PLA-6124, Response to RAI Regarding Application for License Amendment and Related TS Changes to Implement Full-Scope Alternative Source Term in Accordance with 10 CFR 50.67
| ML063310433 | |
| Person / Time | |
|---|---|
| Site: | Susquehanna  |
| Issue date: | 11/14/2006 |
| From: | Mckinney B Susquehanna |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| PLA-6124 | |
| Download: ML063310433 (17) | |
Text
Britt T. McKinney Sr. Vice President & Chief Nuclear Officer PPL Susquehanna, LLC 769 Salem Boulevard Berwick, PA 18603 Tel. 570.542.3149 Fax 570.542.1504 btmckinney@ pplweb.com p
NOV 14 2006 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Mail Stop PP 1-17 Washingt6 n, DC 20555 SUSQUEHANNA STEAM ELECTRIC STATION PROPOSED AMENDMENT NO. 281 TO LICENSE NPF-14 AND PROPOSED AMENDMENT NO. 251 TO LICENSE NPF-22:
"APPLICATION FOR LICENSE AMENDMENT AND RELATED TECHNICAL SPECIFICATION CHANGES TO IMPLEMENT FULL-SCOPE ALTERNATIVE SOURCE TERM IN ACCORDANCE WITH 10 CFR 50.67 - RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION" Docket Nos. 50-387 PLA-6124 and 50-388
References:
1)
PLA-5963, Mr. B. T. McKinney (PPL) to Document Control Desk (USNRC)
Proposed Amendment No. 281 to License NPF-14 and Proposed Amendment No. 251 to License NPF-22: "Application for License Amendment and Related Technical Specification Changes to Implement Full-Scope Alternative Source Term in Accordance with 10 CFR 50.67," dated October 13, 2005.
Supplement to Proposed Amendment No. 281 to License NPF-14 and Proposed Amendment No. 251 to License NPF-22: "Application for License Amendment and Related Technical Specification Changes to Implement Full-Scope Alternative Source Term in Accordance with 10 CFR 50.67," dated May 18, 2006.
Revision to Proposed Amendment No. 281 to License NPF-14 and Proposed Amendment No. 251 to License NPF-22: "Application for License Amendment and Related Technical Specification Changes to Implement Full-Scope Alternative Source Term in Accordance with 10 CFR 50.67," dated September 15, 2006.
Proposed Amendment No. 281 to License NPF-14 and Proposed Amendment No. 251 to License NPF-22: "Application for License Amendment and Related Technical Specification Changes to Implement Full-Scope Alternative Source Term in Accordance with 10 CFR 50.67 - Response to Request for Additional Information,"
dated September 15, 2006.
Document Control Desk PLA-6124
Supplement to Proposed Amendment No. 281 to License NPF-14 and Proposed Amendment No. 251 to License NPF-22: "Application for License Amendment and Related Technical Specification Changes To Implement Full-Scope Alternative Source Term In Accordance With 10 CFR 50.67" dated October 20, 2006
- 6) Letter from US NRC (R. V. Guzman) to Britt T. McKinney (PPL) "Request for Additional Information (RAI) - Susquehanna Steam Electric Station, Units 1 and 2 (SSES 1 and 2) -Application for License Amendment and Related Technical Specification Changes to Implement Full-Scope Alternate Source Term (TAC Nos. MC 8730 and MC 8731)," dated October 18, 2006.
In accordance with the provisions of 10 CFR 50.90, PPL Susquehanna, LLC (PPL) submitted a request (Reference 1) for license amendment and related changes to the Unit 1 and Unit 2 Technical Specifications to implement the full-scope alternate source term in accordance with 10 CFR 50.67. The request has been modified and supplemented as described in References 2-5.
The purpose of this letter is to provide the PPL responses to the NRC RAI (Reference 6).
The Enclosure to this letter contains the NRC RAI's and the PPL responses.
If you have any questions regarding this submittal, please contact Mr. Michael H. Crowthers at (610) 774-7766.
I declare under penalty of perjury that the foregoing is true and correct.
