ML20216H863

Summary of 990714 Meeting with Cyap & Bpc Re Hazards Analysis of Proposed Installation of Natural gas-fired, Turbine Driven Electric Generation Facility on Site of Haddam Neck Plant.List of Attendees & Meeting Notes Encl

ML20216H863
Person / Time
Site:	Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png
Issue date:	09/24/1999
From:	Fredrichs T NRC (Affiliation Not Assigned)
To:	NRC (Affiliation Not Assigned)
References
TAC-MA5757, NUDOCS 9910040077
Download: ML20216H863 (8)

Text

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%,....+f September 24, 1999 LICENSEE: Connecticut Yankee Atomic Power Company FACILITY: Haddam Neck Plant

SUMMARY

OF PUBLIC MEETING DISCUSSING NATURAL GAS HAZARDS OF A PROPOSED INSTALLATION AT HADDAM NECK (TAC NO. MA5757)

On July 14,1999, the NRC staff met with representatives of Connecticut Yankee Atomic Power Company (CY, or the licensee) and Bechtel Power Corporation (Bechtel) to discuss the hazards analysis of a proposed installation of a natural gas fired, turbine driven electric generation facility on the site of the Haddam Neck Plant in Connecticut. The meeting was open to the public. A list of the attendees is included as Enclosure 1.

Bechtel prevented the results of three natural gas hazard scenarios for the installation, as outlined in the enclosed meeting notes (Enclosure 2). In order to present an explosion hazard, natural gas must accumulate in an enclosed space, such as a building. Bechtel summarized the results of two scenarios that examined the building explosion hazards. The third scenario considered the formation of a free gas cloud, followed by ignition and explosion. Bechtel noted that experiments conducted in Germany and England found that methane / air gas clouds were non-detonable. However, Bechtelincluded analysis of the overpressure from an unconstrained cloud of gas under the assumption that ignition was possible.

Bechtel's preliminary conclusion was that the calculated overpressures from an explosion were acceptable for the spent fuel building or an independent spent fuel storage facility.

A summary was presented of the results of an analysis of building fragment missiles, generated by an explosion, striking the spent fuel building and dry storage casks. The mass and velocity of the fragments are within the boundaries of a tornado missile evaluation done for the systematic evaluation program.

The NRC staff suggested the final analysis should consider the following items:

(1) the effect on spent fuel storage safety if the control room is unavailable for use; (2) overpressure peak reflection effects on buildings; (3) natural gas accumulation in the cooling discharge tunnel; (4) when the property underlying the installation should be released for unrestricted use;

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(5) fragment missiles from buildings evaluated in Case 3 (of Bechtel's meeting notes); and (6) risk perspective and the probability of occurrence of an explosion.

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Thomas L. Fredrichs, Project Manager Decommissioning Section Project Directorate IV & Decommissioning Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-213

Enclosures:

1. List of Attendees

2. Meeting Notes cc w/enci 1: See next page i

l

Haddam Neck Plant cc:

Mr. Allan Johanson, Assistant Director Ms. Deborah B. Katz, President Office of Policy and Management Citizens Awareness Network Policy Development and Planning Division P. O. Box 83 450 Capitol Avenue - MS# 52ERN Shelburne Falls, MA 01370-0083 P. O. Bo 341441 Hartford, CT 06134-1441 Mr. G. P. van Noordonnen Manager- Nuclear Licensing Regional Administrator Northeast Utilities Service Company Region 1 362 Injun Hollow road U.S. Nuclear Regulatory Commission East Hampton, CT 06424-3099 475 Allendale Road .

j King of Prussia, PA 19406 Mr. D. K. Davis Chairman, President and Chief Board of Selectmen Executive Officer Town Office Building Connecticut Yankee Atomic Power Co.

Haddam, CT 06438 580 Main Street Bolton, MA 01740 Mr. James S. Robinson Manager, Nuclear Investments Mr. T. W. Bennet and Administration Vice President and Chief Financial officer New England Power Company Connecticut Yankee Atomic Power Co.

, 25 Research Drive 580 Main Street Westborough, MA 01582 Bolton, MA 01740 Mr. Russell A. Mellor Director Vice President - Operations and Monitoring and Radiation Division  !

