NRC-13-0002, Proposed License Amendment to Revise the Fermi 2 Licensing Bases for Protection from Tornado-Generated Missiles

Proposed License Amendment to Revise the Fermi 2 Licensing Bases for Protection from Tornado-Generated Missiles

ML13011A377
Person / Time
Site:	Fermi  (NPF-043)
Issue date:	01/11/2013
From:	Conner J DTE Energy
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
NRC-13-0002
Download: ML13011A377 (68)

Text

J. Todd Conner Site Vice President DTE Energy Company 6400 N. Dixie Highway, Newport, MI 48166 Tel: 734.586.4849 Fax: 734.586.6296 Email: connerj@dteenergy com DTE Energy-10 CFR 50.90 January 11, 2013 NRC-13-0002 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington D C 20555-0001

Reference:

Fermi 2 NRC Docket No. 50-341 NRC License No. NPF-43

Subject:

Proposed License Amendment to Revise the Fermi 2 Licensing Bases for Protection from Tornado-Generated Missiles Pursuant to 10 CFR 50.90, DTE Electric Company (DTE) proposes to update the Fermi 2 Updated Final Safety Analysis Report (UFSAR) to describe the methodology and results of the analysis performed to evaluate the protection of the plant's structures, systems and components (SSCs) from tornado generated missiles. The analysis is consistent with the guidance provided in Regulatory issue Summary 2008-14, "Use of TORMIS Computer Code for Assessment of Tornado Missile Protection." provides an evaluation of the proposed license amendment, including an analysis of the issue of significant hazards consideration using the standards of 10 CFR 50.92. DTE has concluded that the change proposed in this submittal does not result in a significant hazards consideration. Enclosure 2 provides information on a Piping Penetration Screening Algorithm utilized in the analysis. Enclosure 3 provides marked up pages of the Fermi 2 UFSAR to show the proposed changes including a list of plant targets included in the analysis. Enclosure 4 provides a list of plant targets excluded from the analysis or included for information only.

DTE has reviewed the proposed change against the criteria of 10 CFR 51.22 and has concluded that it meets the criteria provided in 10 CFR 51.22(c)(9) for a categorical exclusion from the requirements for an Environmental Impact Statement or an Environmental Assessment.

USNRC NRC-13-0002 Page 2 Approval of the proposed license amendment is requested by January 11, 2014. Once approved, the amendment will be implemented within 60 days.

No new commitments are being made in this submittal.

In accordance with 10 CFR 50.91, a copy of this application, with attachments, is being provided to the designated Michigan State Official.

Should you have any questions or require additional information, please contact Mr. Zackary Rad of my staff at (734) 586-5076.

Sincerely,

Enclosures:

1. Evaluation of the Proposed Change

2. Piping Penetration Screening Algorithm

3. Section 3.5 of the UFSAR Showing Proposed Changes

4. List of Targets Excluded or Included For Information Only cc:

NRC Project Manager NRC Resident Office Reactor Projects Chief, Branch 5, Region III Regional Administrator, Region III Supervisor, Electric Operators, Michigan Public Service Commission

USNRC NRC-13-0002 Page 3 I, J. Todd Conner, do hereby affirm that the foregoing statements are based on facts and circumstances which are true and accurate to the best of my knowledge and belief.

J. Td nner Sit ce President, Nuclear Generation On this II day of nO a xg

, 2013 before me personally appeared J. Todd Conner, being first duly sworn and says that he executed the foregoing as his free act and deed.

Notary Public SHARON S. MARSHAl.L NOTARY PUBLIC, STATE OF MI COUNTY OF MONROE MY COMMISSION EXPIRES Jun 14, 2013 ACTING IN COUNTY OF tc n r 2

to NRC-13-0002 Fermi 2 NRC Docket No. 50-341 Operating License No. NPF-43 Proposed License Amendment to Revise the Fermi 2 Licensing Bases for Protection from Tornado-Generated Missiles Evaluation of the Proposed License Amendment NRC-13-0002 Page 1 Evaluation of the Proposed License Amendment

Subject:

Revision of UFSAR for Tornado Missile Protection

1.

SUMMARY

DESCRIPTION

2. DETAILED DESCRIPTION

3. TECHNICAL EVALUATION

4. REGULATORY EVALUATION 4.1 Applicable Regulatory Requirements/Criteria 4.2 No Significant Hazards Consideration Determination 4.3 Conclusions

5. ENVIRONMENTAL CONSIDERATION

6. REFERENCES NRC-13-0002 Page 2 1.0

SUMMARY

DESCRIPTION The proposed amendment would modify the Fermi 2 Plant Licensing Bases by revising the Updated Final Safety Analysis Report (UFSAR) to describe the methodology and results of the analysis performed to evaluate the protection of the plant's structures, systems and components (SSCs) from tornado generated missiles. The analysis utilized a probabilistic approach implemented through the application of the TORMIS computer program as described in Regulatory Issue Summary (RIS) 2008-14.

2.0 DETAILED DESCRIPTION DTE Electric Company (DTE) proposes to update the Licensing Bases in the Fermi 2 UFSAR with safety analysis performed using an updated version of the TORMIS computer code. The analysis was performed in accordance with the guidance provided in the 1983 TORMIS SER (Reference 1), as clarified by RIS 2008-14 (Reference 2), dated June 16, 2008.

The updated Fermi 2 analysis is based on the NRC approved methodology as detailed in two topical reports, EPRI NP-768/769, "Tornado Missile Risk Analysis and Appendices," May 1978 (References 3 and 4) and EPRI NP-2005, "Tornado Missile Risk Evaluation Methodology,"

August 1981 (Reference 5), utilizing the TORMIS computer code. TORMIS employs Monte Carlo techniques in order to assess, through a Probabilistic Risk Assessment (PRA) methodology, the probability of multiple missile strikes causing unacceptable damage to unprotected, safety-related plant features. This is accomplished by simulating tornado strikes on the plant in such a way that, for each tornado strike, a tornado wind field is simulated, missiles are injected and flown, and missile impacts on SSCs are analyzed. These models are then linked to form an integrated, time-history simulation. By replicating these simulations, the cumulative mean annual probability of missiles impacting and damaging individual target SSCs and groups of target SSCs are estimated. Statistical convergence of the results is achieved by performing multiple replications with different random number seeds. The statistical confidence bounds of the results can then be estimated using conventional methods.

Consistent with the guidance provided in Reference 2, the Fermi 2 analysis performed thirty replications for each of the five selected Enhanced-Fujita tornado wind speed classifications (EF1-EF5), each replication consisting of 2,000 simulated tornado strikes. Each simulated tornado strike consisted of 5,000 missiles sampled from the total missile population and flown as tornado missiles. Therefore, the total number of TORMIS simulations represented in the analysis is 30 x 5 x 2,000 x 5,000 = 1.5 billion. The results of the new TORMIS analysis predict a site mean aggregate tornado missile damage probability of 6.82 x 10-7 per year for an identified scope of 81 safety-related targets. This value satisfies the acceptance criterion of 10-6 per year established in NRC Standard Review Plan Section 2.2.3.

The current Fermi 2 UFSAR, Section 3.5.1.3.2.3, describes the results of a probabilistic analysis performed in accordance with the EPRI TORMIS methodology to determine the mean strike NRC-13-0002 Page 3 probability of a design basis Tornado Generated Missile strike on 51 identified penetrations in the exterior walls of the Reactor and Auxiliary buildings. The analysis was performed in 1989 to address an internal condition report regarding the adequacy of protection from tornado missiles associated with these penetration areas in the buildings that do not have the same protection provided by the reinforced concrete walls. Due to the significant cost associated with potential physical modification to the plant structures to provide protection from the missiles, the probabilistic analytical approach was selected to address the identified vulnerability. The missile hazard analysis was performed using the TORMIS methodology developed by EPRI (References 3, 4 and 5). The analysis was evaluated in accordance with 10 CFR 50.59 and determined to not result in an Unreviewed Safety Question. Accordingly, the UFSAR was updated to describe the design basis analysis.

In November, 2008, the NRC issued inspection report number 05000341/2008-004 (Reference 6) to document inspection activities and associated findings regarding compliance with rules and regulations. The inspection report included a finding of an inadequate 10 CFR 50.59 evaluation of reactor building missile protection. Specifically, the report stated:

The inspectors identified a Green (Severity Level IV) NCV of 10 CFR 50.59(a)(2)(1) for the failure to obtain NRC approval prior to revising UFSAR Section 3.5.1.3.2.3 to include the tornado missile hazard analysis for the reactor and auxiliary building exterior wall penetrations and openings.

Title 10 CFR 50.59(a)(2)(i) (1989) stated, in part, that a licensee shall obtain a license amendment pursuant to Section 50.90 prior to implementing a proposed change, test, or experiment if the change, test, or experiment would result in an increase in the probability of a malfunction of equipment important to safety previously evaluated in the UFSAR.

Contrary to the above, on September 22, 1989, the licensee approved a 10 CFR 50.59 evaluation (SE-89-0094) incorporating a change to the Fermi design basis which resulted in an increase in the probability of a malfunction of equipment important to safety previously evaluated in the UFSAR without obtaining a license amendment.

Corrective actions included modifications to provide missile shields to affected components. At the conclusion of this inspection, long term corrective actions were still being evaluated. However, because this violation was of very low safety signficance and it was entered into the CAP as CARD 08-20821, this Severity Level IV violation is being treated as an NCV consistent with Section VI.A.1 of the NRC Enforcement Policy.

As a result of the above NRC finding and in accordance with the Fermi 2 corrective action program, a thorough review of the analysis performed in 1989 was conducted to assess compliance with References 1 and 2. This review concluded that the 1989 analysis did not fully comply with NRC requirements for applying the EPRI methodology as provided in References 1 and 2.

NRC-13-0002 Page 4 Also, a detailed walkdown of the site area identified approximately 30 additional targets that should be considered as potential tornado missile hazard areas. For some targets, it was determined that the vulnerability can be best addressed through the implementation of plant modifications to provide physical protection from tornado generated missiles. These plant modifications have been fully implemented. For many other targets, additional costly protective barriers or other alternative systems would be required to provide the required protection from missiles. Therefore, a new TORMIS analysis has been performed to address the remaining identified deficiencies. The new analysis described herein was performed in accordance with the guidance provided in the 1983 TORMIS SER (Reference 1), as clarified by RIS 2008-14 (Reference 2), dated June 16, 2008.

3.0 TECHNICAL EVALUATION

Reference 1 established the following required attributes:

1. Data on tornado characteristics should be employed for both broad regions and small areas around the site. The most conservative values should be used in the risk analysis or justification provided for those values selected.

2. The EPRI study proposes a modified tornado classification. F'-scale for which the velocity ranges are lower by as much as 25% than the velocity ranges originally proposed in the Fujita, F-scale. Insufficient documentation was provided in the studies in support of the reduced F'-scale. The F-scale tornado classification should therefore be used in order to obtain conservative results.

3. Reductions in tornado wind speed near the ground due to surface friction effects are not sufficiently documented in the EPRI study. Such reductions were not consistently accounted for when estimating tornado wind speeds at 33 feet above grade on the basis of observed damage at lower elevations. Therefore users should calculate the effect of assuming velocity profiles with ratios Vo (speed at ground level) + V33 (speed at 33 feet elevation) higher than that in the EPRI study Discussion of sensitivity of the results to changes in the modeling of the tornado wind speed profile near the ground should be provided.

4. 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.

5. Once the [TORMIS] methodology has been chosen, justification should be provided for any deviations from the original [EPRI] methodology.

NRC-13 -0002 Page 5 The manner in which the Fermi 2 analysis satisfies the SER criteria is as follows:

1, Definition of the Fermi 2 TORMIS Tornado Sub-Region:

A site-specific analysis was performed to generate a tornado hazard curve data set for the TORMIS analysis. The tornado data retained in the National Climatic Data Center Storm Events Data Base (NCDC, 2006) files for the years 1950-2005 were used to analyze both broad and small regions around Fermi 2 in order to identify a suitable representative sub-region for the site. Tornado occurrences were mapped for the large region, a 150 longitude x 150 latitude area centered on the Fermi 2 site, and statistical tests were performed using 1 x 10 and 30 x 30 blocks to identify a suitably homogeneous sub-region. The historical records of tornado occurrences within the sub-region tornado were used to establish the tornado occurrence rate, Enhanced-Fujita (EF)-scale intensities, path length, width, and direction variables to be specified as input for use in the TORMIS analysis.

The statistical analysis of the sub-region data established a mean occurrence rate of 3.1E-4 per square mile per year over the 56-year period. In accordance with the TORMIS methodology, backwards averaging was used to estimate a de-trended occurrence rate to correct for changes in the annual reporting trends. The adjusted mean occurrence rate was determined to be 4.002E-4/year based on the 30-year backwards average.

2. Tornado Wind Speed Intensity:

The hazard curve developed for the Fermi 2 analysis does not utilize either the SER specified Fujita (F) scale or the SER prohibited modified Fujita (F') scale. Instead the analysis utilizes the original Enhanced Fujita (EF) scale wind speeds as per NUREG/CR-4461 (Reference 7).

Though the 1983 NRC SER called for the use of the F-scale of tornado intensity for assigning tornado wind speeds to each intensity category (Fl-F5), the NRC subsequently adopted the EF scale in the positions of NRC Regulatory Guide 1.76 Revision 1 that are based on NUREG/CR-4461, Rev 2.

3.

Characterization of Tornado Wind Speed as a Function of Height Above Ground Elevation:

The Fermi 2 TORMIS simulations were performed with the TORMIS rotational velocity Profile 3, which has increased near ground wind speeds over the TORMIS Profile 5 values that were used in the 1981 EPRI TORMIS reports. Hence, the Fermi 2 runs were made with higher near ground wind speeds than in the EPRI study. A sensitivity study was conducted by running the original EPRI profiles and comparing the results. The Profile 3 results (enhanced near ground wind speeds below 33ft) produced damage probabilities that averaged approximately 4% higher than the Profile 5 results. Hence, the use of Profile 3 with higher near ground wind speeds was conservative when compared to Profile 5.

