ML071240406
| ML071240406 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 05/04/2007 |
| From: | Gerald Bichof Dominion, Dominion Nuclear Connecticut |
| To: | Document Control Desk, NRC/NRR/ADRO |
| References | |
| 06-0841A | |
| Download: ML071240406 (20) | |
Text
Dominion Nuclear Connecticut, Inc.
51100 Dominion Boulevard, Glen Allcn, Virgini.1 23060 K c b.Address: www.dom.com May 4, 2007 US. Nuclear Regulatory Commission Attention: Document Control Desk One White Flint North 11 555 Rockville Pike Rockville, Maryland 20852-2738 Serial No.06-084 1 A MPS LicNVDB RO Docket No.
50-336 License No.
DPR-65 DOMINION NUCLEAR CONNECTICUT, INC,:
MILLSTONE POWER STATION UNIT 2 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING INSTRUMENTATION TECHNICAL SPECIFICATION CHANGES During a conference call on April 20, 2007, the NRC requested additional information (RAI) from Dominion Nuclear Connecticut, Inc. (DNC) regarding a proposed change to the Millstone Power Station Unit 2 (MPS2) instrumentation technical specifications. The requested information is necessary in order folr the NRC staff to complete its review.
The response to the RAI is provided in Attachment I of this letter. Attachment 2 of the letter contains a calculation requested in thle conference call. The personal privacy information contained in Attachment 2 is exempt from public disclosure pursuant to 10 CFR 2.390(a)(6) as an unwarranted invas~ion of personal privacy. To permit placing this response in the Public Document Room, a redacted version is provided.
The additional information provided in this letter does not affect the conclusions of the significant hazards consideration discussi~on in DNC's original submittal dated November 8,2006.
In accordance with 10 CFR 50.91(b), a copy of this response is being provided to the State of Connecticut.
Should you have any questions about the information provided or require additional information, please contact Mr. Paul R. Willoughby at (804) 273-3572.
Very truly yours, Gerald T. Bischof u Vice President - Nuclear Engineering
Serial No. 06-0841A Docket No. 50-336 Response to Request for Additional Information Page 2 of 3 Attachments:
(2)
- 1. Response to Request for Additional lnformation
- 2. Calculation PA79-219-00767GE, Rev 01, dated 12/8/04, Millstone Unit 2 Wide Range Neutron Flux Channel Loop Uncertainty Commitments made in this letter: None.
cc:
U.S. Nuclear Regulatory Commission Region I Regional Administrator 475 Allendale Road King of Prussia, PA 19406-1415 Mr. J. D. Hughey NRC Project Manager Millstone Units i! and 3 U.S. Nuclear Regulatory Commission One White Flint North 1 1555 Rockville Pike Mail Stop 8B3 Rockville, MD 20852-2738 Mr. S. M. Schneider NRC Senior Resident Inspector Millstone Power Station Director Bureau of Air Management Monitoring & Radiation Division Department of Environmental Protection 79 Elm Street Hartford, CT 061 06-51 27
Serial No. 06-0841A Docket No. 50-336 Response to Request for Additional Information Page 3 of 3 COMMONWEALTH OF VIRGINIA
)
COUNTY OF HENRICO
)
)
The foregoing document was acknowledged before me, in and for the County and Commonwealth aforesaid, today by Gerald T. Bischof, who is Vice President - Nuclear Engineering, of Dominion Nuclear Connecticu~t, Inc. He has affirmed before me that he is duly authorized to execute and file the foregoing document in behalf of that Company, and that the statements in the document are true to the best of his knowledge and belief.
Acknowledged before me this My Commission Expires:_
Notary Public (SEAL)
Serial No. 06-0841A Docket No. 50-336 ATTACHMENT I INSTRUMENTATION TECHNICAL SPECIFICATION CHANGES RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION DOMINION NUCLEAR CONNECTICUT, INC.
MILLSTONE POWER STATION UNIT 2
Serial No. 06-0841A Docket No. 50-336 Response to Request for Additional Information Page 1 of 2 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION During a conference call on April 20, 2007, the NRC requested additional information (RAI) from Dominion Nuclear Connecticut, In~c. (DNC) regarding a proposed change to the Millstone Power Station Unit 2 (MPS2) instrumentation technical specifications. The requested information is necessary in order for the NRC staff to complete its review.
