ML12248A149

Submittal of Revision to Locked Rotor Radiological Accident Analysis: License Amendment Request 244, Proposed Revision to Radiological Accident Analysis and Control Room Envelope Habitability Technical Specifications

ML12248A149
Person / Time
Site:	Kewaunee
Issue date:	08/29/2012
From:	Price J Dominion Energy Kewaunee, Dominion
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
12-521, TAC ME7110
Download: ML12248A149 (43)

Text

Dominion Energy Kewaunee, Inc. D 5000 Dominion Boulevard, Glen Allen, VA 23060 August 29, 2012 U. S. Nuclear Regulatory Commission Serial No.12-521 Attention: Document Control Desk LIC/CDS/R4 Washington, DC 20555 Docket No. 50-305 License No. DPR-43 DOMINION ENERGY KEWAUNEE. INC.

KEWAUNEE POWER STATION SUBMITTAL OF REVISION TO LOCKED ROTOR RADIOLOGICAL ACCIDENT ANALYSIS: LICENSE AMENDMENT REQUEST 244. PROPOSED REVISION TO RADIOLOGICAL ACCIDENT ANALYSIS AND CONTROL ROOM ENVELOPE HABITABILITY TECHNICAL SPECIFICATIONS (TAC NO. ME7110)

By application dated August 30, 2011 (Reference 1), Dominion Energy Kewaunee, Inc.

(DEK), requested an amendment to Facility Operating License Number DPR-43 for Kewaunee Power Station (KPS). This proposed amendment (LAR 244) would revise the KPS Operating License by modifying the Technical Specifications (TS) and the current licensing basis (CLB) to incorporate changes to the current radiological accident analysis (RAA) of record. This amendment would also fulfill a commitment made to the NRC in response to Generic Letter 2003-01, "Control Room Habitability" (Reference 2) to submit proposed changes to the KPS TS based on the final approved version of TSTF-448, "Control Room Habitability."

The purpose of this letter is to submit a supplement to the Locked Rotor Accident (LRA) radiological analysis that was originally submitted in LAR-244 (Reference 1), . The reason for submitting this supplemental LRA analysis is discussed below.

1. In response to a request for additional information (see NRC question ME7110-RAII-AADB-Brown 004-2012-05-13), DEK determined that the exhaust velocities of steam directed through steam generator PORV exhausts following a LRA do not exceed five times the 9 5 th percentile wind speed. In the current configuration of the PORV exhausts, the time-dependent vertical velocity of the release does not justify dividing the X/Q by 5 as described in the original LAR.

2. One of Dominion's other nuclear plants recently identified that the time needed to cool down the Reactor Coolant System (RCS) following a Locked Rotor Accident (LRA) with a Loss of Offsite Power (LOOP) (i.e., the time period to cool down the RCS to Residual Heat Removal (RHR) system entry conditions, which terminates the associated radiological release) would be longer than assumed in the current radiological analyses. The reason for the extended cooldown time is that some of the Control Rod Drive Mechanism (CRDM) fans are not powered from vital power busses, and the Emergency Operating Procedures for a natural circulation Aj o0

Serial No.12-521 Revision to LAR 244 LRA Page 2 of 4 cooldown require a slower cooldown rate than assumed in the originally submitted LRA analysis.

An extent of condition review for the Dominion fleet identified that a similar condition exists at Kewaunee Power Station (KPS). Specifically, none of the CRDM fans at KPS are powered from a vital or emergency bus after a LOOP.

Under these conditions, the KPS EOPs require a longer cooldown time than the eight hours assumed in the LRA radiological analysis originally submitted in LAR 244. The result is a longer duration of steam generator steam releases compared to the originally submitted LRA analysis in Reference 1. Dominion's first response to this emergent discovery was to evaluate the existing design basis for the currently approved LRA to determine if challenges to operability exist. Based on existing plant conditions and reasonable assumptions using engineering judgment, DEK concludes that the currently approved LRA continues to meet regulatory dose limits.

The LRA radiological analysis originally submitted in LAR 244 contains little margin to the 5 Rem control room dose limit. The originally submitted LRA radiological analysis was reviewed to determine where excessive conservatisms might exist that could be used to offset the additional steam mass releases that result from extending the cooldown time to RHR entry conditions. DEK has determined there are insufficient conservatisms in the originally submitted analysis to offset the increased steam releases. Therefore, DEK is planning to modify the physical plant to gain X/Q reductions (via increased steam release velocity from the Steam Generator PORVs) and revise the method and inputs to the LRA radiological analysis in order to achieve acceptable control room doses within regulatory limits. Separately, calculated offsite doses compared to regulatory limits are not challenged by this concern.

DEK has revised the LRA analysis originally submitted in LAR 244 to incorporate the effects of the extended RCS cooldown and the physical plant modification. The re-analysis is provided in Attachment 1 to this letter.

4 Serial No.12-521 Revision to LAR 244 LRA Page 3 of 4 If you have any questions or require additional information, please contact Mr. Craig Sly at 804-273-2784.

Sincerely, Price J. Ale President - Nuclear Engineering STATE OF CONNECTICUT COUNTY OF NEW LONDON The foregoing document was acknowledged before me, in and for the County and State aforesaid, today by J. Alan Price, who is Vice President - Nuclear Engineering, of Dominion Energy Kewaunee, Inc. He has affirmed before me that he is duly authorized to execute and file the foregoing document in behalf of that Company, and that the statements in the document are true to the best of his knowledge and belief.

Acknowledged before me this __alLday of . L..LL%- ,2012.

My Commission Expires: 311 27.01 NOTARYPUBLIC 0 )

MY COMMISSION EXPIRES MAR. 31 Ntary Public

Attachment:

1. Revised Pages to LAR 244, Attachment 4, Proposed Revision to Radiological Accident Analysis and Control Room Envelope Habitability Technical Specifications Commitments made in this letter:

1. DEK will modify the steam generator PORV exhaust pipes to promote increased exhaust exit velocities during the next scheduled refueling outage utilizing approved design change processes and reviews.

References:

1. Letter from J. A. Price (DEK) to Document Control Desk (NRC), "License Amendment Request 244, Proposed Revision to Radiological Accident Analysis and Control Room Envelope Habitability Technical Specifications," dated August 30, 2011. [ADAMS Accession No. ML11252A521]

2. Letter from Craig W. Lambert (NMC) to Document Control Desk (NRC), "Generic Letter 2003-01; Control Room Habitability - Supplemental Response," dated April 1, 2005. [ADAMS Accession No. ML050970303]

Serial No.12-521 Revision to LAR 244 LRA Page 4 of 4 cc: Regional Administrator, Region III U. S. Nuclear Regulatory Commission 2443 Warrenville Road Suite 210 Lisle, IL 60532-4352 Mr. K. D. Feintuch Project Manager U.S. Nuclear Regulatory Commission One White Flint North, Mail Stop 08-H4A 11555 Rockville Pike Rockville, MD 20852-2738 NRC Senior Resident Inspector Kewaunee Power Station Public Service Commission of Wisconsin Electric Division P.O. Box 7854 Madison, WI 53707

Serial No.12-521 ATTACHMENT I SUBMITTAL OF REVISION TO LOCKED ROTOR ANALYSIS:

LICENSE AMENDMENT REQUEST 244, "PROPOSED REVISION TO RADIOLOGICAL ACCIDENT ANALYSIS AND CONTROL ROOM ENVELOPE HABITABILITY TECHNICAL SPECIFICATIONS" REVISED PAGES TO LAR 244, ATTACHMENT 4, "RADIOLOGICAL ANALYSIS AND DISCUSSION OF ASSOCIATED TECHNICAL SPECIFICATION CHANGES" KEWAUNEE POWER STATION DOMINION ENERGY KEWAUNEE, INC.

