ML20083F036
| ML20083F036 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 12/21/1983 |
| From: | Crouse R TOLEDO EDISON CO. |
| To: | Stolz J Office of Nuclear Reactor Regulation |
| References | |
| RTR-NUREG-0737, RTR-NUREG-737, TASK-2.F.1, TASK-TM 1014, NUDOCS 8312300111 | |
| Download: ML20083F036 (3) | |
Text
_______________
vi Docket No. 50-346 u3tgoo License No NPF-3 Rcano R camu Serial No. 1014 V(a Present Nxty
" * " " 8' December 21, 1983 Director of Nuclear Reactor Regulation Attention:
Mr. Joyh F. Stolz Operating Reacton Branch No. 4 Division of Operating Reactors United States Nuclear Regulatory Commission Washington, D. C.
20555
Dear Mr. Stolz:
This letter is being submitted to update our letter dated November 30, l
1983 (Serial No. 1010), on the status of certain TM1 Lessons Learned Items (NUREG-0737) for the Davis-Besse Nuclear Power Station, Unit No. 1.
As discussed in your Order dated March 14, 1983 (Log No. 1245) confirming t
our commituents, the schedule for completing Items II.F.1.1 and II.F.1.2 l
concerning accident monitoring for noble gas and iodine / particulate sampling is December 31, 1983.
Initial installation of the Kaman station vent stack monitors (RE 4598 units) was scheduled in conjunction with the Kaman containment monitors (RE 4597 units) during the 1982 Refueling Outage. This installation wes delayed until after the refueling outage due to the unanticipated problem with the steam generator auxiliary feedwater header and the necessity to divert resources to complete repairs. This forced a delay in the perform-ance of outage work on the vent stack monitors until the 1983 outage.
Although all necessary outage work to support the completion of the project by December 31, 1983 was performed during the 1983 refueling outage, additional events as listed below have severely impacted our stack monitor installation and testing schedule.
1.
Component Failures in the Central Processing Units - A high failure rate of electronic components along with difficulties in acquiring spare parts affected the availability of the Central Processing Units (CPU) for both the containment monitors and the vent stack monitors. This shortage of parts resulted in the necessity to cannibalize from the vent stack monitor CPU to maintain the containment monitors operational.
2.
Instrument Grounds - During the testing phase of the containment monitors, an iodine channel saturation problem was identified and an instrument grounding problem was determined to be the most probable cause. Because the vent stack monitors are almost 4
THE TOLED0 EDISON COMPANY EDISON PLAZA 300 MADISON AVENUE TOLEDO, OHIO 43652 8312300111 831221 I
O PDR ADOCK 05000346 P
Docket No. 50-346 License No. NPF-3 Serial No. 1014 December 21, 1983 Page 2 identical to the containment monitors, there was a high confidence level that this channel saturation problem would occur on the vent stack monitors. We undertook the installation of a dedicated instrument grounding system for the micro-processor to resolve this problem which required five months to complete. The permanent grounding modification was completed on the containment and vent stack monitors in October 1983.
3.
Software Problems - In addition to the dedicated instrument grounding system, it was determined that software changes to both the vent stack and containment monitors would be necessary to alleviate the iodine channel saturation problem. Testing of the modified software for the containment monitors required plant operation at greater than 70 percent pcuer.
The 1983 Refueling Outage began before the software changes could be completed and tested. Therefore the modified software and dedicated instrument ground system were verified after the refueling outage when the station again attained greater than 70 p
percent power in November 1983. New software for the vent stack
.j monitors was received and implemented in December, 1983.
c:
Physical tie-in to the vent stack of one channel of the Kaman vent stack o,
monitoring system was completed in early December 1983. Testing of the
@j station vent sample line showed that sample line design flow rates g{
revealed plateout of particulates resulting in lower than expected
@g readings. Toledo Edison, Bechtel, and Kaman have determined that further y,
modification and testing is required to obtain necessary data to resolve c
this problem by applying a correction factor to the monitor indications.
@g The correction factor will assure that accurate monitoring of stack
,q releases is available.
Further engineering evaluation will be performed g1 to determine an appropriate long term solution to the problem.
- i gc Toledo Edison now feels that the Station Effluent Monitoring System will W'
be installed and operable by March 31, 1984. This completion date allows
@f time for the following steps to be completed.
mj E
Further modification and testing to determine the appropriate o
correction factors g;
oc Functional testing of the first channel to determine its operability Hj d'
Tie-in of the second channel of instrumentation to the vent stack y[
UI Testing of the second unit to determine its operability 5l Until the first channel of the Kaman vent stack monitoring system is hi declared operable, a channel of the previous stack monitoring system will g,
remain in service and operable.
5 8'
E' l
Docket No. 50-346 License No. NPF-3 Serial No. 1014 December 21: 1983 Page 2 identical to the containment monitors, there was a high confidence level that this channel saturation problem would cccur on the vent stack monitors. We undertook the installation of a dedicated instrument grounding system for the
-micro-processor to resolve this problem which required five months to complete. The permanent grounding modification was
. completed on the containment and vent stack monitors in Ociu'ver 1983.
3.
Software Problems - In addition to the dedicated instrument grounding syst am, it was determined that sof tware changes to both the vent stack and containment monitors would be necessary to alleviate the iodine channel saturation problem. Testing of the modified software for the containment monitors required plant operation at greater than 70 percent power.
The 1983 Refueling Outage began before the software changes could be completed and tested. Therefore the modified software and dedicated instrument ground system were verified after the refueling outage when the station again attained greater than 70 percent power in November 1983. New software for the vent stack monitors was received and implemented in December, 1983.
Physical tie-in to the vent stack of one channel of the Kaman vent stack monitoring system was completed in early December 1983. Testing of the station vent sample line showed that sample line design flow rates revealed plateout of particulates resulting in lower than expected readings. Toledo Edison, Bechtel, and Kaman have determined that further modification and testing is required to obtain necessary data to resolve this problem by applying a correction factor to the monitor indications.
The correction factor will assure that accurate monitoring of stack releases is available.
Further engineering evaluation will be performed to determine an appropriate long term solution to the problem.
Toledo Edison now feels that the Station Effluent Monitoring System will be installed and operable by March 31, 1984. This completion date allows time for the following steps to be completed.
Further modification and testing to determine the appropriate correction factors Functional testing of the first channel to determine its operability Tie-in of the second channel of instrumentation to the vent stack Testing of the second unit to determine its operability Until the first channel of the Kaman vent stack monitoring system is declared operable, a channel of the previous stack monitoring system will remain in service and operable, m
^
Dockst No. 50-346 License No. NPF-3 Serial No.1014 December 21.-1983 Page 3 Based on the above factors, Toledo Edison requests an extension on the completion date for NUREG 0737 itens II.F.1.1 and II.F.1.2 until March 31, 1984.
Very truly'yours, f
e :- ~
RPC:SGW:nif cc: DB-1.NRC Resident Inspector I
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