The information requested is provided below.
NRC Question No. 1.
The licensee stated in the License Amendment Request that the proposed changes 2 and 3 for 92 days Channel Functional Test frequency is based on topical report CEN-327. In evaluating CEN-327, by letter dated November 6, 1989, the NRC stated that the surveillance test intervals (STI) for the RPS and ESFAS could be extended contingent on the licensee's confirming that instrument drift occurring over the proposed ST1 would not cause setpoint values to exceed those assumed in the safety analysis.
The licensee should demonstrate that the drift occurring in each channel over the period of extended ST1 will not cause any setpoint value to exceed it's acceptable value established in the setpoint calculation.
Specifically The licensee proposed revising SR 4.3.1.1.2 and SR 4.3.2.1.2 to specify that the bypass function and the automatic bypass removal function shall be demonstrated OPERABLE during CHANNEL FUNCTIONAL. TEST once within 92 days prior to each reactor startup. The licensee quoted topical report CEN-327, "RPS/ESFAS Extended Test Interval Evaluation" in support this change. In NRC's evaluation of CEN-327, by letter dated November 6, 1989, the NRC stated, "The licenses must confirm that they have reviewed instrument drift information for each instrument channel involved and have determined that drift occurring in that channel over the period of extended ST1 will not cause the setpoint value to exceed the allowable value as calculated for that channel by their setpoint methodology." The staff requests additional information on the related drift evaluation the licensee has performed.
DNC Response The equipment vendor conducted a 24-month study of the instrument drift characteristics associated with the wide range nuclear instrument racks. This data was used as an input to DNC Calculation PA79-219-00767GE, Rev 01, "Millstone Unit 2 Wide Range Neutron Flux Channel Loop Uncertainty," dated December 8, 2004. This calculation was prepared to determine the Total Probable Error (TPE) for the associated instrument channels.
The determination of TPE takes into account the following
Serial No. 06-0841A Docket No. 50-336 Response to Request for Additional Information Page 2 of 2 parameters:
Process Measurement Accuracy, Sensor Calibration Accuracy, Rack Calibration Accuracy, Rack Drift, Rack temperature Effects, and Measurement and Test Equipment Allowance. The TPE is used as a basis for establishing the setpoint value such that the setpoint value will remain less than the allowable value over the period of the surveillance interval. Accordingly, with a 'TPE of k0.20 decade based on a 24 month drift value, the wide range neutron flux zero mode bypass bistable trip upper limit will be set at less than or equal to 6.3E-05%. Thus,the setpoint value will remain less than the allowable value of 1.OE-4% over the proposed 92 day surveillance interval.
During the conference call on April 20, ZOO7, regarding the above response, the staff requested a copy of DNC Calculation PA79-219-00767GE, Rev 01.
DNC Calculation PA79-219-00767GE, Rev 01 is provided as Attachment 2.
The personal privacy information contained in Attachment 2 is exempt from public disclosure pursuant to 10 CFR 2.390(a)(6) as an unwarranted invasion of personal privacy. To permit placing this response in the Public Document Room, a redacted version is provided.
Serial No. 06-0841A Docket No. 50-336 ATTACHMENT 2 INSTRUMENTATION TECHNICAL SPECIFICATION CHANGES CALCULATION PA79-219-00767GE, REV 01, DATED DECEMBER 8,2004, MILLSTONE UNlT 2 WIDE RANGE NEUTRON FLUX CHANNEL LOOP UNCERTAINTY DOMINION NUCLEAR CONNECTICUT, INC.
MILLSTONE POWER STATION UNlT 2
I.
- I
,,I ; -
Approved 1 11 1 7/03 Effective 11/21/03 CALCULATION TITLE PAGE Total Number of Pages: 17 Millstone Unit 2 Wide Range Neutron Flux Channel Loop llncertainty TITLE Approved 1 11 1 7/03 CALCULATIOh 1 1 un K,urn PA79-2 19-00767GE 01 CALCULATION No.
Revision No.
