05000289/LER-1917-004, Regarding Items Nonconforming to Design for Tornado Missile Protection
| ML18037A705 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 02/05/2018 |
| From: | Callan E Exelon Generation Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| TMI-18-010 LER 17-004-00 | |
| Download: ML18037A705 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(i) |
| 2891917004R00 - NRC Website | |
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Exelon Generation Three Mile Island Unit 1 Telephone 717-948-8000 Route 441 South, P.O. Box 480 Middletown, PA 17057 February 5, 2017 TMl-18-010 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555-0001 THREE MILE ISLAND NUCLEAR STATION, UNIT 1 (TMl-1)
RENEWED FACILITY OPERATING LICENSE NO. DPR-50 DOCKET NO. 50-289
SUBJECT:
LICENSEE EVENT REPORT (LER) NO. 2017-004-00 "Items Nonconforming to Design For Tornado Missile Protection" 10 CFR 50.73 This report is submitted in accordance with 10 CFR 50.73(a)(2)(i)(B), 10 CFR 50.73(a)(2)(ii)(B), 10 CFR 50.73(a)(2)(v)(D) and 10 CFR 50.73(a)(2)(vii)(D). For additional information regarding this Licensee Event Report contact Michael Fitzwater, Sr. Regulatory Engineer, TMI Unit 1 Regulatory Assurance at (717) 948-8228.
There are no regulatory commitments contained in this LER.
Respectively, ru OL-J E.W. Callan, Jr.
Site Vice President, Three Mile Island Unit 1 Exelon Generation Co., LLC cc:
NRC Senior Resident Inspector-Three Mile Island Nuclear Station, Unit 1 Regional Administrator-NRC Region I NRC Project Manager-Three Mile Island Nuclear Station, Unit 1 R. R. Janati - Bureau of Radiation Protection, Commonwealth of Pennsylvania
, U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 03/31/2020 (04-2017)
, the httg://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3/)
NRG may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 3. PAGE Three Mile Island Unit 1 05000289 1 OF 4
- 4. TITLE Items Nonconforming to Design for Tornado Missile Protection
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED YEAR I SEQUENTIAL I REV FACILITY NAME DOCKET NUMBER MONTH DAY YEAR NUMBER NO.
MONTH DAY YEAR 05000 FACILITY NAME DOCKET NUMBER 12 06 17 2017 - 004
- - 00 02 05 18 05000
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)
D 20.2201 (bl D
20.22os(a)(s)(il D
50.73(a)(2)(ii)(A)
D 50.73(a)(2)(viii)(A)
NO D
20.2201 (dl D
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D 50.73(a)(2)(viii)(B)
D 20.22os(a)(1)
D 20.22os(a)(4l D
50.1s(al(2l(iiil D
50.73(a)(2)(ix)(A)
D 20.22os(aJ(2J(il D
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D 50.73(a)(2)(iv)(A)
D 50.73(a)(2)(x)
- 10. POWER LEVEL D
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D 50.73(a)(2)(v)(A)
D 1s.11(aH4l D
20.22os(a)(2J(iiil D
50.s6(c)(2J D
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D 1s.11 (a)(5l D
20.2203(a)(2)(iv)
D 5o.46(a)(sJ(iil D
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D 1s.11(a)(1J 100 D
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[8J 50.73(a)(2)(v)(D)
D 1s.11(aJ(2J(il D
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D 50.73(a)(2)(i)(C)
D OTHER Specify in Abstract below or in SEQUENTIAL NUMBER 004 REV NO.
00 recently identified non-conforming SSCs were considered acceptable due to the low likelihood of damage to the SSCs from tornado-generated missiles during the time of the original design and licensing process.
TMl-1 identified four SSCs as non-conforming conditions to the plant design and licensing basis because of and in concert with a collective industry effort to address the NRC issuance of Regulatory Issue Summary 2015-06 "Tornado Missile Protection".
C. ANALYSIS/ SAFETY SIGNIFICANCE There were no actual consequences resulting from these identified non-conforming conditions. A tornado that could produce the design basis missile is highly unlikely in the mid-Atlantic region. The probability of missiles striking any one of the identified non-conforming SSCs in a fashion to render the SSC inoperable is also very low.
The TMl-1 FSAR described characteristics of the design basis tornado (DBT) wind hazard and tornado generated missile hazard, design requirements are stated as:
Tangential wind velocity of 300 mph. (A gust factor of 1.3 has been used for those structures designed for tornado loadings.)
An external vacuum of 3 psig.
Missile equivalent to a utility pole 35 foot long, 14 inches in diameter, weighing 50 pounds per cubic foot, and traveling at 150 mph.
Missile equivalent to a 1 ton automobile traveling at grade at 150 mph.
TMl-1 reviewed these requirements against the plant SSCs needed to achieve safe shutdown in the event of a tornado. The result was the identification of four non-conforming conditions described in the event description which were declared inoperable.
NRC Enforcement Guidance Memorandum EGM 15-002, Revision 1, provides for application of NRC enforcement discretion which allows the four identified non-conforming conditions to be returned to an operable status based on the application of compensatory measures which are intended to reduce the likelihood that the tornado event would result in a failure of any one of the identified non-conforming conditions. TMl-1 applied the guidance in EGM 15-002, Revision 1, and, NRC DSS-ISG-2016-01 Revision 1 Appendix A, to determine the acceptable initial and comprehensive compensatory measures necessary to ensure that the identified nonconforming condition could be treated by the NRC with enforcement discretion.
D. CORRECTIVE ACTIONS
Compensatory measures were implemented in accordance with NRC guidance contained in the EGM 15-002 (revision 1) and DSS-ISG-2016-01 (revision 1) as described earlier. Enforcement discretion provided by EGM 15-002 remains in effect until June 10, 2020, for TMl-1, at which time modifications, license amendments or other actions must be implemented to fully resolve the issue. TMl-1 intends to request a SEQUENTIAL NUMBER 004 REV NO.
00 license amendment to allow for probabilistic methods to be applied to demonstrate that the risk associated with tornado generated missiles on specific components is sufficiently small such that plant modifications are not warranted.
E. PREVIOUS OCCURENCES
No previous similar events have occurred at the site. Page _4_ of _4_