ML20203A224

Informs of Errors Discovered in App R Cooldown Calculation Submitted to NRC on 970829.Input & Cooldown Comparison Between Original Calculation & Final Revised Calculation Encl

ML20203A224
Person / Time
Site:	Crystal River
Issue date:	12/10/1997
From:	Rencheck M FLORIDA POWER CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
3F129-04, 3F129-4, NUDOCS 9712120045
Download: ML20203A224 (2)

Text

.

v Florida Power 7,a T A .

December 10,1997 3F1297-04 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555-0001

Subject:

Revised Calculation Correcting Errors in the Appendix R Cooldown Calculation Submitted to NRC on August 29,1997

References:

1. FPC to NRC letter,3F0897-48, dated August 29,1997

2. NRC to FPC letter,3N0997-24, dated September 19,1997

3. NRC Memorandum to File, dated July 30,1997, " Transmittal of Attachment D to the Minutes of Restart Panel Meeting for Crystal River"

Dear Sir:

On August 29,1997, Florida Power Corporation (FPC) submitted summary results from a calculation that demonstrated compliance with 10 CFR 50 Appendix R, Section Ill.L.1(d) cooldown to Cold Shutdown conditions (200 F) within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> (Reference 1).

On September 19, 1997, the Nuclear Regulatory Commission (NRC) acknowledged receipt of these results (Reference 2) and closed item 15 in Attachment D of Restart Panel Meeting minutes (Reference 3).

Subsequent to the receipt of NRC's letter (Reference 2), two errors in the decay heat calculation were discovered relating to a failure to include decay heat contribution from actinides, and failure to include neutron capture correction factor (G(t)). Both of these errors contribute to higher calculated decay heat. FPC management had an independent organization, Framatome Technologies, Inc. (FTI), provide revised decay (CCASll CRYSTAL RNER ENERGY COMPLEX: 16780 W. Power Une Street

• Crystal R#ver, Florida 344284708 * (152) 7954488 9712120045 971210 -

PDR ADOCK 050 2 ,f .ilf ,f,f,f,f {f e

y U. S. Nuclear Regulatory Commission -

3F1297 04 Page 2

-heat calculations and conduct an independent evaluation of the FINC code used by FPC for cc 'iown calculations.

The FTI- 1ations for decay heat and the independent verification of the FINC code are complene. The FINC code has been ' rerun to determine the cooldown times using .

the revised / higher decay heat load and changes in assumptions. These assumptions included: 1) credit for the minimum relieving capability of the turbine driven' emergency feedwater pump EFP-2,2) a more accurate determination of core cycle burnup of 700 EFPD,3) use of a core power level average of 2568 MW, and 4) a higher cooldown rate for the decay heat removal system from 280*F to 200 F.

The Attachment provides an input and cooldown results comparison betweeq the original calculation in Reference 1 and the final revised calculation. The revised results demonstrate cooldown on natural circulation to 280 F within 64 hours7.407407e-4 days <br />0.0178 hours <br />1.058201e-4 weeks <br />2.4352e-5 months <br /> (includes an 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> hold at Hot Standby), and cooldown from 280*F to 200 F using the Decay

- Heat Removal system, within 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />. This analysis reconfirms the Crystal River Unit 3 (CR-3) design basis requirement under 10 CFR 50 Appendix R, Section Ill.L.1(d) for achieving Cold Shutdown conditions within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.

if you have any questions regarding this letter, please contact Mr. David F.

Kunsemiller, Manager, Nuclear Licensing at (352) 563-4566.

Sincerely,

. 1^~L..

M. W. Rencheck Director, Nuclear Engineering and Projects MWR/inb Attachment

- xc: Regional Administrator, Region ll Senior Resident inspector NRR Project Manager

U. S. Nuclear Regulatory Commission -

' 3F1297-04 Page 3 ATTACHMENT .

Inputs and Cooldown Results Comparison Between Flawed Calculation in 3F0897-48 and Final Revised Calculation Parameter Description - Key inputs and Results from 3F0897-48 Revised Key Inputs with Fm' al Results ANSI /ANS 5.1-1979 decay heat correlation *CR; GEN decay heat correlation with 3 full Decay Heat with 3 cycles of core irradiation at 725 24 month fuel cycles of core irradiation at EFPD per cycle 700 EFPD per cycle initial Power Level 102% of 2544 MW 2 100% of 2568 MW Post-Fire Hold Time at Safe Shutdown / Hot 8 Hours 8 Hours Standby Conditions Before Cooldown RCS Cooldown Rate prior to DH cut-in 10'F/ hour 10*F/ hour Subcooling Margin 60*F 60*F Makeup Temperature 125'F 125'F Atmospheric Dump Valve (ADV) 301,246 lb./ hour / valve, T = 540*F, P = 948 301,246 lb./ hour / valve, T = 540 F, P = 948 Nominal Flow psig (saturated conditions) psig (saturated conditions)

Number of ADVs Operable 2 2 Credit For Turbine Driven Emergency No 'Yes, constant 67 lb./ min. steam flow is Feedwater Pump EFP-2 conservatively assumed Emergency Feedwater Temperature 95'F 95'F Containment Temperature 130*F 130 F Time to Cooldown to 280*F (includes 8 Hour 57.2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> 63.6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> Hold Time at Hot Standby Conditions)

Emergency Feedwater Required 284,420 gallons 319.780 gallon?

Time to Cooldown from 28G'F to 200 F 9.1 hours1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> *5.0 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> ~

Total Time from Hot Standby to 200*F 66.3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> 68.6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> 1

As determined in the ORIGEN code deca heat runs,700 EFPD resulted in a fully depleted core. -l 100% of 2568 MW core power was useu .n the revised analysis which remains conservative for this Append!x R Calculation.

67 lb./ min. is the low end value of steam flow to the EFP-2 pump turbine at the Decay Heat Removal cut-in temperature.

A higher cooldov.n rate for one train of Decay Heat Removal was used. This is well within system design.

- _ _ _ _ _ - - _ _ _ _ _ _ _ - _ - _ - _ - -