ML17132A231
| ML17132A231 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 05/16/2017 |
| From: | Balwant Singal Plant Licensing Branch IV |
| To: | Halpin E Pacific Gas & Electric Co |
| Singal B, 301-415-3016 | |
| References | |
| CAC MF6399, CAC MF6400 | |
| Download: ML17132A231 (8) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 Mr. Edward D. Halpin Senior Vice President, Generation and Chief Nuclear Officer Pacific Gas and Electric Company Diablo Canyon Power Plant P.O. Box 56, Mail Code 104/6 Avila Beach, CA 93424 May 16, 2017
SUBJECT:
DIABLO CANYON POWER PLANT, UNITS 1 AND 2 - CORRECTION LETTER REGARDING AMENDMENT NOS. 230 AND 232 TO ADOPT ALTERNATIVE SOURCE TERM (CAC NOS. MF6399 AND MF6400)
Dear Mr. Halpin:
By letter dated April 27, 2017 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML17012A246), the U.S. Nuclear Regulatory Commission (NRC, the Commission), issued Amendment No. 230 to Facility Operating License (FOL) No. DPR-80 and Amendment No. 232 to FOL No. DPR-82 for Diablo Canyon Power Plant (DCPP), Units 1 and 2, respectively. The amendments revised the licensing bases to adopt alternative source term as allowed by Title 10 of the Code of Federal Regulations Section 50.67, "Accident source term," and approved the methodology for evaluating radiological consequences of design-basis accidents as described in Regulatory Guide 1.183, "Alternative Radiological Source Terms for Evaluating Design Basis Accidents at Nuclear Power Reactors," July 2000 (ADAMS Accession No. ML003716792).
By e-mail dated May 3, 2017, Mr. Michael Richardson of Pacific Gas and Electric Company identified the following typographical errors in Tables 3.3-1 and 3.3-4 on pages 63 and 65 of the safety evaluation (SE) (Enclosure 3 to the letter dated April 27, 2017).
Typographical error in Table 3.3-1 in the value of the total effective dose equivalent for a loss-of-coolant accident and associated footnote.
Typographical errors in Table 3.3-4 in the values for average internal weighted gas space venting rate to atmosphere from 7,200 to 183,289 seconds.
During the review, the NRC staff identified the following additional errors on pages 65, 87, and 89 of the SE:
On page 65, footnotes 8 and 9 inadvertently got deleted in the final version of the SE.
Footnotes 10 and 11 on pages 87 and 89 got renumbered as a result of deletion of footnotes 8 and 9.
E Halpin The NRC staff determined that the errors were inadvertently introduced during the preparation of the license amendments and are entirely typographical in nature. The corrections do not change any of the conclusions in the SE associated with the amendments and do not affect the associated notice to the public.
Enclosure to this letter contains corrected SE pages 63, 65, 87, and 89. Please use these pages to replace corresponding pages issued by Amendment Nos. 230 and 232 for DCPP, Units 1 and 2.
If you have any questions, please contact me at 301-415-3016 or via e-mail at Balwant.Singal@nrc.gov.
