Text

Response to the Request for Additional Information Regarding the License Amendment Request to Revise the Licensing Bases for Protection from Tornado Generated Missiles
	ML18191B151
Person / Time
Site:	McGuire, Mcguire ; (NPF-009, NPF-017)
Issue date:	07/03/2018
From:	Teresa Ray; Duke Energy Carolinas
To:	; Document Control Desk, Office of Nuclear Reactor Regulation
References
	MNS-18-036
	Download: ML18191B151 (56)
	v • d • e

(_~ DUKE ENERGY July 3, 2018 Serial No. MNS-18-036 U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 ATTENTION: Document Control Desk Duke Energy Carolinas, LLC McGuire Nuclear Station, Units 1 and 2 Docket Nos. 50-369 and 50-370 Renewed License Nos. NPF-9 and NPF-17 Thomas D. Ray, P.E.

Site Vice President McGuire Nuclear Station Duke Energy MGOlVP I 12700 Hagers Ferry Road Huntersville, NC 28078 10 CFR 50.90 0: 980.875.4805 f: 980.875.4809 Tom.Ray@duke-energy.com

Subject:

Response to the Request for Additional Information regarding the License Amendment Request to Revise the Licensing Bases for Protection from Tornado-Generated Missiles By letter dated December 8, 2017 (ADAMS Accession No. ML17352A364 ), Duke Energy requested changes to the McGuire Nuclear Station, Units 1 and 2 (McGuire) Updated Final Safety Analysis Report (UFSAR). The proposed License Amendment will revise the McGuire licensing bases for protection from tornado-generated missiles.

This letter provides the additional information requested by the NRC staff via electronic mail from Michael Mahoney dated May 18, 2018 (ADAMS Accession No. ML18138A466). The NRC staff's questions and Duke Energy's responses are provided in Attachment 1. Revised UFSAR mark-ups are provided in Attachment 2.

The conclusions reached in the original determination that the LAR contains No Significant Hazards Considerations and the basis for the categorical exclusion from performing an Environmental Impact Statement have not changed as a result of these responses to the request for additional information.

Please contact Lee A. Hentz at 980-875-4187 if additional questions arise regarding this RAI response.

www.duke-energy.com

U.S. Nuclear Regulatory Commission MNS-18-036 Page 2 I declare under penalty of perjury that the foregoing is true and correct. Executed on July 3, 2018.

Sincerely, 6~

Vice President McGuire Nuclear Station Attachments cc w/ Attachments:

C. Haney, Administrator, Region II U.S. Nuclear Regulatory Commission Marquis One Tower 245 Peachtree Center Ave., NE, Suite 1200 Atlanta, GA 30303-1257 A. Hutto, NRC Senior Resident Inspector McGuire Nuclear Station M. Mahoney, Project Manager U.S. Nuclear Regulatory Commission 11555 Rockville Pike Mail Stop 0-8 G9A Rockville, MD 20852-2738 W. L. Cox, Ill, Section Chief North Carolina Department of Environment and Natural Resources Division of Environmental Health Radiation Protection Section 1645 Mail Service Center Raleigh, NC 27699-1645

ATIACHMENT 1 By letter to the U.S. Nuclear Regulatory Commission (NRC) dated December 8, 2017 (Agencywide Documents Access Management System (ADAMS) Accession No. ML17352A364), Duke Energy, (the licensee), requested changes to the McGuire Nuclear Station, Units 1 and 2 (McGuire) Updated Final Safety Analysis Report (UFSAR). The proposed amendment will revise the McGuire licensing bases for protection from tornado-generated missiles.

The NRC requires that nuclear power plants be designed to withstand the effects of tornado and high-wind-generated missiles so as not to adversely impact the health and safety of the public in accordance with the requirements of General Design Criterion (GDC) 2, "Design Bases for Protection against Natural Phenomena," and GDC 4, "Environmental and Dynamic Effects Design Bases," of Appendix A, "General Design Criteria for Nuclear Power Plants," to Title 10 of the Code of Federal Regulations (10 CFR) Part 50, "Domestic Licensing of Production and Utilization Facilities."

The safety evaluation report (SER) approving the TORMIS methodology dated October 26, 1983 (ADAMS Accession No. ML080870291) requires licensees using the methodology to consider and address five points in their applications.

In accordance with Regulatory Issue Summary (RIS) 2008-14 dated June 16, 2008 (ADAMS Accession No. ML080230578), the TORMIS methodology is an NRC-approved method for addressing identified deficiencies in complying with a plant's current licensing basis for tornado missile protection. It provides licensees the option of revising the plant's licensing basis for tornado missile protection from a purely deterministic methodology to one that includes limited use of a probabilistic approach. In RIS 2008-14, the TORMIS methodology is approved for situations where (1) a licensee identifies existing plant structures, systems, and components (SSCs) that do not comply with the current licensing basis for positive tornado missile protection of the plant and (2) it would require costly modifications to bring the plant into compliance with the current licensing basis.

The NRC staff has reviewed the application and, based upon this review, determined that additional information is needed to complete our review. Please provide a response on the docket within 45 days of this correspondence.

1

ATIACHMENT 1 Request for Additional Information (RAl)-01 The proposed UFSAR, Section 3.5.2.8 markup included in Enclosure 2 does not appear to be consistent with current UFSAR Section 3.3.

The proposed UFSAR, Section 3.5.2.8 markup states:

"Table 3-8 provides a summary of the design basis tornado-generated missiles. The integrity of all Category 1 structures is not impaired by these missiles. This is accomplished either deterministically by designing the exposed structure of steel reinforced concrete capable of withstanding the impact of tornado-generated missiles, or probabilistically by showing that the structure will not be impacted or will not be damaged beyond an acceptable criteria if impacted as discussed in Section 3.5.2.8.1.3" Current UFSAR Section 3.3 states, "All Category 1 structures, except those structures not exposed to wind, are designed for tornado wind loads."

The proposed UFSAR Section 3.5.2.8 markup seems to imply that some Category 1 structures are not deterministically designed to withstand missiles, which appears to be at inconsistent with current UFSAR, Section 3.3.

RAl-01a: The NRC staff requests the licensee to clarify the application of the proposed USFAR, Section 3.5.2.8 markup with respect to Category 1 structures.

RIS 2008-1 4 states:

The TORMIS methodology is not currently approved for the following :

Justifying not providing positive tornado missile protection (i.e., barrier) for plant modifications removing existing tornado missile barriers eliminating or relaxing of TS [Technical Specifications] requirements that have been established for tornado missile barriers and safety-related equipment promoting operational flexibility or convenience The current wording in the proposed UFSAR, Section 3.5.2.8 markups stating, in part,"...

accomplished either deterministically by designing the exposed structure of steel reinforced concrete capable of withstanding the impact of tornado-generated missiles, or probabilistically by showing that the structure will not be impacted or will not be damaged beyond an acceptable criteria... " appears to support such applications of the future use of TORM IS.

RAl-01 b: The NRC staff requests the licensee to clarify its application of proposed UFSAR, Section 3.5.2.8, with regard to future use of TORMIS.

2

ATTACHMENT 1 Duke Energy Response for RAl-01a:

UFSAR Section 3.3 only addresses wind loads on Category 1 structures. UFSAR Section 3.5 addresses missile protection. Section 3.5.1.3 in particular is for tornado-generated missiles.

This section has a proposed UFSAR change as shown in the LAR Enclosure 2, page 5. A revised version is given below.

Change the proposed UFSAR change to Section 3.5.2.8 from:

To:

Table 3-8 provides a summary of the design basis tornado-generated missiles. The integrity of all Category 1 structures is not impaired by these missiles. This is accomplished either deterministically by designing the exposed structure of steel reinforced concrete capable of withstanding the impact of tornado-generated missiles, or probabilistically by showing that the structure will not be impacted or will not be damaged beyond an acceptable criteria if impacted as discussed in Section 3.5.2.8.1.3.

Table 3-8 provides a summary of the design basis tornado-generated missiles. The integrity of aU Category 1 structures is not impaired by these missiles. This is accomplished by designing the exposed structure of steel reinforced concrete capable of withstanding the impact of design basis tornado-generated missiles. Modifications to existing or the design of new Category 1 structures shall conform to the requirements of NRC RIS 2008-14.

Table 3-63 provides a list of Category 1 structures, systems, and components that have not been designed to withstand the impact of design basis tornado-generated missiles.

These SSCs were probabilistically shown that they will not be impacted or will not be damaged beyond an acceptable criteria if impacted as discussed in Section 3.5.2.8.1.3.

Also, change the proposed UFSAR change to Section 3.5.1.3 from:

To:

All Category 1 structures exposed to these design basis missiles are designed to withstand their effect with the exception of those Structures Systems and Components included in the TORMIS probabilistic tornado risk analysis listed in Table 3-63 and as discussed in Section 3.5.2.8.1.1. A tabulation of the design basis tornado generated missiles is given in Table 3-8 AU Category 1 structures exposed to these design basis missiles are designed to withstand their effect with the exception of those Category 1 Structures Systems and Components included in the TORMIS probabilistic tornado risk analysis listed in Table 3-63 and as discussed in Section 3.5.2.8.1.1. A tabulation of the design basis tornado generated missiles is given in Table 3-8.

3

ATTACHMENT 1 Duke Energy Response for RAl-01b:

MNS's intention is to use TORMIS in the future if additional existing Category 1 structures are discovered that do not meet the protection requirement from design basis tornado-generated missiles as listed in UFSAR Table 3-8. Designs of future new SSCs and modification to existing SSCs will meet the requirements of UFSAR Section 3.5.1.3, "Tornado Generated Missiles" and Section 3.5.4, "Barrier Design Procedure." The proposed UFSAR changes are modified below to include a reference to the above stated RIS 2008-14 TORMIS methodology limitations.

Change the proposed UFSAR change to Section 3.5.2.8 from:

To:

Table 3-8 provides a summary of the design basis tornado-generated missiles. The integrity of all Category 1 structures is not impaired by these missiles. This is accomplished either deterministically by designing the exposed structure of steel reinforced concrete capable of withstanding the impact of tornado-generated missiles, or probabilistically by showing that the structure will not be impacted or will not be damaged beyond an acceptable criteria if impacted as discussed in Section 3.5.2.8.1.3.

Table 3-8 provides a summary of the design basis tornado-generated missiles. The integrity of ~ Category 1 structures is not impaired by these missiles. This is accomplished by designing the exposed structure of steel reinforced concrete capable of withstanding the impact of design basis tornado-generated missiles. Modifications to existing or the design of new Category 1 structures shall conform to the requirements of NRC RIS 2008-14.

Table 3-63 provides a list of Category 1 structures, systems, and components that have not been designed to withstand the impact of design basis tornado-generated missiles.

These SSCs were probabilistically shown that they will not be impacted or will not be damaged beyond an acceptable criteria if impacted as discussed in Section 3.5.2.8.1.3.

Revised UFSAR mark-ups showing the above are provided in Attachment 2.

4

ATTACHMENT 1 RAl-02 The LAR provides discussion on each of the five attributes of TORM IS SER. One of the five review points in the TORMIS SER specifies users should provide sufficient information to justify the assumed missile density based on site specific missile sources and dominant tornado paths of travel.

The LAR includes a brief statement on page 18, "The plant site is described by specifying the geometry, location, and material properties of the structures/components and the location of potential missile sources. Missile sources (buildings, houses, storage areas, vehicles, etc.) are modeled to a distance of approximately 2,500 feet. This process includes the development of missile origin zones around the plant and surveying the types and quantities of missiles in each zone."

The LAR neglects potential shielding effects by stating in Enclosure 1, page 14, "In TORMIS, the effects of local obstructions, buildings, and structures are neglected in simulating the tornado winds. Thus, for example, tornado winds flow through the Turbine Building without consideration of either terrain/site roughness or blockage/interference of the reinforced concrete and heavy steel frame structures."

Bases on its review of the submittal, the NRC staff is unable to locate details or layouts of the development missile origin zones depicting the type, quantity or density of missile in each zone. The LAR also does not appear to include list of targets, shields and buildings (missile source), which are typically provided in TORM IS submittals. In addition, it is unclear what buildings are used for deconstruction to derive 214,000 missiles.

Therefore, the NRC staff requests the licensee to justify how the TORM IS SER was met and provide details of the assumed missile density based on location-specific missile counts and provide the list of targets, shields and buildings (missile source) used in the analysis.

Duke Energy Response:

TORMIS SER review point 4 states:

"The assumptions concerning the locations and numbers of potential missiles presented at a specific site are not well established in the EPRI studies. However, the EPRI methodology allows site specific information on tornado missile availability to be incorporated in the risk calculation. Therefore, users should provide sufficient information to justify the assumed missile density based on site specific missile sources and dominant tornado paths of travel."

LAR Enclosure 1, page 18 discusses the walk-downs undertaken to characterize the site-specific population of potential missiles located throughout the MNS site, and the total number of potential missiles considered for each level of tornado intensity. The following provides additional details regarding the development of the zone and structure missile populations at the site, and the complete listing of safety, missile shielding, and missile source targets in the MNS TORMIS model.

5

ATTACHMENT 1 Zone Missile Details Missiles source zones were defined based on review of overall site plans and aerial photos of the plant. Zone boundaries were defined by features such as roads, fence lines, edges of buildings, changes in land use, and homogeneity of areas. The missile zones cover an area that extends out a minimum of 2500 feet in all directions from the safety-related targets. This distance is based on a sensitivity study performed in the original TORMIS research (LAR References 3 and 4). The sensitivity study concluded that missiles beyond 2,000 feet did not need to be considered in the risk assessment. This value was factored up to 2500 feet in modern TORMIS analyses to be conservative. This distance from the safety-related targets is maintained in all directions and not just along the most likely tornado paths.

Figure 1 shows the location of the 33 missile zones defined for the analysis overlaid onto an aerial photo of the plant. Figure 2 shows a 3-D AutoCAD rendering of the TORM IS model that shows the missile source zones in green, safety-related targets in red, missile shielding targets in gray and missile source targets in orange. Only the 2-D footprints of the missile source structures are shown in this rendering.

6

ATTACHMENT 1 Figure 1. Zone Layout for MNS TORMIS Analysis 7

ATIACHMENT 1 Figure 2. 3-D AutoCAD Representation of MNS TORMIS Model - Southwest Isometric 8

Subset I

2 3

4 5

6 7

8 9

10 I I 12 13 14 15 16 17 18 19 20 21 22 23 Subs e t I

2 3

4 5

6 7

8 9

10 II 12 13 14 IS 16 17 18 19 20 21 22 23 ATTACHMENT 1 The total number of missiles was surveyed by missile type for each missile source zone. Table 1 summarizes the number of missiles observed by missile type for each of the 33 zones.