4. Missile Characterization and Site-Structure Models:

NRC-13-0002 Page 6 Walkdowns of the Fermi 2 site were performed to characterize the missile sources and plant configuration. This information was developed into the plant modeling inputs for the TORMIS analysis that describe the facility 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.) were catalogued and modeled to a distance of approximately 2,500 feet. This is done by specifying missile origin zones around the facility and a statistical description of missile types, based on the facility survey. The site surveys were conducted just prior to refueling outages to maximize the estimated population of available missiles and missiles sources; thus, the analysis is intended to represent a reasonable bounding maintenance configuration.

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.

The number of missiles produced from this total inventory was specified to be dependent on the wind speeds experienced by the building. For example, light damage might be expected in 100 mph winds, while catastrophic failure might occur in 200 mph winds. The research performed in the development of the HAZUS wind model (Reference 8) was used as the basis for determining the number of missiles available for each building type in each tornado EF-scale.

HAZUS Damage State Exceedence Probabilities for EF Scale Mid-Point Wind speeds Enhanced Windspeed (mph)

Hazard Building Type Damage State EFO EFl EF2 EF3 EF4 EF5 65-85 86-110 111-135 136-165 166-200 200-230 Trailer, Manufactured Bldg 2

0.01 0.03 0.54 0.96 1.00 1.00 Wood Frame/Modular 4

0.00 0.01 0.12 0.75 0.99 1.00 Masonry Frame 4

0.00 0.01 0.03 0.35 1.00 1.00 Pre Engr Steel Frame 4

0.00 0.00 0.02 0.32 0.85 0.98 Engineered Frame 4

0.00 0.00 0.00 0.03 0.50 0.90 All postulated missiles were conservatively treated as minimally restrained so that each sampled missile is injected into the wind field near the peak aerodynamic response, thus maximizing its transport range and impact speed and increasing the missile strike and damage frequencies.

The total number of modeled missiles used in the TORMIS analysis of Fermi 2 includes:

Zone Structure Intensity Origin Origin Total Missiles Missiles EFl 75,369 1,571 76,940 EF2 75,369 4,636 80,005 NRC-13-0002 Page 7 EF3 75,369 33,095 108,464 EF4 75,369 101,511 176,880 EF5 75,369 127,734 203,103 The Fermi 2 site missiles include the standard TORMIS missiles in EPRI NP-769 (Reference 4), including structural sections, pipes, wood members, other construction materials, and an automobile category. In addition to the 20 standard TORMIS missile types, three Fermi 2 specific missiles were created for the analysis.

5. Deviations from the Original EPRI Methodology:

The TORMIS code is a legacy FORTRAN computer code that has been ported to modern computers and compilers and has had bug fixes and other enhancements since 1981. The updated Fermi 2 analysis was performed using a version of TORMIS developed from the original EPRI NP-2005 (Reference 5) version of the code by Applied Research Associates, Inc (ARA). The updates and enhancements made to TORMIS since 1981 include: porting the legacy code from mainframe to minicomputer to PC computers; post processing data routines; updates to the random number generation; minor update to aerodynamic tip loss function; enhanced output options; and addressing compiler differences and numerical round-off issues in various functions from the legacy code. All code changes have been checked and verified through comparisons to the preceding version.

Also included in the updates were the replacement of the original main frame based random number generator. A new machine independent algorithm and the code was re-dimensioned to allow larger numbers of missiles and targets.

The TORMIS code verification includes duplications and comparison to each preceding TORMIS version as well as the original TORMIS Sample Problem in EPRI NP 2005. These statistical comparisons show that the basic TORMIS code calculational approach has not deviated from the original version. In the context of 10 CFR 50.59, alterations such as those described above would not be considered deviations from the original approved methodology.

An enhanced method for evaluating missiles passing through openings, such as pipe penetrations in reinforced concrete walls was used for Fermi analysis. This calculation was done in addition to the standard TORMIS hit probability calculation for such targets. Hence, it provides supplemental outputs that are intended to cover special cases of missiles flying through openings. The method consists of identifying the minimum required missile size, angle of orientation, and angle of incidence at impact necessary for a missile to be capable of passing through a pipe penetration target. Missiles that are too large, not oriented correctly, or impinge obliquely on a target are screened out on these criteria. This method eliminates from the calculated cumulative risk those impacts which would not realistically have resulted in missile penetration of a pipe penetration target. Since this method of screening out missile strikes on penetrations is an enhancement of the originally reviewed and approved NRC-13-0002 Page 8 methodology, it is presented in this submittal for formal review and approval. A detailed description of this algorithm is included as Enclosure 2.

Subsequent to the original NRC SER (Reference 1), the NRC issued Regulatory Issue Summary 2008-14 (Reference 2) to inform licensees of NRC experience with shortcomings identified in submitted licensee TORMIS analyses.

1. The RIS identified that licensees had failed to meet the constraints of the original SER by:

a. not providing adequate justification that the analysis used the most conservative value for tornado frequency

b. not including the entire TORMIS missile spectrum

c. not providing adequate explanation for the number and adequacy of tornado simulations and histories

d. inadequate justification and information regarding the development and use of area ratios

2. Licensees did not fully address the fifth point identified in the SER and explain how the methodology was implemented when the parameters used differed from those specified in the TORMIS methodology. Examples include the following:

a. inappropriately limiting the number of targets modeled

b. failing to address missile tumbling when modeling targets

c. failing to properly consider and use the variance reduction techniques and parameters specifed by TORMIS

d. inappropriately crediting nonstructural members

e. failing to consider risk signficant, non-safety-related equipment

3. Licensees used the TORMIS methodology to address situations for which the methodology was not approved. Examples include the following:

a. proposing the elimination of existing tornado barriers

b. proposing changes to Technical Specifcations, and

c. proposing plant modifications DTE considered these observations in the development of the updated TORMIS analysis.

Specifically:

(1) a. Justification for Tornado Frequency:

The Fermi 2 tornado frequency value conservatively considers regions around the plant and corrects for reporting trend and tornado classification error and random encounter NRC-13-0002 Page 9 errors, per the TORMIS methodology. The developed tornado hazard curve is conservative when compared to USNRC Region I characterization Fermi 2 Tornado Hazard Probabilities 1.E-03 1.E-04 L

1.E-05 Z-o NURREG/CR-4461, i

1.E-06 Rev2 TORMlS Plant Safety Envelope K

1.E -0 7

' +

0 100 200 300 Peak Gust Windspeed (mph)

(1) b. Spectrum of Missile Considered:

In addition to the 20 standard TORMIS missile types, three Fermi 2 specific missiles were created for the analysis: one to represent scaffold clamps of which there were a large number present during the site missile hazards walkdown; one to represent the NRC-13-0002 Page 10 sections of metal siding that enclose the upper portions of the reactor, auxiliary, and turbine buildings; and the third to represent the large number of concrete blocks also identified during the site walkdowns.

(1) c.

Justification for the Number and Adequacy of Tornado Simulations:

Thirty complete TORMIS replications (2,000 tornado strikes and 5,000 sampled missiles for each of 5 EF Scales) were run with different random number seeds. A total of 300 million missile simulations were performed for each EF scale, for a total of 1.5 billion missile simulations. The standard deviations ((a) of these replications were computed and the standard error ($) in the aggregate mean probability (p) was computed from £ = G/n.

The 95% confidence bounds in the mean probability were conservatively approximated by u+ 2-s.

NRC-13-0002 Page 11 1.E-03

.1.E-04*

+Invividual Runs r-U-Running Mean 5

--- Mean -2 Std Err

-+--

Mean + 2 Std Err 1,E-05 0

5 10 15 20 25 30 TORMIS Run Number 1.E-05

+ Invividual Runs

-U-Running Mean Mean - 2 Std Err Mean + 2 Std Err S1.E 1.E-07

'I 0

5 10 15 20 25 30 TORMIS Run Number (1) d. Use of Area Ratios:

Area ratios are not used to adjust the TORMIS outputs for small targets, based on a ratio of hit probabilities from a large target or surface. However, a variance reduction approach that is available in TORMIS was used for Fermi 2 that allows for increasing the size of small targets explicitly within the code. TORMIS applies the input variance reduction weight (ka) in the TORMIS scoring equation. These adjustments are used within TORMIS for the single missile impact probability. They are NOT used to "ratio down" the multiple missile impact probabilities following a TORMIS simulation. It is not NRC-13-0002 Page 12 technically acceptable to ratio down the TORMIS results since it can result in an underestimation of the multiple missile risk. Such an approach was used in some TORMIS submittals to the USNRC; however, ARA's technical review of that practice lead to the RIS Item (1)d comment.

(2) a.

Inappropriately limiting of the number of targets modeled:

The original Fermi 2 TORMIS analysis considered approximately 51 unprotected features of the plant consisting exclusively of penetrations and doors located on the exterior of the reactor and auxiliary buildings including a large (10 ft x 10 ft, 6 inch thick) removable concrete panel, a security door, and the reactor building airlock door.

The updated TORMIS analysis expands the scope of targets to consider a population of 161 potential plant features identified primarily as a result of a site tornado hazard walkdown. Of these, 81 targets were identified as the specific features to be evaluated probabilistically as not requiring unique tornado missile protection in the new TORMIS analysis. These targets are to be explicitly identified in a new UFSAR Table (3.5-3) as described in Enclosure 3. The scope of specific targets included in this table generally represents wall penetrations and doors in the exterior surfaces of these structures.

Generally, no specific safety-related systems are associated with any particular penetration; hence, the tornado missile hazard associated with these penetrations and openings is limited to and characterized by the probability of missile penetration of the target itself. Exceptions include the targets associated with missiles penetrating the reactor building railroad air lock doors, the first floor auxiliary building south wall entrance, and the EDG removable wall panels. tabulates the balance of targets considered that were excluded from or otherwise considered for information only in updated TORMIS analysis including the basis for exclusion. The criteria for exclusion consist of the following:

Unprotected safety-related equipment not identified in UFSAR Table 3.3-2 as required for safe reactor shutdown following a tornado was not included as targets.

Examples include Control Room Emergency Filtration system as associated with the south emergency makeup intake and the south portion of the Auxiliary Building rooftop and the Standby Gas Treatment equipment located on the refuel floor.

Equipment already specifically licensed as not requiring additional tornado missile protection was excluded. For example, the RHR Mechanical Draft Cooling Tower Fans are specifically licensed for post-tornado repair and restoration (See UFSAR Section 3.5.1.3.2.2) and the Spent Fuel Pool which was evaluated and accepted on the basis of an alternative risk analysis (See Section 3.5.1.3.2.1) were both excluded from the scope of analysis.

NRC-13-0002 Page 13 Other features that were excluded for this risk analysis are the buried underground cable vaults between the RHR complex and the auxiliary building and the EDG fuel oil tank vents and the EDG exhaust stacks, which are located on the roof of the RHR complex. Both of these rooftop features are provided with tornado missile shield protection specifically designed to prevent vertically travelling missiles from entering the RHR complex and damaging the EDG fuel oil tanks and diesel engines.

These existing design bases are taken to remain valid and therefore excluded from consideration in the updated TORMIS analysis.

(2) b. Consideration of Missile Tumbling:

With the exception of pipe penetrations, all targets were modeled to allow for tumbling missile hits (offset hits) per the TORMIS technical reports (References 3, 4 and 5). The size of all safety-related targets that are vulnerable to "offset" hits (tumbling missiles) was increased by 1.5 ft for each free face in the three-dimensional model. Pipe penetration targets were not increased in size to reflect tumbling missiles since offset hits of large missiles cannot result in penetration of a small opening in a concrete wall. See the discussion of the pipe penetration screening method introduced under SER Item 5 above.

(2) c.

Use of Variance Reduction Techniques:

The new Fermi 2 analysis used the following variance reduction techniques:

1. Tornado Strike Probability (Analytical Equivalence)

2. EF Scale (Stratified Sampling)

3. Tornado Offset (Importance Sampling)

4. Missile orientation (P =1)

5. Missile Injection Height (yz = 2.0)

6. Trajectory Termination (Prr = 0.5)

7. Target Size (ka by target surface)

The first two techniques are an inherent part of the TORMIS methodology. Techniques 3-7 were used for Fermi 2 specifically. Due to the large number of simulations performed, no variance reduction techniques were used for tornado wind speed, tornado direction, missile zone population, missile type, or missile impact orientation. The effectiveness of the application of these variance reduction methods is demonstrated in the calculation convergence data provided in the response to item (b) above (2) d. Inappropriate Credit For Non-Structural Members:

The updated TORMIS analysis generally did not take credit for missile resistance for non-structural members. Targets representing penetration P-156 (nitrogen system) and NRC-13-0002 Page 14 Residual Heat Removal Service Water (RHRSW) and Emergency Equipment Service Water (EESW) piping located on the first floor of the Reactor Building (RB1), the removable EDG walls, mechanical draft cooling tower fan motor doors, RB5 refuel floor equipment hatch cover, and the third floor of the Auxiliary Building (AB3) doors and block walls were evaluated for perforation damage.

(2) e.

Failure to consider Risk Significant, Non-Safety-Related Equipment:

Of the safe shutdown equipment identified in UFSAR Table 3.3-2 none relies solely on risk significant, non-safety-related equipment. While Reactor Core Isolation Cooling (RCIC), which is identified as a credited injection source can utilize the water in the Condensate Storage Tank (CST), the analysis excluded consideration of the CST on the basis that this tank was not designed to be tornado proof and is designed to automatically swap RCIC suction to the safety-related and inherently missile protected suppression pool.

(3)

Inappropriate use of TORMIS:

TORMIS has not been used to propose the elimination of tornado barriers, changes to the plant technical specification, or as justification to modify plant features to reduce or eliminate or otherwise engineer the design of existing or new tornado missile protection features.

4.0 REGULATORY EVALUATION

4.1 Applicable Regulatory Requirements/Criteria The proposed changes have been evaluated to determine whether applicable regulations and requirements continue to be met. DTE's technical analysis, which includes risk information, satisfies all applicable regulatory requirements and criteria as per the 1983 NRC SER, RIS 2008-14, the two topical reports, EPRI NP-768/769 (May 1978) and EPRI NP-2005 (August 1981), NRC Regulatory Guide 1.76, Revision 1, and the NRC Standard Review Plan (NUREG-0800) sections. There are no formal commitments to administrative controls needed to ensure compliance.

Based on these considerations, there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, such activities will be conducted in compliance with the Commission's regulations, and the issuance of the amendment will not be inimical to the common defense and security or the health and safety of the public.