Docket Nos. 50-275 and 50-323
Enclosure:
Corrected SE pages 63, 65, 87, and 89 cc w/encl: Distribution via Listserv Sincerely,
~~-- 'C.$1~~
Balwant K. Singal, Senior Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation
ML17132A231 OFFICE NRR/DORL/LPL4/PM NRR/DORL/LPL4/LA NRR/DORL/LPL4/BC NRR/DORL/LPL4/PM NAME BSingal PBlechman RPascarelli BSingal DATE 05/16/17 05/16/17 05/16/17 05/16/17
ENCLOSURE CORRECTED SAFETY EVALUATION PAGES FOR AMENDMENT NOS. 230 AND 232 TO FACILITY OPERATING LICENSE NOS. DPR-80 AND DPR-82 DATED APRIL 27, 2017 PACIFIC GAS AND ELECTRIC COMPANY DIABLO CANYON POWER PLANT, UNITS 1 AND 2 DOCKET NOS. 50-275 AND 50-323 Table 3.3-1 Total Effective Dose Equivalent per Accident in Roentgen Equivalent Man {rem)
SRP 15.0.1 and 10 CFR 50.67 RG 1.183 Control and GDC 19, Accident EAB LPZ Limit Room 1999 Limit Loss-of-Coolant Accident 5.6 1
25 3.73 5
Fuel Handling Accident in 1.0 0.1 6.3 1.0 5
Fuel Handling Building Fuel Handling Accident in 1.0 0.1 6.3 4.3 5
Containment Locked Rotor Accident 0.5 0.1 2.5 1.7 5
Control Rod Ejection Accident Containment Release 0.7 0.3 6.3 3.4 5
Secondary Release 0.7 0.2 6.3 0.5 5
Main Steam Line Break Pre-incident Iodine Spike 0.1
<0.1 25 2.0 5
Accident Initiated Iodine 0.7 0.2 2.5 4.1 5
Spike Steam Generator Tube Rupture 1.3 0.1 25 0.6 5
Pre-incident Iodine Spike 0.7
<0.1 2.5 0.3 5
Accident Initiated Iodine Spike Loss of Load Pre-incident Iodine Spike
<0.1
<0.1 2.5
<0.1 5
Accident Initiated Iodine
<0.1
<0.1 2.5
<0.1 5
Spike 3 The total control room dose due to occupancy is 3. 7 rem, which includes the dose due to direct shine of 0.7 rem, and dose due to ingress/egress to control room of 0.037 rem Table 3.3-4 LOCA MEDT Iodine Release Fraction and Gas Venting Rate to Atmosphere Average Interval From Time To Time Iodine Release Weighted Gas Space Fraction to Atmosphere Venting Rate to Atmosphere Seconds Seconds Fraction 1releasedllenterino6 Fraction VMrnT/ day7 829 7,200 4.521 E-07 5.024E+OO 7,200 28,800 1.386E-08 3.024E-02 28,800 86,400 2.362E-07 3.324E-01 86,400 183,289 3.950E-07 6.497E-OO 183,289 345,600 1.236E-028 Foot Note9 345,600 752,400 2.028E-028 Foot Note9 752,400 1,530,000 2.390E-028 Foot Note9 1,530,000 2,592,000 2.166E-028 Foot Note9 Table 3.3-5 LOCA Assumptions Parameter Value Core power level (105% of rated power of 3580 MWt 3411 MWt)
Fuel release fractions Per RG 1.183 Fuel release timing Gap Onset: 30 seconds Gap Duration: 0.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> Early in Vessel Onset: 0.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> Early in Vessel Duration: 1.3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> Chemical form of Iodine released from 4.85% Elemental fuel to containment atmosphere 95% Particulate 0.15% Organic Chemical form of Iodine released from 97% Elemental RCS and sump water 3% Organic Containment Vacuum/Pressure Relief Parameters Minimum containment free volume 2.550E+06 ft3 Chemical form of iodine released 97% Elemental 3% Organic Maximum RCS flash fraction after LOCA Noble Gases 100%
Haloqens 40%
Maximum Containment Pressure Relief 218 actual cfs Line Air Flow Rate Maximum duration of release via 13 seconds containment pressure relief line 6 lre1easect is the total iodine mass released to atmosphere during the specified time interval in grams. !entering is the total iodine mass entering the MEDT during the specified time interval in grams.
7 Fraction VMEDT is the rate of fractional MEDT gas volume vented during the specified time interval.
8 The iodine release fractions after spillover assume instantaneous release of iodine to the environment without holdup in the room.
9 After the MEDT overflows at 183,289 seconds, the gas venting rates are 2640 cfm from the equipment drain receiver tank room and 1760 cfm from the Unit 1/Unit 2 pipe tunnels.
Section 1 of the Enclosure to letter dated June 17, 2015 provides the following description of the revised source terms.
The AST methodology as established in Regulatory Guide (RG) 1.183, "Alternative Radiological Source Terms for Evaluating Design Basis Accidents at Nuclear Power Reactors," July 2000, [Reference 3 of the letter] is used to calculate the offsite and Control Room radiological consequences for DCPP Units 1 and 2. Attachment 4 [to the Enclosure of letter dated June 17, 2015]
contains a summary of the analyses and results for the following events that are expected to produce the most limiting dose consequences. Conformance to RG 1.183 is provided in Attachment 5 [to the Enclosure of letter dated June 17, 2015].