Executed on:
ti I (qi (,
Respectfully, Britt T. McKinney Document Control Desk PLA-6124
Enclosure:
PPL RAI Responses Attachments: - Figure 1 - PPL Drawing E-105004, Sheets 3 and 6 - EC-RADN-1128, Revision 1 - EC-ENVR-1058, Revision 1 cc:
NRC Region I Mr. A. Blarney, NRC Sr. Resident Inspector Mr. R. V. Guzman, NRC Project Manager Mr. R. Janati, DEP/BRP
Enclosure to PLA-6124 PPL RAI Responses
Enclosure to PLA-6124 Page 1 of 11 NRC RAI 1: The NRC staff notes two differences between the 1999-2003 meteoro-logical data summaries provided as part of the October 13, 2005 license amendment request and the 1973-1976 data summaries in the Susquehanna Final Safety Analysis Report (FSAR). During 1999-2003, neutral atmospheric dispersion conditions and winds from a generally northeasterly direction were somewhat more prominent than during the 1973-1976 period. Were both data sets collected using temperature difference with height (A-T) measurements between the 60-meter and 10-meter levels to estimate atmospheric stability, and were both periods of data collected at the same tower location?
Were the 1999-2003 measurements used in this license amendment request made at the location shown in Figure 2.1-22 of the FSAR? Is this the same place described in FSAR Section 2.3.3.1, that is, about 340 meters to the southeast of the cooling towers?
PPL Response: In 1972, a 300-foot primary meteorological tower was erected at the SSES approximately 340 meters southeast of the cooling towers. The delta temperature measurements for the 1973-1976 data were based on the temperature difference between the 90-meter and 10-meter elevations on the 300-foot primary meteorological tower.
In June 1981, the primary meteorological tower was modified by moving the upper wind and temperature sensors to 60 meters to comply with Regulatory Guide 1.23. In November 2001 the 300-foot primary tower was replaced with a 200-foot tower which is located 20 feet south-southwest of the location of the 300 foot tower. The distance measurement is from centerline to centerline of each tower' s slab. The delta temperature measurements for the 1999-2003 data were based on the temperature difference between the 60-meter and 10-meter elevations on the primary meteorological tower.
The 1999-2003 meteorological measurements were obtained from the primary meteorological tower as shown in Figure 2.1-22 of the FSAR which is the same structure/location as described in Section 2.3.3.1 of the FSAR.
The tables that follow are Tables 6 and 12 from the 2005 Meteorological Summary Report for the PPL Susquehanna Station. The tables provide historical annual average values for predominant wind direction and stability class occurrences for the PPL Susquehanna Station.
Enclosure to PLA-6124 Page 2 of 11 TABLE 6. 2005 PREDOMINANT WIND DIRECTIONS, 1973-2005 PRIMARY TOWER: 10 METER LEVEL Highest Frequency Second Highest Frequency Year Direction Percent Direction Percent From Occurrence From Occurrence 1973-1976 WSW 10.77 W
10.68 1977 W
13.98 WSW 13.00 1978 W
13.42 ENE 13.32 1979 ENE 11.64 E
10.59 1980 W
10.49 ENE 9.92 1981 W
11.58 E
9.54 1982 ENE 12.17 WSW 10.15 1983 NE 12.88 SW 10.83 1984 SW 13.17 SW 11.82 1985 ENE 13.14 ENE 11.72 1986 ENE 11.01 SW 10.71 1987 ENE 14.72 NE 10.69 1988 ENE 13.79 SW 9.80 1989 ENE 15.29 SW 9.91 1990 ENE 15.30 SW 10.90 1991 ENE 16.12 SW 10.36 1992 ENE 15.02 NE 9.55 1993 ENE 15.33 NE 9.92 1994 ENE 16.73 SW 10.90 1995 ENE 14.37 SW 11.01 1996 ENE 14.83 SW 10.59 1997 ENE 15.37 SW 11.58 1998 ENE 17.09 NE 10.01 1999 ENE 16.16 SW 10.23 2000 ENE 16.13 SW 9.86 2001 ENE 16.98 SW 10.49 2002 ENE 14.46 SW 11.47 2003 ENE 14.14 NE 10.96 2004 ENE 13.60 NE 11.39 2005 ENE 15.26 SW 9.63 This table presents the first and second most predominant wind directions at the SSES site.
In 2005, winds were most frequent from the East-northeast, originating from that sector 15.26%
of the time.