Serial No.12-521 ATTACHMENT 4 Supplement LICENSE AMENDMENT REQUEST 244:

PROPOSED REVISION TO RADIOLOGICAL ACCIDENT ANALYSIS AND CONTROL ROOM ENVELOPE HABITABILITY TECHNICAL SPECIFICATIONS RADIOLOGICAL ACCIDENT ANALYSIS AND DISCUSSION OF ASSOCIATED TECHNICAL SPECIFICATION CHANGES KEWAUNEE POWER STATION DOMINION ENERGY KEWAUNEE, INC.

Serial Number 12-521 Attachment 4, Rev. 1 Page 2 of 38 Summary of Changes to LAR 244, Attachment 4, "Radiological Accident Analysis and Discussion of Associated Technical Specification Changes" The following table provides a summary of the changes that are being made to Kewaunee License Amendment 244, Attachment 4. The changes submitted in this attachment are referred to as Revision 1 changes. The originally submitted LAR 244, is referred to as Revision 0. LAR 244, Attachment 4, Revision 0 contained a total of 191 pages numbered sequentially.

The first column below lists the page numbers for the information contained in Revision 1 to LAR 244, Attachment 4, "Radiological Accident Analysis and Discussion of Associated Technical Specification Changes."

Revision 1 Effect on Revision 0 (page # of 38) (page # of 191) 3-6 Supplements Section 1.1, "Introduction," on pages 5 and 6 7-8 Replaces Table 1.3-4, "Control Room Atmospheric Dispersion Factors," on pages 12 and 13.

Replaces a portion of Table 2.0.1. Specifically, replaces the portion 9 of Table 2.0.1 titled, "Locked Rotor Accident (Section 3.6)" on page 23.

Replaces Sections 3.1, "Determination of Atmospheric Dispersion 10-18 Factors (X/Q)," Section 3.1.1, "Control Room X/Q," and Section 3.1.2, "Offsite (EAB and LPZ) X/Q," on pages 27-34.

19 Replaces Section 3.4.4.1, "SGTR Atmospheric Dispersion Factors,"

on page 93.

20 Replaces Section 3.4.5.3 3, "SGTR Plume Rise Determination," on page 103 21 Supplements Section 3.5.4.1, "MSLB Control Room X/Qs," on pages 110 and 111.

22-37 Replaces Section 3.6, "Locked Rotor Accident Analysis," on pages 127-138 38 Replaces Section 3.7.4.1, "REA Control Room X/Qs," on page 143.

Serial Number 12-521 Attachment 4, Rev. 1 Page 3 of 38 I 1.0 Introduction & Background 1.1 Introduction This supplement to Attachment 4 of License Amendment Request 244 (LAR-244) documents the changes in radiological evaluations related to the Locked Rotor Accident (LRA) analysis. Applicable sections within the originally submitted Attachment 4 (to be referred to as Revision 0) affected by this reanalysis effort are included. Change bars highlight what has changed from Attachment 4, Revision 0.

The reason for this supplement is to describe and resolve two emergent issues that affect inputs and assumptions that are integral to the LRA analysis contained in LAR-244, Attachment 4.

1) DEK identified inconsistencies in Emergency Operating Procedure instructions and assumptions dealing with natural circulation and cooldown following a Locked Rotor Accident (LRA) with Loss-Of-Offsite-Power (LOOP). DEK determined that the Control Rod Drive Mechanism (CRDM) fans are not powered from a vital power source and therefore would not be available to help remove residual heat from the reactor coolant system and components. The effect of not having the CRDM fans powered from a vital power source and thus not available during a LRA with LOOP, is an extended cooldown and steaming period to get the plant down to Residual Heat Removal (RHR) entry conditions which will terminate the associated radiological release. DEK has analyzed the necessary actions and hold points that would be necessary for control room operators to safely cool the plant within prescribed limits and cooldown rates. The LRA radiological analysis has been revised with newly analyzed steaming rates and times which extend the release duration and mass releases beyond what is necessary to achieve the conditions necessary to align the plant onto RHR without voiding the reactor vessel.

2) In response to a request for additional information (ME71 10-RAII-AADB-Brown-004-2012-05-13), DEK determined that the linear interpolation method used to determine the 9 5 th percentile wind speed was not conservative. Using a

Serial Number 12-521 Attachment 4, Rev. 1 Page 4 of 38 traditional power law function to determine the 9 5 th percentile wind speed yields a higher value. Five times the higher predicted 9 5 th percentile wind speed is 47 m/sec. In contrast, the LRA average exhaust velocity from a 20-inch muffler SG PORV release over the 2 to 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> period is discussed in the original LAR as being 43 m/sec. Hence, the exhaust velocity during this period does not exceed five times the 9 5 th percentile wind speed with the current configuration of the PORV exhausts, and does not justify dividing the X/Q by 5 as described in the original LAR.

The original LRA analysis submitted in LAR-244, Attachment 4 contains little margin to the 5 Rem control room dose limit. There are insufficient conservatisms in the design basis LRA analysis to offset the increased releases and SG PORV X/Q values that would result from the additional steaming to cooldown the plant and the corrected 95th percentile wind speed determination. Therefore, Kewaunee is planning to modify the SG PORV exhausts to gain X/Q reductions and revise the method and inputs to the LRA radiological analysis in order to achieve acceptable control room doses within regulatory limits. Offsite doses compared to regulatory limits are not challenged by the extended cooldown time.

DEK proposes to modify the following elements of the originally submitted LAR-244, with this supplement in order to achieve acceptable control room dose from a LRA with LOOP.

Kewaunee is planning to modify the plant SG PORV exhausts during the next scheduled refueling outage, utilizing approved design change processes and reviews. The modification will involve removal of existing PORV exhaust diffusers and extending the 8-inch exhaust pipes within the existing 20-inch mufflers to the same elevation as the muffler exhaust. Before the modification can be made, it will be evaluated under the 10CFR 50.59 process. Review and approval of this SG PORV modification by the NRC is not anticipated and should not be required as part of the review of LAR-244.

Serial Number 12-521 Attachment 4, Rev. 1 Page 5 of 38 The X/Q calculations for the 'A' and 'B' SG PORV release points are being revised to incorporate the following changes:

o Incorporated new elevations of the 8" SG PORV exhaust release points o Used Taut-string distances from these new source elevations to receptors (control room intake and worst inleakage location when intervening buildings are present) o A new meteorological data file for 2002-2006 which was developed to address issues identified in the original data file (The new data file was previously sent to the NRC as part of RAI responses) o Revised the 9 5 th percentile wind speeds determined at the new SG PORV exhaust elevations, which are required for X/Q reduction by a factor of five per Regulatory Guide 1.194 criteria o Increased the calculated SG PORV exhaust exit velocity by more than five times as a direct result of reducing SG PORV exhaust diameter from the existing 20-inch muffler to an 8-inch exhaust pipe The LRA calculation was revised to incorporate the following changes:

o New mass steam flows extend the radiological release beyond the current 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> assumption, based on achieving RHR entry conditions within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> in accordance with station emergency procedures.

o Steaming from both the 'A' and 'B' steam generators was assumed (Steaming from both SG PORVs is realistic and replaces the current assumption where 100% of the steam flow from both steam generators was assumed to be releasedfrom a single worst case SG PORV).

o Increase in assumed failed fuel from 25% to 30% to provide additional margin for future reload fuel and core designs.

