ML18009A522
| ML18009A522 | |
| Person / Time | |
|---|---|
| Site: | Harris  |
| Issue date: | 04/30/1990 |
| From: | NRC |
| To: | |
| References | |
| NUDOCS 9005110102 | |
| Download: ML18009A522 (3) | |
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t UNITEO STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, O. C. 20555 SAFETY REVIEW BY, THE OFFICE OF NUCLEAR REACTOR REGULATION ON THE AIRCRAFT HAZARDS STUDY OF SHEARON HARRIS NUCLEAR POWER PLANT UNIT. I 1.
INTRODUCTION A Wakesouth Regional Airport is proposed to be built about 4.3 miles from the site of the Shearon Harris Nuclear Power Plant, Unit I (Harris).
The licensee, Carolina Power Im Light Company, submitted their Aircraft Hazards Study of the proposed airport to the U. S. Nuclear Regulatory Commission on January 17, 1990 and supplemented the initial submission with additional information by telephone converations on March 22 and 23, 1990.
I The staff review is based on the acceptance criteria and review procedures described in Section 3.5.1.6, Aircraft Hazards, Revision 2, of the Standard Review Plan, NUREG-0800, July 1981.
The acceptance criterion for a plant site with respect to aircraft hazards is that the probabi lity of aircraft accidents resulting in radiological consequences greater than 10 CFR Part 100 exposure guidelines is less than about lE-7 (that is, one times ten raised to minus seventh power) per year.
The staff review has led to the comments below.
2.
REVIEW COMMENTS The licensee made a 10-year projection of the probabi lity of aircraft crashes that would result in structural damage to safety-related facilities at Harris.
The safety-related facilities include the waste processing building, fuel'andling building, reactor auxiliary building, reactor containment building, condensate storage tank, control room building, diesel generator building, underground diesel generator fuel oil storage
- tanks, emergency service water screening structure, and emergency service water intake structure.
In the computation of the target areas, the plan view areas of the building structures were
- summed, and the total area was increased to account for the skid and shadow impact angle effects.
No credit was taken for shadow shielding of the containment building.
Shielding of walls by adjacent building structures was considered.
All impacts were assumed to occur at 90 degrees to the impacted surface.
The target areas for aircraft weighing between 8,000 and 12,500 pounds and for aircr aft weighing over 12,500 pounds were calculated separately on the basis of the dead loads and penetration criteria of the structure under consideration.
Aircraft weighing less than 8,000 pounds were found not to exceed significantly the dead loads or penetration criteria of the safety-related faci lities, and the target area for this type of aircraft was assumed to be zero.
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The licensee obtained from the General Aviation Manufacturers Association recent yearly data on the fixed-wing aircraft crashes involving fatalities.
The licensee also obtained from the Aircraft Owners and Pilots Association the annual landing frequencies of fixed-wing aircraft.
Regional differences in the aviation data were not considered in the study.
For aircraft weighing over 12,500 pounds, the licensee estimated the crash rate at the plant site, using aircraft crash rate data given in NUREG/CR-2859, "Evaluation of Aircraft Crash Hazards Analysis for Nuclear Power Plants,"
June 1982.
For aircraft weighing between 8,000 and 12,500 pounds, the crash rate at the plant site was assumed to be about twice that for aircraft weighing over 12,500 pounds.
The licensee obtained the data on annual operations of aircraft of various types from the Master Plan for Wakesouth Regional Airport, Phase 1, prepared by
- Hobbs, Upchurch 8 Associates in October 1987.
On the basis of consultations with the General Aviation Manufacturers Association, Federal Aviation Administra-tion, National Transportation Safety Board, and Aircraft Owners and Pilots Association, the licensee assumed that 15 percent of the multiple engine piston aircraft weigh between 8,000 and 12,500 pounds.
The 10-year projection of the overall probability of aircraft crashes that would result in structural damage to the safety-related facilities is 6.3E-8 per year.
The licensee has not provided a 20-year projection of the probability of aircraft crashes, even though a 20-year projection of the annual aircraft operations is given in the Master Plan.
Using the 20-year projection of annual aircraft operations and the pertinent, data provided in the Aircraft Hazards Study, the staff has computed the overall probability of aircraft crashes that would result in structural damage to the safety-related facilities to be 9.9E-B per year.
The licensee's study does not include a holding pattern analysis.
This type of analysis is recommended in Section 3.5. 1.6 of the Standard Review Plan.
With the width of airway estimated to be 3.6 miles and using the aircraft crash rate data recommended in NUREG/CR-2859, the staff has computed the 10-year and 20-year projections of the probabilities of aircraft crashes from the holding pattern.
Adding the probabilities from the holding pattern to the 10-year and 20-year projections, the corresponding overall probabilities of aircraft hazards at the plant site are, respectively, 7.3E-8 per year and 1.2E-7 per year, The relevant time interval for aircraft hazards study should cover the per iod from the start of airport operation to the end of the plant license.
The licensee has not provided an operational schedule for the proposed airport.
The Harris license was issued on January 12, 1987.
Assuming the airport starts to operate in January 1995, the relevant study period should be 32 years.
If an expansion of the airport operation were to occur beyond ten years of operation, in terms of servicing more frequent flights of aircraft heavier than 8,000 pounds, the probabilities of aircraft hazards through the end of the license could increase well above the risks currently projected.
The licensee did not provide any uncertainty analysis of the results or sensitivity test of the parameters used in the Aircraft Hazards Study.
The staff notes that the target areas provided by the licensee are smaller than those that were used in the aircraft hazards analyses of other nuclear power plants (pages 42 and 43, NUREG/CR-2859).
Although the staff has not independently verified the aviation data, they appear to be realistic.
The staff has determined that the estimated overall probabi lities of aircraft hazards represent the lower bound values.
The licensee has performed an analysis of the aircraft crashes involving a fire at the plant site.
The analysis includes considerations of the potential release of stored chemicals and ingestion of burning fuel at the heating, ventilation, and air-conditioning inlets.
No significant fire hazard was identified in the analysis.
3.
SUMMARY
On the basis of the above discussion, the staff notes that operation of the Shearon Harris Nuclear Power Plant, Unit 1 in the vicinity of the proposed Wakesouth Regional Airport would be acceptable on the condition that the operational level of the proposed airport would not exceed the licensee's 10-year projection.
The staff also notes that no significant fire hazard from aviation activities at the proposed airport is expected.
The staff notes that the 10-year projection of the aircraft crash probability represents a lower bound estimate of the hazards.
Considering the proximity of the proposed airport to the Harris plant site and the relatively long license period remaining, there is a concern on the future growth of aviation activities after the proposed airport begins to operate.
The staff estimates that the probability of aircraft hazards projected at twenty years of airport operation is higher than the 10-year projection with respect to the acceptance criteria in the Standard Review Plan.
An expansion of servicing more frequent flights of aircraft over 8,000 pounds than is reflected in the 10-year projection could increase the risks of aircraft crashes well above the risks that are currently projected.
Therefore, the staff has no basis for assurance, beyond the 10-year projection that operation of the proposed airport would not have a significant impact on the continued safe operation of the Harris plant.