Enclosure to PLA-6124 Page 3 of 11 TABLE 12. ANNUAL PASQUILL STABILITY CLASS OCCURRENCES PRIMARY TOWER 1973-2005 (in percent)
YEAR A
B C
D E
F G
1973-1976 16.23 7.64 4.24 30.72 26.17 10.51 4.49 1977 6.62 3.29 1.45 34.03 38.52 11.49 4.59 1978 1.38 1.82 0.79 34.72 44.72 12.33 4.23 1979 1.36 1.72 1.44 38.18 41.27 11.46 4.56 1980 5.68 4.02 2.41 41.84 27.37 12.34 6.34 1981 11.29 3.45 2.82 32.80 29.29 11.38 8.97 1982 15.68 3.48 2.83 23.41 29.99 14.00 11.59 1983 4.35 3.30 5.02 39.32 28.69 12.02 7.30 1984 3.57 2.72 4.23 34.36 33.51 13.50 8.10 1985 5.36 3.50 3.98 35.44 33.36 12.05 6.30 1986 5.62 3.13 3.67 32.92 35.78 11.26 7.62 1987 9.33 2.53 3.61 34.09 28.72 13.43 8.29 1988 13.83 3.60 4.19 31.10 27.26 12.74 7.28 1989 4.57 3.00 4.51 40.90 30.01 10.72 6.28 1990 3.37 2.53 3.59 39.34 29.79 13.93 7.44 1991 5.25 3.75 4.55 39.38 25.28 14.24 7.55 1992 3.06 2.91 4.80 47.76 26.26 11.09 4.11 1993 3.78 3.56 4.11 39.33 26.68 12.19 7.34 1994 6.24 3.18 4.43 34.25 29.55 13.26 9.08 1995 5.34 3.48 4.62 41.06 27.08 11.29 7.14 1996 2.17 2.22 3.94 44.42 30.79 11.13 5.33 1997 4.98 3.66 5.49 38.80 28.05 12.87 6.16 1998 2.88 2.94 4.08 35.15 30.97 15.58 8.39 1999 5.63 3.35 4.05 38.27 27.24 11.94 9.52 2000 2.65 3.08 4.63 44.92 25.47 11.86 7.39 2001 4.55 3.82 5.22 37.39 27.47 13.49 8.06 2002 3.21 3.71 4.93 40.47 26.43 13.28 7.97 2003 4.10 1.70 2.89 43.99 30.15 11.08 6.09 2004 3.51 3.30 5.24 39.42 32.38 11.56 4.89 2005 12.48 3.32 3.68 30.47 28.85 12.87 8.33 Pasquill stability class assignments were based on the temperature difference between the 90-meter and 10-meter levels from 1973 through July 1981. From July 1981 to present, the stability class assignment is based on the temperature difference between the 60-meter and 10-meter levels.
Enclosure to PLA-6124 Page 4 of 11 NRC RAI 2: Page 11 of Attachment 2 to the October 13, 2005 submittal, references Figures 1 and 2 which show the location of postulated release and receptor locations.
Where are these figures in the submittal? Are the figures of sufficient detail (e.g., drawn approximately to scale and showing true north) to permit the NRC staff to make rough estimates of distances, directions, and heights for comparison with the inputs used in the ARCON96 (computer code) calculations?
PPL Response: These figures were inadvertently omitted from the October 13, 2005 submittal. Figure 1 showed the locations of the buildings, the release points (SGTS and Turbine Building Exhaust Vents) and the receptor (CRHE outside air intake). Figure 2 showed the locations of the Turbine Building and Reactor Building main steam tunnel blowout panels. Attachment 1 to this enclosure contains a revised Figure 1, which shows the buildings, the release points, and the original AST submittal and the new CRHE outside air intake locations. Attachment 2 provides copies of PPL drawings E-105004, Sheet 3 and E-105004, Sheet 6 with distances provided for blowout panel release points.
In the original AST submittal the CRHE outside air intake was located on the Unit 2 Reactor Building roof at column lines U and 36 and at roof elevation 872'-0". It should be noted that the original AST submittal calculations were completed with the outside air intake located at a point that was at the southeast comer of the reactor building roof and not exactly at colunm lines U & 36. The new location of the outside air intake is approximately 2'- 3" west of column line U, 5'- 6.5" south of column line 37.4 at elevation 810' 3". Heights, distances and angles are also included in the Attachment 1 figure. The new intake location is at approximately the same angles from the release points as the original intake location.
The original intake location in the October 13, 2005 AST submittal was at the same elevation as the release points. The new intake location is not at the same elevation as the release points. Additionally, the new intake location increases the distances from the release points to the receptor when compared to the distances from the original intake location used in the analyses. Since the distance from the release points to the new intake increases from that assumed in the analyses and a height difference exists between the release points and the new intake location, and the direction from the release points to new intake location has not changed, the control room atmospheric dispersion factors presented in the AST submittal for the LOCA, CRDA, and EHA/FHA are conservative for the new intake location and do not have to be modified. The Main Steam Line Break accident has been revised as a result of RAI 3. See the response to RAI 3 for detailed discussion. A comparison of the x/Q values for the original submittal intake location and the new intake location for the three release points is provided as follows. The comparison shows that the x/Q values for the original submittal intake location used in the AST radiological analyses bound the x/Q values that would be calculated for the new intake location.