Serial Number 12-521 Attachment 4, Rev. 1 Page 6 of 38 o Control Room inleakage of 800 cfm was assumed from accident initiation through release termination (this assumption addresses NRC question ME7 11 0-RAI I-SCVB-Torres-004-2012-06-15).

o Newly calculated X/Qs are used. The X/Q values have been revised and reduced by a factor of 5 due to high SG PORV exhaust exit velocity.

o Reduction of control room ventilation filter efficiencies by 1% to account for filter bypass leakage (This assumption addresses NRC question ME71 10-RAII-AADB-Blum-01 3-2012-03-02 for the locked rotor analysis only. The 1% bypass was not a significant contributor to dose for the LRA).

The above proposed actions affect selective sections of LAR-244 Attachment 4, specifically:

• Section 1.3, Analysis Assumptions and Key Parameter Values, Table 1.3-4, Control Room Atmospheric Dispersion Factors

• Section 2.9, Summary of Design and Licensing Basis Changes, Table 2.0-1, Comparative Summary of Design and Licensing Basis Changes to Radiological Event Analyses {Locked Rotor Accident}

• Section 3.1, Determination of Atmospheric Dispersion Factors (X/Q)

• Section 3.4.4.1, SGTR Control Room X/Qs {No change to existing analysis}

• Section 3.4.5.3, SGTR Plume Rise Determination {No change in conclusion}

• Section 3.5.4.1, MSLB Control Room X/Qs {No change to existing analysis}

• Section 3.6, Locked Rotor Accident (LRA) Analysis

• Section 3.7.4.1, REA Control Room X/Qs {No change to existing analysis}

Serial Number 12-521 Attachment 4, Rev. 1 Page 7 of 38 1.3 Analysis Assumptions & Key Parameter Values Table 1.3-4 Control Room Atmospheric Dispersion Factors Isolated CR Worst

• Source / Accident / Duration Control Room In-leakage X/Q 3

Intake X/Q (sec/m ) (sec/m 3 )

Reactor Building Stack Exhaust (LOCA, REA & FHA) 0 - 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> 4.88E-03 3.97E-03 2 - 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> 3.51 E-03 2.95E-03 8 - 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> 1.37E-03 1.11E-03 24- 96 hour0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br /> 1.12E-03 8.89E-04 96 - 720 hour0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> 9.41 E-04 7.87E-04 Containment / Shield Building (LOCA & REA) 0 - 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> 1.84E-03 1.74E-03 2 - 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> 1.23E-03 1.16E-03 8 - 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> 5.03E-04 4.70E-04 24 - 96 hour0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br /> 4.22E-04 4.02E-04 96 - 720 hour0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> 3.50E-04 3.28E-04 Auxiliary Building Stack Exhaust (LOCA, REA, FHA, MSLB, WGDT & VCT) 0 - 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> 3.67E-03 2.90E-03 2 - 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> 2.83E-03 2.26E-03 8 - 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> 1.11E-03 8.79E-04 24 - 96 hour0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br /> 7.34E-04 5.80E-04 96 - 720 hour0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> 5.64E-04 4.47E-04 Containment Equipment Hatch (FHA) 0 - 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> 3.41E-03 4.58E-03 2 - 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> 2.88E-03 3.88E-03 8 - 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> 1.22E-03 1.64E-03 24 - 96 hour0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br /> 9.71 E-04 1.32E-03 96 - 720 hour0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> 7.66E-04 1.07E-03 Fuel Area Roll-up Door (FHA) 0 - 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> 1.44E-03 1.53E-03 2 - 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> 1.26E-03 1.35E-03 8 - 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> 5.27E-04 5.61 E-04 24 - 96 hour0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br /> 4.23E-04 4.51 E-04 96 - 720 hour0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> 3.56E-04 3.83E-04

Serial Number 12-521 Attachment 4, Rev. 1 Page 8 of 38 Table 1.3-4 Control Room Atmospheric Dispersion Factors Isolated CR Worst A Source / Accident I Duration Control Room In-leakage X/Q Intake X/Q (sec/m ) 3 (sec/m 3)

"A" Steam Generator PORV (MSLB, SGTR, LRA & REA) Rev. 0 Rev. 1 Rev. 0 Rev. 1 0 - 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> 2.24E-03 1.43E-03"" 2.46E-03 1.71 E-03**

2 - 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> 1.90E-03 1.24E-03 2.13E-03 1.46E-03**

8 - 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> 7.69E-04 5.03E-04 8.60E-04 5.94E-04**

24 - 96 hour0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br /> 6.37E-04 4.13E-04 6.96E-04 4.80E-04**

96 - 720 hour0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> 5.19E-04 3.32E-04 5.81E-04 3.99E-04 "A" Steam Generator Safeties Not Used Not Used Bounded by "A" PORV Bounded by "A" PORV "A" Steam Generator Dumps Not Used Not Used Bounded by "A" PORV Bounded by "A" PORV "B" Steam Generator PORV (MSLB, SGTR, LRA & REA) Rev. 0 Rev. 1 Rev. 0 Rev. 1 0 - 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> 3.96E-02* 3.94E-02** 2.92E-02* 1.98E-02**

2 - 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> 3.20E-02 3.08E-02 2.34E-02 1.53E-02**

8 - 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> 1.21 E-02 1.20E-02 8.67E-03 5.76E-03**

24 - 96 hour0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br /> 1.01 E-02 9.98E-03 6.97E-03 4.57E-03**

96 - 720 hour0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> 8.58E-03 8.38E-03 6.41 E-03 4.11E-03 "B" Steam Generator Safeties Not Used Not Used Bounded by "B" PORV Bounded by "B" PORV "B" Steam Generator Dumps Not Used Not Used Bounded by "B" PORV Bounded by "B" PORV A The most significant pathway of inleakage to the Control Room is through doorway penetrations in communication with the Turbine Building. The worst in-leakage X/Q is the highest X/Q from the following possible intake points to the Turbine Building: TB Fan Room West Louvers, TB Fan Room East Louvers, and TB Roll-up Door.

The value displayed can be and was divided by 5 for use in the SGTR analysis. This reduction by a factor of 5 th was permitted due to the steam exhaust vertical velocity exceeding five times the 95 percentile wind speed at the "B"SG PORV release elevation for the SGTR. Division by 5 is only credited for the 0-2 hour interval for the SGTR. Justification for this reduction by a factor of 5 is given in Section 3.4.5.3 (SGTR) and the results are shown in Tables 3.4-4 (SGTR).

The value displayed can be divided by 5 for use in the SGTR and/or LRA dose analyses. This reduction by a factor of 5 is permitted due to the steam exhaust vertical velocity exceeding five times the 95 percentile wind speed at the release elevation for the SGTR and LRA. Justification for this reduction by a factor of 5 for the SGTR is discussed in Section 3.4.5.3 and for the LRA in Section 3.6.5.3. Only the LRA analysis was revised to credit the Rev. 1 lower X/Q values that result from the use of effective taut-string horizontal distances.

Serial Number 12-521 Attachment 4, Rev. 1 Page 9 of 38 2.9 Summary of Design and Licensing Basis Changes This Section provides a comparative summary of the current design and licensing basis and the proposed changes. The summary is listed in Table 2.0-1. A detailed discussion of the changes, including the reasons for the changes, can be found in Section 3.

