ML17037C138
| ML17037C138 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 09/03/1971 |
| From: | Schneider F Niagara Mohawk Power Corp |
| To: | Morris P US Atomic Energy Commission (AEC) |
| References | |
| Download: ML17037C138 (4) | |
Text
DOCKETED USAEC 6
SEPZOl97t E.
REGUlATOR>
i.
I MAIL SECTION gP'OCKET CLEIIK Regulatory File September 3,
1971 NIAGARA MOHAWK POWER CORPORATION 4IIIJk NIAGARA~
MOHAWK 300 ERIK BOULEVARD WEST SYRACUSE, N Y. I3202 c-Zap
~O
~l
~
1 Dr. Peter A. Morris, Director Division of Reactor Licensing United States Atomic Energy Commission lItashington, D.
C.
20545
Dear Dr. Morris:
On June 19, 1971, with the Nine Mile Poin't Nuclear Station produc-ing 456 N'l~e~, the conductivity of the. water 'in the reactor vessel increased to 10 mmho.
As this is a limiting condition for oper'ation, an orderly shut-down was begun in fiftysix minutes of the occurrence'.
Specifications call for an orderly shutdown started within an hour and the reactor to be 'in cold shutdown in ten hours.
During the load reduction, 'it was found that one of th'e condensate storage tank's'onductivity was approximately 250 mmho, the other 25.
One hour and thirty four minutes after the beginning of load reduction, the con-trol rod drive pump supply water was transfer'red from the condensate storage tank to the'imineralized water storage tank and a second clean-up pump was started to increase purification of the reactor water, Reactor water conduc-tivity immediately started to decrease.
Two hours and twenty four minutes later, reactor water conductivity was at 9.5 mmhos and load was held at 252 hS(e) while cleaning up water.
Four hours and forty six minutes later, reactor water" conducti'vity had reduced to 1 mmho.
Chloride analysis of reactor water taken, during times of maximum conductivity indicated 0.23 ppm, indicating that chloride levels were at all times well within the Technical Specification limit of 1 ppm.
Three hours and twenty minutes later, the contro'1 rod drive pump suction was returned to the condensate storage tank which had decreased in conductivity from 25 mmhos to 5 by spilling to the main condenser and recycling through an idle dimineralizer.
Contamination of the condensate storage tank's occurred by a mal-function of equipment in the radiation waste facility.
i4ater from the waste collector tanks passes through a filter and dimineralizer.
Conductivity is determined by a cell at the dimineralizer discharge.
i!tater of standard quality or above is pumped to the condensate storage tank through one of two flip-flop control valves.
The other valve opens when below standard water is produced, recirculating th'e effluent back to the di'mine'ralizer for additional purification.
The first valve of the pair is left closed during this process.
L5.
0,
Page 2
On this occasion, the conductivity recorder stuck"'and did not permit the contact driven by the recorder mecha'nism to actuate.
Th'erefore, below standard water was sent to the, co'ndensate storage
'tanks',
which in turn was pumped to the -reactor by the control rod drive pumps.
completely separate back-up system is presently being installed to preven't a recurr'ence.
Another conductivity cell'nd 'switch (not.depend-ent on,a recorder movement) are being connected'n parall'el with the present system.
Either system (or both) will cause, the proper.valve action on high-conductivity.
Both systems will have'he same switch point and failure,,of one system will not effect proper operation 'of..the other.
Very truly yours,,
4 -d4 F
J. Schneider.
Vice =President
'- Operations FJS:pw 39S2
- $~
Jt
'k H
'4 r*~'.'i A