ML19305D315
| ML19305D315 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 03/28/1980 |
| From: | William Jones OMAHA PUBLIC POWER DISTRICT |
| To: | Eisenhut D Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8004140362 | |
| Download: ML19305D315 (3) | |
Text
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1623 HARNEY.. O M A H A. NEBRASKA 68102 a TELEPHONE 536 4000 AREA CODE 402 March 28, 1980 Mr. Darrell G. Eisenhut, Acting Director Division of Operating Reactors Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D. C.
20555
Reference:
Docket No. 50-285
Dear Mr. Eisenhut:
The Omaha Public Power District received a letter from the Com-mission, dated February 23, 1980, requesting that the District propose measures to provide assurance that WASH-1400 Event V scenarios do not occur at the Fort Calhoun Station.
In response, an evaluation of Fort Calhoun Station design and operating practice was performed.
It was found that piping configurations at the station do not conform to the Event V configurations of Figures I-4-6 and V-4-3 of WASH-1400.
Design details and provisions currently taken to reduce the probability of overpressurization of low pressure sections of piping are discussed in the attachment to this letter. The evaluation results show that no cause exists to modify the Fort Calhoun Station operating license to require either continuous surveillance or periodic testing.
Sincerely, i.-
W. C. Jones i
Division Manager Production Operations WCJ/KJM/BJH:jmm Attach.
cc: LeBoeuf, Lamb, Leiby & MacRae i
Subscribed and sworn to before me this ' ~ day of
, 1980.
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l Notary Public s u mu ne w -si..es.w J. T. GLEASON Mr Cmast Eso..Assy 28.1982 3 0 0414 0 9 fo &
ATTACHMENT P&ID Orawing CE-E-23866-210-130, sheets 1 and 2, show the arrange-ment of the ECCS piping subject to the concerns of the NRC's letter.
The piping arrangement for one of four parallel loops is shown below for reference.
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' The piping configurations at the Fort Calhoun Station do not conform to the Event Y configurations of Figures I-4-6 and V-4-3 of WASH-1400. For example, a locked closed motor operated valve with overpressure protection inside containment is available, unlike the arrangement referenced in Event V of WASH-1400.
However, precautions taken to assure an acceptably low probability of overpressurization of the low pressure sections of piping are as follows:
a.
The four primary loop check valves (SI-208, 212, 216, and 220) which form the first pressure boundary to the injection lines are continuously monitored for leakage through the valve.
Leakage would result in a pressure buildup against the backup check valves until, at 440 psig, the appropriate pressure control valve (PCV-2949, 2969, 2929, or 2909) opened to route leakage away. Pressure upstream of the pressure control valves is monitored with a readout in the control room, thus ensuring that primary loop check valve leakage is continuously monitored. Tha primary loop check valves have thus far been completely reliable.
b.
Backup check valves on each of the injection lines provide an additional pressure boundary between primary pressure and low pressure piping.
c.
The M0V's on the HPSI/CVCS (line 1), HPSI (line 2), and LPSI (line 3) piping are normally closed, which is unlike Event V in WASH-1400, and provide yet a third pressure boundary between the primary pressure and low pressure piping in the event that (1) leakage occurs at the primary check valve, (2) the controlled leakage system failed to operate, and (3) leakage occurs at the backup check valve.
FSAR paragraph 6.2.3.6, Safety Injection Valves, in reference to the M0V's states in part, "...The valves are closed during normal plant operation and are designed for the reactor coolant system pressure and temperature." The M0V's are opened by a Safety Injection Actuation Signal.
d.
Additional overpressure protection of low pressure sections of safety injection piping is provided by relief valves on each line (SI-187,188,189, and 190) in the event that the above four protective devices fail and leakage continues past the M0V's. These relief valves route to the pressurizer quench tank located inside containment.
Pressure instruments in the control room show pressure in each of these low pressure piping systems.
e.
Inservice inspection requirements in accordance with the Sumer,1975 addenda of the ASME Section XI Code are followed in testing all above primary and backup check valves to insure operability. WASH-1400 credits the annual operability tests for significant reductions in the failure probability of the check valves.
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