Table 2.0-1 Comparative Summary of Design and Licensing Basis Changes to Radiological Event Analyses Parameter Current Basis / Proposed Basis Locked Rotor:Accident (Section 3.6)

Failed Fuel Following 50 30 the Accident (%)

Steam Generator Liquid Mass (Ibm/SG) 87,000 84,000 Control Room 45 60 Isolation (min)

Unfiltered inleakage 0 800 prior to isolation (cfm)

Release Duration (hr) 8 36 Release Pathway 100% steaming from Time 'A' SG 'B' SG single worst SG < 1 hr 0% 100%

> 1 hr 48% 52%

Steam Release Time 'A'SG 'B'SG (Ibm/min) 0 - 2 hr 1750 0-1 hr 0 1508 2-8 hr 1264 1-2 hr 724 784 2-8 hr 477 517 8-12 hr 392 425 12-16 hr 372 403 16-20 hr 330 358 20-24 hr 320 347 24-28 hr 310 336 28-36 hr 292 316 36-720 hr 0 0

Serial Number 12-521 Attachment 4, Rev. 1 Page 10 of 38 I 3.1 Determination of Atmospheric Dispersion Factors (X/Q)

A comprehensive evaluation of X/Q values applicable to the radiological events listed in Section 1.3.1 has been performed. Release points for each accident scenario were identified and paired with possible receptor locations to determine the most limiting X/Q values. The most limiting X/Q values were used to model the dose consequences.

Onsite source/receptor pairs were evaluated using the qualified and tested ARCON96 code (Reference 5) while the offsite source/receptor pairs to the EAB and LPZ were evaluated with a controlled version of the Dominion computer code PAVAND (Reference 7) which is a Dominion variant of the NRC PAVAN code.

A new data file containing meteorological data over the years 2002-2006 has previously been provided to the NRC for review as part of RAI responses dealing with meteorological questions. Enclosure 1 of this supplement includes ARCON96 computer files used in the calculation of the Revision 1 taut-string control room X/Q values.

The meteorological data is hourly as described in Regulatory Guide 1.23. This data has been reviewed by meteorologists for missing or anomalous observations, instrumentation problems, and trends indicative of local effects such as building wakes and excessive vegetation effects. The data meets the requirement of Regulatory Guide 1.23 for annual joint recovery rates of at least 90%.

Revision 0 (text maintained for reference and history)

During the review of the meteorological data, the meteorologists observed that there was a change in the distribution of the atmospheric stability classes in the data during early January of 2005. After January 2005, the occurrence of extremely and moderately unstable stability classes increased from the distribution observed from the previous three years of data. At the same time, the occurrence of slightly stable stability classes decreased. An effort was made to determine the cause of this shift in stability class distribution. During January of 2005, the Kewaunee plant process computer was replaced. The algorithm used to calculate the stability class was examined. The algorithm was found to comply with requirements and methods. The stability classes

Serial Number 12-521 Attachment 4, Rev. 1 Page 11 of 38 since Jan 2005 were compared to available Point Beach data and they matched well.

Point Beach is located just a few miles south of KPS. The conclusion reached was that the change in stability class distribution was tied to the replacement of the plant process computer. However, no conclusion could be reached on whether the stability class distribution, before the plant process computer change, was necessarily incorrect.

Intuitively, an increase in the percentage of highly unstable wind conditions should cause the resulting atmospheric dispersion factors to be smaller. Based on the stability class distribution, it was believed that use of only the final 2 years of data would result in smaller X/Q values. Use of only the first 3 years of data could be overly conservative.

Since the last two years of data meet quality standards and compare favorably to data recorded for the same period at Point Beach, the use of only the first 3 years of data, which contain a larger distribution of stable atmospheric conditions for unknown reasons, did not seem appropriate. Therefore, the meteorological data for all 5 years were used and are believed to be appropriate and conservative.

Revision 1 (New data file)

As identified in RAI responses to meteorological data questions, errors in the original (Revision 0) met data file were identified which necessitated the creation of a new 2002-2006 data file. A copy of the corrected data file was provided as part of the applicable RAI responses. Sensitivity studies performed and discussed in the RAI responses indicate that minimal (or negligible) differences exist between calculated X/Q values using the revised data file compared to those originally submitted in LAR 244 , Revision 0.

DEK proposes to maintain the original values and results as submitted in LAR-244 (with the exception of the new SG PORV X/Qs). The conservative methods employed in the calculation of control room X/Q values for every source-to-receptor pair more than compensate for the minimal changes noted in new X/Q values. This is discussed in the applicable RAI responses.

Serial Number 12-521 Attachment 4, Rev. 1 Page 12 of 38 3.1.1 Control Room X/Q Control room X/Qs are calculated for both ventilation intake and potential inleakage receptor points to the control room and are listed in Table 1.3-4. Figure 3.1-1 provides a relative scaled drawing of the KPS building orientation and control room location showing all identified release points and receptors. The control room envelope is physically within the Auxiliary Building with ingress/egress doors into both the Auxiliary and Turbine Buildings.

DEK believes the primary source of inleakage into the control room occurs through the ingress/egress doors. This conclusion is based on the following:

a. In December of 2004, tracer gas tests were performed to measure the unfiltered in-leakage into the KPS control room. Based on observations and measurements obtained during those tests, the ingress/egress doors appeared to be the most viable source of inleakage when the control room is isolated.

b. The isolation dampers in the normal and alternate control room intakes are bubble-tight dampers. Due to the nature of their design, no inleakage is expected to occur past these dampers when closed.

c. Due to multiple areas within the Auxiliary Building being under suction by the Special Ventilation System, some directly adjacent to the control room boundary, the primary pathway and source of inleakage through the control room doors is considered to be from the turbine building.

Due to the facts above, the most viable intake to the control room when the normal control room intake is isolated is from the Turbine Building through the ingress/egress doors. Various intake points to the Turbine Building were considered as receptor locations and are shown in Figure 3.1-1. These locations are: Turbine Building Fan Room West Louver, Turbine Building Fan Room East Louver, and the Turbine Building Roll-up Door. No credit is taken for dilution within the large Turbine Building volume or additional dispersion within the Turbine Building as the contaminants travel from the intake point to the likely control room inleakage doorways. In essence, the intake into

Serial Number 12-521 Attachment 4, Rev. 1 Page 13 of 38 the Turbine Building is being conservatively treated very similar to a ventilation duct leading directly to the control room.

As a result of the analyses documented in this LAR, the alternate control room intake will be restricted from use. This restriction is required because of the X/Q that would result due to the close proximity of the alternate intake to various release points; one of which is very near the alternate intake. Administrative controls will be in place to assure the alternate control room intake is closed and prohibit its use during normal operation, following an accident, or while moving recently irradiated fuel.

Control room X/Q values for the source/receptor pairs address the most viable locations and limiting accident cases, including those potentially associated with single failure and loss of offsite power. In Revision 0, the ARCON96 input source-to-receptor distances were the shortest horizontal (X-Y) distance between the release point and intake, ignoring intervening buildings (i.e., source to receptor taut-strings or elevation differences were not considered). Tables 3.1-1, 3.1-1a, and 3.1-2 provide the distances and angles for each source to receptor combination.

As a means to gain dose margin, four additional ARCON96 analyses for the "A" and "B" SG PORV release points were performed to support the revised LRA analysis, crediting the shortest taut-string distance from each SG PORV to the normal control room intake and the worst-case inleakage receptor point (i.e., the Turbine Building Fan Room West Louver). These revised ARCON96 runs were performed using the new Revision 1 meteorological data file. It is important to note that the original Revision 0 "A" and "B" SG PORV ARCON96 X/Q values, being greater and more conservative than the new

'taut-string' values, are being maintained and continue to be used for the SGTR, MSLB and REA accident analyses. The SGTR, MSLB, and REA accidents results remain unchanged from original Revision 0 values, not crediting the dose reductions that could be benefited from the new lower SG PORV X/Q values. Once approved, DEK proposes to apply these lower X/Q values in future revisions to applicable design basis accident radiological analyses, as necessary.