Table 1. Number of Missiles Surveyed by Missile Source Zone Missile Description Zone Number I

2 3

4 5

6 7

8 9

10 11 12 13 14 15 Rebar 0

0 8

0 0

0 94 0

0 30 0

0 0

GasCvlinder 0

0 10 0

0 0

0 97 13 2

0 2

0 0

I DrwnTank 0

0 0

0 3

26 0

0 0

2 2

0 2

Ut;JitvPole 0

8 0

7 0

0 0

4 2

0 3

0 0

CableReel 0

0 0

0 I

7 25 0

0 11 0

0 0

Pine 3in 78 SI 138 44 160 145 83 340 203 263 128 270 56 0

81 Pi= 6in 0

0 0

4 0

0 0

so 0

18 0

67 0

0 0

Pine 12in 0

0 I

0 0

0 I

6 0

7 0

0 0

Stora2eBin 4

0 2

0 0

7 I

56 II 10 I

2 0

0 19 Pavers 0

0 0

ConcreteFra1m1ent 0

0 0

12 0

0 ISO 0

0 100 0

0 0

WoodBeam 0

6 0

0 0

24 7

9 0

170 98 0

32 WoodPlank 0

10 22 0

0 0

0 942 11 6 0

0 1,040 0

0 510 Meta1Siding 5

21 10 0

8 5

0 29 35 5

0 32 0

0 so PlvwoodSheet 0

0 0

84 2

0 0

10 0

0 0

W1deFlanoe 0

O*

0 0

10 13 0

0 5

0 0

ChannelSection 0

0 0

19 4

4 0

0 0

SmallEouinment 0

0 I

0 0

I 19 0

0 0

6 LargeEauiornent 0

0 0

3 0

0 0

14 0

0 0

SteelframeGratimz I

I 0

30 0

144 0

108 20 0

0 23 0

0 I

LargeSteelframe 0

I 0

0 0

4 0

0 0

Vehicle 0

I II 0

0 0

2 2 1 15 2

I 24 20 0

745 Tree 0

0 0

0 42 0

35 56 4,900 Total Missiles 88 99 203 88 178 326 90 1,808 720 323 174 1,804 214 56 6,347 Zone Number Missile Description 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 Rebar 0

0 0

30 0

0 0

GasCvlinder I I 0

0 0

I 0

0 0

17 0

21 DrumTank 4

0 0

0 II 0

I UtilrtvPole I I 5

3 0

4 I

5 0

0 4

0 27 0

0 0

Cable Reel I

0 0

0 10 0

0 0

0 Pioe Jin 11,346 0

44 60 439 352 113 2 13 156 194 105 168 255 175 208 Pine 6in 0

0 0

0 28 0

0 Pini' 12in 0

0 0

0 12 0

0 Stora'-!.eBin 3

0 0

3 I

6 10 0

0 0

10 0

2 Pavers 0

0 0

ConcreteFra2.ment 0

0 0

WoodBeam 10 34 0

0 0

0 168 0

2 WoodPlank 400 18 0

7 0

0 0

0 273 0

216 Meta1Sidin2.

8 8

8 0

0 0

12 12 0

0 0

0 SI 0

72 PlvwoodSheet 62 0

0 0

0 15 0

0 0

0 20 0

86 WideFlanQ:e 0

0 0

ChannelSection 0

0 0

SmallEouioment 0

I 0

0 0

2 6

0 0

0 I

0 2

Lar2eEauioment 0

I 0

30 0

0 I

2 6

0 0

0 I

0 2

Stee!FrameGratirw 132 0

0 0

I 4

0 0

36 0

2 LargeSteelframe 0

0 0

0 I

Vehicle 9

65 357 457 I

2 28 0

I 0

0 0

550 0

50 Tree 626 267 0

162 I i2 868 796 149 6,8j4 8,879 4,372 5,644 2,98 1 4,039 3,487 Total Missiles 12,623 399 412 716 566 1,226 958 403 7,013 9,077 4,477 5,869 4,414 4,214 4,152 16 47 10 2 1 7

4 48 1 76 78 34 0

12 207 233 177 6

5 11 7 19 0

71 0

64 980 2,649 33 0

7 7

40 0

11 7 15 IS 9

0 0

130 10 0

40 4

9 4

8 78 2,478 2,97 1 The number of trees over 3 inches in diameter were counted within a 100 foot by 100 foot treed area to estimate a tree density of 70 trees per 10,000 square feet (sf) of treed area. The number of trees within each outlying missile zone was estimated by multiplying the observed tree density (i.e. 70 trees/ 10,000 sf) by the total treed area within each zone as determined from a georeferenced aerial photo.

Structure Missile Details The three-dimensional plant model assumes that all structures, except reinforced concrete buildings and the frames of heavy steel buildings, will break up into component missiles.

9 17 0

0 0

528 523 1,051 TOTAL 209 192 79 131 59 16,466 258 120 19 1 0

274 767 3,787 678 295 33 184 62 69 578 14 3,032 48,230 75,708

Subse t I

2 3

4 5

6 7

8 9

10 II 12 13 14 15 16 17 18 19 20 2 1 22 23 ATTACHMENT 1 Buildings that are expected to experience wind failure include warehouses, trailers and other non-or marginally engineered buildings. Structures with fully-engineered steel or concrete building frames will experience roof system failures and opening failures (windows, doors),

followed by wall and roof deck failures at much higher wind speeds. Frame failures are unlikely for fully-engineered structures, but are expected for non-or marginally-engineered buildings.

The total number of missiles produced by structural failure is based on the expected damage states of various building types based on near-ground wind speeds. This approach includes: (1) defining the inventory of all potential missiles generated by failure of structures, and (2) determining the fraction of the missile inventory that will be produced by each level of tornado intensity (Enhanced Fujita Scale).

Table 2 lists the total number of potential missiles by missile type from each of the missile source structures (i.e. result of step (1) discussed above). The "Missile Source Target Number" in Table 2 can be mapped to the structure name with the "TORM IS Target#" from the complete table of safety-related, missile shielding, and missile source targets presented in the Complete List of Targets ( Table 3) portion of this response.

The total number of missiles available by EF scale from each missile source structure is then determined on a source by source basis as described in on page 19 of the LAR. This approach does not necessarily result in every missile becoming available in all tornadoes. As such, the average number of structure missiles for EF5 tornadoes (214,766) is less than the total number of potential structure missiles shown in Table 2 (229,288).

Table 2. Total Number of Missiles Modeled for Each Missile Source Structure Missile Source Tar2d Number Missile Desc1iption 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 Rebar 40 35 13 3,225 3

364 42 536 10 0

24 32 1,118 6,176 4,300 320 14 3,976 Ga.sC,*lmder 0

0 0

0 I

0 18 0

I 0

2 0

0 37 0

0 0

99 DrumTank 0

0 0

0 I

0 2

38 2

0 5

0 0

52 0

0 0

139 UlilitvPole 0

0 0

0 CableRccl 0

0 0

0 I

0 0

27 J

2 6

1 0

0 0

0 Pine 311 0

0 0

9 0

II 0

0 0

0 Pipe Gin 0

0 0

9 0

66 0

0 0

179 Pipe 12in 0

0 0

22 0

0 0

60 Storae.cBin 24 J

I 225 2

26 5

16 5

23 II 0

78 424 JOO 23 I

258 Pa\\*trs 0

0 0

0 ConcrctcFrn1nnrnt 3,375 0

0 0

0 3,5 10 0

0 1,688 0

0 0

0 52 0

0 0

139 Wood.Beam 10 10 19 900 II 102 II 75 2

0 3

5 312 1,716 1,200 325 24 1,088 IVoodPbnk 44 44 92 4,050 55 457 47 985 12 0

29 209 1,404 7,724 5,400 1,792 11 9 4,906 MctalSidine.

40 20 24 700 19 2 16 85 1,957 18 194 I ll 261 849 2,354 1,576 15 34 1,855 PtrwoodShcct 0

5 20 450 12 5 1 0

40 II 0

26 0

156 833 600 768 23 475 WidcFlanoc 7

10 I

371 0

43 13 215 2

38 13 45 183 712 458 15 I

632 ChaMCIScc1ion 13 16 0

250 0

57 2 1 490 6

12 26 23 3 14 803 6 12 0

0 643 SmaUEm1irva)ent II 2

I 100 1

13 6

53 3

4 6

15 52 278 150 12 I

307 Lar~ Equiptnc nt 0

1 I

25 0

5 0

9 0

0

()

0 26 101 50 4

1 11 9 StcclframcGratil2 0

0

()

0 I

0 0

4 3

8 6

I 0

205 0

0 0

554 LargcStcclFramc 0

0 0

0 I

0 0

208 I

0 2

0 0

8 0

0 0

20 Ve~~

0 0

0 3

0 0

Tree 0

0 0

0

()

0 0

0 Total Miu iles 3,564 146 172 10,302 108 4,844 250 4,665 1.767 292 272 601 4,492 2 1,563 14,646 3,274 218 15,449 10 292 293 J

54 0

8 0

12 0

0 0

5 0

0 0

II 0

4 I

10 0

0 288 9

I II 4

62 2

2 18 I

2 1 I

32 I

58 I

17 I

5 0

39 0

3 0

0 0

0 304 579

ATTACHMENT 1 Table 2. Total Number of Missiles Modeled for Each Missile Source Structure (continued)

Missile Source Tar2et Numbe r Subset Miss ile Description 294 295 296 297 298 299 300 JOI 302 303 304 305 306 307 308 309 31 0 3 11 312 313 I

Rebar 20 522 56 259 13 39 39 59 II I

587 457 35 15 0

7 2

138 78 1,11 6 2

GasCvlildcr 2

90 4

17 4

3 3

0 I

I 0

0 0

3 I

0 I

0 0

14 3

DnunTank 4

126 II 49 0

42 8

0 3

I 0

0 0

4 0

0 I

0 0

19 4

UtilityPolc 0

0 0

0 5

CablcRecl 5

0 14 65 2

0 IO 0

3 I

0 0

6 PIDC 31'1 0

0 0

0 7

p.,. 6in 0

162 0

0 0

5 0

0 I

0 0

25 8

Pix 12in 0

54 0

0 0

2 0

0 I

0 0

9 9

Stora_gcBin 9

18 25 114 II 5

17 5

5 I

4 1 32 0

I I

12 6

76 10 Pa,*crs 0

0 0

0 II ConcrctcFra=nt 1.890 126 0

14,907 945 4.725 3.375 2.700 2.025 0

0 0

0 2,029 0

0 316 0

0 19 12 WoodBcam 3

126 7

33 4

7 5

17 2

I 164 128 116 4

0 14 I

165 80 309 13 WoodPlank 23 576 67 307 16 109 46 73 13 2

738 574 356 16 0

66 2

834 4 18 1,390 14 MctalSidino 35 1,083 265 469 8

65 70 36 20 IO 328 22 130 20 2 11 20 2

180 78 987 15 P tvwood.Shcct 21 0

60 275 0

56 41 9

12 I

82 64 69 0

0 12 0

222 126 145 16 WdcFlanl!c 4

225 30 49 2

8 8

8 3

2 124 107 3

5 5 1 I

I 9

4 204 17 Cha,mcJScction I I 410 61 146 3

21 22 14 7

2 123 0

10 5 1 0

I 0

0 2%

18 Smal!Eauiivnf'nt 5

180 14 65 II 3

10 3

3 I

28 22 4

5 I

I I

9 4

76 19 LargcEQ\\lll)mcnt 0

72 0

0 3

I 0

2 0

0 14 II 0

2 0

I I

6 2

35 20 StcclframcGratinc.

5 504 14 65 0

0 IO 0

3 I

0 0

3 14 2

0 2

0 0

76 21 Larb-eStcclFrnmc 2

18 4

17 3

13 3

0 I

I 0

0 0

I 0

0 I

0 0

3 22 Vehicle

[)

0 0

I 0

0 0

0 23 Tree 0

0 0

0 Total Missiles 2,039 4,292 632 16,837 1,025 5,098 J,667 2,926 2,11 2 26 2,229 1,513 716 2,136 318 123 335 1,575 796 4,799 Missile Source Tarvet Number Subset Missile Description 314 315 316 3 17 318 319 320 321 322 323 324 325 326 327 328 329 JJO JJI 332 333 I

Rebar 516 5 16 8,389 50,l 232 868 41 48 20 II 35 3,793 20 195 516 0

0 0

2 GasCvlindcr 2

65 31 0

25 I

3 14 33 0

0 0

2 0

0 0

3 DrumTank 2

91 17 0

6 9

8 20 21 0

0 0

4 0

0 0

4 U1ilit *Pole 0

0 0

0 5

Cable Reel 0

0 II 0

2 0

II 0

4 0

0 0

5 0

0 0

6 Pinc 3in 14 0

63 0

3 4

0 800 210 0

0 0

7 Pipe 6in 0

11 7 4

0 0

2 0

0 0

0 8

p.,. 12in 0

39 0

0 0

0 9

Stora_l!,c8in 4

23 552 36 45 69 18 59 24 I

3 265 9

15 36 0

0 0

10 Pa,*crs 0

0 0

0 51 51 51 51 II ConcrctcFra2fl\\Cnl 0

91 84 0

0 0

12 WoodBcam 144 130 2163 141 38 228 6

0 0

3 IO 1,059 3

207 544 0

0 0

13 WoodPbnk 624 590 13.356 633 248 1.091 49 22 0

14 44 4.763 23 1.074 2.836 0

0 0

14 Mcta1Sidi1e.

53 1 584 4,186 282 479 645 180 50 0

6 20 1152 35 9

24 1,137 0

0 0

0 15 PlvwoodShect 0

20 1.115 71 3

107 44 0

0 2

5 530 21 501 1.1 60 0

0 0

16 WidcFlan.2.c 104 206 986 178 142 227 49 2

0 6

16 412 3

9 24 0

0 0

17 ChannelScction 120 292 1,580 118 166 253 26 0

110 3

8 294 13 0

0 0

18 SmallEmmlf'llCnt 26 137 385 24 33 50 II 7

12 I

2 118 5

9 20 0

0 0

19 Larc.cEm,inmcnt 16 56 123 12 0

29 0

6 2

I I

JO 0

6 8

0 0

0 20 StcctFr:i.mcGralDle.

