ML20236D199
| ML20236D199 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 03/08/1989 |
| From: | Oconnor P Office of Nuclear Reactor Regulation |
| To: | Trevors G NEBRASKA PUBLIC POWER DISTRICT |
| References | |
| REF-PT21-89 NUDOCS 8903220511 | |
| Download: ML20236D199 (3) | |
Text
. _ _ _ _ - _ _ _ - _ _ _ _ _ _ -
March 8, 1989 bocket No. 50-298 Mr. George A. Trevors, Division Manager - Nuclear Support Nebraska Public Power District Post Office Box 499 Columbus, Nebraska 68601
Dear Mr. Trevors:
SUBJECT:
10 CFR PART 21 NOTIFICATION The NRC staff has received a 10 CFR Part 21 notification from the Washington Power Supply System (WPPS). The notification addresses the discovery of an unmonitored radiological release path at the Washington Nuclear Plant, Unit 2, that was caused by a design error by the architect / engineer, Burns & Roe Inc.
The staff has concluded that although the deficiency at WPPS may be an isolated design oversight, the Nebraska Public Power Districts should be made aware of the deficiency since, Burns & Roe also served as the architect / engineer for Cooper Nuclear Station. Therefore, the staff is forwarding the enclosed Licensee Event Report from WPPS for your information.
Sincerely, 1
/s/
Paul W. O'Connor, Project Manager Project Directorate - IV, Division of Reactor Projects - III, IV, V and Special Projects Office of Nuclear Reactor Regulation
Enclosure:
As stated cc w/ enclosure:
See next page DISTRIBUTION
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March 8, 1989 Docket No. 50-298 l
Mr. George A. Trevors, Division i
Manager - Nuclear Support Nebraska Public Power District i
Post Office Box 499 l
Columbus, Nebraska 68601 1
Dear Mr. Trevors:
SUBJECT:
10 CFR PART 21 NOTIFICATION Tht. NRC staff has received a 10 CFR Part 21 notification from the Washington Power Supply System (WPPS). The notification addresses the discovery of an unmonitored radiological release path at the Washington Nuclear Plant, Unit 2, that was caused by a design error. by the architect / engineer, Burns & Roe Inc.
The staff has concluded that although the deficiency at WPPS may be an isolated design oversight,-the Nebraska Public Power Districts should be made aware of the deficiency since, Burns & Roe also served as the architect / engineer for Cooper Nuclear Station. Therefore, the staff is forwarding the enclosed j
Licensee Event Report from WPPS for your information.
Sincerely, 0
J Paul W. O'Connor, Project Manager Project Directorate - IV, Division of Reactor Projects - III, IV, V and Special Projects Office of Nuclear Feactor Regulation
Enclosure:
As stated i
cc w/ enclosure:
l See next page s
i Mr. George A. Trevors Nebraska Public Power District Cooper Nuclear Station j
cc:
Mr. G. D. Watson, General Counsel Nebraska Public Power District j
e P. O. Box 499 i
Columbus, Nebraska 68601 l
Cooper Nuclear Station ATTN: Mr. Guy R. Horn, Division Manager of Nuclear Operations i
P. O. Box 98 Brownville, Nebraska 68321 Dennis Grams, Director k
Nebraska Department cf Environmental Control P. O. Box 98922 Lincoln, Nebraska 68509-8922 Mr. Larry Bohlken, Chairman q
Nemaha County Board of Connissioners j
Nemaha County Courthouse 1824 N Street Auburn, Nebraska 68305
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Senior Resident Inspector U.S. Nuclear Regulatory Cornmission P. O. Box 218 Brownville, Nebraska 68321 Regional Administrator, Region IV U.S. Nuclear Regulatory Connission 611 Ryan Plazh Drive, Suite 1000 Arlington, Texas 76011 Mr. Harold Borchart, Director Division of Radiological Health Department of Health 301 Centennial Mall, South P. O. Box 95007 Lincoln, Nebraska 68509-5007 l
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LICENSEE EVENT REPORT ILER) i oocas,hv.s.tmas.
Med 8.Ceut e n.est ns Washington Nuclear P1 ant - Unit 2 o t 61 o Io I o 0 1917 1 lorl0 15 Potential Unmonitored Effluent Release Path Due To Design Error By Architect /Erigineer Cause Unknown l
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On May 6,1988 a Plant Design Engineer determined that under certain emergency conditions l
an unoonitored radiological effluent release path from the Turbine Building through Diesel Generator Corridor (0104) to the atmosphere could exist.
The cause of. this event 1
is design error.
Fan DEA-FN-51, which exhausts directly to the atmosphere during both normal and emergency operation, was part of the original Plant design done by Burns & Roe inc.
The effluent path through DEA-FN-51 should have been evaluated for effluent I
monitoring instrumentation in accordance with Regulatory Guide 1.97.
WNP-2 comitted to monitor noble gas effluents in Appendices B and C of the Final Safety Analysis Report (FSAR).
The root cause of this event i s unknown.
During normal and most emergency operations there is no ef fect since DEA-FN-51 is supplied clean outside air by the i
Turbine Building HVAC System, or during some emergencies by the DG Area Cable Cooling System.
However, during some postulated post-accident conditions it is possible that DEA-FN-51 could pull air from the Turbine Building and exhaust it directly to the a tmos phere. The most severe accident (radiologically) in the turbine building is a main steamline break which could generate a sot rce term concentration of 3.312 x 10 uti/cc.