Serial Number 12-521 Attachment 4, Rev. 1 Page 14 of 38 In accordance with the guidance of RG 1.194, the buoyant plume rise associated with energetic releases from steam relief valves or atmospheric steam dumps can be credited if (1) the release is uncapped and vertical, and (2) the time-dependent vertical velocity exceeds the 95th percentile wind speed, at the release point height, by a factor of 5. Justification for crediting buoyant plume rise is given in Section 3.4.5.3 (SGTR) and Section 3.6.5.3 (LRA).

Serial Number 12-521 Attachment 4, Rev. 1 Page 15 of 38 Figure 3.1-1 Kewaunee Source and Receptor Points

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Serial Number 12-521 Attachment 4, Rev. 1 Page 16 of 38 Table 3.1-1 Line-of-Sight Horizontal Distance from Source to Receptor (meters)

Elev.

• Z7.019m 71.9-7M 71.9~7 m &.1)7m RELEASE POINTS Control Room TB Fan Room TB Fan Room TB Roll-up Intake West Louver East Louver Door 51.35 m Rx Bldg Stack 17.05 16.93 21.67 33.61 37.13m Shield Bldg 14.58 12.34 18.45 29.83 27.89 m Aux Bldg Stack 39.60 44.89 44.20 53.23 4.27m Equipment Hatch 39.60 34.61 41.46 50.39 3.51 m Fuel Area Roll-up Doors 1 64.55 62.98 68.83 80.44 12.60 m SG A PORV 53.35 50.87 57.14 68.33 22.35 m SG A Dump 57.93 56.53 62.27 73.95 2

12.60m SG A Safeties 53.79 51.67 57.83 69.15 23.34 m SG B PORV 12.06 12.81 16.84 28.82 3

25.83 m SG B Dumps 24.81 30.56 29.16 38.00 4

23.34 m SG B Safeties 13.25 13.46 17.90 29.85

.1.

• Above grade (meters) 1 Fuel Area Roll-up Door #2 (south) to all receptors 2 Safety #2 to CR Intake, TB FR East Louver; Safety #1 to TB FR West Louver, TB Roll-Up Door 3 Dump #1 (South) for all receptors 4 Safety #I to all receptors Table 3.1-1a Shortest Taut-String Effective' Horizontal Distance (meters)

Elev.* 21.69 m 17.91m Control Room TB Fan Room Intake West Louver 13.60 m SG A PORV 67.62 62.08 24.34 m SG B PORV 12.06 16.04

• • Effective horizontal distances ensure ARCON96 calculated slant path distance is equal to the taut-string distance.

Serial Number 12-521 Attachment 4, Rev. 1 Page 17 of 38 Table 3.1-2 Direction from Receptor to Source (degrees true North)

Control Room TB Fan Room TB Fan Room TB Roll-up RELEASE POINTS I Intake West Louver East Louver Door Rx Bldg Stack 286.40 308.70 293.90 296.10 Shield Bldg 273.30 284.40 279.10 284.20 Aux Bldg Stack 349.40 354.80 346.00 336.70 Equipment Hatch 246.00 252.60 252.90 263.00 1

Fuel Area Roll-up Doors 282.00 287.80 284.60 286.90 SG A PORV 273.20 279.90 277.00 280.90 SG A Dump 283.10 289.60 285.90 288.20 2

SG A Safeties 277.40 281.60 280.80 282.20 SG B PORV 289.70 320.20 298.40 299.10 3

SG B Dumps 356.20 2.80 349.90 336.00 4

SG B Safeties 286.20 314.60 295.30 297.20 1 Fuel Area Roll-up Door #2 (south) to all receptors 2 Safety #2 to CR Intake, TB FR East Louver; Safety #1 to TB FR West Louver, TB Roll-Up Door 3 Dump #1 (South) for all receptors 4 Safety #1 to all receptors

Serial Number 12-521 Attachment 4, Rev. 1 Page 18 of 38 3.1.2 ffsite (EAB and LPZ) X/Q The Exclusion Area Boundary (EAB) and Low Population Zone (LPZ) atmospheric dispersion factors (X/Qs) for Kewaunee Power Station have been revised and are listed in Table 1.3-3. Generated using the PAVAND code, the X/Qs are based upon a conservatively modeled ring with a 300-foot radius centered on Containment. This 300 foot bounding release ring, partially shown in Figure 3.1-1, encompasses all possible release points that exist within the station and is based upon the distance from the center of Containment to the farthest release point (i.e., Northeast Turbine Building corner). All actual release points are contained within this 300 foot bounding ring. The EAB and LPZ X/Q values were conservatively modeled using a ground-level release without credit for building wake effects.

Figure 2.2-2 in the KPS USAR shows the KPS EAB as an exclusion radius of 1,200 meters. The exclusion radius over land falls within the physical site boundary. For conservatism, the LPZ was calculated assuming the bounding shortest radius of 2 miles (3218.7 m). Utilizing the 300-foot (91.4 meters) bounding release ring described above, the shortest distance to the EAB (3,637 ft or 1,108.6 m) and the LPZ (10,260 ft or 3,127.3 m) for all directions (centered on the containment) was used to represent the bounding assumption for all possible release points. Modeled as a ground level release, the resulting EAB and LPZ X/Qs were determined by selecting the largest calculated value across all sixteen downwind directions and the overall site for each prescribed time period. The EAB (0-2 hour) X/Q is a single bounding value of 1.76E-04 sec/m 3 . The LPZ (0-8 hr, 8-24 hr, 1-4 day, and 4-30 day) X/Qs represent the highest calculated values for each time period across all directions. The maximum values occurred in the East-Northeast (ENE) direction for all except one time period, the (4-30 day) period, which occurred in the East (E) direction. Selecting the highest value within each time period across all directions and the overall site assures that the doses calculated for the LPZ are conservative.

Serial Number 12-521 Attachment 4, Rev. 1 Page 19 of 38 3.4.4.1 SGTR Control Room X/Qs As described in Section 3.1, the onsite atmospheric dispersion factors were calculated using the ARCON96 code (Reference 5) and guidance from Regulatory Guide 1.194 (Reference 6). The SGTR Control Room X/Qs listed in Table 1.3-4 (Revision 0 values) were calculated for the following applicable KPS source points:

" "A" Steam Generator PORV

" "B" Steam Generator PORV The control room X/Qs represent the highest values calculated based on the shortest distance measured from each applicable source location to control room receptor location (see Figure 3.1-1). New lower taut-string X/Q values for the 'A' and 'B' SG PORVs calculated in Revision 1 to this document are not being applied to this analysis at this time.

No changes or revision to the SGTR analysis were required.

Serial Number 12-521 Attachment 4, Rev. 1 Page 20 of 38 3.4.5.3 SGTR Plume Rise Determination Following the guidance of RG 1.194, the buoyant plume rise associated with energetic releases from steam relief values or atmospheric steam dumps can be credited if (1) the release is uncapped and vertical, and (2) the time-dependent vertical velocity exceeds the 95th percentile wind speed, at the release point height, by a factor of 5.

The 95th percentile wind velocity was determined using meteorological data from 2002-2006. The values of the 95th percentile 10 meter and 60 meter wind speeds were found to be 7.6 and 11.6 meters per second, respectively. The B SG PORV has a larger atmospheric dispersion factor than the A SG PORV because of the close proximity of B SG PORV to the control room intake and turbine building intake locations.

The steam flow from the B SG PORV is vertical and uncapped at the point where it enters the atmosphere. The elevation at which the steam enters the atmosphere is 685'-

5" at 24.36 meters above grade. The 95th percentile wind speed determined at this elevation is 9.4 meters per second. Five times this speed is 47 meters per second.

