ML20214U949
| ML20214U949 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 11/25/1986 |
| From: | Rice P GEORGIA POWER CO. |
| To: | Grace J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| REF-PT21-87-002-000 GN-1197, PT21-87-002-000, PT21-87-2, NUDOCS 8612090465 | |
| Download: ML20214U949 (4) | |
Text
r Georgo Power Compe A
o post ottca Sca 282
{f
$c#T1 fl7j3413
\\
p 9\\*
g GeorgiaPower R D. RICE Vce Presidert f
O Uc u xndn e**C 5 0"'*
vogtle Progt November 25, 1986 United States Nuclear Regulatory Commission Region II File:
X7BG03-M129 Suite 2900 Log:
GN-1197 101 Marietta Street, Northwest Atlanta, Georgia 30323
Reference:
Vogtle Electric Generating Plant-Units 1 and 2; 50-424, 50-425; Containment Cooling Unit Manifold Nozzles; Letter GN-1125, dated October 21, 1986 Attention: Mr. J. Nelson Grace In previous correspondence, Georgia Power Company dr cribed a potentially reportable condition concerning the containment cooling unit manifold nozzles.
Georgia Power Company has completed the engineering portion of its evaluation and determined that a reportable condition as defined by the reporting criteria of Part 10 CFR 50.55(e) and Part 10 CFR 21 does exist.
An evaluation for a quality assurance program breakdown is currently being performed and GPC will advise the NRC of the results upon completion.
Based upon NRC guidance in NUREG-0302, Revision 1,
and other NRC correspondence, Georgia Power Company is reporting (e)is condition pursuant to the reporting requirements th of Part 10 CFR 50.55 A summary of our evaluation is attached.
This response contains no proprietary information and may be placed in the NRC Public Document Room.
Yours truly, kh Y
kk O
P. D. Rice REF/PDR/tdm Attachment xc:
U. S. Nuclear Regulatory Commission Document Control Desk Washington, D. C.
20555 H. G. Baker D. R. Altman L. T. Gucwa J. P. O'Reilly P. R. Bemis C. W. Hayes G. F. Head J. A. Bailey G. A. McCarley R. E. Conway
- 0. Batum R. W. McManus R. H. Pinson G. Bockhold Sr. Resident (NRC)
C. W. Whitney C. E. Belflower C.C. Garrett (OPC)
- 8. M. Guthrie J. F. D'Amico J. E. Joiner (TSLA)
D. E. Dutton W. D. Drinkard D. Feig (GANE) gc,77 R. A. Thomas E. D. Groover NORMS
EVALUATION OF A POTENTIALLY REPORTABLE CONDITION CONTAINMENT COOLING UNIT MANIFOLD N0ZZLES Initial Report: On September 24, 1986, Mr. R. E. Folker, Vogtle Quality Assurance Engineer, notified Mr. M.
Sinkule of the USNRC-Region II of a
potentially reportable condition associated with the inadequate consideration of thermal stresses in the design of the manifold nozzles for the containment cooling units.
This concern was initially identified during an audit by the NRC Seismic Qualification Review' Team (SQRT) and the Pump and Valve Operability Review Team (PVORT).
In subsequent correspondence, Georgia Power Company indicated that the NRC could expect to be informed of the results of the evaluation of this condition by November 24, 1986.
Backnround Information: There are four separate types of cooling units prov<ded by CVI. Incorporated, under Specification X4AJ16.
They are:
(1) containment cooling units (CCU), (2) the piping penetration area coolers (PPAC), (3)' auxiliary cooling units (ACU) and (4) reactor cavity cooling units (RCCU).
The principal function of the CCU (tag numbers 1/2-1501-A7-001 through 008) is to reduce the containment temper,ature following a design basis accident (D8A), loss of coolant accident (LOCA), or main steam line break (MSLB) inside the containment.
These cooling units also function during normal operation. to maintain the ' containment temperature within a minimum-maximum range of 60* to 120*F.
The PPAC (tag numbers 1/2-1561-E7-001 and 003) are provided to serve the piping penetration filter exhaust system (PPES). The PPES is designed to minimize the release of airborne radioactivity to the outside atmosphere resulting from containment leakage into the piping penetration area during a DBA condition.
The PPAC are located in the auxiliary buildings and provide cooling for the filter units.
These coolers are not required during normal operation, but are required to operate following a DBA.
TheACU(tagnumbers 1/2 1515-A7-001 and 002) augment the cooling capacity of the containment cooling units during normal operation.