NRC-13-0002 Page 15 4.2 No Significant Hazards Consideration Determination DTE Electric Company (DTE) has evaluated whether or not a significant hazards consideration is involved with the proposed amendment by focusing on the three standards set forth in 10 CFR 50.92, "Issuance of Amendment", as discussed below:

1. Does the proposed amendment involve a significant increase in the probability or consequences of an accident previously evaluated?

Proposed for NRC review and approval are changes to the Fermi 2 Updated Final Safety Analysis Report (UFSAR) which in essence constitute a license amendment to incorporate use of an NRC approved methodology to assess the need for additional positive (physical) tornado missile protection of specific features at the Fermi 2 site. The UFSAR changes will reflect use of the Electric Power Research Institute (EPRI) Topical Report "Tornado Missile Risk Evaluation Methodology" (EPRI NP-2005), Volumes I and II. As noted in the NRC Safety Evaluation Report on this topic dated October 26, 1983, the current licensing criteria governing tornado missile protection are contained in Standard Review Plan (SRP) Sections 3.5.1.4 and 3.5.2. These criteria generally specify that safety-related systems be provided positive tornado missile protection (barriers) from the maximum credible tornado threat. However, SRP Section 3.5.1.4 includes acceptance criteria permitting relaxation of the above deterministic guidance, if it can be demonstrated that the probability of damage to unprotected essential safety-related features is sufficiently small.

As permitted in NRC Standard Review Plan (NUREG-0800) sections, the combined probability will be maintained below an allowable level, i.e., an acceptance criterion threshold, which reflects an extremely low probability of occurrence. The Fermi 2 approach assumes that if the sum of the individual probabilities calculated for tornado missiles striking and damaging portions of important systems or components is greater than or equal to 10~ per year per unit, then installation of unique missile barriers would be needed to lower the total cumulative probability below the acceptance criterion of 10-6 per year per unit.

With respect to the probability of occurrence or the consequences of an accident previously evaluated in the UFSAR, the possibility of a tornado reaching the Fermi 2 site and causing damage to plant structures, systems and components is a design basis event considered in the Updated Final Safety Analysis Report. The changes being proposed do not affect the probability that the natural phenomenon (a tornado) will reach the plant, but from a licensing basis perspective they do affect the probability that missiles generated by the winds of the tornado might strike and damage certain plant systems or components. There are a limited number of safety-related components that could theoretically be struck and consequently damaged by tornado-generated missiles. The probability of tornado-generated missile strikes on "important" systems and components (as NRC-13-0002 Page 16 discussed in Regulatory Guide 1.117, "Tornado Design Classification") is what is to be analyzed using the probability methods discussed above. The combined probability of damage will be maintained below an extremely low acceptance criterion to ensure overall plant safety. The proposed change is not considered to constitute a significant increase in the probability of occurrence or the consequences of an accident, due to the extremely low probability of damage due to tornado-generated missiles and thus an extremely low probability of a radiological release.

Therefore, the proposed changes do not involve a significant increase in the probability or consequences of previously evaluated accidents.

2. Does the proposed amendment create the possibility of a new or different kind of accident from any accident previously evaluated?

The possibility of a tornado reaching the Fermi 2 site is a design basis event that is explicitly considered in the UFSAR. This change involves recognition of the acceptability of performing tornado missile probability calculations in accordance with established regulatory guidance. The change therefore deals with an established design basis event (the tornado). Therefore, the proposed change would not contribute to the possibility of a new or different kind of accident from those previously analyzed. The probability and consequences of such a design basis event are addressed in Question 1 above.

Based on the above discussions, the proposed change will not create the possibility of a new or different kind of accident than those previously evaluated.

3.

Does the proposed amendment involve a significant reduction in a margin of safety?

The existing Fermi 2 licensing basis for protection of safety-related equipment required for safe shutdown from design basis tornado generated missiles is to provide positive missile barriers for all safety-related systems and components.

With the change, it will be recognized that there is an extremely low probability, below an established acceptance limit, that a limited subset of the "important" systems and components could be struck and consequently damaged. The change from protecting all safety-related systems and components to ensuring an extremely low probability of occurrence of tornado-generated missile strikes and consequential damage on portions of important systems and components is not considered to constitute a significant decrease in the margin of safety due to that extremely low probability.

Therefore, the changes associated with this license amendment request do not involve a significant reduction in the margin of safety.

NRC-13-0002 Page 17 Based on the above, DTE concludes that the proposed amendment does not involve a significant hazards consideration under the standards set forth in 10 CFR 50.92, and, accordingly, a finding of "no significant hazards consideration" is justified.

4.3 Conclusions In conclusion, based on the considerations discussed above, (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.

5.

ENVIRONMENTAL CONSIDERATION The changes have been evaluated using the identification criteria for licensing and regulatory action requiring an environmental assessment as specified in 10 CFR 51.21.

The proposed changes meet the eligibility criteria for a categorical exclusion as set forth in 10 CFR 51.22. Therefore, pursuant to 10 CFR 51.22(b), an environmental assessment of the proposed change is not required.

NRC-13-0002 Page 18

6.

REFERENCES

1. NRC Safety Evaluation Report - Electric Power Research Institute (EPRI) Topical reports Concerning Tornado Missile Probabilistic Risk Assessment (PRA)

Methodology, dated October 26, 1983 (ML080870291)

2. NRC Regulatory Issue Summary 2008-14, "Use of TORMIS Computer Code for Assessment of Tornado Missile Protection," dated June 16, 2008 (ML080230578)

3.

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

4. Electric Power Research Institute (EPRI) Topical Report NP-769, "Tornado Missile Risk Analysis - Appendices," May 1978

5. Electric Power Research Institute (EPRI) Topical Report NP-2005 Volumes, I & II, "Tornado Missile Risk Evaluation Methodology," August 1981

6. NRC Inspection Report 05000341/2008-004, "Fermi Power Plant, Unit 2, Integrated Inspection Report," dated November 12, 2008

7. NUREG/CR-4461, Revision 2, "Tornado Climatology of the Contiguous United States, (PNNL-15112, Rev 2)," Ramsdell and Rishel, 2007

8. HAZUS-MH MR3, "Multi-hazard Loss Estimation Methodology - Hurricane Model, Technical Manual, FEMA, 2007 to NRC-13-0002 Fermi 2 NRC Docket No. 50-341 Operating License No. NPF-43 Proposed License Amendment to Revise the Fermi 2 Licensing Bases for Protection from Tornado-Generated Missiles Piping Penetration Screening Algorithm NRC-13-0002 Page 1 Piping Penetration Screening Algorithm The approach to evaluating the risk of missiles penetrating piping penetration targets is to use the TORMIS impact data for each missile that hits a piping penetration (PP) target to screen out those missile impacts that obviously cannot pass through a PP opening. This impact data consists of the angles (13 and 0 in Figure 3-1), missile diameter (d), and missile length (L) (see Figure3-2, below)

Z, (Normal to Surface) d Missile MCL Plane of Incidence MCL v

'~~~~7 i;7ao95 Y

Y YD, Pipe Penetration Diameter xs Figure 3-1. TORMIS Missile Impact Geometry Figure 3-2. Missile Impact Geometry on Pipe This screening is done in the processing of the TORMIS impact data without modifying the TORMIS physics engine in the IMPACT Sub-routine. The screening criterion used for Fermi 2 PP targets is shown in Figure 3-5. The following paragraphs discuss the screening sequence of this event tree.

1. Level I Screen (Missile diameter too large?).

The first screen addresses missile diameter relative to PP opening diameter. If the missile diameter (d) is much greater than the PP opening diameter (D), then the missile is assumed to be too large to be able to successfully penetrate a PP target. The PP opening is modeled as a circular hole in the barrier. If the opening is not a circle, its diameter is developed from an equivalent area circle with diameter D. This screen reflects that fact that the missile spectrum at Fermi 2 includes missiles with diameters that are both larger and smaller than the PP diameter.

Since many PP openings are small, many missiles are too large to pass through a PP opening even for a perfectly-aligned strike. That is, they are so large that they cannot simply hit and pass through the PP opening, but must penetrate the concrete barrier. Since the concrete barriers have already been qualified as acceptable protection, we eliminate these large missiles from consideration for PP targets (see Missile Hit Outcome 1 in Figure 3-5). We use a conservative NRC-13-0002 Page 2 factor of 1.1 on the PP diameter for this screen. That is, even if the missile diameter is larger than the diameter of the PP opening (up to 1.1 times larger), we conservatively assume (at the first level of screening in Figure 3-5) that it could still penetrate the PP target and damage any safety-related equipment inside.

2. Level II Screen (Missile length is small relative to opening diameter?).

The second screen in Figure 3-5 regards the length of the missile, given that the missile diameter is smaller than 1.1D. For this screen, if the missile length (L) is less than D, then the missile is small compared to the PP diameter. For this case, a conservative assumption is that any hit on the PP target results in a penetration through the PP target because the missile's greatest dimension is less than D. Hence, we consider any impact by "relatively-small" missiles to be a potential penetration (see Outcome 5 in Figure 3-6). For added conservatism in treating this outcome, we use a screening criteria based on the missile length being less than 2 (1.1D) 2 - d2. This criterion is based on the geometry in Figure 3-3. For a missile whose center of mass hits right on the edge of the opening, if the length (L) of the missile is shorter than 2D2 - d2, we can conservatively consider it a small missile and assume that it passes through the opening regardless of the impact angles. We note that for slender missiles, with d approaching 0, this reduces to L < 2D for the missile to be considered small and pass through the opening every time. This screening criteria for small missiles is obviously much more conservative than one that uses L < D to determine small missiles that are assumed to pass through on every hit, d

Figure 3-3. Small Missile Level II Screen

3. Level III Screen (Missile axis too oblique?).

The third screen in Figure 3-5 is based on the missile impact angle B in Figure 3-1. This screen only applies to relatively long missiles (L > 2D) relative to the opening diameter. For this screen, we develop criteria based on the missile geometry in Figure 3-2. The angle 8 is the largest oblique angle that a long missile can be oriented at impact and still have a feasible chance of passing through the opening. Angles larger that 8 are expected to result in ricochet by virtue of the impact geometry. Impacts that occur with missile orientation angles (13) larger than 6 are assumed to ricochet off the concrete slab. The following trigonometric equation can be solved by numerical methods to yield the angle 6 in Figure 3-2.

NRC-13-0002 Page 3 d - (D cos 6-T sinS) =0 3-1 where d = missile diameter; D = PP opening diameter; and T = slab thickness. Denote the solution of Equation 10-1 for given d, D, and T as 6*. This angle can be solved in advance for each TORMIS missile and PP target and used in the post-processing of the TORMIS impact data. Based on these calculations for every combination of missile and PP target, the Level III screen compares the TORMIS missile impact angle (B) in Figure 3-1 to the critical value 6* from the solution of Eq. 3-1. If B is greater than 6*, then the missile axis at impact is not aligned for a penetration of the PP target and the missile is assumed to ricochet, producing Outcome 4 in Figure 3-5. This screening also uses a conservative factor of 1.1 on 6*, as shown in Figure 3-5.

This screen requires comparisons of impact angles to the actual S* for each PP impact in TORMIS.

4. Level IV Screen (Missile velocity vector too oblique?).

The fourth screen in Figure 3-5 is based on the missile velocity vector angle in Figure 3-2. This screen corresponds to the consideration that the velocity vector has a line of sight through the opening. Outcome 2 corresponds to the case where both the missile orientation and the velocity vector are within the "perfect impact" tolerances and, hence, each long missile impact with these orientations is assumed to be able to penetrate the PP target. Outcome 3 corresponds to the no penetration case where the missile axis is within angle tolerance but the velocity vector isn't. We also introduce a conservative factor of 1.1 on S*0 in this screen.

5. Level V Screen (Multiple Opening Penetrations).

This final screen considers cases where the missile must effectively pass through several openings to reach a target and there is no line of sight to the target as it passes through the PP model of the openings. For this case, the Level III and IV screens need to also consider the pipe tunnel the missile must pass through to reach the second opening. For example, see Figure 3-4, which illustrates a multiple opening scenario in which the missile must clear a second barrier and ricochet down a hallway in order to have any chance of hitting the target of interest. That is, there is no line of sight to the target if the missile passes through the pipe penetration (tunnel) and the missile must pass down a second opening. If the missile is longer than H, the effective diameter of the second opening, then it will ricochet after impact in such a manner that its forward momentum will be lost since it is physically too long to pass through the remaining length of the second opening. Obviously, if there is a line of sight to the target from the modeled PP tunnel, or if there is no second opening, then this screen is not used in the model.

The multiple opening screen for Fermi 2 consists of L:5 H. This includes a conservative factor of 1.1 on H (increase its size to allow more missiles past the screen), and hence this screen for second opening (ricochet required and no line of sight) becomes L < 1.1H for the missile to pass.

If the missile is longer than 1.1H, the screen eliminates the missile from having any chance of hitting the distant target.

NRC-13-0002 Page 4 NFe Pm~ra~

7

~H Figure 3-4. Missile Length Screen (Level V) for Second Opening Conservatisms in PP Model and Deviations from Calculation Approach.

Given that a penetration of a PP target requires a near perfect alignment of a non-rotating missile with sufficient energy to overcome friction and, in most cases, perforate the pipe twice to reach the interior of the target, this approach is very conservative.

In addition, the method applies additional conservatisms:

1. A safety factor of 1.1 on the pipe penetration diameter when compared to impacting missile diameter (or depth). That is, missiles with diameters 10% larger than the PP opening are assumed to be able to penetrate through the opening.

2. Missiles with diameters less than 10% larger than the pipe penetration diameter and lengths less than twice the pipe penetration diameter were assumed to penetrate the opening 100%

of the time. Thus, slender missiles with lengths up to twice the diameter of the PP diameter are assumed to be able to pass through the PP given that it hits the PP, regardless of impact angles of the missile axis or velocity vector.

3. A safety factor of 1.1 on both the missile velocity vector angle and the missile axis impact angle was used in determining if the missile axis is aligned with the opening.

4. A safety factor of 1.1 on second opening diameter when compared to missile length.

5. Missile rotation velocity at impact is neglected. Missile rotation at impact makes it more difficult for the missile to pass through the small opening.