Loss of Coolant Accident (LOCA)
FHA in the Containment FHA in the FHB Locked Rotor Accident (LRA)
Control Rod Ejection Accident (CREA)
Main Steam Line Break (MSLB)
Steam Generator Tube Rupture (SGTR)
Loss-of-Load (LOL) Event During the audit, the NRC staff reviewed Westinghouse Electric Company LLC (WEC) topical report WCAP-16638-P, Revision 1, "Diablo Canyon Units 1 and 2 Replacement Steam Generator Program NSSS [Nuclear Steam Supply System] Licensing Report," dated January 200810 and WCAP-16985, Revision 2, "Diablo Canyon Units 1 and 2 Tavg and T1eed Ranges Program NSSS Engineering Report," dated April 200910 to gain a detailed understanding of the design parameters used for the thermal analysis for the AST. WCAP-16638-P documents the technical basis for the SG replacements for Unit 1 prior to Cycle 16 and Unit 2 prior to Cycle 15.
WCAP-16638P, for the SG replacement was implemented under the 10 CFR 50.59 process.
WCAP-16638P and WCAP-16985, for the SG replacement, provided a frame of reference for the changes to the assumed parameters for the thermal hydraulics of the AST. The assumptions and bases that were employed for the SG replacement analysis were reviewed during the regulatory audit (Regulatory Audit Report dated March 14, 2016; ADAMS Accession No. ML16063A170).
The NRC staff reviewed the FSARU Chapter 15 accident analyses contained in WCAP-16638P, which includes Large-Break LOCA, Small-Break LOCA, LOL, MSLB, LRA, and SGTR. The NRC staff reviewed these Chapter 15 accident analyses to determine the computer codes used for each analysis.
The NRC staff reviewed various calculation notes for different Chapter 15 events, such as MSLB, SGTR, LOL, LRA, and CREA. Various thermal hydraulic parameters were of interest for each event, and are listed below.
10 Document reviewed during the audit from January 12-14, 2016, is a plant specific document and is not publicly available.
Steam Releases and Thermal Hydraulic Input Parameters (MSLB/SGTR)11. The notes on why the change occurred are captured in the MSLB section.
The initial SG liquid mass changed for both the intact and faulted SG. The intact changed from 118,500 lbm to 89,707 lbm and the faulted changed from 106,000lbm to 89,707 lbm. The changes are captured in the specific calculational note. For the ruptured opened power operated relief valve phase, the average was taken from the RETRAN outputs and rounded down to increase the Iodine inventory in the SG liquid.
The steam flow rate to condenser from the ruptured SG and intact SG before trip did not change as the value is from the nominal full power steam flow rate (63,000 lbm/min).
The steam releases from ruptured SG and intact SGs vary over break time. The values change over the break time however there was no change from the CLB to the AST values.
The post-accident minimum SG liquid mass changed for the ruptured SG and intact SG. For the ruptured SG, the liquid mass went from 106,000 lbm to 89,707 lbm. The CLB for ruptured SGs is an average of initial mass and initial stuck open ADV phase. The smaller mass is conservative to increase the iodine activity for the dose consequences. The intact SGs changed from 118,500 lbm/SG to 89,707 lbm/SG. These changes were found in the appropriate calculational notes that were reviewed during the audit. The minimum mass is the initial mass of the SG following the reactor trip.
The tube leakage rate is the same as the MSLB.
The break flow from the RCS into ruptured SG values are similar to the steam releases from the ruptured SG and intact SG. The results of the analysis were consistent between the calculational notes and license amendment.
The NRG staff has reviewed the calculational notes pertaining to the SGTR analysis. The NRG staff determined that the changes made to the SGTR analysis based on the proposed AST to be conservative, and thus acceptable.
3.7.2.2.3 Loss-of-Load The thermal hydraulic parameters of interest for LOL are the RCS mass, primary to secondary SG tube leakage, initial and minimum SG liquid mass, and steam releases.
The RCS mass changed from 499,500 lbm to 446,486 lbm and the change was documented in the calculational note. The notes are captured in the MSLB notes.
The tube leakage rate is the same as the MSLB.
The intact SGs change from 81,500 lbm/SG to 92,301 lbm/SG. The faulted SG was captured in the calculational notes. The mass of the SGs are rounded up and an uncertainty was added based on WEC assumptions to add conservatisms. For the intact SGs, the masses were 11 Document reviewed during the audit from January 12-14, 2016.