NRC Generic Letter 1979-52
| ML031320361 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley, Millstone, Hatch, Monticello, Calvert Cliffs, Dresden, Davis Besse, Peach Bottom, Browns Ferry, Salem, Oconee, Nine Mile Point, Palisades, Indian Point, Kewaunee, Saint Lucie, Point Beach, Oyster Creek, Cooper, Pilgrim, Arkansas Nuclear, Prairie Island, Brunswick, Surry, North Anna, Turkey Point, Vermont Yankee, Crystal River, Haddam Neck, Ginna, Duane Arnold, Farley, Robinson, San Onofre, Cook, Yankee Rowe, Maine Yankee, Quad Cities, Humboldt Bay, La Crosse, Big Rock Point, Rancho Seco, Zion, Fort Calhoun, FitzPatrick, Trojan, Crane  |
| Issue date: | 10/17/1979 |
| From: | Eisenhut D G Office of Nuclear Reactor Regulation |
| To: | |
| References | |
| GL-79-052, NUDOCS 7911270013 | |
| Download: ML031320361 (3) | |
PCAAA_,~~ --_3 /A5t (mNUCLEA UNITED STATESNUCLEAR REGULATORY COMMISSIONWASHINGTON, D. C. 20555 79-VQctober 17, 1979(TO ALL OPERATING NUCLEAR POWER PLANT wIjUwORY DOKr nli CVPTGentlemen:
SUBJECT: RADIOACTIVE RELEASE AT NORTH ANNA UNIT 1 AND LESSONS LEARNEDRecently an incident occurred at North Anna Unit 1, which resulted inthe release of radioactivity to the Auxiliary Building and then to theenvironment. The release path associated with the incident is describedin the enclosure.By letter dated September 13, 1979, you were asked to meet the require-ments proposed by the NRC staff's TMI-2 Lessons Learned Task Force asdocumented in NUREG-0578. Section 2.1.6a of that report requires actionsto minimize the release of radioactivity from systems outside containment.While these actions are primarily directed towards minimizing leakagefrom these systems, the staff has determined that release paths exemplifiedby the North Anna Unit 1 incident or similar release paths as identified inIE Circular 79-21 (to be issued October 19, 1979) should also be considered.Therefore you are requested to address, in conjunction with your responseto Section 2.1.6a of NUREG-0578, the North Anna Unit 1 incident, as itapplies to your facilities, and any similar release paths revealed bythe review of your facilities. Any modifications deemed necessary asa result of your review should be identified by January 1, 1980, alongwith your schedule for completing these modifications on a prioritybasis.
Sincerely,Darrell G. Eisenhut, Acting DirectorDivision of Operating Reactors
Enclosure:
Radioactivity Release Pathway79112700/3 p EnclosureNORTH ANNA UNIT 1RADIOACTIVITY RELEASE PATHWAYOn September 25, 1979, North Anna Unit 1 experienced a reactor trip and safetyinjection. Following termination of safety injection an operator failed torealign the suction of a charging pump from the Refueling Water Storage Tankto the-Volume Control Tank (VCT). As a result, the VCT pressure increasedand a liquid safety relief valve opened a 4 inch line to the High LevelWaste Drain Tank's (HLWDT). The HLWDT is designed to be vented to theprocess vent through a one inch line containing a flow restricting orifice.The process ventilation system contains a particulate and charcoal filterprior to release to the environment. -Due to an error in construction, the HLWDT vent line was open to theauxiliary building atmosphere and the orifice was not in piace. The HLWDTis also vented via an air vent and water overflow 4 inch line to the lowlevel waste drain tanks which were vented through 4 inch lines to theauxiliary building atmosphere. The relief of radioactive fluid from theVCT into the HLWDT caused a pressure surge in the system resulting in arelease of gaseous radioactivity intothe auxiliary building from both thelow level waste drain tank air vents and the open line from the HLWDT.Had the HLWDT vent line been lined up to the process ventilation system,it appears that a release could still have occurred'because of the reliefto the low level waste drain tanks.The activity in the auxiliary building reached approximately 155 times MPC,consisting mostly of noble gases. The activity was subsequently released tothe environment via the auxiliary building ventilation system which containsboth particulate and charcoal filters. The total release has been estimatedto be approximately 7.5 Ci of Xe-133 and resulted in undetectable offsitedose consequences. Although the offsite consequences were minimal, had fueldamage occurred, a significant amount of radioactivity could have beenreleased via this pathwa Mr. William J. Cahill, Jr. 50-3Consolidated Edison Cbmpany of New York, Inc. 50-247cc: White Plains Public Library100 Martine AvenueWhite Plains, New York 10601Joseph D. Block, EsquireExecutive Vice PresidentAdministrativeConsolidated Edison Companyof New York, Inc.4 Irving PlaceNew York, New York 10003Edward J. Sack, EsquireLaw DepartmentConsolidated Edison Companyof New York, Inc.4 Irving PlaceNew York, New York 10003Anthony Z. RoismanNatural Resources Defense Council917 15th Street, N.W.Washington, D. C. 20005Dr. Lawrence R. QuarlesApartment 51Kendal at LongwoodKennett Square, Pennsylvania 19348Theodore A. RebelowskiU. S. Nuclear Regulatory Commission-P. 0. Box 38Buchanan, New York 10511qI 1, ~1