6. The penetration of the pipe itself or the pipe covers, if present, are not credited. Up to two penetrations are required for the missile to make it inside the barrier. Unless the impacts are perfectly aligned, the penetration forces will generally produce a ricochet of the missile instead of a penetration inside the target.

NRC-13-0002 Page 5

7. Friction forces acting on the missile as it slips through the opening ignored. Thus, if a missile is aligned with an opening, it is assumed to pass through the opening and not "stick" in the opening due to frictional and side forces resulting from impact.

8. Assumption that every pipe penetration automatically produces damage to a critical component inside the barrier.

NRC-13-0002 Page 6 Piping Penetration Screening Algorithm Missile Hits PP Target? I. Missile Diameter vs. II. Missile Length vs.

111 Missile Axis vs. PP IV. Missile Vel. Vector V. Missile Length PP Diameter?

PP Diameter? (First Pass-Through Angle?

vs. PP Pass-Through (Second Opening - No Missile Hit Outcome Opening)

Angle?

Line of Sight) d >1.1 D

1. No penetration. Missile too large to penetrate opening.

L _ 1.1 H

2. Penetration. Missile orientation and velocity vector within pass through 0 1.160 Yes p <1.15*

L> 1.1 H 1a. No penetration. Missile too long to pass through second opening.

8 >1.1 6*

3. No penetration. Velocity vector is too oblique.

L>2V(1.1D) d S>1.16*

4. No pentration. Missile axis at impact is too oblique to penetrate PP opening.

d 1.1D Ls 1.1 H

5. Penetrated by small missile. Each hit is assumed to penetrate the PP opening.

L<_ 2V (1.1)2 d2 L>1.1 H la. No penetration. Missile too long to pass through second opening.

Figure 3-5. Screening Criteria for Post-Penetration Missile Impacts on PP Targets The Fermi 2 analysis applied the logic above in the processing of the TORMIS impact results on a missile-by-missile basis for PP targets.

Outcomes 1 or la, 3, and 4 do not produce PP target penetrations (potential penetrations of the target to the interior). Outcomes 2 and 5 produce PP target penetrations and are scored as damage to the target.

to NRC-13-0002 Fermi 2 NRC Docket No. 50-341 Operating License No. NPF-43 Proposed License Amendment to Revise the Fermi 2 Licensing Bases for Protection from Tornado-Generated Missiles Marked-Up UFSAR Pages Section 3.5

FERMI 2 UFSAR 3.5 MISSILE PROTECTION Protection against the hypothetical effects of missiles is provided in accordance with the following damage limit criteria:

a.

The integrity of the containment system is maintained

b.

The capability for shutdown of the reactor and maintenance of core cooling capability is maintained

c.

A missile accident that is not a LOCA does not initiate a LOCA.

Where possible, missile protection is achieved through basic plant component arrangement such that, if a missile-generating failure should occur, the direction of the flight of the missile would be away from Category I structures or other critical system components. Examples of such arrangements are shown in Figure 3.5-1, Sheets 1 through 6, which show the general arrangement of piping, pumps, motor, valves, and other equipment in the drywell indicating component missile protection by separation. Where it is impossible to provide protection through selective plant layout and where the structures available do not provide sufficient missile protection, barriers are provided to prevent potential missiles from damaging critical systems and structures.

An analysis of potential missiles and the missile protection provided follows. Although it is not given in the order specified in Regulatory Guide 1.70, the information requested in the guide is presented. The reason for the change in order is to present a more comprehensive discussion of the missile protection included in the Fermi 2 design.

3.5.1 Missile Selection (Sources) 3.5.1.1 Missiles From Pressurized Equipment 3.5.1.1.1 Missiles Considered Potential missiles from pressurized equipment that were investigated include the following:

a.

Valve bonnets (large and small)

b.

Valve stems

c.

Thermowells

d.

Vessel head bolts

e.

Pieces of pipe

f.

High-pressure gas cylinders.

3.5.1.1.2 Design Evaluation Using conservative assumptions, it has been determined that the potential missiles from items

a. through e. above, originating from fluid lines, cannot achieve sufficient energy to penetrate the drywell, critical system components, or missile shields to the extent that safe reactor shutdown would be impaired. An added conservatism exists because of the separation 3.5-1 REV 18 10/12

FERMI 2 UFSAR criteria and barriers described in Subsections 3.5.3 and 3.5.4. The probability of incapacitating more than one of the redundant reactor protection system (RPS) safe-shutdown and engineered safety feature (ESF) system components by a single missile is negligible. The driving force for these potential missiles is assumed to come from the kinetic energy of the water or steam.

In the event of a break in a fluid-carrying component, the velocity of the exiting fluid is determined. The drag force of the fluid that propels a missile is proportional to the product of the fluid mass density and velocity squared. By applying this drag force to each potential missile, the missile attaining the most kinetic energy is determined. Damage resulting from impact of this missile is then analyzed. Small missiles are assumed to achieve maximum fluid velocity instantly, which is conservative because a missile requires a finite time to accelerate to this velocity after being dislodged. In addition, missiles in a horizontal trajectory tend to fall out of the fluid jet. Therefore, the driving force acts for a shorter time and the missile probably achieves a velocity lower than its maximum.

High-pressure gas cylinders on the Fermi 2 site that are capable of generating potentially high-energy missiles are as follows:

a.

Hydrogen gas storage cylinders

b.

Service gas storage cylinders (welding gases, nitrogen, and spare breathing air)

c.

Emergency breathing air cylinders

d.

Oxygen and hydrogen reagent cylinders

e.

Hydrogen and oxygen storage vessels at the HWC Gas Supply Facility The hydrogen and service gas storage cylinders are located more than 300 ft from the reactor building. Any potential missiles must first pass through the first floor of the turbine building and through several concrete walls (with a combined thickness of more than 5 ft) before reaching the reactor building wall. There is insufficient energy stored in these cylinders for any potential missile to penetrate these walls.

Emergency breathing air cylinders are stored in seismically qualified storage racks located along the north wall of the reactor building ventilation room. The concrete walls of this room are sufficient to prevent any potential missiles from reaching critical locations outside of this room. Equipment inside this room can be damaged by potential missiles, but this will not prevent a safe reactor shutdown. A design-basis earthquake (DBE) will not initiate emergency breathing air cylinder damage because the cylinders are secured in seismically qualified storage racks.

The primary containment hydrogen monitors require supplies of hydrogen and oxygen to act as reagent gases. These cylinders are located adjacent to each monitor, thereby minimizing the tubing run to each instrument. The cylinders, regulators, piping, and racks are seismically designed and installed. The racks are also designed to restrain the cylinders to prevent them from becoming missiles if punctured.

Using the barrier and procedures of Subsections 3.5.3 and 3.5.4, respectively, results of the investigation showed that additional missile barriers for potential missiles from pressurized equipment are not required. With the assumption of maximum missile velocity and minimum missile energy required for perforation, the results are conservative.

3.5-2 REV 18 10/12

FERMI 2 UFSAR The HWC gas supply facility is located approximately 1100 feet northwest of the nearest safety-related structure (the RHR Complex). The hydrogen and oxygen storage tanks and the gaseous hydrogen tube bank are designed to remain in position during the design basis earthquake. Since the site for the HWC Gas Storage Facility was chosen to provide the required separation from safety-related structures, a release from this location would not affect plant safety. Potential blast effects from tank ruptures are enveloped by the existing analyses of the design basis tornado and design basis earthquake.

3.5.1.2 Missiles From Rotating Equipment 3.5.1.2.1 Missiles Considered Potential missiles from rotating equipment, which could require a missile barrier, include

a.

High-pressure turbine rotor segment

b.

Low-pressure turbine rotor segment

c.

Recirculation pump or motor segment

d.

Emergency diesel generator (EDG) segment.

All probable paths of flight of these potential missiles have been investigated.

3.5.1.2.2 Design Evaluation As stated in Subsection 10.2.3, after the low pressure (LP) turbine rotor replacement during RFO5, there is no design basis turbine missile at Fermi 2. The HP turbine rotor was replaced in RFO7. The new HP turbine rotor, which was reviewed for overspeed capability, was found to be higher in overspeed than the maximum theoretical overspeed of the unit (LP rotors and generator). Moreover, the seventh stage blades of the HP turbine rotor are smaller in length and lighter in weight that the eighth stage blades of the LP turbine rotors. Based on this, it is concluded that the HP turbine rotor missile analysis is bounded by the LP turbine missile analysis. The HP turbine rotor and generator rotor missiles cannot completely breach their respective outer casings. The new HP and LP turbine rotors are of monoblock construction. The monoblock rotors have higher speed capability than the maximum attainable speed of the turbine generator units. Per General Electric, the supplier of the new rotors, the probability of missiles being generated is well below 10 to the -8 power.

The most substantial piece of nuclear steam supply system (NSSS) rotating equipment is the reactor recirculation system (RRS) pump and motor. This potential missile source is addressed in detail in References 3 and 4.

It is concluded in Reference 3 that destructive pump overspeed can result in certain types of missiles. A careful examination of shaft and coupling failures shows that the fragments will not result in damage to the containment or to vital equipment.

a.

Low-Energy Missiles (Kinetic Energy Less Than 1000 ft-lb)

Low-energy-level missiles may be created at motor speeds of 300 percent of rated as a result of failure of the end structure of the rotor. The structure consists of the retaining ring, the end ring, and the fans. Missiles potentially 3.5-3 REV 18 10/12

FERMI 2 UFSAR generated in this manner will strike the overhanging ends of the stator coils, the stator coil bracing, support structures, and two walls of 1/2-in.-thick steel plate.

Because of the ability of these structures to absorb energy, it is concluded that missiles would not escape this structure. It is at this point that frictional forces would tend to bring the overspeed sequence to a stop

b.

Medium-Energy Missiles (Kinetic Energy Less Than 20,000 ft-lb)

In the postulated event that the body of the rotor were to burst, medium-energy missiles could be created. The likelihood that these missiles would escape the motor is considered less than the likelihood of escape for the low-energy missiles described above, because of the additional amount of material constraining missile escape, such as the stator coil, field coils, and stator frame directly adjacent to the rotor

c.

The Motor As a Potential Missile Since bolting is capable of carrying greater torque loads than the pump shaft, pump bolt failure is precluded. Since pump shaft failure decouples the rotor from the overspeed driving blowdown force, only those cases with peak torques less than those required for pump shaft failure (five times rated) will have the capability of driving the motor to overspeed. When missile-generation probabilities are considered along with a discussion of the actual load-bearing capabilities of the system, it is evident that these considerations support the conclusion that it is unrealistic that the motor would become a missile.

It is concluded in Reference 4 that destructive overspeed of the pump and motor could occur as a result of a full double-ended pipe break LOCA in the recirculation pump suction line. In the event of motor failure, the motor stator and frame structure would prevent the release of any missiles as indicated above. In the event of pump destructive overspeed, impeller missiles could be produced. However, they will not penetrate the pump case. They could be ejected from the open end of the broken pipe. However, pipe restraints have been installed to prevent potential missile points in the pipe from developing. (See Subsection 5.5.1.4.)

Potential missiles from an EDG would be small auxiliary items knocked loose from the engine exterior by blows from within. Analysis has shown that the maximum velocity of these missiles would be 40 fps, with a maximum mass of 5 lb each. These missiles are of lower energy than potential tornado-generated missiles. As the external walls of the EDG rooms are constructed to withstand the tornado-generated missiles, missiles ejected from an EDG will be contained within that EDG room and therefore cannot incapacitate another EDG in the other division.

3.5.1.3 Tornado-Generated Missiles 3.5.1.3.1 General Tornado forces and the design-basis tornado are discussed in Section 3.3. Objects lying in the path of tornadoes may be picked up by the tornado due to aerodynamic lift force or due to the rapid pressure reduction that may have injected the object into the tornado wind field.

The objects that are potential missiles vary in size, shape, and number. The design-basis 3.5-4 REV 18 10/12

FERMI 2 UFSAR missiles selected for consideration in the Fermi 2 design are a 4-in. x 12-in. x 12-ft plank with a density of 40 lb/ft3, and a 4000-lb passenger car traveling at 50 mph at a maximum of 25 ft above grade elevation. The design-basis missiles are given in Subsection 12.2.1.7.1 of the PSAR.

For the Category I 4160-V electrical ductbanks between the RHR cable vaults and the Reactor/Auxiliary building cable vaults, the top of the ductbanks is located approximately six inches below grade, the top of the manholes is located at grade level, and RHR cable vaults are located above grade. The design for this ductbank system is based on Regulatory Guide 1.76 Revision 1 (March 2007) (Reference 17) and, as such, the design is evaluated for the design-basis tornado missiles described in Regulatory Guide 1.76 Revision 1.

3.5.1.3.2 Additional Analyses The missile barriers listed in Subsection 3.5.3 provide protection against tornado generated missiles; however, three areas received additional analysis to ensure resistance to tornado generated missiles. They are the spent fuel pool, the fan blades of the cooling towers in the Residual Heat Removal (RHR) complex, and the miscellaneous penetrations and openings in the exterior walls/roofs of the Reactor/Auxiliary Building and RHR Complex.

3.5.1.3.2.1 Spent Fuel Pool - Reactor Building As the siding above the refueling floor is designed to release in the event of a design-basis tornado, potential damage to fuel in the spent fuel pool from tornado-generated missiles is of concern. The AEC noted this concern in its Safety Evaluation Report on the Construction Permit (Reference 2). The concern was identified as Post Construction Permit Open Item No. 9. This concern has also been the subject of analyses submitted to the AEC by GE (Reference 5). The Edison position on this open item was submitted to the AEC in August 1973 (Reference 6). The Edison position was based on the GE report (Reference 5) and a study of the probability of a tornado striking the site and showed that the probability of damage to fuel in the spent fuel pool by a tornado-borne missile is extremely small (7 x 10-o per year) and that no additional protection is required. The AEC waived the requirement to provide tornado protection of the spent fuel pool in June 1974 (Reference 7) based on its own independent assessment. The AEC cited the low probability of a tornado, the lower likelihood that objects could be lifted to the elevation of the fuel pool and become missiles, and the expectation that where spent fuel damage were to occur, the associated offsite exposure radiological consequences would likely be within 10CFR100 limits.

