum HZP startup physics test program currently in place at both the Surry and North Anna Power Stations.

Please contact us should you have questions concerning these modifications in our startup physics test program.

Very truly yours,

~l%J W. L. Stewart Senior Vice President - Nuclear Attachments

1. Original Hot Zero Power Startup Physics Testing Program with Rod Swap

2. Current Minimum Hot Zero Power Startup Physics Testing Program with Rod Swap

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

Suite 2900 Atlanta, Georgia 30323 Mr. W. E. Holland NRC Senior Resident Inspector Surry Power Station Mr. J. L. Caldwell NRC Senior Resident Inspector North Anna Power Station

• ATTACHMENT 1 ORIGINAL HOT ZERO POWER STARTUP PHYSICS TESTING PROGRAM WITH ROD SWAP (Table A.2 From VEP-FRD-36A)

Reactivity Computer Checkout Boron Endpoint - ARO Temperature Coefficient - ARO M/D Flux Map - ARO Reference Bank Worth Boron Endpoint - Reference Bank In Temperature Coefficient - Reference Bank In M/D Flux Map - Rodded Control Rod Bank Worths (Control and Shutdown)

. (

• ATTACHMENT 2 e

CURRENT MINIMUM HOT ZERO POWER STARTUP PHYSICS TESTING PROGRAM WITH ROD SWAP Reactivity Computer Checkout Boron Endpoint - ARO Temperature Coefficient - ARO Reference Bank Worth Boron Endpoint - Reference Bank In Control Rod Bank Worths (Control and Shutdown)

• M/D Flux Map - ARO

• The M/D flux map for reload startup physics testing is taken to measure the. degree of azimuthal symmetry of the neutron flux at as low a power as practical. Virginia Electric and Power Company uses the flux distribution method described in ANSI/ANS-19.6.1-1985, which indicates the nuclear power level shall be less than or equal to thirty percent of rated thermal power.