2 363 5

0 24 0

II 132 97 0

0 0

5 0

0 0

21 Lar~cStcclFramc 4

13 243 0

39 0

3 4

4 0

0 0

2 0

0 0

22 Vchic~

I 0

4 0

0 0

2 0

0 0

23 Tree 0

0 0

0 Total Missiles l, 11 0 3,333 33,397 1,999 1,485 3,583 460 1,164 539 48 144 12,516 150 2,025 5,168 1, 137 51 51 5 1 51 11

ATTACHMENT 1 Table 2. Total Number of Missiles Modeled for Each Missile Source Structure (continued)

Missile Source Tar2et Number Subse t Miss ile Desc1ip1ion 334 335 336 337 338 339 340 34 1 342 343 344 345 346 347 348 349 350 351 352 353 I

Rebar 0

0 0

20 48 0

0 0

2 GasCvlindcr 0

0 0

33 14 0

0 0

3 DrumTank 0

0 0

21 20 0

0 0

[)

0 0

0 (J

0 4

UtilitvPolc 0

0 0

0 5

CablcRecl 0

0 0

4 0

0 0

0 6

PIDC 3in 0

0 0

2!0 800 0

0 0

7 Pinc Gin 0

0 0

0 8

Pooc 12;,,

0 0

9 Stora~Bi:n 0

0 0

24 59 0

0 0

10 Pavcrs 51 51 51 0

0 0

II ConcretcFragmcnt 0

0 0

0 12

\\VoodBcam 0

0 u

0 0

6 0

0 0

0 (J

0 0

(J 0

0 0

0 13 WoodPlank 0

0 0

0 22 21 0

0 0

0 14 Mct:i.LSidinl!.

0 0

50 0

204

~97 702 156 182 120 594 594 120 1,656 1,4 18 1,514 204 497 15 PtvwoodShcct 0

0 0

56 0

0 0

0 16 WdcFlam~e 0

0 0

0 2

0 0

0 17 ChaMCIScction 0

0 0

IIO 0

0 0

0 18 SmaUEmmmcnt 0

0 0

12 7

0 0

0 19 LarocEn1,inn\\Cnl 0

0 0

2 6

0 0

0 (J

0 0

0 20 StcclFramcGrating 0

0 0

97 132 0

0 0

21 LanzcStcc!Framc 0

0 0

4 4

0 0

0 22 Vehicle 0

0 0

2 0

0 0

0 23 Tree 0

0 0

0 Total Miss iles 51 51 51 539 1,164 83 204 497 702 156 182 120 594 594 120 1,656 1,4 18 1,5 14 204 497 Miss ile Source Tan e l Number Subse t Missile Ducription 354 355 356 357 358 359 360 36 1 362 363 364 365 366 367 368 369 370 37 1 TOTAL I

Rebar 0

0 0

255 0

0 0

0 39,766 2

G:isCylinder 0

0 0

0 533 3

DrwnTank 0

0 0

0 738 4

Utalrt'\\Pole 0

0 0

5 Cable Reel 0

0 0

0 182 6

Pioe Jin 0

0 0

0 2,124 7

Pioe 611 0

0 0

0 58 1 8

Pioe 12in 0

0 0

0 19 1 9

StorngeBin 0

0 0

18 0

0 0

0 3,077 10 Pa\\'ers 0

0 0

0 51 0

0 0

408 II Concretefragment 0

0 0

0 42,293 12 WoodBeam 0

0 0

71 0

0 0

0 11,864 13 WoodPlank 0

0 0

320 0

0 0

0 58,791 14 MetalSiding 702 156 182 120 594 594 120 1.656 1,418 1.514 0

249 35 69 79 139 20 58 40,222 15 Pl\\"\\oodSheet 0

0 0

36 0

0 0

0 8,358 16 Wideflan*e 0

0 0

43 0

9 JO 17 4

8 6,103 17 ChruuielSection 0

0 0

72 0

16 18 32 8

16 7,874 18 SmallEQuipment 0

0 0

12 0

0 0

0 2,350 19 LargeEquipment 0

0 0

6 0

0 0

0 802 20 SteelFrameGratiru!'

0 0

2,388 21 Lare.eSteelFrame 0

0 0

0 630 22 Vehicle 0

0 0

0 13 23 Tree 0

0 0

Total Mis siles 702 156 182 120 594 594 120 1,656 1,4 18 1,5 14 51 1,082 35 94 107 188 32 82 229,288 12

ATTACHMENT 1 Complete List of Targets Table 3 lists all 87 safety-related targets, 63 missile pass through targets (representing the Utility Port Barriers), 123 missile shielding targets, and 98 missile source targets. The comment cited in RAI #2 from page 14 of Enclosure 1 of the LAR pertains only to the effect of shielding on the tornado winds, and not tornado missiles. As such, the missile shielding targets all represent portions of reinforced concrete, Category I structures that have been designed to resist the design basis missiles in the MNS UFSAR. However, as described in item 2 on page 14 of :

2. In TORMIS, the effects of local obstructions, buildings, and structures are neglected in simulating the tornado winds. Thus, for example, tornado winds flow through the Turbine Building without consideration of either terrain/site roughness or blockage/interference of the reinforced concrete and heavy steel frame structures.

These structures have no effect on the tornado wind fields simulated in TORMIS.

13

ATIACHMENT 1 Table 3. Sequential Numbering of Safety-related, MPT, Shielding, and Missile Source Targets TORMIS Target Grou11 TORM IS Target Descri11tion l llltkty

[~IPT l shidd Tal'l!etll 1

U 1 D Steam Line D - PORV 1SV 1AB Exhaust Above Roof 1

2 D - PORV 1SV 1AB Exhaust Above Roof-- PP 2

3 U 1 A Steam Line A - PORV 1SV 19AB Exhaust Above Roof 3

4 A - PORV 1SV 19AB Exhaust Above Roof-- PP 4

5 U 1 D Steam Line D - MSSV Ext DH Exhausts Above roof 5

6 D - MSSV in Ext DH Exhaust Above Roof -- PP 6

7 U 1 A Steam Line A - MSSV Ext DH Exhausts Above Roof 7

8 A - MSSV in Ext DH Exhaust Above Roof -- PP 8

9 C - Class B Piping to PORV 1SV-7ABC Int DH 9

10 C - Class B Piping to PORV 1SV-7ABC Int DH Pipe Hanger 10 II C - Pnuematic PORV 1SV7ABC - Int DH 11 12 U 1 C Steam Line C - PORV 1SV7ABC Exhaust - Int DH 12 13 C - PORV 1SV7ABC Exhaust - Int DH -- NorthWest sway strut -- lower 13 14 C - PORV 1SV7ABC Exhaust - Int DH -- NorthEast sway strut -- lower 14 15 C - PORV 1SV7ABC Exhaust Above Roof - Int DH 15 16 C - PORV 1SV7ABC Exhaust Above Roof -- PP 16 17 B - Class B Piping to PORV 1SV-13ABC - Int DH 17 18 B - Class B Piping to PORV 1SV-13ABC - Int DH Pipe Hanger 18 19 B - l" Schedule 80 Off Class B Piping to B PORV 19 20 B - Pnuematic PORV 1SV13AB - Int DH 20 21 U I B Steam Line B - PORV 1SV13AB Exhaust - Int DH 21 22 B - PORV ISVl3AB Exhaust-Int DH -- SE Sway Strut -- Lower 22 23 B - PORV ISV 13AB Exhaust-Int DH -- SW Sway Strut -- Lower 23 24 B - PORV 1SV 13AB Exhaust Above Roof 24 25 B - PORV 1SV 13AB Exhaust Above Roof -- PP 25 26 C - MSSV - Int DH Exhaust Pipes Inside DH 26 27 U 1 C Steam Line C - MSSV - Int DH Exhaust Pipes Above Roof 27 28 C - MSSV - Int DH -- Exhaust Above Roof -- PP 28 29 B - MSSV - Int DH -- Exhaust Pipes 29 30 U l B Steam Line B - MSSV - Int DH Above Roof -- Exhaust Pipes 30 31 B - MSSV Exhaust Above Roof -- PP 31 32 Unit 1 TE TE Svstem Pipe -- U l Int DH 32 33 D - Class B piping to PORV lSV IAB -- U2 Ext DH 33 34 D - Class B piping to PORV ISV IAB - Hanger 34 35 D - Pnuematic PO RV 2SV 1AB above floor 35 36 D - PORV 2SV IAB Exhaust 36 37 U2 D Steam Line D - PORV 2SV 1AB Exhaust -- West Hanger 37 38 D - PORV 2SV 1AB Exhaust-- East Hanger 38 39 D - PORV 2SV 1AB Exhaust-- Sway Strut SW - Lower 39 40 D - PORV 2SV 1AB Exhaust -- Sway Strut SE - Lower 40 41 D - PORV 2SV 1AB Exhaust Above Roof - PP 41 42 D - PORV 2SV 1AB Exhaust Above Roof 42 43 A-Class B Piping to PORV 2SV 19AB -- U2 Ext DH 43 44 A - Class B Piping to PORV 2SV 19AB -- U2 Ext DH Pipe Hanger 44 45 A - Pnuematic PORV 2SV IAB -- Above Floor 45 46 A - PORV 2SV 1AB Exhaust 46 47 U2 A Steam Line A-PORV 2SV 1AB Exhaust-- West Hanger 47 48 A-PORV 2SV1 AB Exhaust -- East Hanger 48 49 A - PORV 2SV1AB Exhaust --*Sway Strut SW - Lower 49 50 A - PORV 2SV 1AB Exhaust-- Sway Strut SE - Lower 50 51 A-PORV 2SV 19AB Exhaust Above Roof -- PP 51 52 A - PORV 2SV 19AB Exhaust Above Roof 52 53 D - MSSV in Ext DH Exhaust Inside 53 54 U2 D Steam Line D - MSSV in Ext DH Exhaust Above Roof 54 55 D - MSSV in Ext DH -- Exhaust Above Roof -- PP 55 56 A - MSSV in Ext DH Exhaust Inside 56 57 U2 A Steam Line A - MSSV in Ext DH Exhaust Above Roof 57 58 A - MSSV Exhaust Above Roof -- PP 58 14 1:rouru

ATTACHMENT 1 TOM11S Target Group TORM IS Target Description l safr1y 1,tPT l ihicld I source Tar2et #

59 C - Class 8 Piping to PORV 1SV-7A8C Int DH U2 59 60 C - Class 8 Piping to PORV 1SV-7A8C Pipe Hanger U2 60 61 C - Pnuematic PORV ISV7A8C - Int DH U2 61 62 U2 C Steam Line C - PORV 1SV7A8 C Exhaust - Int DH U2 62 63 C - PORV 1SV7A8C Exhaust - Int DH U2 - Sway Strnt NW Lower 63 64 C - PORV 1SV7A8C Exhaust-Int DH U2 -Sway Strut NE Lower 64 65 C - PORV 1SV7A8C Exhaust Above Roof-- PP 65 66 C - PORV ISV7A8C Exhaust Above Roof 66 67 8 - Class 8 Piping to PORV ISV-1 3ABC Int DH U2 67 68 8 - Class 8 Pioing to PORV ISV-1 3A8C Pioe Hanger U2 68 69 8-Pnuematic PORV 1SV13A8 - Int DH U2 69 70 U2 8 Steam Line 8-PORV ISV l3A8 Exhaust - Int DH U2 70 71 8 - PORV ISV I3AB Exhaust - Int DH U2 -- Sway Strut SW Lower 71 72 8 - PORV ISVl3A8 Exhaust - Int DH U2 - Sway Strut SE Lower 72 73 8 - PORV ISV I3A8 Exhaust Above Roof-- PP 73 74 8 - PORV ISV 13A8 Exhaust Above Roof 74 75 C - MSSV - Int DH Exhaust Inside DH 75 76 U2 C Steam Line C - MSSV - Int DH Exhaust Above Roof 76 77 C - MSSV Exhaust Above Roof -- PP 77 78 8 - MSSV - Int DH Exhaust Inside DH 78 79 U2 8 Steam Line 8 - MSSV - Int DH Exhaust Above Roof 79 80 8 - MSS V Exhaust Above Roof -- PP 80 81 Unit 2 TE TE System Pipe -- U2 Int DH 8 1 82 Unit I VC/YC VC/YC Air Intake IA and 18 -- Vertical Pipe 82 83 VC/YC Air Intake I A and I 8 -- Horizontal Pipe 83 84 Unit 2 VC/YC VC/YC Air Intake 2A and 28 -- Vertical Pipe 84 85 VC/YC Air Intake 2A and 28 -- Horizontal Pipe 85 86 Spent Fuel Pools Unit I Spent Fuel Pool 86 87 Unit 2 Spent Fuel Pool 87 88 Missile Pass Through U I Int UP8 South Ooening West (small)

I 89 Targets UI Int UP8 South Opening Middle (large) -- comer 2

90 U I Int UP8 South Opening Middle (large) - Center - High 3

91 U l Int UP8 South Ooening East (large) - Corners 4

92 U l Int UP8 South Opening East (large) -- Center - High 5

93 UI Int UP8 East Opening South (large) -- comers 6

94 U I Int UP8 East Opening South (large) -- Center - High 7

95 UI Int UP8 East Opening Middle (large) -- comers 8

96 U I Int UP8 East Ooening Middle (large) -- Center - High 9

97 U l Int UP8 East Opening North(Iarge) -- corners IO 98 UI Int UP8 East Opening North(large) - Center - High II 99 U I Int UP8 North Ooening West (small) 12 100 U I Int UP8 North Opening Middle (small) 13 IOI U I Int UP8 North Opening East (large) -- corners 14 102 U I Int UP8 North Ooening East (large) -- Center - High 15 103 U2 Int UP8 South Opening WEST (large) -- corners 16 104 U2 Int UP8 South Ooening WEST (large) -- Center - High 17 105 U2 Int UP8 South Opening Middle (large) -- corners 18 106 U2 Int UP8 South Opening Middle (large) -- Center - High 19 107 U2 Int UP8 South Opening East (small) 20 108 U2 lnt UPB West Opening South (large) ** corners 21 109 U2 Int UP8 West Opening South (large) - Center - High 22 110 U2 Int UP8 West Opening Middle (large)-- corners 23 III U2 Int UP8 West Ooening Middle (laree) - Center - Hieh 24 I 12 U2 Int UP8 West Opening North (large) -- corners 25 I 13 U2 Int UP8 West Opening North (large) -- Center - High 26 114 U2 Int UP8 North Opening WEST (large) -- corners 27 115 U2 Int UP8 North Opening WEST (large) -- Center - High 28 116 U2 Int UP8 North Opening Middle (small) 29 15

ATTACHMENT 1 TORl\\'IIS Ta_rget Group TORMIS Target Description l urety IMPT l shidd I JOUl'Ce Ta,,.et #