Decommissioning Department of Environmental Protection Connecticut Yankee Atomic Power Co. 79 Elm Street 362 Injun Hollow Road Hartford, CT 06106-5127

! East Hampton, CT 06424-3099 l Mr. G. H. Bouchard, Unit Director i Mr. J. A. Ritsher Connecticut Yankee Atomic Power Co.

Connecticut Yankee Atomic Power Co. 362 injun Hollow Road i Ropes & Gray East Hampton, CT 06424-3099 1 One International Place Boston, MA 02110-2624 Mr. J. D. Haseltine Strategic Planning Director Mr. K. J. Heider, Decommissioning Director Connecticut Yankee Atomic Power Co.

Connecticut Yankee Atomic Power Co. 362 Injun Hollow road 362 Injun Hollow Road East Hampton, CT 06424-3099 East Hampton, CT 06424-3099 ,

Mr. Russell A. Mellor l Mr. M. D. Cavanaugh Vice President- Operatiens and Communications Manager Decommissioning Connecticut Yankee Atomic Power Co. Connecticut Yankee Atomic Power 362 Injun Hallow Road Company East Hampton, CT 06424-3099 362 Injun Hollow Road East Hampton, Connecticut 06424-3099

l ATTENDEES l Connecticut Yankee Public Meeting Natural Gas Hazards of a Proposed installation at Haddam Neck July 14,1999 NAME ORGANIZATION l Tom Fredrichs NRC

' Ann Hodgdon NRC 1

Michael T. Masnik NRC Sam Nalluswami NRC Steven West NRC K. M. Campe NRC John Hasettine CY Gerry van Nordennen CY Keith Sickles CY Steve Routh Bechtel Allen Viera Bechtel

( Yijen Ling Bechtel Jim Ray Bechtel Ron Fischer Bechtel Ping Wan Bechtel I David Lochbaum . Union of Concerned Scientists Steve Shulin The IBEX Group l l l )

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Enclosure 1 l

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4 NRC/CYAPCO Meeting Haddam Neck Repowering Hazards Analyses July 14,1999 Purpose of Meetine e Technical working meeting with NRC Staff to address details of planned technical evaluation of Natural Gas (NG) hazards e To present approach to assessing effects of NG hazards e To obtain NRC input

. To result in subsequent complete submittal that will be acceptable to NRC Staff DescrIDilon of NG Facility e Separate facility, developed and operated by an independent developer / owner e Constmeted and placed into operation while spent fuel is stored in Spent Fuel Building (SFB) and decommissioning activities are underway

. Will be in operation during long term storage of spent fuel in the onsite Independent Spent Fuel Storage Installation (ISFSI)

. Specifics and General Arrangement DescriDtion of Natural Gas Hazard Scenarios e Case 1 - Explosion Inside the Combustion Turbine Generator (CTG) Building

. Evaluate NG and Hydrogen (used for cooling) e Evaluate effect of missile fragments as result of explosion e Case 2 - Flammable Clouds in Free Field Traveling Toward SFB and ISFSI e Case 3 - Explosion Inside Buildings Within Flammable Cloud Range I

Assumptions e NG Explosion in CTG Bldg - Case 1

. Entire CTG Building fills up with NG e Flammable limits of NG similar to methane (LFL=5%; UFL=15%)

• Amount of NG available for explosion conservatively assumed to be 15% of free volume

• Assume building does not impede explosion effects l

i e NG Cloud in Free Field - Case 2

+ Look at both 10" and 16" lines

. Upon assumed pipe break, assume horizontaljet toward SFB and ISFSI e Release is continuous at constant rate l

ENCLOSURE 2 L

• Release is simulated by considering a series of continuous puffs (Regulatory Guide 1.78) e Flammable mass integrated along paths of the puffs to simulate continuous release

. Conservatively assume CTG Building has no effect in diluting initial release (Building effects not considered) e F (stable) stability assumed to minimize atmospheric dispersion. (Centerline concentrations for unstable and neutral conditions also estimated and found to be lower)

• No plume rise, for conservatism

. Experiments in Germany and UK indicate methane / air mixtures non-detonable.

However, overpressures estimated assuming detonation is possible e To estimate overpressure, assume explosion occurs at location of maximum flammable mass.

