ML20084G149
| ML20084G149 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 04/23/1984 |
| From: | Foster D GEORGIA POWER CO. |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| GN-344, NUDOCS 8405070093 | |
| Download: ML20084G149 (4) | |
Text
Georg;a Power Company Route 2. Box 293A N
Waynesboro, Gear 9 a 30830 M
Telephone 404 554-0961. Ex.t 3360
'a 404 724 8114. Eit 3360
.n 3 4 Georgia Power c Pr s ent and Project Gercrat Manager tN southern ererfrsc sprem Vogre PicMct April 23,1984 United States Nuclear Regulatory Commission File: X78G03-M60 Office of Inspection and Enforcement Log:
GN-344 Region II-Suite 3100 101 Marietta Street Atlanta, Georgia 30302
{
Vogtle Electric Generating Plant-Units 1 and 2, 50-h, 50-425;
Reference:
Control Room Filtration Unit Housings Attention: Mr. James P. O'Reilly Gentlemen:
On March 23, 1984, Mr. C. W. Hayes, Vogtle Project Quality Assurance Manager, reported a potential deficiency to Mr. John Rogge of the USNRC that concerned the design of the control room filtration unit housing. Georgia Power Company has completed its evaluation and has concluded that this con-dition is reportable as a substantial safety hazard and a significant deft-ciency.
Based upon NRC guidance in NUREG-0302, Revision 1, and other NRC corres-pondence regarding duplicate reporting of significant deficiencies and sub-stantial safety hazards, Georgia Power Company is reporting this event as a significant deficiency pursuant to the requirements of Part 10 CFR 50.55(e).
A summary of our evaluation is attached for your information.
This letter contains no proprietary information and may be placed in the NRC's Public Document Room upon receipt.
Yours truly, h6 D. O. Foster xc:
U. S. Nuclear Regulatory Commission Document Control Desk Washington, D. C.
20555 xc:
R. J. Kelly D. E. Dutton J. A. Bailey L. T. Gucwa R. E. Conway W. F. Sanders
- 0. Batum M. Malcom G. F. Head R. H. Pinson G. Bockhold H. H. Gregory, III C. W. Hayes P. D. Rice B. M. Guthrie J. T. Beckham, Jr.
D. M. MacLemore R. A. Thomas E. D. Groover J. L. Vota l
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' EVALUATION FOR A SUBSTANTZAL SAFETY HAZARD EVfLUATION FOR _A SIGNIFICANT DEFICIENCY 4
Control' Room Filtration Unit Housing Design Initial Report:
On March 23, 1984, Mr. C. W. Hayes, Vogtle Project Quality Assurance Manager, informed Mr. J. Rogge of tne USNRC of a potential deficiency in the design t
of the control room filtration unit housings.
Background Information; s
During a rev few of the control room filtration unit' specification (X4AJ07), it was determined that the internal pressure was inc.orrectly incorporated into the data sheets for the control room filtration unit housing.
Two redundant and physically separated air filtration unit trains are provided for each power unit to process intake airflow and rt: circulation airflow in the shared control room. Thus, the control room has four filtration units.
The control room filtration units (1-1531-N7-001,1-1531-N7-002, 2-1531-N7-001 and 2-1531-N7-002) provide cooling, moisture elimination,high efficiency particulate filtration and activated carbon adsorption of all the air supplied to the control room to ensure trotection 3f the plant' operators, instrumentation and equipment following a design basis event. Any one of the four units is capable of meeting the cooling, air filtration and pressurization requirements following a design basis event.
These units were fabricated by American Air Filter, Inc.
The 8echtel Power Corporation specification for the control room filtration unit housing required' the filter plenum to withstand negative 20 inches water gauge (w.g.).
This is in compliance with ANSI N509-1980 paragraph 4.6.2.2, " Units located on the inlet side of the fan...shall be designed to withstand a negative internal pres.sure equal to.or more negative than the peak pressure of the fan." When originally submitted, the vendor drawings were corrected to indicate the negative 20 inches w.g. design requirement, how-ever, subsequent revisions of the vendor drawings were inadvertently approved which indicated a negative 2 inches w.g.
Because of this, the filtration units were fabricated and shipped.to, the jobsite with a design pressure of negative 2 inches w.g. instead of negative 20 inches w.g. as required by the system design.
Engineering Evaluation:
The filtration units and their enclosure housings are located on the suction side of the fans.
The of 14 inches of water. fans are designed to develop a differential pressure During normal testing / operation of the filtration system, the filtration housings will experience a pressure of at least negative 6 inches w.g., due to tne combined pressure drop across all the components
~
l inside the housing.
TheseconcJst'ofapressuredropacrossthemoisture i
separator of 0.75 inch w.g., the,electrin heater of 0.5 inch w.g., the l
first HEPA filter bank of 1 inch W.g., the charcoal adsorber of 1.25 inches w.g.,
the second HEPA filter bank cf 1 inch w.g., and the cooling coil of 1.85 inches w.g.
All the control room tiltratio1 unit housings are designed and l
fabricated to withstand negative 2 thches w.g.
Therefore it is likely that u
Control Room. Filtration Unit Housing Design Page 2 the unit housings will fail during normal testing / operation of the filtra-tion system.
If the unit housings survive initial startup, they would eventually fail as pressure drop increases when filters become loaded with dirt.
Additionally, in the unlikely event that the inlet dampers failed in the closed position and/or an obstruction occurred in the duct work during filtration system operation, the filtration housings will experience the full fan shut off pressure of negative 14 inches w.g.
This condition would make the unit housing failures almost cartain.
Because the design and fabrication of all control room filtration units are identical, the units are subject to the possibility of common mode failure during system operation.
This would result in the loss of all the control room filtration units. Because the deficient unit housing design can result in a failure of the control room filtration units and consequential failure of plant operators', protection with potential radiation dose exposure in excess of guidelines, it has been concluded that this deficiency represents a substantial safety hazard and significant deficiency in the control.oom filtration unit design, and is reportable under both 10 CFR Part 21 ani 10 CFR 50.55(e).
Evaluation'of Quality Assurance' Program Breakdown:
The fabrication of the control room filtration units was in accordance with approved drawings and procedures. This is an isolated occurrence, and does not impact any other HVAC units. Therefore, it has been concluded that a quality assurance program breakdown does not exist.
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Conclusion:==
This event is considered reportable since, were it to have remained uncorrected, it could have affected adversely the safety of operation of the nuclear power plant at any time throughout the exoected lifetime of the plant. Additionally, this event represents a significant deficiency in the final design as approved and released for construction such that the design does not conform to the criteria and bases of the safety analysis report.
This event also represents a substantial safety hazard since it could have resulted in the exceeding of exposure guidelines to the plant operators.
In NUREG-0302, Revision 1 and other NRC correspondence, the NRC advises that the duplicate reporting of events is not required.
Georgia Power Company has evaluated and concluded that this event is reportable as a substantial safety hazard and significant deficiency.
However, to avoid duplicate reporting, Georgia Power Company is reporting this event under the reporting requirements of 10 CFR 50.55(e).
r Control Room Filtration Unit Housing Design Page 3 Corrective Action:
The vendor has redesigned all four control room filtration unit housings to withstand the required internal pressure of negative 20 inches w.g.
and is presently fabricating the necessary material. The fabricated materials for reinforcing the unit housing, together with the required drawings, will be shipped to the jobsite for field installation by Georgia Power Company. A supplementary analysis to update the seismic analysis of the units will be performed.
This corrective action will upgrade the units to meet all specification requirements and to comply with ANSI N509-1980, paragraph 4.5.2.2.
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