ML20082S840

Forwards Cycle 6 Reload & COLR

ML20082S840
Person / Time
Site:	Beaver Valley
Issue date:	04/24/1995
From:	George Thomas DUQUESNE LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20082S843	List: ML20082S840 ML20082T522
References
NUDOCS 9505030240
Download: ML20082S840 (6)

Text

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%ygg Beaver Vayey Power Station t==t^ " """

(412) 643-8069 FAX i

GEORGE S. THOMAS UNices Nuclear Power Division April 24, 1995 U. S. Nuclear Regulatory Commission Attention: Document Control Desk i Washington, DC 20555-0001 ,

Subject:

Beaver Valley Power Station, Unit No. 2 Docket No. 50-412, License No. NPF-73 Cycle 6 Reload and Core Operating Limits Report Beaver Valley Power Station, Unit No. 2 completed the fifth cycle of operation on March 24,1995, with a burnup of 16,338 MWD /MTU. This letter describes the Cycle 6 reload design, documents our review in accordance with 10 CFR 50.59 and our L determination that no unreviewed safety question is involved, and provides a copy of the Core Operating Limits Report (COLR) in accordance with Technical Specification.

6.9.1.14.

No technical specification change is required; however, a proposed change to Bases 2.1.1, Reactor Core, is provided in Attachment A. The change incorporates the improved standard technical specification wording of NUREG-1431 to address the change in peaking factors provided in the COLR. Therefore, it is requested that the Commission  :

issue revised Bases pages B 2-1 and B 2-2 provided in Attachment A for inclusion in the Technical Specifications.

The new core configuration is arranged in a low leakage loading pattern and involves replacing one (1) Region 2, eight (8) Region 5A, four (4) Region 5B, eight (8) Region SC, forty (40) Region 6A, and eight (8) Region 6B fuel assemblies with fifty-six (56) fresh Region 8A fuel mmblies enriched to 3.6 weight percent, twelve (12) fresh Region 8B fuel assemblies tomhed to 4.2 weight percent, and one (1) Region 5B fuel assembly reinserted from Cycle 4.

The mechanical design of the new Region 8A and 8B fuel assemblies is similar to the previous reload fuel except for the following factors:

(1) The bottom grid spring was modified to give a higher spring force at the beginning of life and to counter the relaxation of the springs from irradiation at higher fuel burnup. Evaluations were performed to detennine the effects of modifying the bottom grid spring to provide a higher spring force. The modifications to the bottom '

grid spring have no adverse effect on the thermal-hydraulic performance. The structural suppon of the fuel rod end is enhanced with the increased bottom grid spring forces. Therefore, the resistance of the fuel rod to crossflow excitations is 9505030240 950424 1, PDR ADOCK 05000412 .y 1 p PDR I

i Beaver Valley Power Station, Unit No.

Cycle 6 Reload and Core Operating Limits Report Page 2 improved. The ability of the grid to withstand externally applied loads has not changed. All bottom grid design criteria continue to be met. The extended burnup bottom grid spring force design does not compromise the perfomlance of any safety-related system nor result in any adverse effect on any analysis, since this change does not affect the normal plant operating parameters, the safeguards systems actuation, or the assumptions and input parameters used in these analyses.

(2) The length of the radius section just above the top nozzle spring tang was increased to maintain product standardization among top nozzle spring designs. All top nozzle and holddown spring design criteria continue to be met. The modification to the top nozzle holddown spring design does not compromise the performance of any safety-related system nor result in any adverse effect on any analysis, since this change does not affect the normal plant operating parameters, the safeguards systems actuation, or the assumptions and input parameters used in these analyses. i (3) The pitch of both the thimble screw holes and the flow holes was slightly adjusted to provide for cold alignment of the thimble tubes and thimble screw holes. This improves the part fit-up du: ring bottom nozzle removal / replacement. The modification does not compromise the performance of any safety-related system nor result in any adverse effect on any analysis, since this change does not affect the nonnal plant operating parameters, the safeguards systems actuation, or the j assumptions and input parameters used in these analyses.

l In addition, twelve (12) Region 6 fuel assemblies will utilize a damper rod assembly i I

to reduce the potential for flow induced vibration of the VANTAGE 5H fuel assemblies.

Each damper assembly consists of twenty-four (24) solid Zircaloy-4 damper rodlets attached to a holddown assembly. The damper rods are inserted into the fuel assembly guide thimbles and are designed to be used in fuel assemblies without rotated grids. The pettinent thennal-hydraulic and boiling criteria were evaluated and found to be acceptable. The use of vibration damping assemblies does not compromise the perfonnance of any safety-related system nor result in any adverse effect on any analysis, since this change does not affect the normal plant operating parameters, the  !

safeguards systems actuation, or the assumptions and input parameters used in these  !

analyses.

i These modifications meet fuel assembly / rod design criteria and will not adversely  !

affect reactor core safety considerations. Fuel rod design evaluations for the new fuel l were perfonned using NRC approved methodology to demonstrate that the fuel rod design bases are satisfied.

Beaver Valley Power Station, Unit No. 2 Cycle 6 Reload and Core Operating Limits Report Page 3 Duquesne Light Company has performed a review of this reload core design including review of the core characteristics to detennine those parameters affecting the postulated accidents described in the Updated Final Safety Analysis Report (UFSAR).

The consequences of those accidents described in the UFSAR which could potentially be

! affected by the reload core characteristics were evaluated in accordance with the NRC approved methodology described in WCAP-9272-P-A " Westinghouse Reload Safety Evaluation Methodology." The effect of the reload design was accommodated within the conservatisms of the assumptions used in the current analysis design basis, or it was demonstrated through evaluation that the reload parameters would not change the l conclusions in the UFSAR.

The NRC-approved dropped rod methodology (WCAP-10298-A [non-proprietary),

June 1983) was used for this design evaluation and confirmed that the peaking factors will not exceed the safety analyses limits.

The reload core design will be verified by perfomling the standard Westinghouse reload core physics startup tests. The results of the following startup tests will be submitted in accordance with Technical Specification 6.9.1.3:

1. Contral rod drive tests and rod drop time measurements.

l 2. Critical boron concentration measurements.

3. Control rod bank wonh measurements.

4. Moderator temperature coefficient measurements.

I

5. Startup power distribution measurements using the incore flux mapping l system. j l

The COLR (enclosed) has been updated for this cycle to include new heat flux hot channel factor [FQ(Z)], enthalpy rise hot channel factor [F(NAH)], and radial peaking ,

factor at rated thennal power [Fxy (RTP)] limits for unrodded core planes. Figure 4 has l been replaced with a new figure to address the new radial peaking factor limits. ,

Beaver Valley Power Station, Unit No. 2 Cycle 6 Reload and Core Operating Limits Report Page 4 The Beaver Valley Onsite Safety Committee and the Duquesne Light Company Offsite Review Committee have reviewed the Reload Safety Evaluation and Core Operating Limits Report and detennined that this reload design will not adversely affect the safety of the plant and does not involve an unreviewed safety question.

Sincerely,

' ., QChf %

George S. Ttcmas Enclosure c: hir. L. W. Rossbach, Sr. Resident inspector Mr. T. T. Martin, NRC Region I Administrator Mr. D. S. Brinkman, Sr. Project Manager