ML20064D533
| ML20064D533 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 09/08/1978 |
| From: | TENNESSEE VALLEY AUTHORITY |
| To: | |
| Shared Package | |
| ML20064D524 | List: |
| References | |
| NUDOCS 7811070240 | |
| Download: ML20064D533 (1) | |
Text
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f ENCLOSURI SEQUOYAH NUCLEAR PLA1T USITS 1 AND 2 INCORRECT SOLENOIDS 15 CVCS VALVES NCR 1P FINAL RZPORT Description of Deficiency During preoperational testing of portions of the chemical volu=e and control syste= (CVCS), valve stroke times for four flow contrcl and isolation valves in the normal RCS letdown line vere found containment to be much longer than that specified. This was due to construction personnel neglecting valve asse=bly drawings which instructed the= to This f ailure to install a particular solenoid onto a particular valve.
follow design drawings resulted in incorrect solenoics with undersized orifices being installed on these valves.
Safety I=elications The af fected valves are located in the normal RCS letdown line. During accident conditions, the function of these valves is to provide containment severe case in this situation vould be a break in isolation. The most the letdown line downstrea= of the outboard isolation valve FCV 62-77 (see FSAR figure 9.3-13).
This vould constitute an isolatable LOCA outside of contain=ent. The slow closure ti=e of the deficient valves would permit blevdown of radioactive coolant in excess of that allowed Thus, under these circu= stances, an accident of by the original design.
in the original this type vould be more severe than a si=ilar accident design with correctly installed solenoids on valves.
Corrective Action The deficiency affected only the portion of the Westinghouse supplied air operated valves (A0V's) which were delivered to the site unasse= bled.
All of these valves were inspected to deter =ine if installation had been made in accordance with the current Westinghouse supplied asse=bly d rawings. This inspection revealed that 25 A0V's in the CVCS and 2 It was further A0V's in the RCS vere asse: bled with incorrect solenoids.
deter ined that all of these A0V's had been asse= bled under the guidance of one individual who did not follow established procedures when selecting individual parts f or valve assembly.
Increased e=phasis has been placed en ensuring that individuals responsible for field asse:bly of cc:penents All af f ected A0V's have been reasse= bled adhere to established procedures.
with correct solenoid s.
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