ML19296A974
| ML19296A974 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 02/12/1980 |
| From: | TENNESSEE VALLEY AUTHORITY |
| To: | |
| Shared Package | |
| ML19296A973 | List: |
| References | |
| NCR-CEB-79-1, NUDOCS 8002190567 | |
| Download: ML19296A974 (2) | |
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5 ENCLOSURE SEQUOYAll NUCLEAR PLANT UNITS 1 AND 2 PIPING EMBEDDED IN STRUCTURAL CONCRETE NCR CE3 79-1 REVISED FINAL REPORT Description of Condition TVA failcd to comply with some of the requirements of ACI 318-63, section 703. " Conduits and Pipes Enhedded in Concretc." Our investigation has identified the following types of code violations:
1.
Testing Pressures that Were Less Than 150 Percent of the Design Tressure - Violation of Section 703(b)3 a.
ERCW piping (24-inch diameter) in ERCW pumping station - Test pressure was 125 to 137 percent of the 180-psi design pressure.
b.
Hypochlorite system (1-inch diameter) in ERCW pumping station -
Tested to 138 percent of the 180-psi design pressure.
c.
Raw service water (1-and 2-inch diameter) in ERCW pumping station - Tested to 138 percent of the 180 psi design pressure.
2.
Embedded Piping Subjected to Pressures Greater than 200 psig After Concrete has Hardened - Violation of Section 703(b)2 a.
ERCN piping (24-inch diameter) in intake pumping station was pressurized to 240 psi during system testing.
b.
Raw water and fire protection (8-and 12-inch diameter) in intake pumping station pressurized to 250 psi during system testing.
c.
ERCW piping (24-inch diameter) in ERCW pumping station pressurized to 225 to 246 psi during system testing, d.
CO2 fire protection piping (1/4-and 1/2-inch diameter) in diesel generator building is expected to be subjected to its design pressure of 300 psi.
ERCW piping (6-to 14-inch diameter) in diesel generator building -
e.
Test pressure was 250 psi during system testing.
I f.
HPFP piping (6-inch diameter) in the ERCW pumping station will be pressurized to 225 to 250 psi during system testing.
3.
Use of Screw Connections Embedded in Concrete - Violation of Section 103(b)9 a.
Hydrochlorite system (1-inch diameter) in ERCW pumping station.
b.
Service air (1-an 2-inch diameter) in ERCW pumping station.
Raw service water (1-and 2-inch diameter) in ERCW pumping station.
c.
d.
CO2 fire protection (1/4-and 1/2-inch diameter) in diesel generator building.
00021go 6b
1 e.
Service air (1-and 1-1/2-inch diameter) in diesel generator building.
f.
Potable water (1/2-to 2-inch diameter) in diesel generator building.
g.
Potable water (1-and 2-inch diameter) in auxiliary building.
h.
Potable water, air, gas (1-inch diameter) in auxiliary building.
4.
Failure to Retest, After the Concrete has Hardened, Pipes Carrying Liquid or Gas ',ihich is Explosive or Injurious to Health - Violation of Section 703(b)4 a.
Hypochlorite system (1-inch diameter) in ERCW pumping station.
b.
Burner gas - Propane or butane (1-inch diameter) in auxiliary building.
Safety Implication Statement The Seismic Category 1 structures affected by the deficiency are the intake pumping station, ERCW pumping station, diesel generator building, and auxiliary building.
The results of the investigations into each violation, as reflected below, indicate that the integrity of the structures and the piping systems were not degraded by these violations.
Therefore, ha.d the deficiency gone uncorrected, the safety of operation of the plant would not have been adversely affected.
Corrective Action The structural integrity of the affected structures was evaluated, and it was concluded that the structural capacities would not be impaired by embedded pipes having been subjected to pressures greater than 200 psi.
TVA does not consider the screw connections embedded in concrete as listed in item 3 to be detrimental to concrete structural integrity because where this type of connection is used, the concrete thickness is several times the pipe diameter.
For example, the 2-inch diameter service air piping in the ERCW pumping station is embedded in a slab that is 24 inches thick.
The piping systems in items 1, 2, and 4, above, were designed, fabricated, and tested in accordance with recognized piping codes, either the ASME Code or ANSI Codes, as specified by the design documents.
Use of these codes gives assurance of the structural adequacy and leak tightness of the embedded pipes.
Therefore, TVA intends to use the pipes as constructed.
TVA has revised the general civil design criteria for Sequoyah Nuclear Plant to emphasize that, in the future, the civil engineering organization responsible for the design of the affected structures should perform a review of embedded conduits and piping to ensure meeting the requirements of Section 703 of ACI 318-63.