ML17037C517
| ML17037C517 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 01/09/1974 |
| From: | Raymond P Niagara Mohawk Power Corp |
| To: | Skovholt D US Atomic Energy Commission (AEC) |
| References | |
| Download: ML17037C517 (8) | |
Text
AEC TRIBUTION FOR PART 50 DOCKET M RIAL
(~fPORARY FORM)
CONTROL NO:
FILE:
377 FR%
Niagara Mohawk Power Corp.
- Syracuse, N,Y. 13202 Mr. P.D.
Raymond DATE OF DOC 1-9-74 DATE REC'D 1-14-74 MEMO RPT OTHER CLASS UNCLASS XXX TO:
D.J ~ Skovholt PROP INFO ORIG 1 si ed INPUT CC OTHER NO C S REC'D SENT AEC PDR SENT LOCAL PDR
. DOCKET NO:
50-220 DESCRIPTION:
Ltr re eheir 7-20-73 and 12-19-73 ltrs.....concern changes made to the drywell vacuum breakers.......
submitting proposed changes to the tech specs for Nine Mile Point 81....
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ENCLOSURES:
ACKNOWI,ZDGZD PLANT NAME. Nine Mile Point 81 FOR ACTION/INFORMATION O> REMOVE JB BUTLER(L)
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Ao~latoIy NIAGARA MOHAWKPOWER CORPORATION NIAGARA ~+)
MOHAWK 300 ERIE BOULEVARD WEST SYRACUSE. N. Y. 13202 January 9,
1974
'All/gQgpss g'g~~ @fg Mr. Donald J. Skovholt Assistant Director for Reactor Operations Division of Reactor Licensing United States Atomic Energy Commission Washington, D. C.
20545
Dear Mr. Skovholt:
Re:
Nine Mile Point Unit 1 Docket No. 50-220 4
~4gj dy oo@4wo ~oo
~<o Og Our letters to'you of July 20 and December 19, 1973 described changes made to the drywell vacuum breakers at Nine Mile Point Unit l.
In order to implement these
- changes, the following changes to the Technical Specifications and Bases are proposed.
Replace "Limiting Condition for Operation" 3.3.6 a, b and c
with a new specification 3.3.6 a,',
c and d as follows:
When primary containment is required, all drywell-suppression chamber vacuum breakers shall be operable and,positioned in the closed position as indicated by the position indication system, except during testing and as 'specified in 3.3.6 b and c, below.
b.
Any drywell-suppression chamber vacuum breaker may be non-fully closed as indicated by the position indication, system provided that a drywell to suppression chamber pressure differential can be maintained. greater than 1/2 the initial differential pressure for 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> with no nitrogen makeup.
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Mr. Donald J. Skovholt United States Atomic Energy Commission January 9,
1974 c.
Up to one drywell-suppression chamber vacuum breaker may be secured in the closed position.
- d. If Specifications 3.3.6 a, b or c cannot be
- met, the situation shall be corrected within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or the reactor shall be placed in a cold shutdown condition within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />."
Replace "Surveillance Requirement" 4.3.6 a, b and c with a new specification 4.3.6 a, b, c and d as follows:
"a.
Each drywell-suppression chamber vacuum breaker shall be exercised through an opening-closing cycle monthly.
b.
When it is, determined that any vacuum breaker valve is not fully closed as indicated by the position indication system at a time when such closure is required, the apparently malfunctioning vacuum breaker valves shall be exercised and pressure tested as specified in 3.3.6 b immediately and every 15 days thereafter until the apparently malfunctioning valves have been returned to normal service.
c.
Once each operating cycle, each vacuum breaker valve shall be visually inspected to ensure proper maintenance and operation.
d.
A leak test of the drywell to suppression chamber structure shall be.conducted during each refueling outage."
The Bases for these specifications will be revised by adding the following paragraphs.
"Each drywell-suppression chamber vacuum breaker is equipped with two independent switches to indicate the opening of the valve disc.
Re-dundant control room alarms are provided to permit detection of any drywell-suppression chamber vacuum breaker opening in excess of the described allowable limits.
,The containment design has been examined to establish the allowable bypass area between the drywell and suppression chamber as 0.053 square feet.
1 v
Mr. Donald J. Skovholt United States Atomic Energy Commission January 9, 1974 The limit on each individual valve will be set such that with all valves at, their limit, the maximum value of cumulative leakage will not exceed the maximum allowable.
The valve will be at approximately 0.06 inch of disc travel off its seat and will be alarmed in the control room.
The instruments that would be used for surveillance testing and leak rate testing of the drywell vacuum breaker valves read out.in the auxiliary control room.
Their range and accuracy are as follows:
Pressure Temperature PSID 0
50 psia
+.05 psi 0 200 F + 1 F
0 1.0 psid
+.001 psi With an initial differential pressure, between the drywell and sup-pression chamber of 0.15,to 0.25 psid,,this differential pressure will decay to about 1/2 the initial,value in 10 to 20 minutes through a 1.0 inch orifice (0.0055 square feet).
Therefore, the criterion that the differential pressur'e between the drywell, and suppression chamber must be greater than,l/2 the initial value at the end of a one hour period demonstrates that a by-pass area significantly less than the allowable limit is maintained.
During each refueling outage, a leak rate test shall be performed to verify that significant leakage flow paths do not exist between the drywell and suppression chamber.
The drywell pressure will be increased by approximately 1 psi with respe'ct to the suppression pool pressure and then held constant.
The subsequent suppression chamber transient will be monitored with a sufficiently sensitive pressure instrument.. If the drywell pressure cannot be increased by 1 psi over the suppression chamber pressure, it would indicate existence of a significant leakage path, which will be identified and eliminated before further drywell vacuum breaker testing."
The proposed changes have been approved by the Site Operations Review Committee and the Safety Review and Audit Board.
They will be implemented upon approval by your staff.
Very truly yours, Philip D. Raymond Vice President Engineering CVM/sjz
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