. NG Explosion in Other Buildings Within Flammable Cloud Range - Case 3

• No NG sources in other buildings

• NG accumulation in buildings unlikely

• CTO Building wake would impede cloud from reaching intermediate buildings.

. Conservatively assume NG cloud would leak into buildings e Evaluate explosions originating in buildings in which passing cloud is within NG flammability limits e Evaluate Office Building #3 and Warehouse #141 e Amount of NG available for explosion conservatively assumed to be 15% of free volume e Building does not impede explosion effects e Fragment Missile Evaluation from CTG Building Explosion e Comparisons made to study done for NRC on Fort St. Vrain docket

• CTG Building valume is same as that modeled in Fort St. Vrain study Methodolorv e Pipe frictional loss considered in estimating release rates through constant area pipe e Two pipe break locations evaluated:

e 16" pipe at metering station - Assume 500 psi,82.55 kg/sec release (Main line expected to be at 350 psi) e 10" pipe supplying eastemmost CTG (closest to SFB)- Assume 450 psi,68.56 kg/sec release (Main line expected to be at 350 psi) e Safe distance calculated as per Regulatory Guide 1.91

• Puff model used based on Regulatory Guide 1.78 e Detailed overpressure estimates based on report by T.V. Eichler for Argonne National Laboratory (referenced in Regulatory Guide 1.91)

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• Flammable mass calculated using volume integration of puff between outer (lean flammable limit) and inner (rich flammable limit) ellipsoids (relationship between off-centerline concentration and centerline concentration of a puff is in form of an ellipse) e To accurately calculate flammaable mass:

. Calculate lean and rich flammable limits of plume at every 25 m distance e Estimate average concentrations e Flammable mass converted to TNT equivalent energy to calculate overpressure e Calculate mass of equivalent TNT energy for unconfined vapor cloud using empirical formula in loss Prevention data (1994), with approximate energy of decomposition forTNTof 2000 Btu /lb e Used conservative effective yield of 20% (Zalosh,1995) based on turbulent jet-like release e For confined explosion, estimate mass of equivalent TNT energy using method in Regulatory Guide 1.91 (240%)

l Preliminary Results 1

e Flammable clouds do not exist beyond 200 m for 16" pipe break and beyond 175 m for 10" pipe break e This is conservative, based on Computational Fluid Dynamics study done for l

comparative purposes e Worst case effect is due to explosion in CTG Building e Results in 1.66 psi overpressure at SFB l

e Results in 0.60 psi overpressure at ISFSI l

e Effect on the SFB is expected to be acceptable l

l e Peak overpressures are less than the design capacity of the NAC cask e ISFSI will be located a sufficient distance from the NG facility to ensure any postulated missiles are less than previously evaluated for the NAC cask  ;

• SFB location of 720' from epicenter af assumed CTG explosion would result in steel missiles reaching SFB that are no greater than 1/8" thick, with velocities no greater than 193 ft/sec This is enveloped by the tomado missile evaluation performed for the SEP.

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September 24, 1999 (5) fragment missiles from buildings evaluated in Case 3 (of Bechtel's meeting notes); and (6) risk perspective and the probability of occurrence of an explosion.

ORIG. SIGNED BY Thomas L. Fredrichs, Project Manager Decommissioning Section Project Directorate IV & Decommissioning i Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-213

Enclosures:

1. List of Attendees

2. Meeting Notes cc w/ encl 1: See next page DISTRIBUTION:

E-Mall HARD COPY JZwolinski/SBlack SWest MFairtile Docket File 50-213 GRichards DWheeler DLange PUBLIC GPangburn, RI Pray OGC LPittiglio _ MWebb PDIV-D r/f WHuffman JMinns RDudley AHodgdon RBellamy,RI ACRS/ACNW KCampe JHickey To receive a copy of this document, indicate "C" in the box OFFICE PDIVD/PM C PDIV-1/L4 0 N PDIV-2/SC C NAME TFredrichs $ fLBerry h MMasnik fY DATE 9 /d /99 9 /$[/99 9 / gj/99 DOCUMENT NAME: G:\PDIV-3\Haddam\ summary.wpd OFFICIAL RECORD COPY i