ML20005E225
| ML20005E225 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 12/27/1989 |
| From: | Keuter D SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | Knighton G NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| AGM-NUC-89-270, NUDOCS 9001040120 | |
| Download: ML20005E225 (4) | |
Text
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,e SMUD SACAAMENTo MUNICIPAL UTILITY DISTRICT D 6201 S Street. P.o. Box 16830. Secremento CA 95852-1830.(916) 462 3211 AN ELECTRIC SYSTEM SERVING THE HEART OF CALIFORNIA-
.AGM/NUC 89-270 December 27, 1989 U. S. Nuclear Regulatory Commission Attn: Document Control Desk e
Hashington, DC 20555 i
Docket No. 50-312 Rancho Seco Nuclear Generating Station License No. DPR-54 RANCHO SECO HEATHER STATION UPGRADE
REFERENCES:
- 1) District Letter GCA 87-029, Heteorological System and Program Improvements (CCTS Item No. T870603400)
- 2) NRC Inspection 86-31 Meteorological Tower Lightning Protection System (CCTS Item No. T861031108)
- 3) Survey of Proposed Primary Meteorological Monitoring Site at Rancho Seco Nuclear Generating Facility, Prepared for SMUD by Stone & Webster Engineering Corp., Hay, 1989 Attention: George Knighton The District has previously committed to upgrading the Rancho Seco meteorological system.
References 1 and 2 are Computerized Commitment Tracking System (CCTS) items that discuss planned upgrades of the meteorological system.
The attached is an update of that plan and our Q~
commitments.
Members of your staff with questions requiring additional information or clarification may contact Steve Crunk at (209) 333-2935, extension 4913.
Sincerely, w
v Dan R. Keuter Assistant General Manager Nuclear Attachments g
Al'/f,/ [Md cc; J. B. Hartin. NRC, Halnut Creek I l A. D'Angelo, NRC, Rancho Seco 00[
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RANCHO SECO NUCLEAR GENERATING STATION D 14440 Twin Cities Road, Herald, CA 95638 9799;(209) 333 2935
v ATTACHMENT 1 1.
PROBLEMS TO BE SOLVED The present meteorological equipment is difficult to maintain in calibration and therefore in service. These maintainability problems affect the availability of the system and are due to:
1.
The present large free-standing 60 meter tower creates a micro-climate which affects the 10 meter wind speed and wind direction readings.
It is virtually impossible to eliminate the effect of the existing free-standing tower on instrumentation at 10 t
meters.
Reg. Guide 1.23 recommends that the wind sensors be positioned at least two tower diameters (34 feet) from the tower in I
order to minimize the tower micro-climate effects._ It is not i
practical to install a 34 foot horizontal boom on the present tower i
so that the wind sensor instrumentation can be pr,sitioned in I
accordance with Reg. Guide 1.23.
2.
The present 60 meter tower is immediately adjaceni. to a paved i
blacktop road and parking lot which generate thermal waves.
This effect, especially prevalent on hot, sunny suarner days, affects the i
10 meter temperature readings and subsequently the delta-temperature values.
3.
Transmission of data is a current loop from the 60 meter tower to l
the Control Room. The current loops are long and any change in I
leakage or resistance affects current loop calibration.
1 4.
The commercial grade equipment that is presently installed for the i
current loop is not capable of meeting strict tolerance requirements.
For example, this type of equipment is not able to 1
reliably push a current loop a distance of 3/4 mile from the tower to the Control Room.
5.
Rainfall causes water intrusion into the cables and cabinets that are located in the equipment shack at the base of the 60 meter tower. This condition affects availability.
l 6.
The present 60 meter tower does not have adequate lightning l
protection.
The tower itself is grounded, but the monitoring l
equipment is not.
7.
An emergency generator is located at the base of the tower to supply l
electrical power to the instrumentation in case of a power interruption. However, the emergency generator continues to supply l
power even after the normal power supply is restored.
There is no l'
Control Room annunciator or indication that this generator is
- running, i
t
L,*
l ATTACHMENT 2 II. PLANNED SOLUTIONS 1
listed below are the District's planned solutions for each of the previous problems.
1.
Reference 3 is a study performed to assess the location of meteorological tower instrumentation.
The study confirms the present tower is suitable for the 60 meter instrumentation.
However, the present tower is not suitable for the 10 meter instrumentation; therefore, a new 10 meter high tower will be constructed specifically for the 10 meter instrumentation.
The District will locate the new 10 meter tower approximately 150 feet north of the present 60 meter tower.
2.
The present 10 meter temperature sensors are subject to the thermal effects of the adjacent blacktop road.
The new 10 meter tower and instrumentation located 150 feet north of the present tower will eliminate this thermal problem. The ground surface around the new tower will remain in the natural state as much as possible.
3.
The current loop used for data transmission will be replaced with digital transmission via a modem at each end; i.e., one at the meteorological tower instrumentation and the other at the Control Room. This type of data transmission has been successfully demonstrated by the Rancho Seco IDADS system and at other nuclear stations to be trouble free and accurate.
Redundant paths will transmit data from all sensors so that either transmission system can be taken out of service for maintenance or testing with no loss of data.
Redundant computers will process the incoming data at the Control Room for data storage, data retrieval, and report preparation.
4.
The new equipment will meet strict tolerance requirements.
5.
New cable will be included with all new instruments installed on the 10 meter and 60 meter towers.
In addition, new equipment racks and enclosures will be installed in the service building located at the base of the 60 meter tower. All new cables will use connectors that can withstand the anticipated environmental exposure.
6.
All equipment will have proper grounding and power and signal lead protection.
This grounding and protection will provide the needed lightning protection.
7.
The District will provide indication in the Control Room to display when the meteorological tower emergency generator is in use.
= i:
ATTADMulT 3 III. COMPLETION SCHEDULE 1.
Construction of the new 10 meter tower and installation of the new equipment is scheduled for completion in June,1990.
- 2. 1 Testing of the system and turnover to Operations should be completed in August, 1990.
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