These units are isolated during a DBA and do not perform a safety function, but are required to maintain the integrity of their pressure boundaries.
The RCCU (tag numbers 1/2-1511-E7-001 and 002) are designed to provide cooling air during normal and loss of offsite power conditions to prevent the reactor cavity concrete from exceeding its allowable temperature.
These units are isolated during a DBA and do not perform a safety function, but are required to maintain the integrity of their pressura boundaries.
Although cooling units are manufactured by CVI, the stress analyses for these units were performed by Karagozian and Case (KC), consultant to CVI.
The pressure boundary components for these cooling units are constructed in accordance with American Society of Mechanical Engineering (ASME) Boiler and Pressure Vessel (B&PV) Code Section III, Class 2 and 3.
r l
Failure to maintain the pressure boundaries of ACU and RCCU during DBA conditions in conjunction with a single failure of unit isolation : valves could result in loss of the nuclear service cooling water (NSCW) inventory and could potentially impact plant safety,
~
s i
During the SQRT and PVORT audit in June 1986, the NRC expressed 'a concern that thermal stresses in the header nozzles;on the cooling coils of I
the RCCU were not addressed in the stress analysis.
r Engineerina Evaluation: In response to this concern, Bechtel Western i
Power Corporation (BWPC) engineering and the CVI consultant reviewed the calculations of the cooling units supplied under Specification X4AJ16.
j This review concluded that thermal stresses due to temperature difference between the structural frame and the inlet manifolds of these four units 1
had not been properly addressed for:
Piping / manifold / nozzle interfaces.
Cooling coil tubing.
During normal plant operation, the four types of units (CCU, PPAC, ACU, and RCCU) are subject to temperature differentials of about 40*F'between 4
.l the cooling unit structural frame and the inlet cooling water piping and tubing.
Under DBA conditions the CCU and PPAC are subject to a temperature differential of about 197'F and 40*F respectively between the cooling unit structural frame and the inlet cooling water piping and tubing.
I Containment Cooling Units (CCU):
t The pipe support configuration of the CCU was found to provide insufficient flexibility, and as a result calculated pip'ing thermal stress exceeded the allowable stress limits under both normal and DBA conditions.
Piping Penetration Area Coolers (PPAC):
j The impact of the thermal stresses on the PPAC pipe supports as a result of the described temperature differential was considered in the reanalysis.
The reanalysis demonstrated that piping stresses were within i
allowable stress limits under both normal and DBA conditions.
- Thus, the present configuration is acceptable.
Auxiliary Cooling Units (ACU):
The pipe support configuration of the ACU was found to provide insufficient flexibility, and as a result calculated piping thermal stresses exceeded the allowable stress limits ur. der normal conditions.
I i
__,m.-
-.,w-~,..-,,,,,,.
w.-
._,,,n.--,,,-..-.....,-.n--.--..-,
ReactorCavityCoolingUnits(RCCU):
The impIct of the thermal stresses, on the RCCU pipe support as a result of the described temperature differential was considered in the reanalysis.
The result of the reanalysis demonstrated that piping stresses were within allowable stress limits under both nonnal and D8A conditions. Thus, the present configuration is acceptable.
Cooling coil Tubing (CCT):
CVI developed a test program in accordance with Appendix II of ASME Section III to determine whether failure of the coil tubing would have resulted under the described conditions.. The result of the testing demonstrated that the present installation is acceptable for both Units 1 and 2.
Evaluation of Quality Assurance Program Breakdown:
An evaluation of a quality assurance breakdown is currently being performed and GPC will advise the NRC of the results upon completion.
==
Conclusion:==
Based on the above evaluation, the plant safety could have been impacted if the condition associated with inadequate thermal stress analysis for the containment cooling u' nits had gone uncorrected.
Therefore, Georgia Power Company has concluded that a reportable condition as defined by the reporting criteria of 'Part 10CFR50.55(e) and Part 10CFR21 does exist.
Based on the guidance in NUREG-0302, Revision 1, concerning duplicate reporting of an event, Georgia Power Company is
' reporting this event per the criteria of Part 10CFR50.55(e).
Corrective Action:
a.
Pipe support modifications for the CCU and ACU pipe supports have been completed on Unit 1.
b.
Corrective actions for the CCU and ACU of Unit 2 are tracked under completion of work '(PCW)~ iten no.
2B1587 and will be complete commensurate with Unit 2 construction schedules.