3.5.1.3.2.2 Residual Heat Removal Complex Mechanical Draft Cooling Towers A study was performed to determine the probability that both cooling tower divisions can be rendered out-of-service by tornado-generated missiles entering the fan discharge stack (Reference 8). The result of this study, as determined below, is that this probability is very small and is conservatively estimated between 109 and 10-10 per year. The RHR cooling towers and their missile protection features are described in Subsection 9.2.5.

In the cooling tower study, several potential design-basis tornado missiles are considered.

These represent the complete range of all possible missiles that may be potential threats to the safety of the cooling towers:

3.5-5 REV 18 10/12

FERMI 2 UFSAR

a.

A 4-in. x 1-ft x 12-ft wood plank

b.

A 13.5-in.-diameter x 35-ft-long utility pole

c.

A 1-in.-diameter x 3-ft-long steel rod

d.

A 6-in.-diameter x 15-ft-long schedule 40 steel pipe

e.

A 12-in.-diameter x 15-ft-long schedule 40 steel pipe.

Other missiles cited in the literature, such as a 2-in. x 4-in. x 1-ft wood piece, a 9-in. brick, a 6-in. x 12-in. x 2-in.-thick concrete slab, a 1-ft block concrete, and a "standard" automobile are not able to reach the level of the cooling towers if they are injected at ground level or at elevations of 200 ft or less (Reference 9).

Each design-basis missile was then analyzed for its ability to impact the cooling tower fan blades.

Using the three-dimensional wind flow field proposed by Bates and Swanson (Reference 10),

the vertical impact velocities of the design-basis missiles at different roof elevations have been calculated assuming the objects are injected into the tornado wind field at different elevations. The results are shown in Table 3.5-1.

None of the missiles except the wood plank picked up at ground level or injected at 50-ft or 100-ft elevations, is able to reach the level of the cooling tower. The steel rod injected at 50 ft and other objects injected into the tornado wind field at higher elevations (250 ft) may be hurled into the cooling towers, but only a few missiles could be of this type.

Even if a missile lands in the cooling tower, it will not damage the cooling tower fan blades.

The Marley Company, the manufacturer of the Fermi 2 RHR complex mechanical draft cooling towers, has calculated that the fan blades would safely withstand the impact from an object weighing 17 lb falling freely from an elevation of 250 ft. This is equivalent to a kinetic energy of about 8.5 x 104 ft-lb. Therefore, the fan blades are able to withstand the impact from smaller missiles; e.g., design-basis missile c. listed above (1-in.-diameter x 3-ft-long steel rod).

The number of missiles assumed to impact a cooling tower is then determined. The number of missiles that are injected into the tornado field depends on factors such as the number of "loose" objects lying in an area of a 3000-ft radius circle around the RHR complex, which contains the cooling towers. Therefore, the number of missiles injected into the tornado funnel cannot be decided with any degree of certainty. It is assumed that of all the potentially damaging objects available, two of them will be picked up by the design-basis tornado at just the right time and location to become a missile.

The cooling tower system is designed such that it can function even if one tower division is damaged and rendered out of operation. Therefore, for the cooling tower system to be out of service, both tower divisions must be damaged simultaneously by tornado missiles. For this to happen, the following sequence of events must occur:

a.

A tornado strikes a point in the plant site. Based on the meteorological data and on Thom's model, the probability of this event is calculated as 7 x 10~4 per year 3.5-6 REV 18 10/12

FERMI 2 UFSAR

b.

An object which is accelerated horizontally does not bounce and is ejected into the tornado at a 450 angle. This probability is conservatively estimated at 10-1

c.

The object maintains the orientation inside the tornado and exposes its maximum cross-sectional area to the full wind force. Since objects will tend to tumble, the probability of this event is conservatively estimated at 10-1

d.

The object is thrown into a cooling tower division. Objects of the type being considered here could land anywhere within 100 ft of the tornado funnel. This is a circular area of 500 ft diameter. The area of the cooling tower fan discharges in the RHR complex is about 850 ft2. Therefore, the probability of a missile landing in a cooling tower division is approximately 4.3 x 10-.

This is multiplied by two because it was assumed earlier that the two objects would be injected into the tornado wind field

e.

The missiles land simultaneously in both tower divisions. The probability of this joint occurrence is calculated as the product of the probability of one missile landing in one tower division and the probability of the second missile landing in the other tower division simultaneously. Using the concept of statistical independence of these events, the probability of the joint event is conservatively estimated to be between 10~9 and 10"10 per year.

The draft ANSI standard on Plant Design Against Missiles (Reference 11) recommends that no protective measures be required if the combined probability of missile ejection and subsequent unacceptable damage is less than 10-7 per year. As the probability of tornado damage to the cooling tower unit calculated above is considerably lower than the acceptable limit, and because certain components and portions of the tower structure are hardened against tornado missiles and the fan blades can be replaced after a tornado (as described in subsection 9.2.5.2.2), it is concluded that no missile protective covers are required for the cooling towers. It may be noted that the probability evaluated herein is very conservative because most tornadoes have velocities lower than 300 mph. Some missiles, even though hurled into the towers, may lose part of their kinetic energy if they strike the walls. Such missiles are not effective in damaging the fan blades.

The 8-lb steel-rod missile could damage the fan blades if the velocity were high enough (i.e.,

slightly higher than listed in Table 3.5-1?. The latest probability study on damage to the towers indicated a probability of 5 x 10~ 8 per year for all four cooling tower fans to be damaged by 20 steel-rod (rebar) missiles.

3.5.1.3.2.3 Exterior Walls/Roofs - Reactor/Auxiliary Building/RUR Complex n

y to d m e h z r ye a t h e er a ulna bl r a il ty3s on5 e

Ve r 1 a 1 o The e'tfier w~alls of the Reactor/Auxiliary Buiilding have been designed to resist the impact of tornado generated mLisle. The missile protection adequacy of ertain small penietrations 3.5-7 REV 18 10/12

FERMI 2 UFSAR and some dors and HAC intake enalllsuoes on the exterie walls was evaltCed.ope door on the soth wall.

and openings is limited to the penetration of missiles suich the cited areas which may the impaet aed damage safety nelated items inside the buildings For the rail car door, perforatione o edrws ousiderothe yiste y

Se ate truues dvae evalcuatedbsd probabilitisaesarthanissl paaer ar.lysir aggfregte as)

Thena spie cific Itar for which not rado is protecti n addition, som e of the tenrationeprotected mstan co oelin f d

rhowever, these flanges were The ent fth c

ltie alcula of the d amg probabili tie sd forida at thaes ssltea Sicemp onservely th ua eder misie ageama damage probability o.

x ~prya svr buildings have been designed to resist the impact of tornado-generated missiles such that the safety related systems and components required for safe shutdown as identified in Tables 3.3-2 and 3.5-2 are generally protected. A limited number of these Seismic Cateory I systems and conmonents located outside of (or otherwise not protected by these) Seismic Cateaor I structures are evaluated based on a probabilistic missile damNae analysis (Reference 19 The specific targets for which no tornado missile protection was required based on the risk analysis are listed in Table 3.5-3. The specific acceptance criterion for tornado damae for the unprotected systems and components required for safe-shutdown following a tornado event is that the cumulative sum of the mean damae probabilities for these systems and components be less than 10 6 er year. The areate mean damagae probability corresponding to the scome of equipment identified in Table 3.5-3 is 6.82E-07 3er y.3 which satisfies the reVulatorv acceptance criterion.

The manner in which these targets were identified and selected for evaluation is described under the "Scope" section below. The use of TORMIS as an appropriate tool for evaluating tornado missile risk was generically accepted by the NRC in Reference 23 subject to site-specific approval of the first application. The "Analysis" section below describes the manner and degree to which the Fermi 2 analysis meets the constraints of the original NRC SEP. or was otherwise found to be acceptable in the site-specific SEP. approving its use (Reference 23).

3.5.1.3.2.3.1 Sco e The exterior walls/roofs of the Reactor. Auxiliary, and Residual Heat Removal Complex buildings have been designed to resist the impact of tornado-generated missiles such that the safety related systems and components required for safe shutdown identified in Tables 3.3-2 3.5-8 REV 18 10/12

FERMI 2 UFSAR and 3.5-2 are generally protected. A limited number of these Seismic Category I systems and components located outside of (or otherwise not protected by these) Seismic Category I structures are evaluated as not requiring unique tornado missile protection by burial or barriers on the basis of a probabilistic missile damage analysis.

Table 3,5-3 identifies the specific features evaluated in the probabilistic tornado missile analysis. The specific targets included in this table represent wall penetrations and doors in the exterior surfaces of these structures. No specific safety-related systems are associated with any particular penetration: hence, the tornado missile hazard associated with these penetrations and openings is limited to and characterized by the probability of missile penetration of the target itself. Exceptions include the targets associated with missiles penetrating the reactor building railroad air lock doors, the first floor auxiliary building south wall entrance, and the EDG removable wall panels.

Unprotected safety-related equipment not identified in UFSAR Table 3.3-2 as being required for safe reactor shutdown following a tornado was not included as targets. Examples include Control Room Emergency Filtration system south emergency makeup intake, the south portion of the Auxiliary Building rooftop and the Standby Gas Treatment equipment located on the refuel floor. In addition, the RHR Mechanical Draft Cooling Towers which are specifically licensed for post-tornado repair and restoration (See UFSAR Section 3.5.1.3.2.2) and the Spent Fuel Pool which was evaluated on the basis of an alternative risk analysis (See Section 3.5.1.3.2.1) were both excluded from the scope of analysis.

Other features that were excluded for this risk analysis are the buried underground cable vaults between the RHR complex and the auxiliary building, the EDG fuel oil tank vents and the EDG exhaust stacks. which are located on the roof of the RHR complex. Both of these rooftop features are provided with tornado missile shield protection specifically designed to prevent vertically travelling missiles from entering the RHR complex and damaging the EDG fuel oil tanks and diesel engines.

3.5.1.3.2.3.2 Analysis The mean cumulative damage probability for the targets identified in Table 3.5-3 was evaluated using TORMIS, a Monte Carlo based program for simulating tornados that was developed from the NRC approved EPRI version of this program (References 20, 21, 22).

Major inputs to the analysis include:

" the regional probabilities of the occurrence of tornados

" the location and size of eligible targets location and number of potential missile sources Given these inputs. TORMIS computes the hit and damage probabilities associated with each target. These probabilities are post-processed to generate the aggregate risk associated with all targets. The term "target damage" is used in a general sense to mean any damage (or "loss of function") criteria caused by a tornado missile hitting the target. Target damage is not necessarily the same as target hit, but hit can equal damage for fragile equipment. The 3.5-9 REV 18 10/12

FERMI 2 UFSAR "damage" probabilities included in this analysis consisted of using the built-in TORMIS penetration, spall, and perforation equations for selected steel and concrete targets. In addition, the missile size, impact orientation, and velocity vector orientation were used to compute the probabilities of missiles entering "pipe-penetration" type openings. The TORMIS feature for overall structural response damage modeling capability was not used for this analysis.

In Reference 23, the NRC approved use of the (EPRI) TORMIS methodology subject to the following constraints:

1. Data on tornado characteristics should be employed for both broad regions and small areas around the site. The most conservative values should be used in the risk analysis or justification provided for those values selected.

2. The EPRI study proposes a modified tornado classification, Modified F (F')-scale for which the velocity ranges are lower by as much as 25% than the velocity ranges originally proposed in the Fujita (F)-scale. Insufficient documentation was provided in the studies in support of the reduced F'-scale. The F-scale tornado classification should therefore be used in order to obtain conservative results.

3. Reductions in tornado wind speed near the ground due to surface friction effects are not sufficiently documented in the EPRI study. Such reductions were not consistently accounted for when estimating tornado wind speeds at 33 feet above grade on the basis of observed damage at lower elevations. Therefore, users should calculate the effect of assuming velocity profiles with ratios Vo (speed at ground level) + V33 (speed at 33 feet elevation) higher than that in the EPRI study. Discussion of sensitivity of the results to changes in the modeling of the tornado wind speed profile near the ground should be provided.

4. 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.

5. Once the EPRI methodology has been chosen, justification should be provided for any deviations from the calculation approach.

The Fermi 2 analysis performed using the TORMIS program is based on the following characteristics of the analysis:

1. Definition of the Fermi 2 TORMIS Tornado Sub-Region A site-specific analysis was performed to generate a tornado hazard curve data set for the TORMIS analysis. The tornado data retained in the National Climatic Data Center Storm Events Data Base (NCDC, 2006) files for the years 1950-2005 were used to analyze both 3.5-10 REV 18 10/12

FERMI 2 UFSAR broad and small regions around Fermi 2 in order to identify a suitable representative sub-region for the site. Tornado occurrences were mapped for the large region, a 150 longitude x 150 latitude area centered on the Fermi 2 site, and statistical tests were performed using 1 x 1 and 30 x 30 blocks to identify a suitably homogeneous sub-region. The historical records of tornado occurrences within the sub-region tornado were used to establish the tornado occurrence rate. (Enhanced-Fujita) EF-scale intensities, path length, width, and direction variables to be specified as input for use in the TORMIS analysis.

The statistical analysis of the sub-region data established a mean occurrence rate of 3.1E-4 per year over the 56-year period. In accordance with the TORMIS methodology, backwards averaging was used to estimate a detrended occurrence rate to correct for changes in the annual reporting trends. The adjusted mean occurrence rate was determined to be 4.002E-4/year based on the 30-year backwards average.

2. Tornado Windspeed Intensity The analysis utilizes the original Enhanced Fujita (EF) scale windspeeds as per Reference 24.

Though the 1983 NRC SER called for the use of the F-scale of tornado intensity for assigning tornado windspeeds to each intensity category (F1-F5), the EF-scale was subsequently adopted in the positions of NRC Reg. Guide 1.76 Revision 1 that are based on Reference 24.

3. Characterization of Tornado Windspeed as a Function of Height Above Ground Elevation The Fermi 2 TORMIS simulations were performed with the TORMIS rotational velocity Profile 3, which has increased near ground windspeeds over Profile 5; the profile used in the 1981 EPRI TORMIS reports. Hence, the Fermi 2 runs were made with higher near ground windspeeds than in the EPRI study. A sensitivity study was conducted by running the original EPRI profiles and comparing the results. The most conservative profile with highest near ground windspeeds was conservatively used.

