ML20085E943
| ML20085E943 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 12/29/1975 |
| From: | Gilleland J TENNESSEE VALLEY AUTHORITY |
| To: | Knuth D NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| Shared Package | |
| ML20085E941 | List: |
| References | |
| NUDOCS 8308170149 | |
| Download: ML20085E943 (4) | |
Text
IE FILE C0q goWi%
831 Power Building g
Q TENNESSEE VALLEY AUTHORITY it CHATTANOOGA, TENNESSEE 374ot
/ r.ggl a December 29, 1975
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Dr. Donald F. Knuth, Director Office of Inspection and Enforcement
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U.S. Nucicar Regulatory Commission
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Washington, DC 20555
Dear Dr. Knuth:
BROWNS FERRY NUCLEAR PLANT UNIT 3 - REPORTABLE DEFICIENCY -
INADEQUATE PROVISIONS FOR PRIMARY CONTAI"' NT ISOLATION Initial report of the subject reportable deficiency was made to G. R. Klingler, NRC-IE, Region II, on November 26, 1975.
In compliance with paragraph 50.55(c) of 10 CFR Part 50, we submit the enclosed final report of the deficiency.
Very truly yours, J. E. G111 eland Assistant Manager of Power Enclosure CC (B1 closure):
Mr. Norman C. Moseley, Director Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Region II - Suite 818 230 Peachtree Street, NW.
Atlanta, Georgia 30303 oh$9 05 PDR l
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ENCLOSURE Z
BROWNS FERRY NUCLEAR PLAhr UNIT 3
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INADEQUATE PROVISIONS FOR PRIMARY CONTAINMENT ISOLATION y
FINAL REPORT f_
DDR No. 222
.2-9 3
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_ Description of Occurrenu.
Jw While examining design drawings of the Demineralized Water System piping, 1
an engineer discovered that the syatem did not have adequate provisions for primary containment isolation.
d Cause of Deficiency The Domineralized Water System piping to the drywell has only a check valve outside the drywell penetration and no valve 1::: mediately inside the pene-tration. Figure 1 shows a schematic to illustrate this.
There are valves 7,
inside at the end of the lines, but these are several feet from the pene-tration. Materials used inside are Class M*; the check valve and the g
penetration p Class D**.
[
Since the piping inside the drywell is Class M and the end valves are k
several feet from the penetration, the end valves cannot be considered
_1.
containment isolation valves and the Demineralized Water System cannot be 5
considered a " closed" system.
Therefore, the system does not meet the isolation valve. criteria stated in subsection 5.2.3.5 of the Browns Ferry g
FSAR and does not provide adequate primary containment isolation.
ga.
'E Safety Implications One of the safety design bases for the Primary Contain=ent System (which includes the drywell) is that it shall provide the capability for rapid I
closure, or isolation, of all pipes which penetrate the primary containment.
This isolation must be by means which provide a containment barrier such 7
that any leakage is maintained within permissible limits.
The present valve
"'E, configuration for the Demineralized Water System does not fulfill this 5
safety design basis because it only provides one barrier (i.e., a check valve).
Thus it is possible that a single failure.of the check valve could violate h_
the primary containment function.
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Jescription of Corrective Action A normally closed hand valve will be added i=ediately outboard of the check valve. This hand valve will be seis=ically cualified and be made of Class D material. Provision for leak testing will be made. Figure 2 is a schematic of the proposed modified design.
Means Taken to Prevent a Recurrence All systems used during normal operations that have penetrations through the primary containment have been previously reviewed to assure that the penetrations have adequate isolation means.
Tce syste-e not used during normal operations (i.e., control air and demineralized water) have been examined to insure that they also have adequate mecas of isolation.
- Class M - Power piping and equipment pressure parts not otherwise classified and which are considered within the scope of the Power Piping Code, ANS B31.1.0-1967.
- Class D - Piping and equipment pressure parts which serve as (a) an extension of containment regardless of operating pressure and temperature; and (b) engineered safeguards systems which must operate to reduce consequences of an accident and which operate _ at either pressures greater than 150 psig or temperatures greater than 2120F.
t 9
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La Dryvell Check Valve 1
/
1" De:sineralized I
Water Line L*
Present Design FIGURE 1 os Normallyblosed Hand Valve i
1 l
w Modified Design FIG'u?S 2
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