ML19340D832
| ML19340D832 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 12/31/1980 |
| From: | Mills L TENNESSEE VALLEY AUTHORITY |
| To: | Schwencer A Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8101050434 | |
| Download: ML19340D832 (5) | |
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400 Chestnut Street Tower II December 31, 1980 Director of Nuclear Reactor Regulation Attention:
Mr. A. Schwencer, Chief Licensing Branch No. 2 Division of Licensing U.S. Nuclear Regulatory Co.amission Washington, DC 20555
Dear Mr. Schwencer:
In the Matter of 'be Application of
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Docket Nos. 50-327 Tennessee Valley Authority
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50-328 Item 2.C(4) of the Sequoyah Nuclear Plant unit 1 operating license requires TVA to submit analyses of the vulnerability of the ERCW intake structure to barge collision. Enclosure 1 is an analysis of the probability of a barge collision and Enclosure 2 is an analysis of the resulting explosion hazard.
If you have any questions, please get in touch with D. L. Lambert at FTS 857-2581.
Very truly yours, TENNESSEE VALLEY AUTHORITY L. M. Mills, Manager Nuclear Regulation and Safety Sworn.t;o and subscribed before me this N / I day of /l 1980 l !b, z.l b h, f
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t ENCLOSURE 1
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SEQUOYAH NUCLEA.; PLANT ERCW INTAKE PUMPING STATION PROBABILITY OF TOW COLLISION The collision of a tow with the ERCW intake pumping station is considered to be an unlikely event. The new intake structure is protected by location from collision with river traffic heading downstream for water surfaces up to elevation 705, which is 22 feet above maximum normal pool level and 15 feet above a flood condition equivalent to one half the Probable Mar 4== Flood. As reported in a previous response,' the probability per year of a collision with a drifting barge hea 4.4 X 10 ging downstream is conservatively estimated to be j
The probability of a collision gnvolving a tow heading upstream has been determined to be 1.6 X 10 / year. The following considerations are applicable.
1.
Tow operators on the Tennessee River have been required to be licensed by the U.S. Coast Guard since 1972. A requirement for this license is that they must abite by the Western Rivers Rules of the Road. These rules provide that only tows having radar may proceed during inclement weather while those not having radar must tie up.
The U. S. Coast Guard has stated that the type of shoreline and mooring cells in the vicinity of Sequoyah Nuclear Plan'; affort excellent radar protection. The plant is located betieen Tennessw River Mile (TRM) 484 and 485; first class safety harbors are located near TRM 483 and 489. The Coast Guard has further stated that the present channel markings are more than sufficient for a prudent navigator. The pumping station is well outside the navigation channel (approximately 300 feet from the boundary) and a daymarker and light is located on the far side of the channel directly opposite the plant to guide upstream traffic i
away from the plant.
2.
Sequoyah Nuclear Plant is located on the convex bank of a bend in the Tennessee River channel. Upstream tows attempting to cut short the navigation of the bend would have a difficult angle of l
approach to the pumping station. As addressed in a previous response, tows losing power in the bend and drifting will drift l
toward the shoreline opposite the intake structure.
The probability of 1.6 X 10-5 collisions / year was obtained using the following information. The calculation is believed to be conservative.
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Data available for the years 1945-1979 was searched for barge
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groundings on the Chickamauga Reservoir. Of the 10 groundings found, 7 were not applicable because of grounding during inclement weather before 1972 or because of intentional grounding caused by loss of power. A range of 40 35 miles (40 35 X 5280 X 2 feet) of shoreline and a total of 19,674 tows during these years were involved. This yields a probability of g ding per tow per foot of shoreline on the reservoir of 3.6 I 10 l
s 2.
The target length of the intake structure susceptibility was conservatively taken as 200 feet.
(The intake structure is 118 feet by 67 feet.) The average number of tows heading upstream past the intake structure during 1974 to 1979 was approximately 225 per year. The number of tows on the Chickamauga Reservoir reached a peak in 1970, but has been roughly uniform during 1974 to 1979 and is believed to be a good indication of the expected number of tows for the next sev gal years. The probability is therefore calculated as 3 6 x 10 groundings per t x 225 tows per year = 1.6 X 10-gw per foot of shoreline x 200 feet collisions / year.
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ENCLOSURE 2 SEQUOYAH NUCLEAR PLANT ERCW INTAKE STRUCTURE - EXPLOSION HAZARD l
In nesponse to concerns raised by the ACRS, the possibility of a barge explosion in the vicinity of the new ERCW pumping station has been reviewed. Our response is as follows:
(1) The ACRS identified liquid natural gas (LNG) as a substance to be considered in an exploding barge scenario. From our review of the barge shipments past Sequoyah for calendar year 1978, there were no shipments of LNG on the Tennessee River. It should be noted that barge shipments of LNG past Sequoyah are not likely since natural gas transportation is handled almost entirely by pipeline in this region. Therefore, we do not consider the potential for an exploding LNG barge near the new ERCW pumping station to be a credible event.
(2) Contrary to the information in FSAR Table 2.2-1, there were, in calendar year 1978, shipments of unspecified fertilizers past the Sequoyah Nuclear Plant. Hence, the possibility of an accidental explosion alst be considered.
In 1966, the U.S. Bureau of Mines issued a study entitled
" Explosion Hazards of Ammonium Nitrate Under Fire Exposure,"
which examined the deflagration and detonation hazards associated with Ammonium Nitrate (AN). The study indicates:
(a) Ordinary fertilizer-grade AN requires strong overpressures j
to initiate detonation within the mixture.
(b) AN and AN-fuel mixtures were exposed to fire with no transition from deflagration to detonation being observed.
(c) A combination of fire and overpressure results in transition to detonation. However, in free-flowing beds of p and AN-fbel mixtures, pressures as high as 8000 lb/in did not generate detonation. Only in experiments where the AN was not allowed to flow freely was transition to detonation observed ip the AN-fuel mixture at pressures above 1000 lb/in, but not with pure AN.
(d) It was found that hot AN (under fire exposure) readily detonated when impacted with a high velocity projectile or shock wave. Explosions in storage and shipments of AN have apparently resulted only when nearby explosions or structure collapse have occurred concurrent with fire in the AN.
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(e) Gas detonations have been shown incapable of initiating detonation in AN mixtures. In general, fertilizers shipped
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on the Tennessee River employ diatomaceous earth and kaolin clay for anticaking dusts rather than using oil sealant, thus detonations are possible only in cargoes where fire and missiles or external detonation are present. Most bulk fertilizers with earth or clay mixtures will not burn without mixing a considerable amount of paper or flammable material into the fertilizer.
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Based on the insensitivity to detonation exhibited by most common fertilizers, the unlikely sequence of events required for detonation must include: Barge collision, fire in the fertilizer cargo, and concurrent detonation or missile-inducing event.
l Therefore, given the low probability of a barge collision and the low percentage of fertilizer shipments on the Tennessee River, it is concluded that, because of the very low probabilities associated with the event, no hazard axists to the intake pumping station
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from the transportation of fertilizers by barge on the Tennessee River system.
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