117 Missile Pass Through U2 Int UPB North Opening East (small) 30 118 Targets (cont)

U2 Ext UPB South Opening West (small) 31 119 U2 Ext UPB South Opening Middle (large)-- corners 32 120 U2 Ext UPB South Opening Middle (large) -- Center-High 33 121 U2 Ext UPB South Opening East (large)-- corners 34 122 U2 Ext UPB South Opening East (large) -- Center - High 35 123 U2 Ext UPB East Opening South (large) -- corners 36 124 U2 Ext UPB East Opening South (large)-- Center-High 37 125 U2 Ext UPB East Opening Middle (large) -- corners 38 126 U2 Ext UPB East Opening Middle (large) -- Center - High 39 127 U2 fa1 UPB East Opening North (large) -- corner 40 128 U2 Ext UPB East Opening North (large) -- Center - High 41 129 U2 Ext UPB North Opening West (small) 42 130 U2 Ext UPB North Opening Middle (small) 43 131 U2 Ext UPB North Opening East (large) -- corners 44 132 U2 Ext UPB North Opening East (large)-- Center - High 45 133 U l Int UPB South Opening Middle (large) -- Center -Low 46 134 U l Int UPB South Opening East (large)-- Center-Low 47 135 U l Int UPB East Opening South (large) -- Center - Low 48 136 Ul Int UPB East Opening Middle (large) -- Center - Low 49 137 U l Int UPB East Opening North(large) - Center - Low 50 138 U l Int UPB North Opening East (large)-- Center-Low 51 139 U2 Int UPB South Opening WEST (large)-- Center - Low 52 140 U2 Int UPB South Opening Middle (large) -- Center - Low 53 141 U2 lnt UPB West Opening South (large)-- Center - Low 54 142 U2 Int UPB West Opening Middle (large)-- Center-Low 55 143 U2 Int UPB West Opening North (large) -- Center - Low 56 144 U2 Int UPB North Opening WEST (large) -- Center - Low 57 145 U2 Ext UPB South Opening Middle (large) -- Center - Low 58 146 U2 Ext UPB South Opening East (large) -- Center - Low 59 147 U2 Ext UPB East Opening South (large) -- Center - Low 60 148 U2 Ext UPB East Opening Middle (large)-- Center - Low 61 149 U2 Ext UPB East Opening North (large) -- Center - Low 62 150 U2 Ext UPB North Opening East {large) -- Center-Low 63 151 Missile Shielding Targets U l Int DH S Gull Wing2 1

152 U l Int DH S Gull Wing 3 2

153 U 1 Int DH E Gull Wing 2 3

154 Ul Int DH E Gull Wing 3 4

155 U l Int DH N Gull Wing 2 5

156 U l Int DH N Gull Wing 3 6

157 U2 Int DH S Gull Wing 2 7

158 U2 Int DH S Gull Wing 3 8

159 U2 Int DH W Gull Wing 2 9

160 U2 Int DH W Gull Wing 3 10 161 U2 Int DH N Gull Wing 2 11 162 U2 Int DH N Gull Wing 3 12 163 U2 Ext DH S Gull Wing 2 13 164 U2 Ext DH S Gull Wing 3 14 165 U l Int DH Grating Floor at 807' -- NORTH 15 166 U 1 Int DH Grating Floor at 807' -- SOUTH 16 167 U2 Ext DH Grating Floor at 807' -- NORTH 17 168 U2 Ext DH Grating Floor at 807' -- SOUTH 18 169 U2 Int DH Grating Floor at 807' -- NORTH 19 170 U2 Int DH Grating Floor at 807' -- SOUTH 20 171 U 1 Blockage on AB Roof 21 172 U2 Blockage on AB Roof 22 173 Colmnn DD51.8 23 174 Column GG52.2 24 175 Coltunn DD595 25 16 L

ATTACHMENT 1 T0~11S Ta~et Group TORM IS Ta~et Description lurny I~IPT l shicld l,oun.:e Tars!et#

176 Missile Shielding Targets Column GG59.5 26 177

( continued)

Column DD66.8 27 178 Column GG68.2 28 179 Unit I TB Mezzanine 29 180 Unit I TB Turbine Deck 30 181 Unit 2 TB Mezzanine 31 182 Unit 2 TB Turbine Deck 32 183 Unit I RB 33 184 Unit2 RB 34 185 Unit I DGBldg 35 186 Unit 2 DGBldg 36 187 Aux Bldg -- CR Area 37 188 Aux Building -- between RBs 38 189 Aux Bldg -- U I N of DH to FHB 39 190 Aux Bldg -- U2 N of DH to FHB 40 191 Int DH South Wall 41 192 Int DH East Wall 42 193 Int DH North Wall 43 194 Int DH West N-S Beam 44 195 Int DH Column DD53 45 196 Int DH Column DD53.2 46 197 Int DH Column EE53.2 47 198 Int DH Column FF53.2 48 199 Int DH Colwnn GGS3.2 49 200 Int DH Column GG53 50 201 Int DH Roof 51 202 Int DH South Gull Wing 52 203 Int DH East Gull Wing 53 204 Int DH North Gull Wing 54 205 U l Ext DH Main Volume (protected) 55 206 Ext DH Roof 56 207 U2 Ext DH E Gull Wing 2 57 208 U2 EXt DH N Gull Wing 2 58 209 U2 Ext DH N Gull Wing 3 59 210 DG Concrete Exhaust Plenum 60 2 11 Slab Over SG Exhaust Plenum 61 212 DG Exhaust Gull Wing 62 213 DG Barrier North End 63 214 DG Barrier South End 64 215 Unit I Condensers 65 216 AB up to 767 under air intakes U I 66 217 AB up to 767 under air intakes U2 67 2 18 RWST missile barrier base 68 219 U2 Int DH South Wall 69 220 U2 Int DH West Wall 70 221 U2 Int DH North Wall 71 222 U2 Int DH Column DD58.5 72 223 U2 Int DH Column DD59.2 73 224 U2 Int DH Column EE58.5 74 225 U2 Int DH Column FF58.S 75 226 U2 Int DH Column GG58.5 76 227 U2 Int DH Column GG59.2 77 228 U2 Int DH Roof 78 229 U2 Int DH South Gull Wing 79 230 U2 Int DH West Gull Wing 80 231 U2 Int DH North Gull Wing 81 17

ATTACHMENT 1 TORMIS Target Group TORM IS Target Description l sarcty (MPT l shidtl l sourcc Tal'l!et #

232 Miss ile Shielding Targets U2 Int DH N-S Beam East 82 233

( continued)

U2 Int DH N-S Beam Center 83 234 U2 Int DH E-W Beam South 84 23S U2 Int DH E-W Beam North 85 236 U2 Ext DH South Wall 86 237 U2 Ext DH East Wall 87 238 U2 Ext DH North Wall 88 239 U2 Ext DH Column DD 68.5 89 240 U2 Ext DH Column DD 69.2 90 241 U2 Ext DH Column EE 69.2 91 242 U2 Ext DH Column FF 69.2 92 243 U2 Ext DH Column GG 69.2 93 244 U2 Ext DH Column GG 68.5 94 245 U2 Ext DH Roof 95 246 U2 Ext DH South Gull Wing 96 247 U2 Ext DH East Gull Wing 97 248 U2 Ext DH North Gull Wing 98 249 U2 Ext DH N-S Beam West 99 250 U2 Ext DH N-S Beam Center 100 2S I U2 Ext DH E-W Beam South IOI 2S2 U2 Ext DH E-W Beam North 102 253 U I Int DH N-S Beam 103 254 UI Int DH E-W Beam South 104 255 UI Int DH E-W Beam North 105 256 U I FHB West Wall 106 257 UI FHB East Wall 107 258 U 1 FHB Roof South 108 259 UI FHB South Wall Upper 109 260 UI FHB Roof North 110 261 Ul FHB West Wall Uooer 111 262 Ul FHB East Wall Unoer 112 263 U I FHB Concrete --Cask Area 11 3 264 U l FHB Concrete --Decon Area 114 265 U2 FHB West Wall 115 266 U2 FHB East Wall 11 6 267 U2 FHB Roof South 11 7 268 U2 FHB South Wall Upper 11 8 269 U2 FHB Roof North 11 9 270 U2 FHB West Wall Upper 120 271 U2 FHB East Wall Upper 121 272 U2 FHB Concrete --Cask Area 122 273 U2 FHB Concrete --Decon Area 123 274 Miss ile Source Targets Valve Shop I

275 RT Booth Building 2

276 22 Tra iler Building 3

277 7455 - OSF 4

278 23 Paint Storage 5

279 CSB 6

280 YM Processing Fac ility 7

281 Warehouse !A 8

282 Chemical Storage Building 9

283 7430- TSB 10 284 Combustible Storage 11 285 Metal Building 12 286 7427 - Admin Building 13 287 7405 - Envrionmental Services 14 18

ATTACHMENT 1 TORMIS Target Group TORMIS Target Description 1,arety I MPT l,hield l,ource Tareet #

288 Missile Source Targets 7408 - Technical Solution Center 15 289 (continued}

74 14 - Energy Exolorium 16 290 Z 15 Trailer Building 17 291 7403 - National Academy for Nuclear Training 18 292 Guard House 19 293 7402 20 294 74 15 21 295 74 12 - Boat Storage I 22 296 74 IO - Boat Storage 2 23 297 Large Concrete Building 24 298 7425 - Old Caroenter Shop 25 299 Z16 Paint Storage 26 300 Misc Discarded Materials Building 27 301 7432 - Medical Facility 28 302 7436 - Hazmat Building 29 303 Misc Site Comm 30 304 Z20 Admin Building 31 305 7438 32 306 7486 - LLRW 33 307 748 1 - Chemical Mix House 34 308 7490 - Water Treatment Plant 35 309 Z25 Small Office Trailer 36 310 WT Blower House 37 311 Z30 Office Trailer Group I 38 312 Z30 Larger Office Trailer 39 313 McGuire Training Facilitv 40 314 7420 - ATF 4 1 315 Fleet Garage 42 316 MOC 43 317 SB North Section (Work Control) 44 318 SB Warehouse/fool Crib Area 45 319 SB Office Extension (South) 46 320 SB Receiving Bay 47 321 U I TB Turbine Deck 48 322 U I TB Mezzanine 49 323 74 17 50 324 Z32 Elongated Brick Building 51 325 cow 52 326 Z9 Gas Bottle Storage Building 53 327 Z32 I Storv House Group 54 328 Z32 2 Story Honse Group 55 329 Aux Srvcs Bldg 56 330 AB SW Pavers 57 331 AB SE Pavers 58 332 DG 2 NE Paver 59 333 DG 2 SE Pavers 60 334 DG I NW Pavers

61.

335 DG I SW Pavers 62 336 SB NW Pavers 63 337 U2 TB Mezzanine 64 338 U2 TB Turbine Deck 65 339 Z14 Pavillion Structure 66 340 U I TB Roof North Edge 67 341 UI TB Roof North Mid 68 342 U I TB Roof South 69 343 U I TB Wall Zone I 70 19

ATIACHMENT 1 TORMIS Target Group TORM IS Target Description 1,afl't~*

J,1PT l,hidd l sou1tt Tareet #

344 Missile Source Targets Ul TBWall Zone9 71 345 (continued)

Ul TB Wall Zone 13 72 346 Ul TB Wall Zone 14 73 347 Ul TB Wall Zone 15 74 348 Ul TB Wall Zone 16 75 349 Ul TB West Wall South 76 350 U l TB East Wall South 77 351 U I TB Wall South 78 352 U2 TB Roof North Edge 79 353 U2 TB Roof North Mid 80 354 U2 TB Roof South 81 355 U2 TB Wall Zone l 82 356 U2 TB Wall Zone 9 83 357 U2 TB Wall Zone 13 84 358 U2 TB Wall Zone 14 85 359 U2 TB Wall Zone 15 86 360 U2 TB Wall Zone 16 87 361 U2 TB West Wall South 88 362 U2 TB East Wall South 89 363 U2 TB South Wall 90 364 SB NE Pavers 91 365 Work Control Bldg on AB Roof 92 366 Vent Structure on AB Roof 93 367 Walkway NE 94 368 Walkway S of Aux Svcs 95 369 Walkway N-S North of WC 96 370 Walkway E-W North of WC 97 371 Walkway West of WC Bldg 98 20

ATTACHMENT 1 RAl-03 The LAR references RIS 2008-14, which includes reference to the TORMIS SER. RIS 2008-14 specifically identified items licensees should address to confirm the TORMIS methodology and computer code have been applied and implemented properly.

RIS 2008-14, Item 1, advises the licensee to provide "adequate justification that the analysis used the most conservative value for tornado frequency" The site specific analysis for development of the tornado hazard curve for McGuire is based on data from the National Oceanic and Atmospheric Administration (NOAA) Storm Prediction Center. As shown in Figure 3-2 of the submittal, the TORM IS developed McGuire tornado hazard curves, i.e., the TORRISK 200 x 200 curve, are used and compared to NUREG/CR-4461, Revision 2, "Tornado Climatology of the Contiguous United States" (ADAMS Accession No. ML070810400), to demonstrate conservatism. However, in Enclosure 1, page 21 of the LAR, it states "It can be seen that the NUREG EF [Enhanced Fujita] curve is below the TORRISK 200 x 200 curve until 180 mph, where they intersect." As such, tornado frequency shown in the tornado hazard curve appears non-conservative beyond 180 miles per hour (mph).

The NRC staff requests the licensee to confirm that values used above 180 mph are conservative and bounding values and provide justification.

Duke Energy Response:

The values used in the MNS TORMIS tornado hazard curve is addressed in two parts:

sensitivity of the tornado missile damage results and justification of the data used to develop the plant safety envelop curve (hazard curve).

LAR Figure clarification. The plant safety envelop curve (labeled as MNS DH EF Plant in, Figure 3-2 of the LAR) was used for the MNS TORM IS plant tornado missile simulations. This curve crosses the NU REG EF MNS curve (NUREG/CR-4461 ) at about 193 miles per hour (mph) as opposed to 180 mph. Figure 3-2 of the LAR compared the MNS DH EF 200 foot (ft) by 200 ft curve and the MNS DH EF Plant curve to the NU REG EF MNS curve however the 200 ft by 200 ft curve was not used in the MNS simulations.

Sensitivity of the Tornado Missile Damage Results. In order to evaluate the sensitivity of the hazard curve values on the missile damage results, a comparison was made between the results from using the hazard curve simulated in the MNS TORMIS analysis to the results from using the NUREG EF MNS curve. This comparison is shown in Table 4 and compares wind speed exceedance frequencies of the NU REG curve to those of the MNS hazard curve for each EF scale. The frequencies used were taken directly from their respective documents (NUREG/CR-4461 and MNS TORMIS analysis) and interpreted for the EF scale wind speeds.