Enclosure to PLA-6124 Page 5 of 11 Comparison of Z/Q values for the New Intake Location @ 810' 3" versus the x/Q values for the Original Submittal Intake Location on the RB Roof Time Period x/Q values for the x/Q values for the Ratio New Intake Location Original Submittal (New Intake
@ 810' 3" Intake Location on Location x/Q) sec/mi3 RB Roof divided by (1) sec/m 3 (Original Submittal (2)
Intake Location Z/Q)
TB U2 Exhaust Vent 0 - 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> 1.21E-03 1.36E-03 0.89 2 - 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> 8.76E-04 1.03E-03 0.85 8 - 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> 3.16E-04 3.36E-04 0.94 1 - 4 days 1.92E-04 2.20E-04 0.87 4 - 30 days 1.61E-04 1.85E-04 0.87 TB U1 Exhaust Vent 0 - 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> 1.09E-03 1.24E-03 0.88 2 - 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> 8.01E-04 9.55E-04 0.84 8 - 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> 2.89E-04 3.14E-04 0.92 1 -
4 days 1.72E-04 1.99E-04 0.86 4 - 30 days 1.50E-04 1.73E-04 0.87 SGTS Exhaust Vent 0 - 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> 1.16E-03 1.45E-03 0.80 2 - 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> 8.64E-04 1.12E-03 0.77 8 - 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> 3.09E-04 3.55E-04 0.87 1 - 4 days 1.87E-04 2.29E-04 0.82 4 - 30 days 1.60E-04 2.01E-04 0.80 (1): CRHE intake along south wall of U2 reactor building (2): CRIIE intake on roof of U2 reactor building
Enclosure to PLA-6124 Page 6 of 11 NRC RAI 3: Page 12 of Attachment 2 states that the X/Q values for releases from the main steamline blowout panels were generated using the puff methodology described in Section 4.4.4, not the ARCON96 calculations that were provided in calculation number EC-ENVR-1058. Are the postulated energy of release and arrangement of the blowout panels adequate to blow out all of the walls that might otherwise temporarily contain and retard dispersion of at least part of the effluent?
Would the puff be buoyant? Is the intake location higher than the height of release?
If so, what is the justification for assuming a difference in elevation between the height of release and the intake height given that Regulatory Guide 1.194, "Atmospheric Relative Concentrations for Control Room Radiological Habitability Assessments at Nuclear Power Plants," states that the difference in height should be assumed to be zero for this case?
PPL Response: For a main steam line break, the blowout panels will release due to the significant increase in steam tunnel pressure. The panels will release on a timeframe of hundredths of a second. Once the blowout panels release, a flow path will be established directly to the environment. The reactor building main steam line blowout panel has a flow area of approximately 420 ft2 (approximately 32' x 13' opening). There are two turbine building blowout panels each with a flow area of approximately 75 ft2 (approximately 14' x 5.5' opening) for a total flow area of 150 ft2. Due to the presence of the large openings to the environment and a pressure difference between the room and the environment, all of the activity from the break until break isolation will be released to the environment.
The atmospheric dispersion calculations for the Main Steam Line Break (EC-RADN-1128) have been revised to conservatively assume that the height difference between the height of the release and the intake height is zero. Additionally, the calculation has been revised to align assumptions concerning atmospheric dispersion factors and activity released. The originally submitted analysis determined atmospheric dispersion factors for the Main Steam Line Break based on the amount of steam release (which is a fraction of the total release) that will yield a maximum X/Q value. The analysis then assumed that the activity released is a function of the total steam released (which is different than the amount of steam released for the atmospheric dispersion analysis). The dose consequences were then calculated based on these two factors. The dose consequences are now calculated by maximizing the product of the atmospheric dispersion factor and the activity release using the same steam release for the atmospheric dispersion calcula-tion and the activity release calculation. These calculations are shown in calculation EC-RADN-1128, Revision 1 which is included as Attachment 3.
Enclosure to PLA-6124 Page 7 of 11 NRC RAI 4: Table 4.1-3 on page 12 of Attachment 2 provides two sets of x/Q values, both listing the same three postulated release points. What is the basis for the differences in the inputs to the two sets of ARCON96 calculations? What is/are the actual intake height(s)?