4. Missile Characterization and Site-Structure Models Walkdowns of the Fermi 2 site were performed to characterize the missile sources and plant configuration. This information was developed into the plant modeling inputs for the TORMIS analysis that describe the facility by specifving 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.) were catalogued and modeled to a distance of approximately 2,500 feet. This is done by specifying missile origin zones around the facility and a statistical description of missile types, based on the facility survey. The site surveys were conducted just prior to refueling outages to maximize the estimated population of available missiles and missiles sources. The Fermi 2 site missiles include the 20 standard TORMIS missiles in Reference 21, including structural sections, pipes, wood members. other construction materials, and an automobile category. In addition to the 20 standard TORMIS missile types, three Fermi 2 specific missiles were created for the analysis, one to represent 3.5-11 REV 18 10/12

FERMI 2 UFSAR scaffold clamps of which there were a large number present during the site walkdown, one to represent the sections of metal siding that enclose the upper portions of the reactor and turbine buildings, and the third to represent the large number of concrete block also identified during the site walkdowns. The TORMIS analysis used over 200,000 missiles in the simulations of EF5 tornadoes striking Fermi 2.

5. Deviations from the Original EPRI Methodology The Fermi 2 analysis is performed using an updated of TORMIS developed from the original EPRI NP-2005 source code. With some exceptions, this version of TORMIS implements the original NRC SER approved methodology. Revisions of the original NRC-approved version of the code generally implement changes necessary to enable continued use of the program on modern computing platforms and to enable analysis of larger problems. Specifically, the original main frame based random number generator has been replaced with a new machine independent algorithm and the code was re-dimensioned to allow larger numbers of missiles and surfaces.

The updated TORMIS program implements an algorithm for evaluating the risk of damage to piping penetrations credited in the Fermi 2 analysis that was not present in the original NRC approved methodology. The method consists of identifying the minimum required missile size, angle of orientation and angle of incidence at impact necessary for a missile to be capable of passing through a pipe penetration target. Missiles that are too large, not oriented correctly, or that impinge obliquely on a target are screened out based on these criteria. This method eliminates from the calculated cumulative risk those impacts which would not realistically have resulted in missile penetration of a pipe penetration target.

3.5.1.3.3 Conclusion As a result of these studies, the tornado-generated missiles to be considered in barrier design are the wood plank and the automobile, previously described.

3.5.1.4 Site-Related Missiles 3.5.1.4.1 Airplanes Airports in the vicinity of the Fermi 2 site are listed in Table 2.2-2 and shown in Figure 2.2-1. Table 2.2-2 also lists the proximity to the site, number of and type of aircraft, and other physical and operations data. As discussed in Section 2.2, the nearest airport (2 miles away) cannot accommodate aircraft large enough to be a hazard to Fermi 2 and the nearest major airport is too far away (19 miles north-northwest of the site) to be considered a potential hazard with regard to large-aircraft takeoff and landing. In addition, there are no nearby military airports that could be expected to accommodate aircraft with bomb or explosive loads.

3.5-12 REV 18 10/12

FERMI 2 UFSAR 3.5.1.4.2 Military Activities There are no military facilities within 10 miles of the plant. There are two restricted areas in Lake Erie, 20 and 27 miles from the plant, which are used as impact areas for small arms, ground artillery, and anti-aircraft artillery from Camp Perry and from the test-firing range at Erie Industrial Park. However, restriction to weapon horizontal-firing range and direction, as well as the nature of the projectiles, preclude a threat to the plant.

3.5.1.5 Primary Containment Internal Missiles The potential for missiles inside the containment due to gravitational effects from unrestrained equipment is possible only during maintenance situations. All equipment and components located inside the containment and associated with reactor operation and safety are restrained. Equipment moved into the containment for maintenance operations (including hoists) is controlled by administrative procedures and is removed when personnel leave the maintenance site or prior to returning to reactor operation. Where possible and practical, maintenance equipment used inside the containment is temporarily restrained. In view of the above, any missiles due to gravitational effects are expected to be relatively small and any resulting damage is anticipated to be minor.

3.5.2 Selected Missiles As a result of the investigations described in Subsection 3.5.1, the missiles to be considered in barrier design are the tornado generated missiles. These missiles are those considered as a design basis in the PSAR and approved by the AEC as documented in the AEC Safety Evaluation Report (Reference 2). For the Category I 4160-V electrical ductbanks between the RHR cable vaults at the RHR complex and the Reactor/Auxiliary building, the tornado missiles identified in Regulatory Guide 1.76 Revision 1 (Reference 17) are considered.

3.5.2.1 Tornado-Generated Missiles The tornado-generated missiles are a 4-in. x 12-in. x 12-ft wood plank with a density of 40 lb/ft3, traveling end-on at a velocity of 255 mph with a contact area of 48 in.2; and a 4000 lb passenger car traveling through the air at 50 mph at a maximum 25 ft above grade elevation.

The car has a contact area of 20 ft2. In the case of tornado-generated missiles, it is assumed that only walls and other vertical exposed surfaces are subject to impacts. Roof structures would be subject only to free-falling ballistic-type projectiles (e.g., wood or stone debris) without high tornadic wind force components. If penetration of the roof structures should occur, such penetration would not constitute a hazard, since the projectile would have very low energy, and the concrete floors and walls protect safety-related equipment for safe shutdown.

The following Design Basis Tornado missiles from Table 2 of Regulatory Guide 1.76 Revision 1 (March 2007) (Reference 17) are considered for the Category I 4160-V RHR cable vaults and the manholes and ductbanks between these cable vaults and the Reactor/Auxiliary building cable vaults:

3.5-13 REV 18 10/12

FERMI 2 UFSAR

a.

6.625" diameter x 15 ft long Schedule 40 steel pipe weighing 287 lbs and traveling horizontally at 135 fps

b.

4,000 lb, 16.4 ft x 6.6 ft x 4.3 passenger car traveling horizontally through the air at 135 fps at a maximum height of 30 ft above ground

c.

1" diameter solid steel sphere, weighing 0.147 lb and traveling horizontally at 26 fps Vertical missiles are all missiles listed above with a vertical velocity equal to 67% of their horizontal speed.

In addition, the following missiles addressed in the Safety Evaluation Report are also evaluated for penetration resistance and regeneration of secondary missiles:

a.

1" diameter x 3 ft long steel rod weighing 8 lbs, traveling horizontally at 250 fps

b.

13.5" diameter x 35 ft long utility pole weighing 1490 lbs, traveling at 247 fps Vertical missiles are all missiles listed above with a vertical velocity equal to 67% of their horizontal speed.

3.5.3 Missile Barriers and Loadings Structures, shields, and barriers designed to withstand missile effects are given in Table 3.5-2 according to the equipment protected. In addition to these barriers, the steel plate primary containment vessel is completely enclosed in and surrounded by a reinforced-concrete structure as described in Subsection 3.8.4. This concrete structure, in addition to serving as a radiation shield for personnel in the reactor building, provides a major structural barrier for the protection of the containment and reactor system against missiles that may be generated external to the primary containment.

The suppression chamber has no source of internal or external missile generation. The vent pipes connecting the suppression chamber to the drywell are protected by jet deflectors. The vent discharge headers and piping are designed to withstand the jet reaction force caused by flow discharge into the suppression pool. The control rod drive (CRD) mechanisms are located in a concrete vault below the reactor pressure vessel.

3.5.4 Barrier Design Procedures 3.5.4.1 Overall Structural Response To determine the capability of the missile barriers provided, the impact and penetration of potential missiles must be determined. Since the missile mass is small compared with the mass of any Category I structure, the only meaningful overall structural response is that of the structural element impacted by the missile. The overall response of the structural element is investigated by designing the element for the forces transmitted to it by the missile.

3.5-14 REV 18 10/12

FERMI 2 UFSAR 3.5.4.2 Edge Impact For edge impact, punching shear stress was checked after obtaining the maximum force impacted to the element by the missile. The punching shear stress is given by the following expressions:

Qs = mvo° (for rigid missles)

(3.5-2) tdS Qs = s1 (for nonrigid missles)

(3.5-3) where F1 = maximum contact force = 1.14WVo and td

=

impact time _ 2D V0 D'

=

penetration depth calculated by modified Petry Formula (Subsection 3.5.4.7)

Vo

=

initial velocity of missile m

=

mass of missile s

=

perimeter of area enclosed by a border extending one-half of the panel thickness beyond contact area W

=

weight of missile 3.5.4.3 Central Impact For central impact in the case of rigid missiles, the maximum force impacted to a structural element is calculated by the following expression:

F =

(3.5-4) and td = duration of force (355)

V0 After the force F and its duration td are obtained, the element is designed for this dynamic load. For central impact in the case of nonrigid missiles, the panel is modeled as a single degree of freedom system with equivalent mass and equivalent stiffness. The equation of motion for impact is solved to get maximum deflection of the element. This deflection is compared with allowable (or ductility ratio) to arrive at a satisfactory design.

3.5.4.4 Impact Analytical Procedures The impact of the missile is considered plastic because of the local unrecoverable deformations of either the missile or the target or of both. The velocity of the missile and the 3.5-15 REV 18 10/12

FERMI 2 UFSAR target (concrete panel) after the impact, Va, is determined from the consideration of conservation of linear momentum and is expressed by the following equation:

MmVi = MmVa + MeVa (3.5-6) where Mm =

mass of missile Vi

=

velocity of impact Me

=

effective mass of target For the Category I 4160-V RHR cable vaults and the manholes and ductbanks between these cable vaults and the Reactor/Auxiliary building cable vaults, overall structural response is based on the dynamic response of the structures and impulse-load time history. A simplified method based on idealization of the structure to an equivalent single-degree-of freedom system is utilized.

The procedure used in determining impactive force and time duration of the impact follows the guidance in Reference 16.

The impactive force and time duration of a hard missile, such as the 6" diameter schedule 40 steel pipe, is determined by the expression shown in Section 3.5.4.3. The impactive force and time duration for soft missiles, such as the automobile and wood plank, is determined by the Riera formula, as outlined in Reference 16.

3.5.4.5 Punching Shear Analytical Procedure Reinforced-concrete panels are checked for the punching shear failure and the flexural yielding failures. The effective mass, Me, of the panel for the case of punching shear failure is obtained as follows:

Me = (A + d)(B + d)dw (3.5-7) where A, B =

dimensions of missile d

=

thickness of panel w

=

density of target material 3.5.4.6 Flexural Failure Analytical Procedure The effective mass for the case of flexural failure of a panel is defined as that mass which must be concentrated at the point of impact on an equivalent weightless slab so that it will have the same kinetic energy as the actual slab when the point of impact is subjected to unit velocity.

For a flexural failure, the energy transferred to the slab is compared with its energy capacity at an appropriate ductility ratio. For a punching shear failure, the shear capacity at the critical section is compared with the shear force transferred to the slab.

3.5-16 REV 18 10/12

FERMI 2 UFSAR 3.5.4.7 Depth of Penetration Analytical Procedure The depth of penetration into concrete walls is calculated using the Modified Petry Formula (Reference 12), The concrete barrier thickness was selected to prevent secondary missiles formed by scabbing from damaging both divisions of protected systems safe shutdown equipment.

Concrete wall/slab thickness provided for the Category I 4160-V RHR cable vaults, manholes, manhole covers, and ductbanks between these cable vaults and the Reactor/Auxiliary building cable vaults are more than the minimum acceptable barrier thickness required as shown in Table 1 of NUREG-0800, Standard Review Plan 3.5.3 Revision 3, dated March 2007 (Reference 18).

Modified Petry Formula (Reference 12) is used to determine the concrete protective cover thickness to prevent penetration and regeneration of secondary missiles for the two additional tornado missiles identified in the Safety Evaluation Report.

The method of calculation used to determine the energy required to penetrate a steel plate is based on extensive tests conducted by the Stanford Research Institute (Reference 13).

During these tests, rod-shaped missiles were impacted against square steel plates having clamped edges. The results of the tests are described by the following expression for minimum energy per unit diameter of missile required for perforation of a steel plate:

= U (0.344T2 +

0.032T)

(3.5-8) where E

=

critical energy required for penetration, ft-lb D

=

diameter of missile, in.

U

=

ultimate tensile strength of steel plate, lb/in.2 T

=

plate thickness, in.

W

=

length of side of square window in the target frame between the rigid supports, in.

WS

=

test constant = 4 in.

No composite section (concrete with steel plate backing or the like) has been used for missile-resistant structural elements.

The impact of a turbine-generator missile on the reactor building or auxiliary building is discussed and references are cited in Subsection 10.2.3. The impact of a turbine missile on the RHR complex has also been evaluated.

3.5.5 Missile Barrier Features The missile barriers listed in Table 3.5-2 provide adequate protection against potential tornado-generated missiles. In addition, it has been shown that the probability of missile damage to either fuel in the spent-fuel pool or the RHR cooling tower fans, both of which 3.5-17 REV 18 10/12

FERMI 2 UFSAR could be exposed to such damage, is extremely small. Together with the redundancy and separation provided, the missile protection provided for Fermi 2 is adequate.

The general arrangement of piping and equipment in the drywell showing the separation of redundant systems is given in Figure 3.5-1, Sheets 1 through 6.

For assumed failures of the high pressure coolant injection (HPCI) system, the automatic depressurization system (ADS) functions to reduce the reactor pressure to a value low enough to allow the low pressure coolant injection (LPCI) and core spray systems to pump water to the reactor pressure vessel (RPV) in time to cool the core consistent with the design basis. (See Subsection 6.3.2.2.2.) The ADS uses five of the 15 safety/relief valves (SRVs) of the nuclear boiler pressure-relief system to achieve the automatic blowdown to the suppression pool. Protection from simultaneous damage to the HPCI steam line inside the containment and to the SRVs designated for ADS function due to pipe whip or fragments of pipes is provided by physical separation. The HPCI steam source is provided from main steam line A, while only the SRVs on main steam lines C and D are considered available for performance of the ADS function.

3.5-18 REV 18 10/12

FERMI 2 UFSAR 3.5 MISSILE PROTECTION REFERENCES

1.

Deleted

2.

Safety Evaluation by The Division of Reactor Licensing, USAEC, In the Matter of the Detroit Edison Company Enrico Fermi Atomic Power Plant Unit 2, Docket 50-341, dated May 17, 1971.

3.