With the modifications to the SG PORVs from a 20-inch muffler to an 8-inch exhaust pipe, the new exhaust cross sectional area will be 0.317 square feet. The flow from an open SG PORV would need to equal or exceed 109 Ibm/min* to equal an exit velocity of 47 meters per second. From Table 3.4-4, the steam flow from the affected steam generator exceeds 109 Ibm/min for the entire accident duration. For conservatism, only the 0-2 hour X/Q for the "B" (Affected) SG PORV release is reduced by a factor of five, crediting the plume rise reduction allowed by RG 1.194.

• (assumed at atmospheric pressure saturated steam conditions)

Serial Number 12-521 Attachment 4, Rev. 1 Page 21 of 38 3.5.4.1 MSLB Control Room X/Qs As described in Section 3.1, the onsite atmospheric dispersion factors were calculated using the ARCON96 code (Reference 5) and guidance from Regulatory Guide 1.194 (Reference 6). The MSLB Control Room X/Qs listed in Table 1.3-4 (Revision 0 values) were calculated for the following applicable KPS release points:

• "A" SG PORV

• "B" SG PORV The control room X/Qs represent the highest values calculated based on the shortest distance measured from each applicable source location to control room receptor location (see Figure 3.1-1). New lower taut-string X/Q values for the 'A' and 'B' SG PORVs calculated in Revision 1 to this document are not being applied to this analysis at this time.

No changes or revision to the MSLB analysis were required.

Serial Number 12-521 Attachment 4, Rev. 1 Page 22 of 38 3.6 Locked Rotor Accident (LRA) Analysis This section describes the methods employed and results of the revised Locked Rotor Accident (LRA) design basis radiological analysis accounting for extended natural circulation cooldown to RHR, without voiding the reactor vessel, assuming Loss of Offsite Power (LOOP) coincident with the accident. The analysis assumes failure of 30% of the fuel rods, due to Departure from Nucleate Boiling (DNB) during the accident.

Doses were calculated at the Exclusion Area Boundary (EAB), at the Low Population Zone (LPZ), and in the KPS control room. The methods used to evaluate the control room and offsite doses resulting from the LRA included Regulatory Guide 1.183 methodology, ARCON96-based control room atmospheric dispersion factors, PAVAND-based EAB and LPZ atmospheric dispersion factors, Federal Guidance Reports (FGR)

No. 11 and 12 dose conversion factors, and credit for operator action to actuate the control room emergency ventilation system within one hour of the accident.

3.6.1 LRA Scenario Description The Locked Rotor Accident (LRA) begins with instantaneous seizure of a rotor in one of the two reactor coolant pumps. The sudden decrease in core coolant flow while the reactor is at power results in a degradation of core heat transfer that results in assumed fuel damage due to Departure from Nucleate Boiling (DNB). Although there is no increase in the leak rate of primary coolant to the secondary side during the LRA, a large amount of activity (from the failed fuel) is transported to the secondary side via any pre-existing leaks in both steam generators.

A turbine trip and coincident loss of offsite power are incorporated into the analysis.

Kewaunee Control Rod Drive Mechanism fans are not powered by a vital bus, therefore extended cooldown of residual heat in the reactor head and reactor coolant system are required using natural circulation and proceduralized hold points to assure voiding does not occur. This results in an extended release to the environment via power operated relief valves (PORV) with releases to the environment continuing until cooldown can be performed using the Residual Heat Removal System (RHR). It is assumed that

Serial Number 12-521 Attachment 4, Rev. 1 Page 23 of 38 steaming from both steam generator PORVs will persist for 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> before system pressure and temperature permit use of RHR, at which time releases to the environment terminate. Operator action is credited for control room isolation and emergency ventilation actuation one hour following event initiation.

Kewaunee station is removing credit for the Control Room Ventilation Intake radiation monitor R-23 to provide control room isolation. The R-23 system is not safety grade and consists of a single radiation monitor. In addition, the isolation signal generated by R-23 is only a partial signal that will not assure the closure of all control room inlet and outlet ventilation dampers to provide complete control room isolation. Full isolation requires actions by the operator to close dampers that are not included in the isolation' logic. The current Locked Rotor Accident (LRA) uses and credits the R-23 system for control room isolation. The basis behind the use of R-23 relies on arguments that Operations will take appropriate actions within 45 minutes to isolate the control room if R-23 fails to perform its isolation function. Removing credit for R-23 requires an alternative means to ensure control room isolation. Operator action will be required within one hour following a LRA to isolate the control room. One hour is sufficient time for the operator to identify the accident, take necessary emergency steps in response to the accident, and direct action to isolate the control room and start the control room emergency ventilation system. This time-critical operator action will be incorporated into Operation procedures and validated.

3.6.2 LRA Source Term Definition The core source term used in the Locked Rotor Analysis is taken from Table 3.2-3.

Analyses are based on 30% of the gap activity being released, with gap activity based on Regulatory Position 3 of RG 1.183.

3.6.3 LRA Release Transport The release scenario uses the Technical Specification LCO 3.4.13.d primary to secondary leakage limit of 150 gpd per steam generator. The release from both steam

Serial Number 12-521 Attachment 4, Rev. 1 Page 24 of 38 generators continues for 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> until shutdown cooling can be placed into service to remove decay heat. After 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />, the release from the steam generators is terminated.

The RADTRAD-NAI computer code (Reference 3) is used to model the time dependent transport of radionuclides, from the primary to secondary side and out to the environment via steam relief valves.

3.6.4 LRA Atmospheric Dispersion Factors 3.6.4.1 LRA Control Room X/Qs As described in Section 3.1, the onsite atmospheric dispersion factors were calculated using the ARCON96 code (Reference 5) and guidance from Regulatory Guide 1.194 (Reference 6). The LRA Control Room X/Qs listed in Table 1.3-4 (Revision 1 values) were calculated for the following applicable KPS source points:

" "A" Steam Generator PORV

• "B" Steam Generator PORV The control room X/Qs determined represent values calculated based on the shortest taut-string distance measured from each applicable source location to control room receptor locations (see Figure 3.1-1).

3.6.4.2 LRA Offsite (EAB & LPZ) XIQs As described in Section 3.1, the Exclusion Area Boundary (EAB) and Low Population Zone (LPZ) atmospheric dispersion factors were revised and are listed in Table 1.3-3.

These offsite atmospheric dispersion factors were generated using the PAVAND code (Reference 7) and guidance from Regulatory Guide 1.145 (Reference 8).

Serial Number 12-521 Attachment 4, Rev. 1 Page 25 of 38 3.6.5 LRA Analysis Assumptions and Key Parameters 3.6.5.1 Method of Analysis The RADTRAD-NAI code (Reference 3) is used to calculate the radiological consequences from airborne releases resulting from a LRA at Kewaunee Power Station (KPS) to the EAB, LPZ, and Control Room.

RADTRAD can model a variety of processes that can attenuate and/or transport radionuclides during a LRA. There are aspects of the LRA analysis that require two RADTRAD models due to limitations of the code. This is due primarily to treatment of the source terms because noble gases are released without mitigation and iodines and particulates are released crediting partitioning and moisture carryover. Primary-to-secondary leakage at the Technical Specification limit of 150 gallons per day is assumed into each steam generator creating two release pathways to the environment from this event. The station will utilize both the 'A' and 'B' steam generator PORVs to release residual heat to cool down. The 'B' SG PORV is the worst case release path for pre and post control room isolation. For conservatism, in the first hour, 100% of the steam release is assumed from the 'B' steam generator while activity builds up in the 'A' steam generator liquid. After one hour, steam release from the 'A' and 'B' SG PORVs is conservatively assumed with a 48%/52% split, respectively. In reality, Operations will align both the 'A' and 'B' steam generator PORVs to release steam to control and reduce system residual heat. The resistance created by the reactor coolant pump being locked in one loop will essentially match the resistance in the unaffected reactor coolant pump loop that will no longer be spinning as the plant is being cooled by natural circulation due to LOOP. Operations will attempt to balance the cooldown between both steam generator PORVs. The higher flow (i.e., 52%) assumed from the worst SG PORV ('B' PORV) considers potential variations in control room actions to cool the plant using both SG PORVs. Note that all of the new taut-string Revision 1 X/Q values were reduced by a factor of 5 for the entire release period. This reduction is taken following the guidance of RG 1.194, crediting the effects of plume rise for time dependent high

Serial Number 12-521 Attachment 4, Rev. 1 Page 26 of 38 velocity exhaust steam that exceeds the 9 5 th percentile release height wind speed by a factor of 5. For explanation of this determination, see Section 3.6.5.3.