PPL Response: The first set of data in Table 4.1-3 is taken from EC-ENVR-1059 and represents the atmospheric dispersion (x/Q) values for the CRHE outside air intake.
The intake height input to ARCON96 was 61.9 meters which corresponds to an actual plant elevation of 872' and was at the same elevation as the release points. Note that the new intake height is 810' 3" and the equivalent intake height that would be input into ARCON96 is 44.27m. The height difference is conservatively neglected for the calculation of the atmospheric dispersion factors for the new outside air intake location.
The atmospheric dispersion values from EC-ENVR-1059 were used in RADTRAD to determine the dose contributions (approximately 3.9 Rem TEDE for the DBA LOCA) due to the activity released from various release points to the outside air intake and subsequently drawn into the control room habitability envelope.
The second set of data in Table 4.1-3 is taken from EC-ENVR-1058 and provides atmospheric dispersion (x/Q) values representative of the external cloud engulfing the Control Room Habitability Envelope. The external cloud dose calculated with this set of values is further attenuated by the concrete shield walls of the building resulting in a dose of approximately 0.05 Rem TEDE to the control operators for the DBA LOCA. An average elevation of 36.9 meters was used as the intake and release height, i.e. Ah = 0.
See additional discussion in the response to RAI 5.
Enclosure to PLA-6124 Page 8 of 11 NRC RAI 5: A taut string methodology described in RG 1.194 was used to generate inputs to the ARCON96-generated X/Q values. When this methodology is used, it may be advisable to input the actual release height as both the release and intake heights, so the taut string estimate factors in the slant range for differences in height. In addition, the actual release height should be input to utilize winds representative of the height of release which may be different than winds at the height of the intake. For example, the ARCON96 calculation for the Reactor Building Unit 1 Closest Distance has a release height input of zero meters and an intake height input of 36.9 meters. What criteria was used to determine the closest distance? Is the closest point to the intake at a height of zero meters? Limiting X/Q values generated by the ARCON96 methodology generally occur with moderate, not light, wind speeds so assuming a release near the ground may underestimate the wind speeds and resultant X/Q values if the release could occur at a higher elevation. Therefore, please confirm that the taut string calculations adequately address the heights of release, differences in height of the release and receptor and, based upon these considerations, have correctly identified the limiting source/receptor pairs.
Note that RG 1.194 provides guidance concerning consideration of diffuse area sources for cases when a release may not be from a point location (e.g., a single vent).
PPL Response: Credit for taut string distances was not taken in EC-ENVR-1059 which provides the atmospheric dispersion (X/Q) values for the control structure outside air intake. Conservative horizontal distances were input to ARCON96. As noted in the response to RAI #4, this set of atmospheric dispersion (x/Q) values was used in RADTRAD to determine the dose contributions (approximately 3.9 Rem TEDE for the DBA LOCA) due to the activity released from various release points to the outside air intake and subsequently drawn into the control room habitability envelope.
Calculation EC-ENVR-1058 provides the atmospheric dispersion (X/Q) values used for estimating the dose consequences (approximately 0.05 Rem TEDE for the DBA LOCA) from the external cloud engulfing the CRHE. Calculation EC-ENVR-1058 has been revised in response to RAI 7 to correct the wind speed units input to ARCON96 (meters/sec to mph). In addition, the revision deletes the nine previously analyzed release points not used in the subsequent radiological analyses and retains the atmospheric dispersion (x/Q) values for the three release points used in the AST radiological analyses. These are:
Turbine Building Unit 1 exhaust vent; Turbine Building Unit 2 exhaust vent; Standby Gas Treatment System exhaust vent.
Taut string distances were used for these release points. As noted in the Response to RAI 4, an average elevation of 36.9 meters (121 feet above grade) was used as the receptor and release height, i.e., AH = 0 in the ARCON96 runs. The actual release height for
Enclosure to PLA-6124 Page 9 of 11 these three release points is approximately 60.6 meters (about 200 feet above grade).
This is well above the roof of the Control Building which is at elevation 134 feet above grade.
Therefore, the use of the average value of 121 feet above grade for the release and receptor is considered to provide a conservative set of values, since this is equivalent to the upper portion of the Control Building walls. Nevertheless, to compare the effects of using the release height in ARCON96, the case for the Turbine Building Unit 1 exhaust vent was re-analyzed inputting the release height equal to a receptor height equal to 60.6 meters.