The above concentration is within the range specified in Regulatory Guide 1.97 for which ef fluent monitoring is required.
The ef fects of a main steamline break in the Turbine Building, with a total rel ease to the environment, have been analyzed and the consequences of this potential event reviewed and accepted.
The imediate corrective actions taken included:
an engineering assessment which determined that DEA-FN-51 was not required for cable cooling during normal or emergency conditions, disabling the f an by pulling its power fuses, and closing the back draf t damper.
Corrective actions to be taken include: removal of f an DEA-FN-51 and its accessories, sealing the opening created by the removal of the fan, and a design review to ensure that no other potential Regulatory Guide 1.97 unmonitored leakage paths exist.
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Plant Mode - 5 (Refueling)
Event Description Dn May 6, 1988 a Plant Design Engineer determined that under certain emergency conditions an unmoni tored radiological ef fluent release path from the diesel generator corridor to the atmosphere could exist.
The Plant Design Basis includes an l
FSAR Appendix B II.F.1.1 commitment to monitor noble gas ef fluent and an Appendix C FSAR commitment to meet the intent of Regulatory Guide 1.97, This potential release path was being investigated due to a concern raised by a Plant System Engineer.
The Diesel Generator Area Cable Cooling System is designed to cool critical electrical cabling during normal and emergency conditions.
The system cools cabling l
which runs between the emergency diesel generators and the main control room and l
critical switchgear room.
The System is comprised of two independent and separate systems which cool areas containing both Division 1 and Division 2 cable.
The failure of one system will not affect the operational functions of the other cooling l
l system.
The cable cooling system, which is shown in Figure 1, is comprised of two I
exhaust f ans (DEA-FN-51 and DEA-FN-52) powered from the Division 1 emergency power bus and one supply air handling unit ( DMA-AH-51 ) powered from the Division 2 emergency power bus.
During normal Plant operation DEA-FN-51 runs continuously and exhausts directly to the atmosphere. DEA-FN-52 also runs continuously and discharges to the Radwaste Building.
DPA-AH-51 is normally in standby.
When DMA-AH-51 is I
running it draws air from the outside when the outside temperature is above 40'F or l
l recirculates room air if the temperature is below 40'F.
If not already in service, both DEA-FN-51 and DEA-FN-52 auto start when the Division I diesel generator is started and DFA-AH-51 auto starts when the Division 2 diesel generator is started.
During normal Plant operations DEA-FN-51 draws clean air down the diesel generator corridor (D104) which is supplied by the Turbine Building HVAC System.
During some emergency conditions DEA-FN-51 and DEA-FN 52 are supplied outside air by the supply air handling unit (DPA-AH-51) when the outside air temperature is greater than 40*F or recirculated room air when the temperature is less than 40'F.
However, if during these emergency conditions DMA-AH-51 is not operable, air from the Turbine Building could be drawn in by DEA-FN-51 and exhausted to the atmosphere.
..A main steamline break in the Turbire Building would result in a source whose maximum concentration is 3.312 x 10-4 uCi /c c.
( The source concentration was calculated by dividing the total main steamline break source by 10% of the volume of the ' Turbine Building.)
The above concentration10 pvel I
is within 10(' UCi/cc) specified in Regulatory Guide 1.97 he range Table 2 (between uti /cc and and, therefore, this release path 9
should have been monitored.
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-. - - c w m.wnn leraediate Corrective Actions An Engineering Assessment determined that DEA-FN-51 was not required for cable cooling during normal or emergency conditions.
The fan was disabled by removing its power fuses and by closing the back draf t damper.
Further Evaluation There were no Plant structures, components, or systems inoperable at the start of this event that contributed to this event.
The cause of this event is a design error.
This fan was part of the original Plant design done by Burns & Roe Inc., the Architect / Engineer for WNP-2, and should have been evaluated in accordance with Regulatory Guide 1.97.
The root cause of this event can not be determined, l
i This event is reportable per 10CFR50.73(a)(2)(ii)(B) and 10CFR Part 21.
The Plant 1
was in a condition outside its design basis.
Further Corrective Actions to be Taken A Plant Modification Request is being processed to remove DEA-FN-51 and its associated accessories and to seal the opening created by the removal of the fan.
j A Plant Design Review will be performed to verify that no other potential unmonitored release paths requiring monitoring by Regulatory Guide 1.97 exist.
Burns & Roe, Inc.
will be notified of the 10CFR Part 21 determination.
Safety Significance The maximum potential release through this path would be the entire source genera *.ed by a main steamline break.
This release has been analyzed (FSAR, Chapter 15, Section i
15.6.4) and found acceptable even if all the activity is released directly to the environment.
Therefore, the consequences of this potential event have been previously reviewed and accepted.
Since an actual emergency condition did not occur during the event period, this event posed not threat to the health and safety of the public or Plant pe sonnel.
Similar Events None E!!S Information Text Reference Ells Reference System Component Olesel Generator Corridor NB
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System Component Diesel Generator Area Cable Cooling System exhaust fan (DEA-FN-51)
VJ FAN Turbine Building HVAC VK Diesel Generator Area Cable Cooling System Supply air Handling Uni t ( DPA-AH-51 )
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Diesel Generator Area Cable Cooling System VJ Division 1 Diesel Generator EL DG Division 2 Diesel Generator EL DG Main Control Room NE Critical Switchgear Room NE t
Diesel Generator Area Cable Cooling System exhaust fan (DEA-FN-52)
VJ FAN Division 1 emergency power bus EL BU Divison 2 emergency power bus EL BU l
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