A schematic shown in Figure 3.6-1 provides a summary of the LRA releases to environment.

3.6.5.2 Basic Data & Assumptions for LRA Changes have been made to the AST LRA. Table 3.6-1 provides a complete list of inputs and assumptions used to reanalyze the KPS LRA. The revised LRA analysis also addresses several previously submitted NRC RAI questions that had the potential to increase dose consequences of the LRA.

Serial Number 12-521 Attachment 4, Rev. 1 Page 27 of 38 Figure 3.6-1 LRA Radioactive Release Schematic SG Steam Release SG Steam Release Iodine, particulates, and progeny Iodine, particulates, and progeny released via 0.01 partitioning to the released via 0.01 partitioning to the environment environment Hr Ibm/ min Hr Ibm/min 0 0.0 0 15.1 1 7.24 1 7.84 2 4.77 2 5.17 8 3.92 8 4.25 12 3.72 12 4.03 16 3.30 16 3.58 20 3.20 20 3.47 24 3.10 24 3.36 28 2.92 28 3.16 36 0.0 36 0.0 0

RCS Mass = 262,735 Ibm 30% Fuel Failure

• NGs are released directly from the RCS to the environment.

Serial Number 12-521 Attachment 4, Rev. 1 Page 28 of 38 Table 3.6-1 Basic Data and Assumptions for LRA Parameter or Assumption CLB Value Proposed Value Reason for Change Primary to Secondary Leak 150 No Change rate (gpd/SG)*

Failed Fuel Following the 50 30 Rods-in-DNB analysis show Accident (%) approximately 12% rods-in-DNB following a LRA for the current cycle. 30% will be specified in the reload safety analysis checklist (RSAC).

Fraction of Core Activity in Gap (%)

1-131 8 No Change Kr-85 10 Other Noble Gases 5 Other Halogens 5 Alkali Metals 12 Iodine Partitioning PC = 100 No Change Alkali Metal Partitioning PC = 100 No Change Iodine chemical form of Elemental 97 No Change Primary-to-Secondary Organic 3 Leakage (%) Particulate 0

Serial Number 12-521 Attachment 4, Rev. 1 Page 29 of 38 Table 3.6-1 Basic Data and Assumptions for LRA Parameter or Assumption CLB Value Proposed Value Reason for Change Initial Secondary Side Coolant Included Not Included Because fuel failure occurs, Activity modeling of initial coolant activity is not required. CLB analysis shows less than 1% contribution to dose from secondary side activity.

Core Activity Table 3.2-3 No Change Radial Peaking Factor 1.7 No Change Tube Uncovery. No tube bundle uncovery No Change assumed.

RHR Cut-In Time (hr) 8 36 Extended cooldown is required due to LOOP and lack of vital power to CRDM fans necessitating plant cooldown following prescribed rates and hold points to safely reach RHR entry conditions Reactor Trip Time (sec) 0 No Change Loss of Offsite Power (sec) 0 No Change Safety Injection Signal None No Change

Serial Number 12-521 Attachment 4, Rev. 1 Page 30 of 38 Table 3.6-1 Basic Data and Assumptions for LRA Parameter or Assumption CLB Value Proposed Value Reason for Change Reactor coolant mass (gm) 1.19E+08 No Change Steam Generator Liquid Mass (Ibm/SG)

(Ibm/SG) 0 - 30 min 0-30 87,000 0 - 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />

-Minimum 84,000 MnmmSSG liquid iudvlmvolume used to minimize hold-up 30 min - 8 hrs 116,900 Release Pathway Release from both PORVs is 100% steaming of both Time 'A' SG 'B' SG more realistic. Based on 150 SG from single SG < 1 hr 0% 100% gpd into each SG, both SGs

> 1 hr 48% 52% release activity based on the required cooldown rate. 'A' PORV is assumed unavailable for the first hour for conservatism since the 'B' PORV has higher X/Q due to proximity to control room receptor points. 'B' PORV release is conservatively assumed greater than the 'A' PORV to consider potential variations in control room actions to cool the plant using both SG PORVs.

Serial Number 12-521 Attachment 4, Rev. 1 Page 31 of 38 Table 3.6-1 Basic Data and Assumptions for LRA Parameter or Assumption CLB Value Proposed Value Reason for Change Steam Release (Ibm) 0- 2 hr 210,000 0-2 hr 181,000 Extended cooldown is required 2-8 hr 455,000 2-8 358,000 due to LOOP and lack of vital 8- 12 196,000 power to CRDM fans necessitating cooldown following 12 - 16 186,000 prescribed rates and hold points 16 -20 165,000 to safely reach RHR entry 20 - 24 160,000 conditions 24-28 155,000 28-36 292,000 Steam Release (Ibm/mmn) 0 - 2 hr 1750 Time 'A' SG 'B' SG Extended cooldown is required 1264 0-1 hr 0 1508 due to LOOP and lack of vital 2 -8 hr 1-2 hr 724 784 power to CRDM fans 2-8 hr 477 517 necessitating cooldown 2-82 hr 47 4251 following prescribed rates and 8-12 hr 392 425 hold points to safely reach 12-16 hr 372 403 RHR entry conditions 16-20 hr 330 358 20-24 hr 320 347 24-28 hr 310 336 28-36 hr 292 316 36-720 hr 0 0

Serial Number 12-521 Attachment 4, Rev. 1 Page 32 of 38 Table 3.6-1 Basic Data and Assumptions for LRA Parameter or Assumption CLB Value Proposed Value Reason for Change EAB X/Q (sec/m3 )

0 - 2 hr 2.232E-04 1.76E-04 New PAVAND X/Q values (see Table 1.3-3 and Section 3.1.2)

LPZ X/Q (sec/m3 )

Period LPZ Period LPZ New PAVAND X/Q values (see Table 1.3-3 and Section 3.1.2) 3.977E-05 0 - 8 hr 3.36E-05 0 - 2 hr 2 - 24 hr 4.100E-06 8 - 24 hr 2.37E-05 1 - 2 day 2.427E-06 1 - 4 day 1.12E-05 2 - 30 day 4.473E-07 4 - 30 day 3.94E-06 Control Room Volume (ft3) 127,600 No Change Control Room Isolation (min) 45 60 CLB is based on R-23 not being redundant. 45 minutes credits 25 minutes for control room radiation monitors to detect radiation and 20 minutes for operator action to isolate the control room.

Time to control room isolation was increased to 60 minutes to allow more time for operator action utilizing multiple inputs as indicators of the accident (e.g., Rx coolant low flow and control room radiation monitor alarms).

Serial Number 12-521 1 Attachment 4, Rev. 1 # G Page 33 of 38 Table 3.6-1 Basic Data and Assumptions for LRA Parameter or Assumption CLB Value Proposed Value Reason for Change Normal Ventilation Unfiltered 2,750 No Change Makeup Air Flow (scfm)

Filtered Recirculation Air 2,250 No Change Flow (scfm)

Control Room Post Accident 45 60 CRPARS initiation is assumed to Recirculation system occur at 60 minutes, coincident (CRPARS) Ventilation (min) with the operator action to isolate the control room.