For comparison the last column shows the MNS to NU REG ratios. For the EF5 tornadoes at 201 mph, the TORM IS freq uency is about 13% lower than the NUREG, but all other frequencies are considerably higher for the other tornado EF scales (i.e. 4.23 times higher for EF3, 2.65 times higher for EF4 tornadoes, etc.).

21

ATTACHMENT 1 Intensity Peak Gust Wind Speed (mph)

NUREG Exe.

MNSDH EF MNS/NUREG min max MidPt Frequency Plant Freq.

EFl 86 110 98 2.98E-04 4.0lE-04 1.35 EF2 111 135 123 6.54E-05 l.92E-04 2.94 EF3 136 165 150.5 l.44E-05 6.08E-05 4.23 EF4 166 200 183 2.51E-06 6.66E-06 2.65 EF5 201 230 215.5 2.51E-07 2.20E-07 0.87 Table 4: MNS TORMIS and NUREG Tornado Hazard EF Scale Wind Speed Exceedance Frequencies The TORM IS equations that relate tornado occurrence rates to missile damage frequency were used to quantify the sensitivity of the computed MNS missile damage frequencies to the tornado hazard curve. These results are given below:

1. The first sensitivity analysis is to quantify the effect of the NU REG EF MNS curve on the MNS TORM IS missile damage frequencies. This is illustrated in Figure 3 using the NU REG EF MNS curve with extrapolations to lower wind speeds. Just as TORM IS simulates individual EF intensities and aggregates the results to get the overall missile damage frequencies, the contribution by EF scale was computed using the NUREG EF frequencies. This approach provides an analytical quantification using the TORMIS results with the NUREG EF MNS curve. As illustrated in Table 5, missile damage frequency results that are more than a factor of three lower than the MNS DH EF Plant curve results as documented in the LAR. The significantly higher TORMIS frequencies for EF1-EF4 (as shown in Table 4) contribute to this result. Hence, by virtue of comparing these results, the MNS DH EF Plant curve produces MNS missile damage frequencies that are approximately 300% higher than those that would be produced using the NUREG EF curve.

22

~

QI E;

~

.a

.ll 0...

Cl.

QI u

C QI QI u

)(

w ATTACHMENT 1 MNS Tornado Hazard Curves and Enhanced EFS Frequency l.OOE-04 l.OOE-05 l.OOE-06 l.OOE-07 0

so 100 150 200 Peak Gust Wind Speed

--t-NUREG

_._ NUREG Extrapolated

--- MNS DH EF Plant

~

MNS EFS Enhanced 250 J

Figure 3: MNS Tornado Hazard Curves and Illustration of Enhanced EFS Frequency

2. The second sensitivity evaluates the EF5 frequencies, which corresponds to wind speeds greater than 201 mph. The TORM IS EF5 frequency was multiplied by a factor of 2.5 in order to create a TORM IS hazard curve that is above the NU REG for the full range of EF5 wind speeds, then updated damage frequencies were produced keeping all other TORMIS frequencies the same (see the orange curve in Figure 3 labeled "MNS EF5 Enhanced"). For this case, the aggregate damage frequency increased by about 4% for each Unit, as shown in Table 5. Hence, the effect of increasing EF5 frequencies produced a minimal impact on the MNS missile damage frequencies. This result follows from the previous results illustrate that the contributions to the missile damage frequencies from much more frequent, but lower intensity tornadoes, dominates the tornado missile risk for MNS.

23

ATTACHMENT 1 MNS Damage Frequency (y.-1) for Different Tornado Hazard Curves Target Group and Ratio MNS DH EF Plant (Base)

NUREG MNS EFS Enhanced Unit 1 Unit2 Unitl Unit2 Unit 1 Unit2 Main Steam Boolean 2.42E-07 7.13E-07 7.54E-08 2.17E-07 2.SOE-07 7.36E-07 TE System Pipe 6.29E-08 4.27E-08 2.0SE-08 l.93E-08 6.60E-08 4.56E-08 VC/YC Air Intake and SFP Boolean 5.41E-08 l.71E-08 5.72E-08 Arithmetic Sum over all Target Groups 3.59E-07 8.lOE-07 l.13E-07 2.54E-07 3.73E-07 8.39E-07 Ratio to Base 1.00 1.00 0.31 0.31 1.04 1.04 Table 5: Sensitivity Analysis Comparison of MNS Tornado Missile Damage Frequencies Justification of Data Used. See the following regarding the justification of the MNS frequencies for high wind speeds.

1. The LAR discusses the hazard curve for the smaller 200' x 200' target, which was not used to perform the TORMIS simulations. The hazard curve used in the simulations is the curve developed for the plant safety envelope that is shown as the red curve in Figure 3-2 of the LAR, reproduced in Figure 3 herein. There is clearly very little difference in the frequencies of the NU REG curve and the TORM IS curve at 200 mph.

2. Figure 4 shows the starting region and the 1.4 x 1.4 degree grid used for the development of the MNS subregion from which the tornado frequencies were developed.

The starting region covers most of the Eastern US and extends into portions of the Midwest. The location of reported tornadoes for the years 1950-2016 is shown in Figure

5. The MNS subregion was developed using multi-variate statistical methods to determine how the cells grouped (or clustered) to form subregions within the larger, starting region. The variables considered in the subregion analysis and computed for each 1.4 x 1.4 degree grid cell included: latitude and longitude; mean and standard deviation of elevation; number of tornado days per year; fraction of land within the cell to the total area of the cell (considering large bodies of water like the Atlantic Ocean);

tornado path direction; moderate occurrence rate (EF2/3); strong occurrence rate (EF4/5); and point strike probability.

24

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3. The MNS subregion was developed from multiple plots of cluster groups around the plant and selected the final subregion shown in Figure 6, which encompasses an area of 73,377 square miles. MNS is in the eastern shadow of the Appalachian Mountains. The subregion extends in directions away from the Appalachian Mountains and broadly follows the Piedmont topography of the Carolinas. The subregion also extends into Virginia and down into eastern Georgia. In comparing the MNS subregion with the tornado map in Figure 5, the cluster analysis associated the MNS home cell with cells in a broad area with similar tornado and physiographic metrics from Georgia to Virginia. MNS did not associate with regions of higher tornado risk, such as areas from Alabama westward or up into the Midwest portion of Figure 5.

25

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4. Figures 7a, b, and c show the point strike probability, the moderate (EF2/3) and the strong (EF4/5) occurrence rates for 1 degree cells used in the MNS region analysis. The cell statistics were compared for these metrics within the MNS subregion. Seven of the nine cells in the subregion were found to have a higher point strike probability than the MNS home cell. Five cells have higher moderate or strong occurrence rates than the home MNS cell.

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ATIACHMENT 1

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Figure 7: 1.4° Cell Metric Plots

5. The occurrence rate adjustments for MNS included a time trend adjustment occurrence rate increase of 164%, an 18% occurrence rate increase for unreported events in the modern era (1995-2016), and a conservative reallocation of 15% of the reported EFO tornadoes across all intensities to reflect the NWS modern era practice of reporting all unknown intensities as EFOs. No EF5 tornadoes were reported in the MNS subregion.

6. The use of a large MNS subregion encompasses a consistent physiographic region and the application of the adjustments noted above produced a reasonably conservative hazard curve for the MNS site. A systematic method was used to develop the hazard curve that is consistent with the TORMIS methodology. The hazard curve used for MNS clearly produces higher damage frequencies by hundreds of percent over the data in NU REG CR-4461 and the results are not particularly sensitive to EF5 frequencies for this plant.

7. Since the EF scale wind speeds are allowed for tornado missile LAR analyses, conservatism was applied to the resulting exceedance frequency values in the hazard curve at these EF scale wind speeds, rather than to the EF scale wind speeds.

27

ATTACHMENT 1 RAl-04:

One of the five review items in the TORM IS SER is to justify any deviation from the calculation approach. In addition, RIS 2008-14 (Item 2.d) includes the concern with taking credit for non-structural members. The unique McGuire configuration of the safety-related targets within the doghouses necessitated the use of the TORM IS ricochet routine to ensure conservatism in the TORMIS analysis. The doghouse openings contain non safety-related barriers (utility port barriers (UPBs)) to protect internal components from missiles. The UPBs consist of vertical and horizontal 5/8 inch diameter (No. 5) rebar spaced at five inches to six inches, on center. They are welded together at rebar intersection points and are welded to a structural steel angle frame which is either anchor bolted to doghouse concrete or welded to steel plates embedded in the doghouse concrete. As specified in the LAR, these UPBs in the openings at the top of the McGuire doghouses are credited for their ability to resist or slow down missiles impacting them.

UFSAR, Chapter 3, Table 3-8 describes velocity values for tornado missiles.

As indicated in the LAR, missile ricochet has been an option in the TORMIS computer code dating back to Electric Power Research Institute (EPRI) NP-769, "Tornado Missile Risk Analysis

- Appendixes" dated May 1978, however, it has not previously been used in a TORMIS analysis supporting an LAR. To accomplish modeling of barriers, the ricochet routine within the TORMIS software was modified to include a missile-pass-through option to credit the barrier. The LAR states on page 7, "The original TORMIS missile ricochet routine (References 3 and 4) redirects missiles that impact rigid surfaces with a reduced velocity." RIS 2008-14 (Item 2.d) raises a concern about taking credit for non-structural members, and the UPBs used for the dog house design appear to be non-structural.

The NRC staff requests the licensee to clarify if the ricochet model showing a reduced impact velocity is intended to mitigate the concern about crediting non-structural members, and discuss how the UPB can withstand the reduced velocity. Also explain the meaning of the missile velocities in USFAR, Table 3-8 with respect to the reduced velocity.

Duke Energy Response:

Use of Ricochet Routine The majority of the safety-related targets at MNS are located inside the Main Steam Doghouses and are exposed to missiles through openings at the top level. These openings are bounded by large concrete columns and are partially protected by angled, "gull wing" reinforced concrete type missile barriers as shown in Figure 8. Missiles can ricochet off of these concrete surfaces and be directed towards the safety related targets inside the Doghouses.

28

ATTACHMENT 1 Figure 8: MNS Unit 2 Exterior Doghouse The unique configuration of safety related targets within the Doghouses necessitated the use of the TORMIS ricochet routine to ensure conservatism in the TORMIS analysis. Missile ricochet has been an option in the TORMIS computer code dating back to EPRI NP-769 (LAR Reference 4). Instead of terminating a missile history when a missile strikes a missile shielding or safety-related target, the TORMIS missile ricochet routine continues the missile history at a new angle and velocity away from the surface it just impacted. The result is that the missile keeps flying and can still impact and possibly damage targets following the initial impact. Missile histories are continued following impacts on all missile shielding and safety target surfaces that are not perforated by the missile. Missile source targets are conservatively modeled with "imaginary surfaces" that allow missiles to fly through them unimpeded. Missiles are allowed to ricochet up to three times before the missile history is terminated by the TORMIS code.

Utility Port Barriers (UPBs) in Doghouse Openings The UPBs were not designed or constructed to stop design basis tornado-generated missiles nor are they credited for any ability to resist or slow down the design basis tornado-generated missiles, as described in UFSAR Table 3-8. This table will not change with the LAR.

Figure 9 shows an example of a UPB adjacent to the Main Steam Safety Valve (MSSV) exhausts from the inside of the Doghouse. While these barriers are not qualified to resist the MNS design basis tornado-generated missiles, they do offer considerable resistance to the lightweight TORMIS-generated tornado missiles that most commonly enter the doghouse openings, including metal siding, wood plank, wood beam, and plywood missiles.

29

ATIACHMENT 1 Figure 9: UPB in Doghouse Wall Opening Adjacent to MSSV Exhausts The TORMIS missile ricochet routine redirects missiles with a reduced velocity. A TORMIS code change was made to credit the ability of nonqualified barriers (i.e., the MNS UPBs) to resist or slow down missiles. This change was implemented within the existing TORMIS ricochet routine to perform the following steps when the missile velocity at impact exceeds a user-analyzed critical missile velocity:

1. Continue the missile trajectory through the barrier, instead of ricocheting it off of the surface.

2. Calculate the residual missile velocity based on the change in kinetic energy.

Critical missile velocity is determined based on the minimum amount of kinetic energy that is lost for a given missile type that penetrates a given barrier. The critical missile velocities for wood planks, metal siding, and plywood missiles was determined using a deterministic Finite Element Analysis (FEA) and used as input to TORMIS. Critical missile velocities for the wood beam missile were determined using the kinetic energy results for the wood plank missile.

These critical velocities consider the size of the UPB, the impact location, and the minimum expected change in kinetic energy for a missile passing through the UPB. A reduction factor of 0.9 was applied to the critical velocities determined from the FEA for additional conservatism.

Table 6 shows the missile velocities input to TORMIS for the UPBs. The critical missile velocities for the other 19 TORM IS missile types was set to O ft/s, which allows all of these missile types to pass through the UPBs unimpeded with no reduction in velocity.

30

ATTACHMENT 1 TORMIS Input Critical Velocity (ft/s)

UPB Impact Location Wood Metal Plywood Wood Plank Siding Sheet Beam Corner of Large UPBs 51 68 32 19 Center of Large UPBs 70 102 72 26 Side of Large UPBs 51 94 45 19 Anywhere on Small UPBs 36 68 32 13 Table 6: Missile Pass Through Velocities for UPBs (from FEA)

This missile pass through option was implemented without modifying the TORMIS physics engine that flies missiles within a tornado wind field. As such, this change does not deviate from the EPRI methodology, but improves the functionality of the ricochet routine to account for missiles that have the ability to pass through non-qualified missile barriers, like the UPBs.

Targets representing the UPBs are referred to as "Missile Pass Through" targets in the listing of all targets provided in the response to RAl-02.

31

ATTACHMENT 1 RAl-05 The LAR, Enclosure 1, page 8 states: "Target missile hit frequencies are the frequency of at least one tornado missile hitting a target over a period of one year. For very large targets, tornado generated missiles are likely to hit the target for almost every tornado strike and hence the missile hit frequency may approach or be essentially equal to the tornado strike frequency for such targets. As the target size reduces, as the target is shielded by other structures, or if only one surface of the target is exposed, the missile hit frequency reduces accordingly. In general, tornado missile hit frequencies are dependent on many geometrical factors as well as missile types, numbers, and proximity. The degree to which the elevation of the target is above the elevation of the nearby missile sources can also be a critical factor."

The frequencies presented in Enclosure 1, Table 3-2 of the LAR represent the average frequency produced over 60 replications representing all outage and non-outage conditions modeled. According to that table, the four targets with the highest hit frequencies are the VCNC (Control Room Area Ventilation) Air Intakes (targets 82-85) located outside of the doghouses next to the Reactor Buildings.

The NRC staff requests the licensee to provide additional information on the "geometrical factors, missile types, numbers, proximity" etc., which explains this result.

