ML15253A007
| ML15253A007 | |
| Person / Time | |
|---|---|
| Site: | Indian Point  |
| Issue date: | 10/07/2015 |
| From: | Mccree V NRC/EDO |
| To: | Judson T Nuclear Information & Resource Service (NIRS) |
| Chereskin A, NRR/DORL, 301-415-2549 | |
| Shared Package | |
| ML15239B009 | List: |
| References | |
| CORR-15-0073, LTR-15-0435, LTR-15-0435-1 | |
| Download: ML15253A007 (3) | |
Text
October 7, 2015 Mr. Timothy Judson Nuclear Information and Resource Service 6930 Carroll Avenue, Suite 340 Takoma Park, MD 20912
SUBJECT:
INDIAN POINT NUCLEAR GENERATING UNIT NOS. 2 AND 3 - RESPONSE TO LETTER DATED AUGUST 25, 2015
Dear Mr. Judson:
In your letter of August 25, 2015, you expressed concerns regarding the safety of the proposed Spectra Energy Algonquin Incremental Market (AIM) natural gas pipeline and its proximity to the Indian Point Energy Center (Indian Point). In addition, you requested that the U.S. Nuclear Regulatory Commission (NRC) retract its finding of no significant impact submitted to the Federal Energy Regulatory Commission (FERC) regarding the AIM natural gas pipeline. As the Federal agency charged with regulating the Nations civilian use of radioactive materials, our mission is to protect public health and safety. The NRCs regulations require that licensees of nuclear power plants evaluate external hazards near their plant. As you have noted, one of the external hazards near Indian Point would be the proposed AIM natural gas pipeline.
As required by NRC regulations, the licensee for Indian Point, Entergy Nuclear Operations, Inc.
(Entergy), prepared a hazard analysis of the proposed AIM natural gas pipeline. The NRC staff performed an onsite inspection of Entergys hazard analysis, conducted a walk-down of the proposed pipeline routing, and assessed the adequacy of analysis controls under Entergys quality assurance program. As part of its inspection, the staff thoroughly reviewed Entergys hazard analysis and reviewed the qualifications of the individual who performed the hazard analysis. Through the inspection and review, the staff confirmed the results of Entergys hazard analysis.
In addition to the licensees hazard analysis, the NRC staff also independently analyzed the effect of a possible natural gas pipeline rupture and subsequent explosion and fire on the Indian Point facility. The NRCs independent confirmatory analysis made conservative assumptions that produced more severe results than could possibly occur if there were a real pipeline rupture. These assumptions include the following:
Based on input from Spectra Energy, the initial analysis assumed a closure time of 3 minutes for pipeline isolation valves. In addition to the 3-minute valve closure case, the NRC evaluated a bounding case. This second case assumes the upstream side of the ruptured pipe is connected to an infinite source of gas for 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />.
The NRC staff modeled a pipe break at the location closest to plant structures. Because of a limitation of the ALOHA software, the staff doubled the predicted gas release from the upstream side of a pipe break to account for flow escaping from both sides of the break. This approach is conservative because in the event of an actual break, the
T. Judson downstream side of the pipe would release much less gas than the estimated release from the upstream side.
For the evaluation of the explosion hazard, the NRC used the peak gas release rate resulting from a pipe rupture to estimate the mass of natural gas. This approach predicts more gas released than other approaches such as a time dependent gas release or a release averaged over time.
Because of the conservative assumptions above, the bounding analysis prepared by the staff postulates more severe results than a transient analysis would estimate. The staffs analysis assumed that the maximum release rate was sustained and did not decline in the manner that a transient analysis would predict. This conservative approach assumes more gas is available to explode than in a transient analysis, and produces results that bound more detailed analyses, such as a transient analysis.
To summarize the results of the NRC staffs independent analysis, a postulated explosion at the pipeline would produce a pressure wave at safety-related structures on the Indian Point site of less than 1 pound-per-square-inch. To provide context, a pressure wave of this magnitude would be able to shatter glass. However, it would not be able to damage the robust safety-related structures at Indian Point. Likewise, a postulated fire at the gas pipeline would create a heat flux at the Indian Point site fence that could be a threat to humans, but would not be sufficient to melt plastic. As mentioned above, the conservative assumptions of the staffs independent analysis produced results that are more severe than what could possibly occur during an actual event. In addition, a transient analysis would produce results that are less severe than those in the independent analysis.
The NRCs independent analysis computed conservative results that demonstrate that an extremely unlikely fire or explosion at the proposed pipeline would not affect the safe operation or shutdown of the Indian Point reactors. Therefore, at this time the NRC is not reconsidering the input provided to FERC. Thank you for contacting the NRC to discuss your safety concerns.
We appreciate, and share, your interest in the safety of New Yorks nuclear power plants.
Sincerely,
/RA/
Victor M. McCree Executive Director for Operations Docket Nos. 50-247 and 50-286
T. Judson downstream side of the pipe would release much less gas than the estimated release from the upstream side.
For the evaluation of the explosion hazard, the NRC used the peak gas release rate resulting from a pipe rupture to estimate the mass of natural gas. This approach predicts more gas released than other approaches such as a time dependent gas release or a release averaged over time.
Because of the conservative assumptions above, the bounding analysis prepared by the staff postulates more severe results than a transient analysis would estimate. The staffs analysis assumed that the maximum release rate was sustained and did not decline in the manner that a transient analysis would predict. This conservative approach assumes more gas is available to explode than in a transient analysis, and produces results that bound more detailed analyses, such as a transient analysis.
To summarize the results of the NRC staffs independent analysis, a postulated explosion at the pipeline would produce a pressure wave at safety-related structures on the Indian Point site of less than 1 pound-per-square-inch. To provide context, a pressure wave of this magnitude would be able to shatter glass. However, it would not be able to damage the robust safety-related structures at Indian Point. Likewise, a postulated fire at the gas pipeline would create a heat flux at the Indian Point site fence that could be a threat to humans, but would not be sufficient to melt plastic. As mentioned above, the conservative assumptions of the staffs independent analysis produced results that are more severe than what could possibly occur during an actual event. In addition, a transient analysis would produce results that are less severe than those in the independent analysis.
The NRCs independent analysis computed conservative results that demonstrate that an extremely unlikely fire or explosion at the proposed pipeline would not affect the safe operation or shutdown of the Indian Point reactors. Therefore, at this time the NRC is not reconsidering the input provided to FERC. Thank you for contacting the NRC to discuss your safety concerns.
We appreciate, and share, your interest in the safety of New Yorks nuclear power plants.
Sincerely,
/RA/
Victor M. McCree Executive Director for Operations Docket Nos. 50-247 and 50-286 DISTRIBUTION: LTR-15-0435-1 PUBLIC LPL1-1 R/F RidsNrrDorl RidsEdoMailCenter RidsNrrDorlLpl1-1 RidsNrrDorlDpr RidsNrrOd RidsNrrMailCenter RidsNrrPMIndianPoint RidsNrrLAKGoldstein RidsNrrDseaRpac ABurritt, RI RidsRgn1MailCenter RidsAcrsAcnw_MailCTR M. Evans, NRR MMcCoppin, NRO ADAMS ACCESSION NOS.: Package ML15239B009;Incoming ML15254A44; Response ML15253A007
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