ML19256D703
| ML19256D703 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 07/12/1976 |
| From: | Eisenhut D Office of Nuclear Reactor Regulation |
| To: | Goller K Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 7910220620 | |
| Download: ML19256D703 (6) | |
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Piar.t Systems Branch was requested to reviev proposed codificatio.-
to the Tachrlical Specifications for Three f: file Islar.d Unit 1 (T'!I-1) :n d t c' provide the results and conclusions of the evaluntion.
Fe h v2 cenrlatai our review of the T':I-l subnittal, dated I'acerbcr 12. 1973, and hav:
concluded that the proposed changes to the T'!I-1 Technical Specificatic--,
are acceptable.
The enclosed report provides the details of our evaluation and the basis for our conclusion.
D. G. Eisenhut, Assistant lirectcr for Ooerational Technolo;"
Division of Neratinc "eactcrs
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EVALUATION REPORT PROPOSED TECHNICAL SPECIFICATION CHANGES THREE MILE ISLAND UNIT 1 (TMI)
1.0 INTRODUCTION
By letter dated December 12, 1975, the !!etropolitan Edison Company (the licensee) requested certain changes to the TMI Technical Specifications in regard to:
(1) the method for checking, and (2) the interval between calibrations for certain radiation monitors.
Our evaluation of this request is described below.
2.0 BACKGROUND
2,.1 Instrument Channel Check The design of the licensee's radiation monitoring system provides the capability for verifying the operability of the sensing device and tonitoring channel by use of low activity check sources.
However, in certain locations the continuous background radiation level is such that the incremental increase in counts per minute (CPM) due to the insertion of the check source is minimal.
The licensee states that, when the back-ground reading exceeds twice the value which would result from the check source alone, the background reading is sufficient to meet the requirements of Specification 1.3.3 (Instrument Channel Check).
The definition of " check" is:
an instrument 1453 098
. channel check is a verification of acceptable performance by observation of its behavior and/or state; this verifica-tion includes comparison of output and/or state of independent channels measuring the same variable.
The licensee states that the proposed approach satisfies the requirements of an instrumet t channel check, as defined above, and will verify that the monitor responds properly.
2.2 Calibration Interval The licensee has stated that three area radiation monitors, RM-G6, RM-G7, and RM-G8 are located in high radiation areas of the reactor building and are inaccessible during power operation.
The licensee proposes that the present requirements of quarterly calibration be modified to read as follows:
" quarterly or at the next scheduled reactor shutdown following the quarter in which the calibration would normally be due, if a shutdown during the quarter does not occur."
The licensee states that the current requirement is contrary to the "as low as practicable" (ALAP) objective of minimal radia-tion exposure to plant personnel.
The three monitors are located in areas where the radiation levels are in excess of 100 mr/hr during reactor operation.
3.0 EVALUATION 3.1 Instrument Channel Check The licensee has stated that when the background readiag is twice that of the check source alone, it meets the require-1453 099
. ments of an instrument channel check as defined in the Tech Specifications.
The licensee has further stated that, until the background reaches this level, the insertion of the check rource provides a noticeable increase in the output reading to verify instrument operability.
A comparative verification is made, where possible, for those instruments in locations where the backround exceeds the leve) for which the check source provides a detectable increase.
Where comparative readings are not possible, special procedures (e.g., inserting an external source of a higher value) will be used to verify instrument operability.
We have verified that the definition of channel check in the licensee's Technical Specifications is comparable to the definition in our Standard Technical Specifications.
We have concluded, based on the information provided above that the proposed change to the licensee's Technical Specific ti a ons relating to the instrument channel check meets the requirements of IEEE Std 279, " Criteria for Protection Systems for Nuclear Power Stations," Section 4.9, " Capability for Sensor Checks" and is, therefore, acceptable.
3.2 Calibration Interval The licensee has stated that radiation monitors RM-G6, RM-G7 and RM-G8 are located inside the containment in areas where the radiation levels exceed 100 mr/hr during reactor 1453 100
_ operation.
The current Technical Specifications require calibration every quarter.
The licensee has requested that the calibration interval be changed to a period that could be as much as 18 months for the detectors identified above.
We concur with the licensee that the existing requirement is contrary to the ALAP objective in regard to pers'ennel exposure.
The current requirements for calibration intervals in our Standard Technical Specifications are every 18 months for all instruments.
We requested the licensee to identify the manufacturer of the monitoring system and to identify the location and describe the safety related functions of the three radiation monitors.
The licensee stated that the system is supplied by Victoreen, who has also supplied radiation monitoring systems to other nuclear power plant owners.
Radiation monitors RM-G6, and BM-G7 are located near the reactor vessel head and are required during refueling operations.
Radiation monitor RM-G8 is located in the dome area of the containment and is utilized to monitor gross failures such as a LOCA.
The licensee's current operating procedure, 1502-1,
" Refueling Procedure - Refueling Operation," requires that 1453 101
O
_3-the RM-G6 and RM-G7 setpoints be adjusted to a lower value during refueling operations.
The licensee has committed to include, in this procedure, a requirement to calibrate RM-GS and RM-G7 prior to proceeding with refueling operations.
We conclude, based on the information described above, that the change in the calibration interval for RM-G6, RM-G7 and RM-G8 meets our requirements for calibration intervals as delineated in our Standard Technical Specifications and is, therefore, acceptable.
4.0 CONCLUSION
On the basis.of our evaluation of the information provided, we conclude that the licensee's proposed change, in regard to both the method of checking and the extension of the calibration interval for the above cited instruments, is acceptable.
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