ML15264A460
| ML15264A460 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 05/05/1987 |
| From: | Pastis H Office of Nuclear Reactor Regulation |
| To: | Tucker H DUKE POWER CO. |
| References | |
| TAC-48225, TAC-48226, TAC-48227, NUDOCS 8705120387 | |
| Download: ML15264A460 (7) | |
Text
Docket Nos.:
50-269, 50-270 and 50-287 Af~1 1987 Mr. H. B. Tucker, Vice President Nuclear Production Department Duke Power Company 422 South Church Street Charlotte, North Carolina 28242
Dear Mr. Tucker:
Subject:
Request for Additional Information - EFW Tornado Protection (TACS 48225, 48226 and 48227)
Re:
Oconee Nuclear Station, Units 1, 2, and 3 We have reviewed your submittal of September 15, 1986 on the protection of the emergency feedwater system (EFW) from the effects of high winds and tornado missiles. As a result of our review, we have prepared the enclosed request for additional information on some detailed aspects of your submittal.
Please respond to this request within 45 days of receipt of this letter.
Sincerely, Helen N. Pastis, Project Manager Project Directorate 11-3 Division of Reactor Projects-I/II
Enclosure:
As stated cc:
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Mr. H. B. Tucker Oconee Nuclear Station Duke Power Company Units Nos. 1, 2 and 3 cc:
Mr. A. V. Carr, Esq.
Duke Power Company Duke Power Company P. 0. Box 33189 Post Office Box 33189 422 South Church Street 422 South Church Street Charlotte, North Carolina 28242 Charlotte, North Carolina 28242 J. Michael McGarry, III, Esq.
Bishop, Liberman, Cook, Purcell & Reynolds 1200 Seventeenth Street, N.W.
Washington, D.C. 20036 Mr. Robert B. Borsum Babcock & Wilcox Nuclear Power Generation Division Suite 220, 7910 Woodmont Avenue Bethesda, Maryland 20814 Manager, LIS NUS Corporation 2536 Countryside Boulevard Clearwater, Florida 33515 Senior Resident Inspector U.S. Nuclear Regulatory Commission Route 2, Box 610 Seneca, South Carolina 29678 Regional Administrator U.S. Nuclear Regulatory Commission 101 Marietta Street, N.W.
Suite 3100 Atlanta, Georgia 30303 Mr. Heyward G. Shealy, Chief Bureau of Radiological Health South Carolina Department of Health and Environmental Control 2600 Bull Street Columbia, South Carolina 29201 Office of Intergovernmental Relations 116 West Jones Street Raleigh, North Carolina 27603 Honorable James M. Phinney County Supervisor of Oconee County Walhalla, South Carolina 29621
ENCLOSURE REQUEST FOR ADDITIONAL INFORMATION OCONEE NUCLEAR STATION, UNITS 1, 2 AND 3 PROTECTION OF EMERGENCY FEEDWATER SYSTEM (EFWS)
AGAINST TORNADO MISSILES AND HIGH WINDS The staff has some concerns regarding the use of the TORMIS code when cal culating structural damage by tornado missiles. Please address the follow ing:
- a. The licensee should provide a list of buildings or structures which contain the EFWS and SSFASW and the tornado or wind speed causing damage to each such structure. Areas containing these systems with little or no tornado protection should also be identified.
- b. For each of the Fujita scale tornado wind speed groupings, provide a listing of the various potential missiles which can be lifted.
For those potential missiles provide a listing of the structures con taining the EFWS and SSFASW which would be penetrated by these missiles.
- c. The TORMIS code assumes a varying tornado intensity along the path length of each tornado. Reanalyze the TORMIS results using an assump tion that the maximum tornado intensity estimated for each tornado is uniform along the entire estimated tornado area.
- d. Show that your TORMIS study included the effect of secondary missiles and missile ricochet on equipment and structures, or provide new cal culations which include such considerations. Note that this concern also includes the upper surge tanks.