Letter from E. A. Hughes, GE, to R. C. DeYoung, NRC,

Subject:

"GE Recirculation Pump Potential Overspeed," dated January 18, 1977. A set of questions from NRC dated August 4, 1977, was responded to in a November 17, 1977, letter from GE to NRC.

4.

Letter from General Electric Company, to the NRC,

Subject:

GE Recirculation Pump Potential Overspeed, Revision 2, dated March 30, 1979.

5.

D. R. Miller and W. A. Williams, Tornado Protection for the Spent Fuel Storage Pool, APED-5696, November 1968.

6.

Letter from C. M. Heidel, Detroit Edison, to A. Giambusso, AEC,

Subject:

"Protection of the Spent Fuel Storage Pool From Tornado Missiles," EF2-18679, as amended by Letter EF2-19171, dated August 14, 1973.

7.

Letter from W. R. Butler, AEC, to H. Tauber, Detroit Edison,

Subject:

"Approval of Waiver of Requirement for Additional Tornado Protection for the Spent Fuel Pool," dated June 11, 1974.

8.

Probability Analysis of Tornado Missile Damage to RHR Complex Cooling Towers, S&L Report SL-3084, January 31, 1974.

9.

D. F. Paddleford, Characteristics of Tornado Generated Missiles, WCAP-7897, Westinghouse Electric Corporation, Pittsburgh, Pennsylvania, April 1969.

10.

F. C. Bates and A. E. Swanson, "Tornado Design Consideration for Nuclear Power Plants," ANS Transaction, November 1967.

11.

American National Standards Institute, Plant Design Against Missiles, ANSI-N177, March 1973.

lipa.

"Probabalistic Analysis of Tonmfldo Missile H4azard Due to Some Penletrationt and 521, February 23, 1989.

12.

J. M. Doyle, M. J. Klein, and H. Shah, "Design of Missile Resistant Concrete Panels," 2nd International Conference on Structural Mechanics in Reactor Technology, Berlin, Germany, September 1973.

13.

R. W. White and N. B. Butsfard, Containment of Fragments From a Runaway Reactor, Stanford Research Institute, SRIA-113, September 15, 1963.

14.

Letter from W. J. McCarthy, Jr., Detroit Edison, to R. S. Boyd, AEC,

Subject:

"RHR Service Water Pond Design Report," EF2-16331, Docket 50-341, dated April 17, 1973.

3.5-18 REV 18 10/12

FERMI 2 UFSAR 3.5 MISSILE PROTECTION REFERENCES

15.

Letter from R. C. DeYoung, AEC, to C. M. Heidel, Detroit Edison,

Subject:

"Approval of RHR Complex Design," dated April 1, 1974.

16.

ASCE Manual, "Structural Analysis and Design for Nuclear Power Facilities",

1980, Chapter 6.

17.

Regulatory Guide 1.76, Design-Basis Tornado and Tornado Missiles For Nuclear Power Plants, Revision 1 (March 2007).

18.

NUREG-0800 Standard Review Plan, Section 3.5.3 Barrier Design Procedures, Revision 3 (March 2007).

19.

ARA-001067001067 Revision 2. Tornado Missile TORMIS Analysis of Fermi 2 Nuclear Power Station.

20.

EPRI NP-768. "TORNADO MISSILE RISK ANALYSIS AND APPENDICES" issued May 1978.

21.

EPRI NP-769. "TORNADO MISSILE RISK ANALYSIS AND APPENDICES". issued May 1978.

22.

EPRI-NP-2005."Tornado Missile Risk Evaluation Methodology," Volumes I and II, issued August 1981 and Computer Code Manual.

23.

Safety Evaluation Report (SER) on TORMIS. dated October 26. 1983.

24.

NUREG/CR-4461. Rev 2, Tornado Climatology of the Contiguous United States.

(PNNL-15112. Rev 2). Ramsdell and Rishel. 2007.

3.5-19 REV 18 10/12

FERMI 2 UFSAR TABLE 3.5-1 MISSILE TRAJECTORY DATA FOR TORNADO MISSILES NEAR THE RESIDUAL HEAT REMOVAL COMPLEX COOLING TOWERS Initial Peak Vertical Elevation Elevation Velocity at Missile (ft)

(ft)

Impact (fps)

a. 4-in. x 1-ft x 12-ft-long wood plank 0

734 97 50 739 97 100 732 97 250 702 96

b. 13,5-in, diameter x 35-ft-long utility pole 0

0 60 60 100 100

c. 1-in. diameter x 3-ft-long steel rod 0

2 50 662 133 100 664 132 250 604 128

d. 6-in. diameter x 15-ft-long Schedule 40 0

steel pipe 50 50 100 100 250 268 96 e, 12-in, diameter x 15-ft-long Schedule 40 0

steel pipe 50 50 100 100 250 250 77 Page 1 of 1 REV 16 10/09

FERMI 2 UFSAR TABLE 3.5-2 EQUIPMENT PROTECTED FROM MISSILES AND ASSOCIATED MISSILE BARRIERS A. REACTOR AND AUXILIARY BUILDINGS Equipment Protected Missile Barriers

1. All items whose failure could affect the

1. a.

All exterior concrete walls operation and functions of the primary reactor

b.

Reactor building fifth floor concrete slab containment and those that are necessary for safe shutdown of the reactor

c.

Auxiliary building concrete roof slab

d.

Auxiliary building fifth floor concrete slab e,

Reactor building fifth floor equipment hatch cover

2.

Air conditioning equipment for the control

2.

a.

Auxiliary building concrete roof slab center

b.

Walls between auxiliary and turbine building

c.

Shield barrier at the Auxiliary Building / Turbine Building third floor portal. (see Note 1)

3. Reactor pressure vessel

3. Shield plug over reactor pressure vessel

4.

Main control room, battery room ESF switch-

4.

Combined thickness of walls and/or floors of the gear room, emergency closed cooling water reactor and auxiliary buildings above and including system, residual heat removal system, relay the fourth floor. Removable exterior precast panel in room, control rod drive units Division I Switchgear Room South Wall is protected by a 1-inch steel plate.

Note 1: There are two EECW lines in the Auxiliary Building which are potentially susceptible to tornadic induced missiles coming from the Turbine Building through the connecting portal on the third floor.

B. RHR COMPLEX BUILDING Equipment Protected Missile Barriers All items whose failure could affect the operation a,

All exterior concrete walls and functions of the primary containment and those

b.

All concrete roof slabs except the RHR complex that are necessary for safe shutdown of the reactor cooling tower discharges (including the EDGs)

c.

Isolation walls between redundant systems Page 1 of 2 REV 18 10/12

FERMI 2 UFSAR C.

Category 14160-V RHR cable vaults and the manholes and ductbanks between these cable vaults and the Reactor/Auxiliary building cable vaults Equipment Protected Missile Barriers All items whose failure could affect the operation

a.

All ductbanks and functions of the primary containment and those

b.

All concrete walls that are necessary for safe shutdown of the reactor (including the EDGs)

c.

All concrete roof slabs

d.

Access covers at RHR cable vaults

e.

Manholes Page2of2 REV 18 10/12

FERMI 2 UFSAR TABLE 3.5-3 List of Unprotected Plant Targets Accepted Based on TORMIS Analysis TORMIS BUILDING /

Target DESCRIPTION SITE LOCATION 1

Pipe penetration P-150 AB 2

Pipe penetration P-151 AB 3

Pipe penetration P-152 4

Pipe penetration P-153 AB 5

Electrical penetration E-11117 AB 6

Electrical penetration E-11116 AB 7

Instrumentation penetration 1-5504 AB 8

Instrumentation penetration 1-5505 AB 9

Ventilation penetration V-521 AB 10 Electrical Penetration E-5654 AB 11 Pipe penetration P-139 AB 12 Pipe penetration P-140 AB 13 Pipe penetration P-141 AB 14 Pipe penetration P-142 AB 15 Pipe penetration P-143 16 Electrical penetration E-11153 AB 17 Electrical penetration E-11154 AB 19 Pipe penetration P-136 20 Pipe penetration P-137 AB 21 Pipe penetration P-138 AB 22 Electrical penetration E-1270 AB 23 Electrical penetration E-1271 AB 24 Electrical penetration E-1272 AB 25 Electrical penetration E-1273 AB 26 Pipe penetration P-10765 AB 27 Electrical penetration E-15132 AB 28 Electrical penetration E-11054 AB 29 Pipe penetration P-10766 AB 53 Class 1E Electrical Cables East of Door R1-15 (Safety related AB electrical cables East of R1-15) 30 Electrical penetration E-5757 RB 31 Pipe penetration P-5609 RB 32 Pipe penetration P-5624 RB Page 1 of 3

FERMI 2 UFSAR TABLE 3.5-3 List of Unprotected Plant Targets Accepted Based on TORMIS Analysis TORMIS BUILDING /

Target DESCRIPTION SITE LOCATION 33 Pipe penetration P-5625 RB 34 Pipe penetration P-17305 RB 35 Pipe penetration P-17319 55 Outer Railroad Air Lock Door R1-1 36 Electrical penetration E-5543 RB 37 Electrical penetration E-10764 RB 38 Pipe penetration P-156 (Area around pipe protected by flange)

RB 39 Pipe penetration P-156 (Pipe in opening)

RB 40 Electrical penetration E-5521 RB 41 Pipe penetration P-158 BB 42 Pipe penetration P-157 RB 43 Pipe penetration P-161 RB 44 Pipe penetration P-162 RB 45 Instrumentation penetration 1-5657 RB 46 Pipe penetration P-160 RB 47 Pipe penetration P-12343 RB 48 Pipe penetration P-159 B

61 Removable Panel (EDG-11)

RHR 62 Removable Panel (EDG-12)

RHR 63 Removable Panel (EDG-13)

RHR 64 Removable Panel (EDG-14)

HR 65 Door to Motor Drive for Cooling Tower Fan (North End. East RHR Tower. Top Door) 66 Door to Motor Drive for Cooling Tower Fan (North End, East RHR Tower. Bottom Door) 67 Door to Motor Drive for Cooling Tower Fan (North End, West RHR Tower. Top Door) 68 Door to Motor Drive for Cooling Tower Fan (North End, West RHR Tower. Bottom Door) 69 Door to Motor Drive for Cooling Tower Fan (South End, East RHR Tower, Top Door) 70 Door to Motor Drive for Cooling Tower Fan (South End. East RHR Tower, Bottom Door) 71 Door to Motor Drive for Cooling Tower Fan (South End, West RHR Tower, Top Door) 72 Door to Motor Drive for Cooling Tower Fan (South End, West RHR Tower, Bottom Door)

Page 2 of 3

FERMI 2 UFSAR TABLE 3.5-3 List of Unprotected Plant Targets Accepted Based on TORMIS Analysis TORMIS BUILDING /

Target DESCRIPTION SITE LOCATION 77 Roof Penetration MK-142 RHR 78 Roof Penetration MK-144 RHR 94 West Wall Penetration MK-219 RtI 95 West Wall Penetration MK-220 HR 96 West Wall Penetration MIK-221 RHR 97 West Wall Penetration MK-222 BHR 98 West Wall Penetration MK-344 RHR 99 West Wall Penetration MK-345 BJD 100 West Wall Penetration MK-346 RHR 101 West Wall Penetration MK-347 BHR 49 Doors R3-13 (Security Door RBD17) & R3-28 AB 50 Door R3-12 (Security Door RBD21)

AB 51 Concrete Block Wall # 215 52 Refuel Floor Equipment Hatch Cover (A/B - 10/11)

RB 56 Inner Railroad Air Lock Door R1-2 (effectively modeled as intersection with targets 57, 58, 59. and 60) 54 Class 1E Equipment West of Interior Access Door R1-12 AB Safety-related piping behind Railroad Air Lock Doors (Div. 2 EESW RB supply & return & RHR Containment Spray) 58 Safety-related piping behind Railroad Air Lock Doors (Div. 1 EESW RB supply & FPCCU supply & return) 59 Safety-related piping behind Railroad Air Lock Doors (RHR RB

-9 Containment Spray - vertical) 60 Safety-related piping behind Railroad Air Lock Doors (RHR RB Containment Spray - horizontal)

Page 3 of 3 to NRC-13-0002 Fermi 2 NRC Docket No. 50-341 Operating License No. NPF-43 Proposed License Amendment to Revise the Fermi 2 Licensing Bases for Protection from Tornado-Generated Missiles List of Targets Excluded or Included for Information Only NRC-13-0002 Page 1 Page_1_List of Targets Excluded or Included for Information Only TARGET TORMIS SCOPE BUILDING/SITE DESCRIPTION BASIS FOR EXCLUSION STATUS LOCATION Target in original Fermi 2 TORMIS Architectural penetration A-analysis was eliminated by installing 1

N/A Excluded Auxiliary Building 2654 an engineered missile barrier (EDP-36069) consisting of 1" thick steel plate.

RB & CCHVAC/CREFS South air intake - path has a 900 turn with cast-in-place concrete wall overlap. South INFO Ventilation penetration V-intake provides makeup air for control 2

18 ONLY Auxiliary Building 10836 room pressurization via the CREFS/CCHVAC. The CREFS is not identified as required for post tornado safe-shutdown (UFSAR Table 3.3.2).

Unprotected Division 1 EECW supply and return piping exposed at interface Auxiliary/Turbine 3rd Floor Corridor I Room B-between turbine and auxiliary building 3

N/A Excluded Building 20A was protected by installing an engineered tornado missile barrier (EDP-35685).

This portion of roof, which covers the division 1 and 2 standby gas treatment 4

N/A Excluded Auxiliary Building North AB Roof slab filter and control center HVAC equipment rooms, is protected by 5'-6" thick concrete slab.

NRC-13-0002 Page 2 List of Targets Excluded or Included for Information Only TARGET TORMIS SCOPE BUILDING/SITE DESCRIPTION BASIS FOR EXCLUSION STATUS LOCATION This portion of roof, which covers the south control center emergency air intake and control room emergency INFO Aui South AB Rf filtration system filters, is protected by ONLY Auxilary Building AB Roofslab a 4-inch thick roof slab. The CREFS is not identified as required post-tornado safe-shutdown (UFSAR Table 3.3.2).

This spare RB1 penetration was 6

N/A Excluded Reactor Building (RB)-

Pipe penetration P-17304 eliminated by installing an engineered South tornado missile barrier (EDP-36498).