Duke Energy Response:

The VCNC Air Intakes for both units at MNS are located outside between the Reactor Buildings to the South and the Turbine Buildings to the North. The Unit 1 Intakes are located West of the Auxiliary Building and the Unit 2 Intakes are located East of the Auxiliary Building.

Figure10 shows an AutoCAD representation of the TORM IS model for the VCNC air intakes and the immediate proximity. In the figure, safety-related targets are shown in red, missile shielding targets are shown in gray, and missile source targets are shown in orange. The location of these targets causes them to have the highest missile hit frequency of all targets in the MNS TORMIS analysis for several reasons, including:

1. They are located outside of any Category 1 structure. The majority of the targets in the MNS TORMIS analysis are located within the Main Steam Doghouses and missiles must pass through the openings at the upper level of the doghouses to impact the targets.

Further, to enter the Doghouses, missiles must have a horizontal or upward trajectory to pass through the openings that are partially protected by concrete gull-wing barriers.

Conversely, the VCNC Air Intakes are located outside and can be impacted from most directions and angles, including by falling missiles. As a result, the VCNC air intakes are expected to have higher missile hit frequencies due to their location outside of all buildings.

2. They are located at a lower elevation. The VCNC Air Intakes are located on top of the Diesel Generator Rooms at an elevation of about 7 feet above plant grade. This is a much lower elevation than the openings in the Main Steam Doghouses that start 48 feet above grade, and the exposed MSSV and PORV tailpipes above the doghouse roofs that start 64 feet above grade. Targets at a lower elevation are more likely to be impacted by missiles because all missiles must come down, but they do not have to reach higher elevations. As a result, the VCNC Air Intakes are expected to have higher missile impact frequencies due to their elevation.

32

ATTACHMENT 1

3. Their proximity to missile sources. The VC/YC Air Intakes are located immediately adjacent to missile sources such as the Unit 1 and 2 Turbine Buildings, as well as the metal-clad work control building and enclosed walkways on the roof of the Auxiliary Building. We also note that the intakes are located at a lower elevation than the missiles being generated from these missile sources. The net result is that the air intakes are closer to and located below the point where missiles are generated from these sources.

This is especially significant for the VC/YC Air Intakes because it was conservatively assumed that any missile hit on the intakes renders them inoperable. As a result, the VC/YC Air Intakes are expected to have higher missile impact frequencies due to their proximity to these missile sources.

Figure 10: AutoCAD Representation of TORM IS Model for VC/YC Air Intakes and Proximity 33

ATTACHMENT 1 RAl-06 NUREG-0800, "Standard Review Plan [SRP] for the Review of Safety Analysis Reports for Nuclear Power Plants: LWR Edition," Chapter 3, Sections 3.5.1.4 and 3.5.2, contain the current acceptance criteria governing tornado missile protection. These criteria generally specify that SSCs that are important to safety be provided with sufficient, positive tornado missile protection (i.e., barriers) to withstand the maximum credible tornado threat. SRP, Chapter 3, Section 3.5.1.4 permits relaxation of the above deterministic criteria if it can be demonstrated that the probability of damage to unprotected essential safety-related features is sufficiently small.

RIS 2008-14 describes identified items that licensees should address when performing an approved TORMIS methodology per the TORMIS SER. The SER found that once the EPRI methodology has been chosen, justification should be provided for any deviations from the calculational approach. Enclosure 1, Section 3.2 of the LAR describes how the licensee complies with the TORM IS SER criteria. Enclosure 1, Section 3.1.5, page 11 of the LAR states "Boolean logic is applied to targets to account for redundancy in the structural or system design or TORM IS modeling of a component as multiple targets.", Section 3.1.5, page 11 of the LAR states "... the Unit can sustain damage to one Main steam line, and it can be in multiple places (PORVs [power operated relief valves], MSSVs

[main steam safety valves], or associated components) on the same Main Steam line." Proposed USFAR changes in Enclosure 2, Section 3.5.2.8.1.3d states "[t]he failure logic for redundancy of the Main Steam lines when missile damage to the PO RVs and MSSVs is beyond acceptable criteria, is that the Unit can sustain damage to one of four Main Steam line and the damage can be in multiple places on the same Main Steam line (PORVs, MSSVs, or associated components)." The basis for failure criteria is unclear. The NRC staff requests the following :

a. Describe the basis for all failure criteria used in the McGuire TORMIS analysis where Boolean logic is used. Examples include failure criteria for Main Steam line and PORVs or the failure criteria for Control Room Area Ventilation (VC/YC) air intakes and spent fuel pools (SFPs).

Duke Energy Response for RAl-06a:

Basis for the failure criteria used for Main Steam line, PORVs and MSSVs The failure criteria used for the Main Steam line (including the MSSVs and the PORVs) Boolean logic in the MNS TORMIS analysis was defined in a Main Steam line redundancy analysis performed in support of this LAR. This analysis determined an acceptable level of tornado missile damage to the Main Steam lines such that the plant response to the resulting damage and loss of function was bounded by the applicable MNS UFSAR Chapter 15 accident analyses.

The failure criteria resulting from this analysis can generally be stated that if a Unit does not have the system/component configuration required to mitigate a tornado event, concurrent with a loss of offsite power, and complete a controlled unit cooldown, then it fails. In order to not fail, this requires that three of the Unit's four Main Steam lines remain intact and at least one of the PORVs associated with any of the three intact Main Steam lines is undamaged and fully functional. If this is not the case, then the failure criteria is met.

34

ATIACHMENT 1 A Main Steam line is defined as not intact, or damaged, by any one of the following:

A missile strike to any MSSV downstream exhaust pipe that crimps it beyond its crimping limit, or causes the downstream exhaust pipe support to fail so as not to perform its design function, or causes the end of the downstream exhaust pipe to displace enough to strike the process piping attached to an MSSV.

A missile strike to any PORV valve body or its actuator would result in it not being able to perform its design function.

A missile strike to the downstream PORV exhaust pipe that crimps it beyond its crimping limit, or punctures the wall or failures of any the downstream exhaust pipe supports so as not to perform its design function.

A missile strike to the process piping upstream of a PORV that causes it to crimp beyond its limit, or a puncture or to fail any upstream process piping supports so as not to perform its design function.

To determine crimping limits, tornado missile target strike/damage analysis was performed to determine how much damage these targets could take due to a missile strike and still perform their design functions. The damage evaluated was the local reduction in internal flow area due to pipe deformation resulting from a tornado missile strike, also called pipe crimping.

Basis for the failure criteria used for Control Room Area Ventilation (VC/YC) Air Intakes and Spent Fuel Pools The four VC/YC Air Intakes are located on top of the Auxiliary Building roof, two near the south end of the Unit 1 Reactor Building, and two near the south end of the Unit 2 Reactor Building. Based on their location, the Air Intakes are susceptible to tornado missile damage. The Air Intakes for each Unit consist of 2 side-by-side "candy cane" pipes. See Figure 11 below. Given their close proximity to each other, both pipes for each unit are modeled together in TORMIS (i.e. a missile hitting either pipe hits both pipes). The candy-cane shape for each unit is represented in TORMIS as two targets, one representing the vertical pipe, and a second representing the curved section (as a horizontal target). As discussed above, both of these targets represent both pipes for the respective unit. The Boolean logic described in the LAR states that a missile hit on either the vertical or horizontal section results in damage to both intakes for the unit. In other words, any missile impact on either target results in failure of the Unit 1 VC/YC Air Intakes. Unit 2 is treated in the same way.

Each MNS Spent Fuel Pool is housed in a concrete and steel superstructure. The concrete superstructure encloses the Spent Fuel Pool except for the North end of the structure, which is enclosed by a steel structure with siding. The concrete structure provides protection from tornado winds and tornado missiles, but the North end of the Spent Fuel Building does not provide tornado missile protection. As such, the only credible missile paths to the Spent Fuel Pools of each unit are from the North end.

In order to meet the failure criteria for this Boolean combination, a tornado would need to produce missiles that impact and damage the VC/YC Intakes of both Units (that are separated by about 250 feet) on the south side of the Reactor Buildings and have a damaging missile from the same tornado entering at least one of the Spent Fuel Pools from the North end.

35

ATTACHMENT 1 As documented in the MNS UFSAR, the analyzed tornado missile accident postulates a tornado missile penetrating the North end of one of the Spent Fuel Fool Buildings and rupturing spent fuel assemblies in Region 2 of the Spent Fuel Pool. In the worst case scenario of this accident, only one of four VC/YC Air Intakes remains intact to provide air intake to the Control Room filtration system (VC). Despite this worst case scenario, the resulting doses to the Control Room are well within the 10 CFR 50.67 limits.

Additional details regarding the failure criteria for the VC/YC Air Intakes is also provided in the response to RAl-06e.

Figure 11: Control Room Area Ventilation Air Intake 'Candy Canes' 36

ATTACHMENT 1

b. Considering that the criteria in SRP, Section 3.5.1.4 is compared against the probability per year of damage to all SSCs important to safety that are not designed to withstand tornado missile damage, justify comparing McGuire results using selected failure criteria against the criteria in UFSAR and SRP. Also, describe how the use of failure criteria is consistent with the application of the approved TORM IS methodology.

Duke Energy Response for RAl-06b:

In addition to the discussion on the basis for the failure criteria provided in the response to RAl-06a, additional clarity is provided in the RAl-06d response for the VC/YC Air Intakes and Spent Fuel Pool failure criteria. Also, specific discussion is presented in the RAl-06e response on the individual target results and how the target group damage frequencies were derived. The damage frequency values given in Table 3-2 of the LAR are TORM IS results for individual targets which do not include the effects of the Boolean logic. The damage frequencies that include the effects of the Boolean logic are given in LAR Table 3-4 for the Main Steam system and in new Table 7 below for the VC/YC Air Intakes/ Spent Fuel Pools. These tables represent the damage frequencies for the possible combinations of targets within the group and indicate whether the applicable system fails for each combination. The results of these tables are then included in the aggregate damage frequencies for the MNS target groups in the LAR Table 3-5.

Boolean logic is applied to targets to account for redundancy in the structural or system design or TORMIS modeling of a component as multiple targets. With redundancy in the design, the system function could be met even with one or more individual targets damaged by postulated tornado missiles.

Missile hit and damage frequencies for groups of targets evaluated in TORM IS are commonly combined using Boolean operators (U and n). The union (U) operator means that if any one of the targets is damaged in a tornado, the system is assumed to fail. The intersection (n) operator means that all the intersected components must be damaged in a tornado strike for the system to fail. Combinations of union and intersection operators can be put together to describe multi-component system failure logic for plant systems and subsystems. For union groups, summation of the frequencies is often accurate for small frequencies.

Preliminary analyses determined that the summation of damage frequencies for the individual targets in the LAR Table 3-2 approached or exceeded the 1.0E-06 per year threshold. However, these analyses did not consider any redundancies between the Main Steam lines or the VC/YC Air Intakes. LAR Section 3.1.5 discusses the approach to the Boolean logic developed using the TORSCR code to account for the redundancies. TORSCR is a FORTRAN computer code that is used to post-process TORM IS output files. Its primary function is to compute Boolean combinations of target hit and damage probabilities over multiple targets.

Total risk assessment for multi-target combinations are discussed in the original TORMIS documentation in Section 2.2.4.3 of EPRI NP-768, and Section II of EPRI NP-2005. NP-2005 documents the TORMIS function that provides the Boolean union combination over all targets considered in the analysis as well as the union and intersection combinations for 2 user specified targets. The TORSCR post-processor uses the methodology discussed in these references to produce union and intersection results for any number of targets specified.

37

ATTACHMENT 1 TORSCR was initially developed to support the TORM IS analysis performed for the Limerick Generating Station. The TORSCR post-processing computer code and use of the Boolean Logic approach was also previously reviewed and approved by the NRC for the Byron Station TORMIS License Amendment.

Combination Unit 1 VCIYC Unit 2 VCIYC UJSFP U2SPF System Survive Frequency (yr -I)

Number Failure Failure Failure Failure or Fail I

0 0

Survive 3.52E-04 2

I 0

0 0

Survive 7.72E-05 3

0 I

0 0

Survive l.15E-04 4

0 0

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Survive 4.39E-09 5

0 0

0 l

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3. 18E-08 6

I I

0 0

Survive l.04E-04 7

I 0

Survive 1.45E-09 8

I 0

0 I

Survive 2.0IE-08 9

0 I

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Survive 3.IOE-09 10 0

I 0

I Survive 2.58E-08 11 0

0 l

l Survive 2.58E-11 12 1

1 1

0 Fail 4.04E-09 13 1

1 0

1 Fail 5.00E-08 14 I

0 l

l Survive 4.48E-l l 15 0

I l

I Survive l.41 E-ll 16 1

1 1

1 Fail 8.SIE-11 Overall Failure Frequency 5.41E-08 Table 7. Failure Combinations for VC/YC Air Intakes and Spent Fuel Pools 38

ATIACHMENT 1, Section 3.1.5, page 13 of the LAR states "The Boolean logic for the Unit 1 and 2 Spent Fuel Pools and the Unit 1 and 2 VC/YC Air Intakes is that failure is defined as both VC/YC Air Intakes failing by wind missile and missile damage to fuel assemblies in either of the Spent Fuel Pools." Proposed USFAR changes in Enclosure 2, Section 3.5.2.8.1.3d states The failure logic for the Control Room Air Ventilation System (CRAVS) Intakes (VC/YC Air Intakes and Spent Fuel Pools (SFP) is simultaneous tornado generated missile impacts to all the Unit 1 and Unit 2 VC/YC Air Intakes AND the entry of a tornado generated missile into either the Unit 1 or Unit 2 SFP that would impact and Spent Fuel assemblies above acceptable critical velocities." The NRC staff requests the following :

c. Define acceptable critical velocities, their basis, and their effect on SSCs.

Duke Energy Response for RAl-06c:

Acceptable critical velocities for tornado generated missiles entering the SFP is defined as the velocities at which tornado missiles can enter the spent fuel pool and not cause damage to spent fuel assemblies. For wood plank, metal siding, and plywood type missiles the acceptable critical missile velocities set at 528 ft/sec. These three missile types were analyzed for entry into the SFPs at the given velocity for damage to spent fuel assemblies. The analysis shows that they will not cause any damage to spent fuel assemblies. For conservatism in the TORMIS analysis, the failure velocity values used for these three missile types are taken as 90% of the acceptable critical velocities. For all other missile types, entry at any speed into the SFP is considered a failure in TORMIS.