Control Room Unfiltered 1500 800 Maximum (ASTM) E741 tracer Inleakage (cfm) gas test = 447+/-51 cfm (Ref. 20) tested using a special system configuration to enhance inleakage into the control room.

Control Room HVAC Unfiltered inleakage is assumed Parameters (cfm) ' starting from accident initiation.

0-45m 45-30 d 0-60m 60m-30 d The dose increase resulting from Unfiltered Inleakage 0 1500 800 800 this new assumption of including inleakage prior to CR isolation Unfiltered Make-up Air 2750 0 2750 0 indicates an insensitivity to the Filtered Recirculation 0 2250 0 2250 final results.

CRPARS Filter Efficiency

(%) Efficiencies were reduced by Elemental 90 (includes safety factor of 2) 89 1% to account for 1% filter Organic 90 (includes safety factor of 2) 89 bypass Particulate 99 98

Serial Number 12-521 Attachment 4, Rev. 1

.4 Page 34 of 38 Table 3.6-1 Basic Data and Assumptions for LRA Parameter or Assumption CLB Value IProposed Value IReason for Change Control Room X/Q (sec/m 3 ) 'B' SG PORV First hour of release is 0-8h 2.93E-3 Time to NCR assumed only from the 'B' SG 0-1 hr 7.88E-3 PORV to the Normal Control 8 - 24 h 1.73E-3 Room intake (NCR) prior to 1 -4d 6.74E-4 assumed isolation at 60 4 - 30 d 1.93E-4 minutes. Values from Table

'A' SG PORV 1.3-4 have been reduced by a Time to TWL factor of 5 due to plume rise 1 -2hr 3.42E-4 (see Section 3.6.5.3).

2-8 hr 2.92E-4 8- 24 hr 1.19E-4 24 - 36 hr 9.60E-5 After one hour, releases are assumed from both the 'A' and 'B' SG PORVs to the Turbine Bldg West Louver

'B' SG PORV (TWL) {the worst control room Time to TWL inleakage point}. Values from 1 -2hr 3.96E-3 Table 1.3-4 have been 2-8 hr 3.06E-3 reduced by a factor of 5 due 8 -24 hr 1.15E-3 to plume rise (see Section 24 - 36 hr 9.14E-4 3.6.5.3).

Releases terminate at 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />

• The density used to convert volumetric leak rates (gpd) to mass leak rates (Ibm/hr) was consistent with the basis of surveillance tests used to show compliance with leak rate technical specifications.

Serial Number 12-521 Attachment 4, Rev. 1 Page 35 of 38 3.6.5.3 Plume Rise Determination Following the guidance of RG 1.194, the buoyant plume rise associated with energetic releases from steam relief valves or atmospheric steam dumps can be credited if (1) the release is uncapped and vertical, and (2) the time-dependent vertical velocity exceeds the 9 5 th percentile wind speed, at the release point height, by a factor of 5.

The 95th percentile wind velocity was determined using meteorological data from 2002-2006. The value of the 95th percentile 10 meter and 60 meter wind speeds were found to be 7.6 and 11.6 meters per second, respectively. DEK will modify current plant design to assure both the 'A' and 'B' SG PORV steam exhausts are vertical, uncapped, and unencumbered in any way at the point where steam exits to the atmosphere from 8-inch schedule 80 piping. The elevation at which the steam will exit to the atmosphere is 650'-2" (13.61 meters above grade) for the 'A' SG PORV and 685'-5" (24.36 meters above grade) for the 'B' SG PORV.

Using the following common power law relationship:

ux = Ur (Zx / Zr)a where, x is the height of interest r represents the known reference u is the wind speed (m/s) z is the height (m) a = Iog(ux/ Ur) / Iog(Zx/Zr) = 0.236 (derived from 9 et percentile Wind Speed, i.e., 7.6 m/sec at lOm and 11.6 m/sec at 60m, using the 2002-2006 data)

Inserting the known heights and corresponding 9 5 th percentile wind speed taken from the lower level of the meteorological tower (Zr = 10 m and Ur = 7.6 m/s) yields the 9 5th percentile wind speed at the height of interest. Table 3.6.5.3-1 provides the inputs and results to determine the 9 5 th percentile wind speeds for the 'A' and 'B' SG PORV elevations.

Serial Number 12-521 Attachment 4, Rev. 1 Page 36 of 38 Table 3.6.5.3-1 9 5 th Percentile Wind Speed at SG PORV Elevation (u,)

ZX Zr Ur Ux SG PORV (meters) (meters) (m/sec) (m/sec)

A 13.61 10 7.6 8.2 B 24.36 10 7.6 9.4 As described in Regulatory Guide 1.194, X/Qs of vertical, uncapped steam releases that have an exhaust velocity in excess of 5 times the 95th percentile release height wind speed may be divided by 5 to account for buoyant plume rise. Using the larger 9 5 th percentile wind speed between both SG PORV releases above, the minimum threshold velocity to begin to credit "divide by 5" is 47 m/sec. Therefore, X/Qs applied to time periods during which the average steam exhaust velocity exceeds 47 m/sec qualify for being reduced by a factor of 5.

The minimum steam mass flow rate for SG PORV A & B for the duration of the LRA is 292 Ibm/min as shown in Table 3.6-1. The steam mass flow rate is converted to a steam exhaust velocity as follow:

Vsteam Msteam

• V -- A

• C = 125 m/sec

where, Msteam = 292 Ibm/min v = specific volume of saturated steam at atm. conditions = 26.8 ft3/Ibm*

C = unit conversion from ft/min to m/sec = 5.08E-03 A = area (ft2) of the pipe

= 7r * (D/2) 2 = 0.317

where, D = 7.625" (inside diameter)

The minimum steam exhaust velocity of 125 m/sec is >> 47 m/sec and therefore justifies reducing the ARCON96 values from Table 1.3-4 by a factor of five throughout the entire duration of the releases from either SG PORV A or B for the LRA. These reduced Control Room X/Q values are shown in Table 3.6-1.

• (assumed at atmospheric pressure saturated steam conditions)

Serial Number 12-521 Attachment 4, Rev. 1 Page 37 of 38 I 3.6.6 LRA Results The results of the design basis Locked Rotor analysis are presented in Table 3.6-2.

These results show the calculated dose for the worst 2-hour interval (EAB), and for the assumed 30-day duration of the event for the control room and the LPZ. The doses are calculated with the TEDE methodology, and are compared with the applicable acceptance criteria specified in 10 CFR 50.67 and Regulatory Guide 1.183.

Table 3.6-2 TEDE Results for the Locked Rotor Accident Location TEDE (rem) Limits (rem)

EAB 0.5 2.5 LPZ 0.4 2.5 Control Room 4.5 5

Serial Number 12-521 Attachment 4, Rev. 1 Page 38 of 38 3.7.4.1 REA Control Room X/Qs As described in Section 3.1, the onsite atmospheric dispersion factors were calculated using the ARCON96 code (Reference 5) and guidance from Regulatory Guide 1.194 (Reference 6). The REA Control Room X/Qs listed in Table 1.3-4 (Revision 0 values) were calculated for the following applicable KPS source points:

" Reactor Building Exhaust Stack

" Shield Building

" Auxiliary Building Exhaust Stack

" "A" Steam Generator PORV 9 "B" Steam Generator PORV The control room X/Qs determined represent the highest values calculated based on the shortest distance measured from each applicable source location to control room receptor location (see Figure 3.1-1).

New lower taut-string X/Q values for the 'A' and 'B' SG PORVs calculated in Revision 1 to this document are not being applied to this analysis at this time.

No changes or revision to the REA analysis were required.