- e. The Oconee Probabilistic Risk Assessment (OPRA) considers tornado mean damage length and mean damage width (Vol. 1, page A-58, and Appendix K, page K-4) in developing the locus of impact points which is used to determine plant damage resulting from tornado missiles.
This contrast's with the'staff's opinion that a study of tornado missile damage should utilize separate, individual tornadoes and the damage lengths and widths associated with each tornado. Confirm that your TORMIS study made use of individual tornado damage lengths and widths to develop individual loci. If not, modify your TORMIS study to incorporate a separate, individual damage length and width for each tornado.
- 2. The OPRA notes in Table K-6 that the upper surge tanks are susceptible to damage as a result of tornado missile strikes while your September 15, 1986 study states that the tanks are shielded by the reactor building.
Reconcile these apparently contradictory statements.,
- 3. Your evaluation included the possibility of high non-tornadic winds in the F1 and F2 tornado ranges (73-112 MPH and 113-157 MPH). However, these winds cover a far greater area than that associated with a tornado and should therefore be capable of generating far more missiles than tornado winds of the same velocity. Therefore, verify that your analysis is
-3 conservative by showing that tornado damage probability will increase by the ratios, 1 and 2, where:
PF1 PF2 PW1 = probability of wind at 90 mph, PF1 = probability of tornado at 90 mph PW2 = probability of wind at 113 mph, and PF2 = probability of tornado at 113 mph.
Otherwise, modify your analysis, accordingly.
- 4. The OPRA study (Table K-6 which you cite) assumes that half the strikes for various components cause damage. Show that this assumption is conser vative. Was a similar assumption, i.e., a specified portion of the missile strikes assumed to cause damage, used in the TORMIS study? If so, provide the justification for this latter assumption.
- 5. In an earlier submittal (November 19, 1982) you stated that a wind of 95 mph or greater would subject the turbine building to damage and you assumed that such damage would cause the EFWS to fail.
Show that this assumption has been continued for the TORMIS and OPRA studies or justify its omission.
- 6. In the submittal of November 19, 1982, you assumed that EFWS and SSFASW equipment in the penetration rooms is assumed to fail when the respective room walls fail.
Show that this assumption has been continued in the TORMIS and OPRA studies or justify its omission.
-4
- 7.
Discuss the fault trees used to derive the final damaging strike probabil ity for the EFW system as noted in your September 15, 1986 submittal and provide some representative examples.
- 8. Table K-4 of the OPRA notes that both the east and west penetration areas can receive impacts from receding tornadoes in the northeast quadrant.
In your September 15, 1986 submittal, however, it was assumed that their failures were independent of each other (multiplied probabilities of failure). Justify this apparent discrepancy.
- 9. In your analysis of tornado missiles damaging EFW components, no mention is made of possible failure of emergency power for the EFW trains.
Discuss this and justify this omission.
- 10. In your submittal of September 15, 1986 (page 4) you consider only the EFW pumps, upper surge tanks and both east and west penetration rooms for the TORMIS EFW study. Show that there are no other areas where the poten tial for failure of the EFWS exists as a result of high winds and/or tor nadoes which should be included in your wind and missile strike analysis.
- 11.
Does your September 15, 1986 analysis consider the EFWS in Units 1, 2 and 3 to be identical? Show that your TORMIS study considered any differences which may exist.
- 12. In your submittal of August 6, 1982, you note that the auxiliary service water (ASW) system has been specifically designed for tornado protection.
Discuss such protection.
- 13. In response to our question-regarding cold shocking of the dry steam gener ators by auxiliary service water (ASW) after a tornado damages the main and emergency feedwater systems, you note that it is not a concern because of the parallel of injecting cold emergency feedwater into the same location.
However, the steam generator normally contains water when EFW is injected and is dry when ASW is injected. Provide details justifying your conclusion given this difference.