39

ATTACHMENT 1 The overall damage probability Boolean logic in Enclosure 1, Page 13 of the submittal seems to define the failure criteria as a single Unit 1 and a single Unit 2 VC/YC Air Intake Failure and a failure of either SFP results in damage, but the text on Enclosure 2, Page 8 seems to differ from the Boolean logic shown. The NRC staff requests the following:

d. Clarify the failure criteria for VCIYC air intakes and SFPs and address any discrepancies between the failure criteria in Enclosure 1, Page 13 and Enclosure 2, Page 8.

Duke Energy Response for RAl-06d:

The apparent discrepancy between the failure criteria for the VC/YC air intakes as described on, Page 13 and Enclosure 2, page 8 seems to be due to the wording used in, Page 13. The following changes in red will make it more consistent:

The Boolean logic for the Unit 1 and 2 Spent Fuel Pools and the Unit 1 and 2 VC!YC Air Intakes is that failure is defined as ootR the VCIYC Air Intakes of both Units failing by wind missile and missile damage to fuel assemblies in either of the Spent Fuel Pools.

The three main pieces of this logic can then be expressed as the following independent failure events:

To clarify further, Figure 12 is a photograph of the Unit 1 VC/YC Air Intakes and shows that the Intakes for each Unit consist of 2 side-by-side "candy cane" pipes. Given their close proximity to each other, both pipes for each unit are modeled together in TORMIS (i.e. a missile hitting either pipe hits both pipes). The candy-cane shape for each unit is represented in TORMIS as two targets - one representing the vertical pipe, and a second representing the curved section (as a horizontal target). As discussed above, both of these targets represent both pipes for the respective unit. The Boolean logic described on Enclosure 1, Page 13 states that a missile hit on either the vertical or horizontal section results in damage to both intakes for the unit. In other words, any missile impact on either target results in failure of the U1 VC/YC air intakes. Unit 2 is treated in the same way. As such, the language in Enclosure 1, p.13 is consistent with, page 8.

Figure 12. Photo of Unit 1 VCIYC Air Intakes 40

ATIACHMENT 1

e. The individual target damage frequencies for VC/YC air intakes and SFPs in, Table 3-2 do not seem to result in the value given in Enclosure 1, Page 13. Provide details on how the damage frequency for this event was derived, and explain the apparent discrepancy between Table 3-2 and Enclosure 1.

Duke Energy Response for RAl-06e:

The individual target damage frequencies in Table 3-2 of LAR Enclosure 1 do not include any effects of the Boolean logic discussed at the end of Section 3.1.5 on page 13 of Enclosure 1.

To reconcile the relatively high damage frequencies for targets 82-85 (VC/YC air intakes) from Table 3-2 with the relatively low Boolean frequency (i.e. 5.41 E-08 yr-1) reported on page 13 of, the location of the targets with respect to each other needed to be taken into consideration.

Figure 13 shows that the VC/YC Air Intakes for the two Units are located on the south side of the Reactor Buildings and that the Spent Fuel Pools are on the north side of the Reactor Buildings.

Figure 14 shows that the only credible missile paths to the Spent Fuel Pools of each Unit are from the north. In order to meet the failure criteria for this Boolean combination, a tornado would need to produce missiles that impact the VC/YC Intakes of both Units (that are separated by about 250 feet) on the south side of the Reactor Buildings and have damaging missiles entering at least one of the Spent Fuel Pools from the north. Based on these locations, it is expected to be a substantial reduction from the individual target damage frequencies (from Table 3-2) to the Boolean logic defined on Page 13 of Enclosure 1.

The differences were quantitatively resolved by considering the 16 possible combinations of the following four failure events:

1. Missile impact on either portion of the Unit 1 VC/YC Air Intakes (82 U 83)

2. Missile impact on either portion of the Unit 2 VC/YC Air Intakes (84 U 85)

3. Damaging missile impact on fuel assemblies in Unit 1 Spent Fuel Pool (86)

4. Damaging missile impact on fuel assemblies in Unit 2 Spent Fuel Pool (87)

Table 8 shows the damage frequency for each possible combination of events that would lead to failure based on the failure criteria defined on Page 13 of Enclosure 1. Each combination in the table represents a Boolean intersection (n) of the events listed with O indicating no failure and 1 indicating failure. For example, combination 12 (the first of three that lead to system failure) is interpreted as "U1 VC/YC Fails AND U2 VC/YC Fails AND U1 SFP Survives AND U2 SFP Fails". The overall failure frequency for the system is then computed as the arithmetic sum of the three event combinations that are labeled "Fail" in the 5th column. This sum is shown in the bottom row of Table 8.

41

ATTACHMENT 1 Unit 1 VC/YC Unit 2 VC/YC/

Figure 13: Plan View of Location of VC/YC Air Intakes and Spent Fuel Pools Figure 14: 3-D View of Required Missile Path to Spent Fuel Pools 42

ATTACHMENT 1 Combination Unit I VOYC Unit 2 VCIYC UJSFP U2SPF System Survive Frequency (yr _,)

Number Failure Failure Failure Failure or Fail I

0 0

Survive 3.52E-04 2

I 0

0 0

Survive 7.72E-05 3

0 I

0 0

Survive I.I SE-04 4

0 0

I 0

Survive 4.39E-09 5

0 0

0 I

Survive

3. 18E-08 6

I I

0 0

Survive l.04E-04 7

I 0

l 0

Survive 1.45E-09 8

I 0

0 I

Survive 2.0 IE-08 9

0 I

I 0

Survive

3. 1 OE-09 10 0

I 0

I Survive 2.58E-08 II 0

0 l

I Survive 2.58E-1 l 12 1

1 1

0 Fail 4.04E-09 13 1

1 0

1 Fail 5.00E-08 14 I

0 I

I Survive 4.48E-1 l 15 0

I I

I Survive 1.41 E-ll 16 1

I 1

1 Fail 8.SIE-11 Overall Failure Frequency 5.4IE-08 Table 8: Failure Combinations for VC/YC Air Intakes and Spent Fuel Pools 43

ATTACHMENT 2 UFSAR PROPOSED CHANGES (With revisions from RAl-01a&b responses)

UFSAR Chapter 2 McGuire Nuclear Station Spring, summer and autumn storms, phe omena of widespread consequence, are the major bearers of severe weather. For the area of North Car lina, South Carolina and their coastal waters, an average of one tropical storm per year and one hurricane every other year has been computed based on a period of record of 63 years (1901-1963). Within this period, seven years were void of any activity while nine years produced a combined total of three storms per year. Highest winds over the area are 110 miles per hour (fastest mile, Cape Hatteras, N.C., September, 1944) along the coast and 80 miles per hour (fastest mile for inland maxima, Wilmington, N.C., October, 1954). Maximum 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> rainfalls, again higher for coastal stations, have been recorded near 15 inches along the coast (Cape Hatteras, N.C., June, 1949) to near 9 inches inland (Wilmington, N.C., September, 1938). Figure 2-37 relates tornado frequency to two degree squares for the period 1916-1955. For the site area a total of 50 tornados are shown per two degree square (square area about 125 miles by 125 miles). To put in terms of probability for a point (nuclear station), such a translation predicts a recurrence interval of 4405 years. Thunderstorms with greater frequencies during the summer occur 45-50 days per year (from Charlotte, N.C., period of record 73 years). Associated hail can be expected about one day per year in coastal areas and one or more days per year over inland areas from the period of record 1955-1967 (Reference J).

The tornado parameters and tornado frequency values used in the probabilistic analysis (TORMIS) described in Section 3.5.2.8.1 are found in Reference 5.

e eoro og1ca con 1t10ns assume o loadings and in Section 3.8. 1.4 for general wind and snow loadings. Criteria for design tornados include a rotational speed of 300 mph, a translational speed of 60 mph and a vacuum pressure differential of 3 psi in 3 seconds. Design speed for general wind loading is 95 mph (fastest mile). Snow loading for design purposes is 20 pounds per square foot.

Air pollution over the Carolinas is of greatest potential during the fall. An average of ten episode - days per year has been computed for a period of five years (from upper air observations at area Weather Service Stations, i.e., Athens, Georgia; Greensboro, N.C.; Cape Hatteras, N.C. and Charleston, S.C.).

2.3.2 Local Meteorology 2.3.2.1 Data Sources Climatic Atlas of the United States, United States Department of Commerce, Environmental Science Services Administration, Environmental Data Service, June, 1968.

Climate of the States, North Carolina, Climatography of the United States, No. 60-31, United States Department of Commerce, Weather Bureau, February, 1960.

Local Climatologi.cal Data, Annual Summary with Comparative Data, North Carolina, United States Department of Commerce, National Oceanic and Atmospheric Administration, Environmental Data Service, 197 l.

2.3.2.2 Normal and Extreme Values of Meteorological Parameters Table 2-9 depicts normal and extreme values for the following parameters: temperature, rain, sleet and snow, fog, relative humidity, dew point and wind direction and speed.

Thunderstorm occurrence by season is: 11 for spring (March-May), 29 for summer (June-August), 5 for fall (September-November) and I for winter (December-February). (Reference 1) 2.3.2.3 Potential Influence of the Plant and Its Facilities on Local Meteorology Consideration has been given to possible environmental effects associated with heat dissipation from the cooling pond (Lake Norman, vicinity of McGuire Nuclear Station). A review of the literature and operating experience to date would suggest that effects of fogging and icing are minimal for the properly 1

McGuire Nuclear Station UFSAR Chapter 3 the basis for judging the representativeness of data for the year October 17, 1970 - October 16, 1971, with regard to long-term conditions (e.g., five year period). Consideration of wind speed by stability type for the two periods shows a lower speed in general for the period October 17, 1970 October 16, 1971; the occurrence of calms and winds less than 4 knots are up four percentage points from 15% for the period January, 1969 - December, 197 3. A slight shift in stability frequencies is noted for the period October 17, 1970 - October 16, 1971: "G "

increases, "F" and "E " decrease, "D" increases and "C ", "B ", and "A" decrease.

Some change in wind direction frequencies, also minor, is noted for the period October 17, 1970 -

October 16, 1971: easterly, westerly and southwesterly directions increase while southerly, northerly and northeasterly directions decrease. On balance, the period is taken as reasonably representative of long-term conditions in the vicinity of the site with some conservatism with respect to accident relative concentration estimates as indexed by the joint distribution of wind direction and speed by stability type.

An additional year of onsite data have been collected using a measurement system which conforms to the recommendations of Regulatory Guide 1.23. The location of instrumentation is shown in Figure 2-41 marked permanent meteorological facility. Other discussion relating to instrument accuracy and sensitivity at this facility is included in Section 2.3.3. Dispersion estimates have been developed from this data base and are presented in the following summary.

Table 2-14 displays the joint frequencies of wind direction and speed by atmospheric stability type as they were observed on site for the period February, 1976 - January, 1977. Figure 2-49 represents the distribution of hourly dispersion factors at the Exclusion Area Boundary (2500 feet). Frequencies result from cumulative summation of percentage values in Table 2-14 in decreasing order of relative concentration computed for selected wind speed class intervals.

All calm wind occurrences are considered in the distribution. Data recovery for this period was 94% of total observations.

Annual average dispersion factors were also calculated for the period of record using the calculational model in Section 2.3.5. The resulting areal distribution of annual average relative concentration is portrayed in Table 2-15.

2.3. 7 References

1. Meteorology and Atomic Energy, 1968, United States Atomic Energy Commission, Division of Technical Information, July, 1968.

2. Workbook of Atmospheric Dispersion Estimates, D. Bruce Turner, United States Department of Health. Education and Welfare, 1969.

3.

"Severe Local Storm Occurrence, 1955-1967", US. Weather Bureau Technical Memorandum WBTM-FCST #12, September, 1969.

4. Mean Number of Thunderstorm Days in the United States, US. Department of Commerce, Weather Bureau, Technical Paper #19, September, 1~'1!-!'------....

MCC-1139.01-00-0298, "MNS Tornado Missile TORMIS Analysis".

THIS IS THE LAST PAGE OF THE TEXT SECTION 2.3.

2

McGuire Nuclear Station UFSAR Chapter 3 Table of Contents (cont'd) 3.5.2.5.2 3.5.2.5.3 3.5.2.5.4 3.5.2.6 3.5.2.7 3.5.2.8 3.5.2.8.1 3.5.2.9 3.5.3 3.5.4 3.5.4.1 3.5.4.2 3.5.5 3.5.6 3.6 3.6. 1 3.6.1.1 3.6. 1.2 3.6.2 3.6.2. 1 3.6.2.1.l 3.6.2.1.2 3.6.2.1.3 3.6.2.2 3.6.2.2.1 3.6.2.2.2 3.6.2.2.3 3.6.2.3 3.6.3 3.6.3.1 3.6.3.2 3.6.4 3.6.4.1 3.6.4.1.1 3.6.4.1.2 3.6.4.2 3.6.4.3 3.6.5 3.6.5.1 3.6.5.1.l 3.6.5. 1.2 3.6.5.1.3 3.6.5.1.4 3.6.5.2 3.6.5.3 3.6.5.4 3.6.5.5 3.6.5.5.1 3.6.6 3.7 3.7. 1 3.7.1.1 Pressurizer Heaters Systems Connected to the Reactor Coolant System Pressurizer Turbine-Generator M issi Jes Tornado Generated Missiles Probabilistic Tornado Missile Risk Analysis Diesel Generator Missiles Selected Missiles Barrier Design Procedure Protection of Containment Function Penetration Depth Estimates Missile Barrier Features References Protection Against Dynamic Effects Associated with the Postulated Rupture of Piping Systems in which Design Basis Piping Breaks Occur Reactor Coolant System All Other Mechanical Piping Systems Design Basis Piping Break Criteria Postulated Piping Break Location Criteria for the Reactor Coolant System Postulated Piping Break Locations and Orientations Postulated Piping Break Sizes Line Size Considerations for Postulated Piping Breaks General Design Criteria for Postulated Piping Breaks Other Than Reactor Coolant System Postulated Piping Break Locations and Orientations Postulated Piping Break Sizes Line Size Considerations for Postulated Piping Breaks Analysis and Results Design Loading Combinations Reactor Coolant System Design Loading Combinations All Other Mechanical Piping Systems Design Loading Combinations Dynamic Analysis Reactor Coolant System Dynamic Analysis Westinghouse Methodology Steam Generator Replacement Methodology All Other Mechanical Piping Systems Dynamic Analysis Structural Analysis of Postulated Piping Breaks Protective Measures Reactor Coolant System Postulated Pipe Break Restraint Design Criteria for Reactor Coolant System Protective Provisions for Vital Equipment Criteria for Separation of Redundant Features Separation of Piping All Other Mechanical Piping Systems Main Steam and Feedwater System Design Control Room Protection from Postulated Piping Breaks Postulated Pipe Break Restraint Design Criteria for All Other Mechanical Piping Systems Typical Pipe Whip Restraints References Seismic Design Seismic Input Design Response Spectra 3

