ML18040A686

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Responds to 830628 Ltr Re Assessment & Consequences of Immediate or Delayed Gas Cloud Ignition Resulting from Rupture of Transco Pipeline.Heat Flux Does Not Pose Safety Concern
ML18040A686
Person / Time
Site: Susquehanna  Talen Energy icon.png
Issue date: 07/07/1983
From: Curtis N
PENNSYLVANIA POWER & LIGHT CO.
To: Schwencer A
Office of Nuclear Reactor Regulation
References
PLA-1738, NUDOCS 8307110466
Download: ML18040A686 (4)


Text

Pennsylvania Power 8 Light Company Two North Ninth Street ~ Allentown, PA 18101 ~ 215/770-5151 Norman W. Curtis Vlcc President-Englneerlng & Construction-Nuclear 21 5/770-7501 JUL 07 1983 Director of Nuclear Reactor Regulation Attention: Mr. A. Schwencer, Chief Licensing Branch No. 2 Division of Licensing U.S. Nuclear Regulatory Commission Washington, D.C. 20555 SUSQUEHANNA STEAM ELECTRIC STATION ADDITIONAL INFORMATION REGARDING THE PROPOSED TRANSCO PIPELINE ER 100450 FILE 841-2 Docket Nos. 50-387 PLA-1738 50-388

Dear Mr. Schwencer:

In response to your letter dated June 28, 1983, the following is Pennsylvania Power & Light Company's assessment of the possible consequences due to either the immediate or delayed gas cloud ignition resulting from a rupture of the proposed 42" Transco pipeline.

The heat flux associated with either immediate or delayed gas cloud ignition resulting from a rupture of the proposed 42" Transco pipeline does not pose a safety concern to Susquehanna Steam Electric Station.

In PP&L's response to NRC Question 311.1 (letter from N. W. Curtis to A. Schwencer dated January 21, 1982), we discussed the effects of gas cloud ignition with respect to the PG&W gas pipeline.

Considering immediate ignition, the PG&W line is only 500 feet from the nearest plant building and the gasline presents a direct line of sight exposure. While larger gas quantities could escape from the 42 inch line, the magnitude of the exposing flame is still limited to the portion of the gas cloud which is in the combustible range.

Since heat effects are inversely related to the square of distance, the greater distance (1.4 miles vs 500 feet) and the topography which blocks the line of site exposure more than compensates for a possible increase in fire size o 8307ii0466"830707 P,, ',",OS000387 PDR lotDOCK PDR'o0 ((o

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Page 2 SSES PLA-1738 JUL Q 7 1983 ER 100450 File 841-2 Mrs A. Schwencer The PG&W pipeline analysis assumed, in the case of delayed ignition, that a constant flame temperature of 2000oF was in contact with the beams at the top elevation of the Unit 1 and 2 Reactor Buildings. It was predicted that the burn time of the gas cloud was an order of magnitude less than the exposure time required for the beams to reach 1000oF.

The portion of the gas cloud affecting the Reactor Building steel structure would, in all cases, be limited to the portion of the gas cloud which is within the flammable range and in proximity to the building. Therefore, the burn times are relatively independent of the gas quantity released. Also, PG&W gas cloud was not assumed to clear the Reactor Building roofs. Due to the larger quantity of gas required to reach the plant site, the gas cloud from the Transco line is predicted to clear the Reactor Building roof by a large margin (greater than 100 feet). This removes the direct conduction heat transfer and only radiant heat transfer remains.

Therefore, we conclude that the proposed 42 inch Transco pipeline presents a less severe exposure to Susquehanna Steam Electric Station" than was analyzed for the PG&W gas pipeline.

If you have any additional questions, please contact us.

Very truly yours,

. W. Curtis Vice President-Engineering & Construction-Nuclear cc: R. L. Perch NRC

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