ML20151K262
| ML20151K262 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 04/14/1988 |
| From: | Rice P GEORGIA POWER CO. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| REF-PT21-88-038-000 GN-1444, PT21-88-038-000, PT21-88-38, NUDOCS 8804210281 | |
| Download: ML20151K262 (2) | |
Text
_ _ _ _ _
('
Geo.gia Power Cornpany Fbst Off ce Box 282 Waynesboro, Georg:a 30830 TelepMne 404 554-9961, Extens'on 3413 404 724-8114 Extenston 3413 m
Georgia Power R D. Ric.
Q',h Sj,ent Apri1 14, 1988 7,m,,,mf7c ystm 4
c, U. S. Nuclear Regulatory Commission ATTN:
Document Control Desk File:
X78G03-M139 Washington, D. C.
20555 Log:
GN-1444
Reference:
Vogtle Electric Generating Plant - Unit 2; 50-425 Control Room Essential HVAC Letter GN-1396, dated September 14, 1987 In previous correspondence, Georgia Power Company (GPC) notified the NRC of a reportable condition as defined by 10CFR21 and 50.55(e) associated with the Control Room Essential (CRE) HVAC system.
In the referenced lett'er GPC stated the broadness review was not complete, and that supplemental information would be submitted if additional systems were found with this condition.
The broadness review is now complete and no other safety related HVAC systems were found to have this condition.
However, further evaluation of the two unit combined control room operation has identified an additional concern.
If more than two of the four 100%
capacity fans are operating at the same time, the fans would operate in the surge range of the fan curve.
This scenario could resul t in damage to one or more of the fans.
It may also cause the control room post-accident calculated doses reported in the FSAR to be exceeded due to an increase in the quantity of outside air supplied.
The amount of air circulated by a fan operating in the surge mode is indeterminate.
Consequently, the ability of the combined CRE hVAC system to meet the General Design Criterion 19 of 10CFR50 is also indeterminate.
The root cause for this additional concern was determined to be an incorrect assumption in the design calculation.
The assumption made with regard to the pressure in the control room resul ting from multiple fans operating was determined to be inconsistent with simulated conditions.
The entire calculation was reviewed and no other invalid assumptions were found.
Because the reported conditions are isolated to one safety-related HVAC system, they are not indicative of a significant breakdown in the Bechtel Quality Assurance Program.
Corrective action for this additional concern beyond the calculation review involves a logic modification where flow switches are installed in conjunction with a lead / lag circuit.
More than one train per unit of the CRE HVAC system will be prevented from automatically operating at the same time with this logic modification.
The logic 8804210281 880414 PDR ADOCK 05000425 S
(
= <
f i
j l
File:
X78G03-M139 Page two Log: GN-1444 1
modification will be made before Unit 2 fuel load commensurate with j
the Construction schedule and prior to placing the Unit 2 CRE HVAC units in automatic operation.
This correspondence contains no proprietary information and may be placed in the NRC Public Document Room.
l r
L P. D. Rice PDR/wkl xc: USNRC Region II Suite 2900 101 Marietta Street, N.W.
Atlanta, GA 30323 H. G. Baker, Jr.
D. R. Altman L. T. Gucwa G. F. Head J. A. Bailey C. W. Hayes R. H. Pinson G. Bockhold, Jr.
R. W. McManus i
E. D. Groover G. R. Frederick Sr. Resident (NRC)
C. T. Moore J. E. Swartzwelder D. H. Smith (0PC)
R. A. Thomas G. A. McCarley J. E. Joiner (TSLA)
NORMS 4
n.,
,,..,,,,,,_.3._,.,,,,,,
_.,.,.,,.,,,