I The results of this run compared to the values provided in the AST submittal are summarized as follows:
Comparison of X/Q Values for Release - Receptor Heights of 36.9 m and 60.6 m (sec /m3)
TB Unit 1 8 to 24 Release Receptor Exhaust Vent 0 to 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> 2 to 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> hours 1 to 4 days 4 to 30 days Height Height EC-ENVR-1058 5.09E-03 4.15E-03 1.20E-03 1.16E-03 1.01E-03 36.9 m 36.9 m 0 to AST Submittal ARCON96 5.30E-03 4.05E-03 1.15E-03 1.15E-03 L.00E-03 60.6 m 60.6 m Results with Change in Elevations Ratio of X/Q at 1.041 0.976 0.958 0.991 0.990 60.6 m to x/Q at 36.9 m.
As seen except for the time period 0 to 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />, the atmospheric dispersion (X/Q) values based on the elevation of 36.9 meters are bounding. Reviewing the post-LOCA external dose consequences provided in Table 21 of calculation EC-RADN-1125 included with the Reference 1 submittal, it is seen that the dose contribution in the period 0 to 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> is much less than the dose contribution from 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> to 30 days. Therefore, the overall effect would be a reduction in the reported doses. The above values are provided for comparing the effect of the release elevation only on the external cloud atmospheric dispersion (x/Q) values. The final external cloud atmospheric dispersion (X/Q) values corrected for wind speed units are provided in the response to RAI 7. It should be noted these corrected values provide additional conservatism relative to the values used in determining the post-LOCA external cloud dose consequences in the AST submittal.
Enclosure to PLA-6124 Page 10 of 11 NRC RAI 6: Do the X/Q values used in the dose assessments represent the limiting cases should a loss of offsite power or other single failure occur? For example, would the effluent be released to the environment from a different and more limiting location than the current calculations that assume releases from facility vents? Do the X/Q values used in the dose assessments include consideration of possible secondary containment bypass releases to the intake or as unfiltered inleakage?
PPL Response: The atmospheric dispersion (x/Q) values used in the dose assessments represent the limiting cases should a loss of offsite power or other single failure occur.
In the DBA LOCA case, primary containment leakage and ESF leakage to the reactor building are released to the environment via the SGTS vent. The secondary containment bypass leakage and MSIV leakage is released from the Turbine Building vent. No hold-up or filtration of the secondary containment bypass leakage is credited in the analysis.
Enclosure to PLA-6124 Page 11 of 11 NRC RA 7: ARCON96 computer printouts in calculation number EC-ENVR-1058 show wind speed inputs in meters per second whereas EC-ENVR-1059 show wind speed in miles per hour. Were the same hourly meteorological data files used for both sets of calculations? Please review/revise the control room x/Q calculations to ensure that input units are consistent with the meteorology data file(s).
PPL Response: The windspeed information in EC-ENVR-1058, Revision 1 was incorrectly input as meters/ second. The calculation has been revised and is included as. The change in the control room x/Qs using mph compared to meters/second are summarized as follows.
Comparison of X/Q Values Using Wind Speed Input to ARCON96 in Meters/See Versus Miles/Hr For the Location of the CRHE External Cloud (sec /mf3)
Outside Control 8 to 24 Building Location 0 to 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> 2 to 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> hours 1 to 4 days 4 to 30 days TB Unit I Exhaust Vent (m/s) 5.09E-03 4.15E-03 1.20E-03 1.16E-03 1.01E-03 TB Unit I Exhaust Vent (mph) 4.03E-03 3.61E-03 1.56E-03 1.12E-03 8.71E-04 Ratio 0.79 0.87 1.30 0.97 0.86 TB Unit 2 Exhaust Vent (m/s) 6.OOE-03 4.93E-03 1.44E-03 1.38E-03 1.21E-03 TB Unit 2 Exhaust Vent (mph) 4.72E-03 4.25E-03 1.84E-03 1.32E-03 1.03E-03 Ratio 0.79 0.86 1.28 0.96 0.85 SGTS Exhaust Vent (m/s) 5.15E-03 4.22E-03 1.23E-03 1.19E-03 1.04E-03 SGTS Exhaust Vent (mph) 4.15E-03 3.61E-03 1.57E-03 1.12E-03 8.86E-04 Ratio X/Q using miles per hour 0.81 0.86 1.28 0.94 0.85 to X/Q using meters per second The effect of the change in the windspeed units on the calculated DBA-LOCA dose from the external cloud using the data in EC-RADN-1125 will reduce the dose from 0.0515 Rem TEDE to 0.048 Rem TEDE.
to PLA-6124 Figure 1