Residual Heat Removal 10" blind flanged access port is part of 7

N/A Excluded (RHR) Complex - East EDG11 East Wall TORMIS targets # 61, 62, 63 and 64 wall Access port (G-6/7) when closed. Each cover is same thickness as target wall. Online 8

N/A Excluded RHR Complex - East EDG12 East Wall opening of access during maintenance wall Access port (G-5/6) is controlled in accordance with TS RHR Complex - East EDG13 East Wall 3.0.9.

9 N/A Excluded wall Access port (G-8/9)

RHR Complex - East EDG14 East Wall 10 N/A Excluded wall Access port (G-7/8)

Air intakes for Division 1 and 2 11 N/A Excluded RHR Complex - Intake Vent Louvers LV-l essential service water pump room East wall, South end HVAC equipment are provided with NRC-13-0002 Page 3 List of Targets Excluded or Included for Information Only TARGET TORMIS SCOPE BUILDING/SITE DESCRIPTION BASIS FOR EXCLUSION STATUS LOCATION engineered missile protection consisting of 900 turn for air route 12 N/A Excluded RR Complex - Intake Vent Louvers LV-2 inside plenum with 18" thick concrete East wall, North end barrier wall inside the Pump Room.

RHR Complex - Intake Air intakes for EDG combustion air 13 N/A Excluded West wall, Roof (EDG-Vent Louvers LV-4 intake plenums are provided with

11) engineered tornado missile barriers RHR Complex - Intake consisting of 900 turns for air routed 14 N/A Excluded West wall, Roof (EDG-Vent Louvers LV-3 inside plenum with an 18" thick

12) concrete barrier wall inside the Room.

RHR Complex - Intake 15 N/A Excluded West wall, Roof (EDG-Vent Louvers LV-6 13)

RHR Complex - Intake 16 N/A Excluded West wall, Roof (EDG-Vent Louvers LV-5 14)

RHR Complex - Roof, These RHR complex rooftop doors 17 N/A Excluded West wall Access Door D-43 access each of the EDG air intake rooms adjacent to their respective 18 N/A Excluded RHR Complex - Roof, Access Door D-44 EDG air intake louver. The door West wall opens into the missile barriers 19 N/A Excluded RHR Complex - Roof, Access Door D-55 described in items 13-16 above.

West wall 20 N/A Excluded RaR Complex - Roof, Access Door D-56 West wall RHR Complex - South EDG-11 Room Ventilation Each EDG room HVAC ventilation 21 N/A Excluded Roof Exhaust exhaust consists of a 900 turn for air NRC-13-0002 Page 4 List of Targets Excluded or Included for Information Only TARGET TORMIS STATUS BUILDING/SITE DESCRIPTION BASIS FOR EXCLUSION RHR Complex - South EDG-12 Room Ventilation route inside plenum with an 18" thick 22 N/A Excluded Roof Exhaust concrete barrier. Concrete cap overhangs top & sides.

23 N/A Excluded RHR Complex - North EDG-13 Room Ventilation Roof Exhaust 24 N/A Excluded RHR Complex - Roof EDG-14 Room Ventilation Each essential service water pump 25 N/A Excluded RHR Complex - Roof RHR North Pump Room room HVAC ventilation exhaust Exhaust Ventilation Exhaust consists of a 90° turn for air route inside plenum with an 18" thick concrete barrier. Concrete cap overhangs top & sides.

26 N/A Excluded RHR Complex - Roof RHR South Pump Room Exhaust Ventilation Exhaust 122 INFO RHR Roof - North end, RHR MDCT Each of the four cooling tower fan 27 1ONLY East tower cells is protected horizontally by a 22-INFO RHR Roof - North end, inch thick concrete shell. Per UFSAR 28 121 ONLY West tower RUR MDCT Section 9.2.5 the RHR mechanical INFO RHR Roof - South end, draft cooling towers are licensed 29 120 ONLY East tower RTR MDCT assuming tornado damage from INFO RHR Roof - South end vertical missiles with subsequent repair 30 119 N

West R

o en RHR MDCT to restore function. Hit probabilities ONLWsttoerare computed for information only.

NRC-13-0002 Page 5 List of Targets Excluded or Included for Information Only TARGET TORMIS SCOPE BUILDING/SITE DESCRIPTION BASIS FOR EXCLUSION STATUS LOCATION These doors, which access their 31 N/A Excluded RHR South Pump Room Access Door D-3 respective essential service water to Resv. West wall.

pump rooms from the RHR roof, are located at the bottom of a 13'-6" wide x 21'-6" deep x 88'-10" long concrete 32 N/A Excluded RHR North Pump Room Access Door D-28 walled stairway. The doors open into to Resv. West wall.

18" thick concrete barrier wall inside the Pump Room.

RHR North Roof access These doors, which access the RHR 33 N/A Excluded door Access Door D-58 complex north and south rooftops from the EDG switchgear rooms, are 34 N/ARR South Roof access Access Door D-31 protected by a missile barrier having door 18" thick concrete walls and roof.

Div I Pump Room These doors are protected by a missile 35 N/A Excluded RHR East Wall Access Door D-1 barrier having 18" thick concrete walls Div I EDG-12 Room inside the RHR Room and outside with 36 N/A Excluded RHR East Wall Access Door D-6 an 18" thick concrete roof.

Div I EDG-11 Room 37 N/A Excluded RHR East Wall Access Door D-7 Div II EDG-14 Room 38 N/A Excluded RHR East Wall Access Door D-16 Div II EDG-13 Room 39 N/A Excluded RH{R East Wall Access Door D-17 Div II Pump Room 40 N/A Excluded RHR East Wall Access Door D-27 NRC-13-0002 Page 6 List of Targets Excluded or Included for Information Only TARGET TORMIS SCOPE BUILDING/SITE DESCRIPTION BASIS FOR EXCLUSION STATUS LOCATION EDG Fuel Oil Tank Vents Original installed missile shields were 41 73 INFO RHR Roof South Penetrations MK-211 &

installed over their respective EDG ONLY MK-216 day and main fuel oil tank vents to protect EDG main fuel oil tanks from EDG Fuel Oil Tank Vents perforation due to vertical missile 42 74 INFO RHR Roof South Penetrations MK-212 &

impacts.

ONLY MK-215 Each installed missile shield consists EDG Fuel Oil Tank Vents of 18" thick, 7'-6" square concrete slab 43 75 INFO RHR Roof North Penetrations MK-213 &

supported by 18" x 18" square ONLY MK-218 concrete columns at the corners.

TORMIS was used to tally horizontal EDG Fuel Oil Tank Vents strike probability for information only.

44 76 INFO RHR Roof North Penetrations MK-214 &

Due to the small size of opening ONLY MK-217 required to provide vacuum relief, it was not considered credible to assume a strike could pinch a vent closed.

Manhole MH-16946 - Cover Per UFSAR Section 8.3.1.1.8.1, the 45 102 ONLY Yard (Class IE conduits running original installed Class lE cable vaults between RB & RHR) that run between the Auxiliary Manhole MiH-16946 - Vault building south wall and the RHR 46 112 ONLY Yard (Class IE conduits running complex east wall are protected by between RB & RHR) depth of earth and divisional Manhole MH-16946 - SW separation.

47 114 INFO Yard Conduit (Class IE conduits ONLY running between RB &

Original design for manholes (MH)

R

)has

~12" of soil above MH roof with NRC-13-0002 Page 7 List of Targets Excluded or Included for Information Only TARGET TORMIS SCOPE BUILDING/SITE DESCRIPTION BASIS FOR EXCLUSION STATUS

~

LOCATION Manhole MH-16946 - South 2"-3" of soil above MH Cover - 30" O INFO Central Conduit (Class IE cover is malleable iron and support 48 115 ONLY Yard conduits running between ring is cast iron.

RB & RHR)

Manhole MHE-16946 - SE Recently installed high voltage Class INFO Conduit (Class I conduits 1E duct banks (EDP-35607) are 49 118 ONLY Yard running between RB &

excluded from the TORMIS analysis RHR) altogether on the basis that they were Manhole MH-16947 - Cover engineered against the Regulatory 50 103 ONLY Yard (Class I conduits running Guide 1.76 Rev 1 missiles.

between RB & RHR)

Manhole MH-16947 - Vault 51 113 ONLY Yard (Class I conduits running between RB & RHR)

Manhole MH-16947 - NW INFO Conduit (Class I conduits 52 116 ONLY Yard running between RB &

RHR)

Manhole MH-16947 - North F117 ONL Yard Central Conduit (Class I ONLY conduits running between RB & RHR)

Div I RHRSW & EESW Per UFSAR Section 9.2.5.3.1, 55 83 ONLY Yard Supply & Return piping underground service water piping is underground (Section A) protected by physical separation.

Div I RHRSW & EESW 56 84 INFO Yard Supply & Return piping 4'-2" Min. soil cover for the 24" O ONLY underground (Section B)

RHRSW Supply piping at i Elev.

NRC-13-0002 Page 8 List of Targets Excluded or Included for Information Only TARGET TORMIS SCOPE BUILDING/SITE DESCRIPTION BASIS FOR EXCLUSION STATUS LOCATION Div I RHRSW & EESW 577'-10" near West wall of RB. The 57 85 INFO Yard Supply & Return piping 10" 0 EESW Supply piping has the ONLY underground (Section C) worst case of Min. soil cover at 4'-0%"

near the West wall of the RB and ~45'-

INFO Div Ip R

& EESW 0" to the West. The 24" 0 RHRSW 58 86 ONLY Yard Supply & Return piping Return has the worst case of Min. vert.

underground (Section D) divisional separation at 4'-10" edge to edge, and also the worst case horiz. at Div I RHRSW & EESW 16'-0" edge to edge, and 4'-2" Min. soil 59 87 INFO Yard Supply & Return piping cover. The 10" O EESW Return ties underground (Section E) into the 24" O RHRSW Return within 10'-0" West of the RB.

Div II RHRSW & EESW Per UFSAR Section 9.2.5.3.1, 60 88 INFO Yard Supply & Return piping protected by physical separation. 4'-2" ONLY underground (Section A)

Min. soil cover for the 24" 0 RHRSW Supply piping at C Elev. 577'-10" Div II RHRSW & EESW near West wall of RB. The 10" 0 61 89 ONLY Yard Supply & Return piping EESW Supply piping has the worst underground (Section B) case of Min. soil cover at 4'-0%" near Div II RIHRSW & EESW the West wall of the RB and -21'-0" to INFO Div IIp HRS &

R e

ES the West. The 24" O RHRSW Return 62 90 ONLY Yard Supply & Return piping has the worst case of Min. vert.

underground (Section C) divisional separation at 4'-10" edge to edge, and also the worst case horiz. at Div II RHRSW & EESW 16'-0" edge to edge, and 4'-2" Min. soil 63 91 ONLO Yard Supply & Return piping cover. The 10" O EESW Return ties underground (Section D) into the 24" 0 RHRSW Return within 10'-0" West of the RB.

NRC-13-0002 Page 9 List of Targets Excluded or Included for Information Only TARGET TORMIS SCOPE BUILDING/SITE DESCRIPTION BASIS FOR EXCLUSION STATUS LOCATION Door T3-6 is a QA-1 pressure tight Doors T3-6 (Security Door hardened door. Door R3-27 is a QA-1 Auxiliary/Turbine TBD09) & R3-27 from 3 rd Control Center pressure boundary 64 N/A Excluded Building Floor TB laydown area to door. Double concrete walls are Control Room separated for AB/TB expansion threshold.

Auxiliary/Turbine Wall protects.stairwell. No targets on Building (into 4 th Floor other side of wall.

65 N/A Excluded stairwell from Corridor I Concrete Block Wall # 219 Room B-20A to TB 3 rd Floor)

Auxiliary/Turbine Wall protects stairwell. No targets on Building (to 4th Floor other side of wall. Door R3-4 is a QA-66 N/A Excluded stairwell from CorridorI Door R3-4 (Security Door 1M hardened door w/air seal.

Room B-20A to TB 3 rd Floor)

Div. I RHR flood protection Vent is designed for external flood 67 104 ONLY RHR East wall Make-up overflow MK-121 protection. Pipe is directed toward ONLY_(pipe itself)

Pump Room sump pit wall without Div. I RHR flood protection direct access to building internals.

68 105 ONLY RHR East wall Make-up overflow MK-121 (open space around pipe)

Div. I RHR flood protection 69 106 ONLOY RHR East wall Make-up overflow MK-122 (pipe itself)

Div. I RHR flood protection 70 107 ONLY RHR East wall Make-up overflow MK-122 (open space around pipe)

NRC-13-0002 Page 10 List of Targets Excluded or Included for Information Only TARGET TORMIS SCOPE BUILDING/SITE DESCRIPTION BASIS FOR EXCLUSION STATUS LOCATION Div. II RHR flood protection Vent is designed for external flood 71 108 ONLY RHR East wall Make-up overflow MK-284 protection. Pipe is directed toward (pipe itself)

Pump Room sump pit wall without Div. II RHR flood protection direct access to building internals.

72 109 ONLY RHR East wall Make-up overflow MK-284 (open space around pipe)

Div. II RHR flood protection 73 110 INO RHR East wall Make-up overflow MK-285 (pipe itself)

Div. II RHR flood protection 74 111 ONLY RHR East wall Make-up overflow MK-285 (open space around pipe)

Original tornado missile barrier was 75 79 INFO RHR Roof South EDG exhaust opening designed to protect the EDGs from ONLY vertically travelling tornado missiles INFO South-central EDG exhaust entering the EDG room via the EDG 76 80 ONLY RHR Roof opening exhaust penetration.

INFO North-central EDG exhaust TORMIS was used to assess the 77 81 ONLY RHR Roof opening probability of a strike on each of these targets via the open (East) end of the missile barrier through which the 78 82 INFO RHR Roof North EDG exhaust opening exhaust and exhaust muffler extend.

ONLY The exhaust itself was not treated as a target.

NRC-13-0002 Page 11 List of Targets Excluded or Included for Information Only TARGET TORMIS SCOPE BUILDING/SITE DESCRIPTION BASIS FOR EXCLUSION STATUS LOCATION There are no safety-related targets INFO directly beyond this door.

79 92 7L Auxiliarv Building Door R1-8