3-2

McGuire Nuclear Station UFSAR Chapter 3 List of Tables (cont'd)

Table 3-50. Stress Criteria For Supports, Restraints, and Anchors Duke Classes B, C, and F Table 3-51. Stress Criteria For Safety Class 2 and 3 Cylindrical Shell Type Equipment and Components And Their Supports Table 3-52. Westinghouse Design Criteria for ASME Class 2 and 3 Components Table 3-53. Guard Pipe Designs Relying on ASME Code Case 1606 Table 3-54. Comparison of Predicted PWHIP Response - Inelastic Pipe Element. (Example Problem:

Figure 3-117)

Table 3-55. Comparison of Predicted PWHIP Response - Inelastic Yield Element. (Example Problem:

Figure3-118)

Table 3-56. Comparison of Predicted PWHIP Response - Inelastic Yield Element. (Example Problem:

Figure3-1 20)

Table 3-57. HV AC Design Codes Table 3-58. Maximum Deflections for Reactor Internals Under Slowdown and Seismic Excitation (!-

Millisecond Double-Ended Break)

Table 3-59. Maximum Stress Intensities for Reactor Internals ( I-Millisecond Pipe Break and Seismics)

Table 3-60. Electrical ystems & Components Seismic Criteria Table 3-6 1. Post-Accident Equipment (Inside Containment) Operational Requirements Table 3-62. Control Complex Areas Ventilation Systems Analysis Results -----..___

Table 3-63. Structures, Systems and Components Included in TORM IS Analysis Not Designed fo Design Basis Tornado Generated Missiles 4

3-9

McGuire Nuclear Station UFSAR Chapter 3 3.5 Missile Protection 3.5.1 Missile Barriers and Loadings 3.5.1.1 Internal Missiles The interior structural elements of all Category I structures, except those structural elements shielded from internal missiles are designed to withstand the internal missiles effect. For internal missiles characteristics refer to Section 3.5.2.9 3.5.1.2 Turbine-Generator Missiles All Category I structures, with the exception of the New Fuel Storage Vault exposed to these missiles are designed to withstand their effect and meet Regulatory Guide 1.115, Rev. I. The credible turbine-generator missiles are low trajectory and the associated properties are given in Section 3.5.2.

3.5.1.3 Tornado Generated Missiles All Category I structures exposed to these design basis missiles are designed to withstand their effect with the exception of those Structures Systems and Components included in the TORMIS probabilistic tornado risk analysis listed in Table 3-63 and as discussed in Section 3.5.2.8.1.1.

tabulation of the design basis tornado generated missiles is given in Table 3-8.

3.5.1.4 Site Proximity Missiles For the McGuire Station, aircrafts are not considered as credible missiles due to the established flying patterns close to the station.

Table 3-9 provides a summary of the major Category I structures that are designed for missile protection, along with the types of missiles they are protected against.

3.5.1.5 Diesel Generator Missiles Each Diesel Generator shall be protected against missiles produced by the adjacent diesel generator by the appropriate section of the block wall separating Diesel Generator rooms A from B. The credible diesel generator missiles are given in Section 3.5.2.9.

3.5.2 Missile Selection The specific missiles and the basis for selection as credible missiles are discussed in this Section. Some missiles which are not credible are pointed out and justified as prescribed below.

3.5.2.1 Reactor Coolant Pump Flywheel The following precautionary measures, taken to preclude missile formation from the reactor coolant pump flywheel, assure that the flywheel will not produce missiles under any anticipated accident conditions.

I. The flywheel is fabricated from rolled, vacuum-degassed, ASME SA-533.

2. Flywheel blanks are flame-cut from the plate, with allowance for exclusion of flame-affected metal.

3. A minimum of three Charpy tests are made from each plate parallel and normal to the rolling direction to determine that each blank satisfies design requirements.

4. An NDTT less than 10°F is specified.

5.

The finished flywheel is subjected to 100 percent volumetric ultrasonic inspection.

5

McGuire Nuclear Station UFSAR Chapter 3 valves in the relief line, the air operated relief valves, the air operated spray valves, instrumentation assemblies and associated piping.

Supports for these lines should be capable of restraining movement of components and piping, under action of reaction and jet forces from circumferential pipe rupture, in accordance with the criteria of Section 3.6.2.

Characteristics of valve bonnet missiles are given in Table 3-14. Pressurizer instrumentation assembly missile characteristics are included in Section 3.5.2.5.

3.5.2.7 Turbine-Generator Missiles Turbine missiles can be generated by a turbine overspeed. The credible low-trajectory turbine missiles and the associated properties are defined in Table 3-15 and Figure 3-4. Basis for selecting these missiles is given in Section I 0.2.3.

3.5.2.8 Tornado Generated Missiles Table 3-8 provides a Slllmnary of the design basis tornado-generated missiles. The integrity of all Category l structures is not impaired by these missiles. This is accomplished by designing the exposed structure of steel reinforced concrete capable of withstanding the impact of tornado-generated missiles.

Modifications to existing or the design of new Category 1 structures shall conform to the requirements of N RC R[S 2008-14.

Table 3-63 provides a list of Category 1 structures, systems, and components that have not been designed to withstand the impact of design basis tornado-generated missiles. These SSCs were probabilistically show that they will not be impacted or will not be damaged beyond an acceptable criteria if impacted as discussed in Section 3.5.2.8. l.3.

NOTREQU The following was added as part of a NRC request for additional information in order to perform a comparability review. The request was to determine penetration velocities for 2 missiles which were not part of the design basis missiles used during the Construction Permit (CP) stage (Lable 3-8). The requested velocities are for category 1 structures with wall or roofs less than 2 feet thick.

In order to assess the degree of comparability of protection against tornado missiles provided in the CP stage with that presently under review by the NRC, an additional investigation has been performed to evaluate the following missiles:

I.

Steel rods, one inch diameter by three feet long, weight eight pounds.

2.

Utility pole, 13-1/2 inch diameter, 35 feet long, weight 1490 pounds.

Structural concrete barriers designed to provide missile protection having thicknesses less than two feet are as follows:

1. Slabs - None

2.

Walls:

a.

1 '- 0 11 thick located on column line AA between column lines 53 to 59 constructed to elevation 782 feet.

b. 1 '- 6 11 thick, location on column lines 49 and 63 between column line AA (Turbine Building) and Reactor Building shield building constructed to elevation 782 feet.

The maximum horizontal velocities required to penetrate the barrier or generate secondary missiles within the wall elevations are as follows:

6

1 186 232 2

184 229 The horizontal velocity (ft./sec) required for penetration or generation of secondary missiles is based upon a constructed thickness equal to three times the penetration depth.

Separation of redundant components is not considered in the design of barriers for tornado missiles.

3.5.2.8.1 Probabilistic Tornado Missile Risk Analysis

~e\\N section A probabilistic tornado missile risk analysis (Reference 7) was completed using the TORMIS computer code which is based on the NRC approved methodology detailed in References 8, 9, and

10. The TORMIS analysis was performed in accordance with the guidance described in NRC TORMIS Safety Evaluation Report (Reference 11) and as clarified by Regulatory Issue Summary (RIS) 2008-14 (Reference 12).

3.5.2.8.1.1 Scope The TORMIS analysis (Reference 7) includes plant components identified as necessary to safely shutdown the plant and maintain a shutdown condition that are located in areas not fully protected by missile barriers designed to resist impact from design basis tornado generated missiles. The plant components (also referred to as, targets) included in the analysis are listed in Table 3-63 and additional details regarding these targets (i.e. specific identification, description, location, and portion) are included in Reference 7, Volume 3.

3.5.2.8.1.2 TORMIS Computer Code The TORMIS (TORnado MISsile Risk Analysis Methodology) computer code uses a Monte Carlo simulation method that simulates tornado strikes on a plant. For each tornado strike the tornado field is simulated; missiles are injected and flown; and the missile impacts on structures, systems, and components (SSCs) are analyzed. These models are linked to form an integrated time history simulation methodology. By repeating these simulations, the frequencies of missiles impacting and damaging individual plant components (targets) and groups of targets are estimated.

Statistical convergence of the results is achieved by performing multiple replications with different random number seeds.

3.5.2.8.1.3 Analysis The TORMIS results show that the arithmetic sum of damage frequencies for all target groups affecting the individual Units are lower than the acceptable threshold frequency of 1.0E-06 per year per Unit as established in Reference 13.

The following limiting inputs and assumptions were used in the analysis (Reference 7):

a.

A site specific tornado hazard curve and data set for McGuire was developed using statistical analysis of the NOAA/National Weather Service Storm Prediction Center tornado data for the years 1950 through 2016. The analysis utilizes the Enhanced Fujita (EF) Scale wind speeds in the TORM IS simulations.

b. The missile characteristics and locations are based on plant walk down surveys and plant drawings. The plant walk downs were conducted during both non-outage and outage periods to capture both conditions. A stochastic (time dependent) model of the missile population is implemented in TORMIS. The stochastic approach to the missile population varies the missile populations in each of the TORMJS replications to account for 7

predictable changes in plant conditions (i.e. increased missiles during outages) and the randomness inherent in the total number of missiles present at the plant at any given time.

c.

Finite element analysis calculations were performed to determine the missile damage threshold velocity for tornado generated missiles that would cause unacceptable damage to selected targets which is then used as an input in the TORMIS model.

d. Boolean combinations of targets were developed, and the logic was applied to targets or target groups to account for redundancies in the system design or for the TORMIS modeling of a component as multiple targets. The failure logic for redundancy of the MainSteam lines when missile damage to the PORVs and MSSVs is beyond acceptable criteria, is that the Unit can sustain damage to one of four MainSteam line and the damage can be in multiple places on the same MainSteam line (PORVs, MSSVs, or associated components). Damage, beyond the acceptable criteria, on more than one line is considered a failure in TORMIS space. The failure logic for the Control Room Air Ventilation System (CRA VS) Intakes (VCNC Air Intakes) and Spent Fuel Pools (SPF) is simultaneous tornado generated missile impacts to all the Unit 1 and Unit 2 VCNC Air Intakes AND the entry of a tornado generated missile into either the Unit 1 or Unit 2 SFP that would impact any Spent Fuel assemblies above acceptable critical velocities.

e.

Any tornado generated missile strikes to the VCNC Air Intakes were conservatively assumed to crimp the Intakes closed.

f.

The Utility Port Barriers in the Doghouse Upper Openings are conservatively taken into account for their resistance to a conservative selection of tornado generated missiles entering the Doghouse Upper Openings.

g.

All tornado generated missiles are conservatively assumed to strike with an end-on, co-linear impact.

8

3.5.6 References I.

Ernest L. Robinson, "Bursting Tests of Steam-Turbine Disc Wheels," Transactions of the ASME, July, 1944.

2. A. Amirikan, "Design of Protective Structures,"NAVDOCKS P-51, Bureau of Yards and Docks, Department of the Navy, Washington, D. C., August, 1950.

3.

R. C. Gwaltney, "Missile Generation and Protection in Light-Water-Cooled Power Reactor Plants,"

USAEC Report ORNL-NSIC-22, Oak Ridge National Laboratory, September, 1968.

4.

Westinghouse Report No. 296/281 - B of December 1973, Revised April 1974, "The Effects of a High Pressure Turbine Rotor Fracture and Low Pressure Turbine Disc Fracture at Design Overspeed."

5.

R. A. Wiliamson and R. R. Alvy, "Impact Effects of Fragments Striking Structural Elements,"

Holmes and Narver, Inc., Anaheim, California Revised January 1975.

6. NRC Letter to Duquesne Light Company, September 12, 1996, "Acceptance for Referencing of Topical Report WCAP-14535, Topical Report on Reactor Coolant Pump Flywheel Inspection Elimination."

7.

MCC-1139.01-00-0298, "MNS Tornado Missile TORMIS Analysis".

8.

Electric Power Research Institute Report, EPRI NP-768, "Tornado Missile Risk Analysis", May 1978.

9. Electric Power Research Institute Report, EPRI NP-769, "Tornado Missile Risk Analysis -

Appendices", May 1978.

10. Electric Power Research Institute Report, EPRI NP-2005, Volumes 1 and 2, "Tornado Missile Risk Evaluation Methodology", August 1981.

l l. NRC Safety Evaluation Report, "Electric Power Research Institute (EPRI) Topical Reports Concerning Tornado Missile Probabilistic Risk Assessment (PRA) Methodology", October 26, 1983 (Adams ML080870291)

12. NRC Regulatory Issue Summary 2008-14, "Use of TORM IS Computer Code for Assessment of Tornado Missile Protection", June 16, 2008 (Adams ML080230578)

13. Memorandum from Harold Denton, NRR Director, to Victor Stello, Deputy Executive Director for Regional Operations and Generic Requirements, "Position of use of Probabilistic Risk Assessment in Tornado Licensing Action," dated November 7, 1983 (Adams ML030020331).

THIS IS THE LAST PAGE OF THE TEXT SECTION 3.5 9

Table 3-63. Structures, Systems and Components Included in TORMIS Analysis Not Designed for Design Basis Tornado Generated Missiles3 Category 1 SSC Unit I & 2 Main Steam Safety Valves (MSSVs) Exhaust Piping and associated supports' 2 Unit I & 2 Steam Generator Power Operated Relief Valves (PORVs) and associated piping and suppmts 12 Unit I & 2 Turbine Driven Auxiliary Feedwater (TD AFW) Exhaust (TE) Pipe2 Unit I & 2 Control Room Air Ventilation System (CRA VS) Intakes (VC/YC Intakes) 2 Unit I & 2 Spent Fuel Building (north facing wall)

Notes:

I. The SSCs located in the Unit I Exterior Doghouse are not included as they have positive tornado missile protection.

2. Only the pmtion of the Structure that is not protected from the Design Basis tornado generated missiles are included. The Design Basis tornado generated missiles have a horizontal only projection.

3. Additional details and target areas can be found in Section 3.5.6 Reference 7.

10

v t e Letter Sequence Request
EPID:L-2017-LLA-0412, Redacted Response to the Request for Additional Information Regarding the License Amendment Request to Revise the Licensing Bases for Protection from Tornado Generated Missiles (Approved, Closed)
Initiation Request, Request, Request Acceptance Administration Questions 18 May 2018 11 October 2018 Answers Results Approval Other:
MONTHYEAR2018-11-01 [Table View]

Person / Time
ML18191B151
Site:	McGuire, Mcguire (NPF-009, NPF-017)
Issue date:	07/03/2018
From:	Teresa Ray Duke Energy Carolinas
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
MNS-18-036
Download: ML18191B151 (56)
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