NIA.
NIA VENDOR CALCULATiON No.
Revision No.
Nl A VENDOR NAME NUCLEAR INDICATOR:
1 50.59 Evaluat:ion or Screen BCATI Attached ORWQA USBOQA OFPQA OATWSQA ONON-QA YES
[XINO INCORPORATES:
CCN NO:
AGAINST REV.
N/A Calc. Supports Calc. Supports DCIUMMODIEE?
Other Process?
M2-99046 N/A Ref. No.
Reference Determines the tolal probable error ofthe instrument loops for wide range neutron flux safety channels. Errors are determined for the control room indicators and the zero power mode bypass bistable for nonnal environmental conditions.
Revision 1 supporn the replacement of the wide range nuclear instrumentation drawers under DCR M2-99046 Rev. 0, and reformats the calculation to the requirements of the Design Control Manual.
ORIGINAL
@ Calculation represents the installed configuration and approved licensing condition (Calculation of Record) 0 NIA does not affect plant configuration (e.g., study, hypothetical analysis, ek.)
PreparedDesignw Engineer: (Print and Sign)
DCM 05-1A Rev. 01 1 I 01 17 t/
Page 1 of 1 111
Approved 9122104 Effective 9/27/04 1 1 Passport DATABASE INPUTS Page 2 Calculation Number: PA79-2 19-00767GE Revision:
Oi Vendor Calculation NumberIOther: NIA Revision: NIA CCN# NIA Calc Voided:
[7 Yes X No I
Superseded By:
NIA Supersedes CaIc:
NIA Discipline (Up to 10) 1,N 92-030-0 1 :3 12E2 I
I I
I I
I I
I I
i 1 I
I I
I I
U
- The codes required must be alpha codes designed for structure, system and component.
Comments:
I DCM 05-001B Rev 009-01
!C 2 01' 1 7 Page 1 of 1
Calculation No. PA79-219-0767GE, Rev. 01 I
1 Section & Title TABLE OF CONTENTS COVER PAGE................................................................................................................. 1 PASSPORT DATABASE INPUTS......................................,...,.......,...................,,......,................. 2 TABLE OF CONTENTS...,..............................,.,,.............................................,............................. 3 1.0 PURPOSE.................................................................................................................................. 4 2.0
SUMMARY
OF RESULTS..........................,..........................................................................4 3.0 DESIGN INPUTS & REFERENCES........................................................................................ 4 4.0 ASSUMPTIONS.............,.................................................................................................-........ 5 5.0-METHOD OF CALCULATION................................................................. 5 6.0 BODY OF CALCULATION................
............................................................... 1 0
7.0 REVIEWER'S COMMENTS AND RESOLUTION.............................................................. I I 8.0 AlTACHMENTS...................................,.......,,.........,.,...,................................................... 1 1 ThennoGamma-Metrics Document, Results of 24 Month Drift Testing" dated 1130198.... A1 -A2 Calculation Review Comment and Resolution Form...........................................,................ B 1 -B3 DCM FOITII 5-1D...........................................-...............,.........................,..................................
Cl Total Document Pages.......... -.............................................................................................. 17 Page 3 of 11
C a l c u 1 a t : i o n No. PA79-219-0767GE, R e v. 0 1 To determine the total probable error of the instrument loop for wide-range neutron flux channels. Errors will be determined for control room indicators and for the bistable output (5% power) to the Reactor Protection System for normal environmental conditions. Two channels of the wide-range nuclear instrumentation system are environmentally qualified to operate in a post-accident environment.
However, no use is made of the instrument uncertainty in determining an emergency operating procedure setpoint (Reference 3.2.2).
Revision 1 supports the replacement ofthe wide range nuclear instrumentation drawers under DCR M2-99046, Revision 0, and reformats the calculation to the requirements of the Design Control Manual. Revision bars are not used, because every section of the calculation is extensively revised.
1 2.0
SUMMARY
OF RESULTS The uncertainty of the wide-range nuclear instrumentation channels is summarized below.
Normal Control Room Indicators
+ 0.20 decade Zero Power Mode Bistable
+ 0.20 decade 3.O DESIGN MPUTS & REFERENCES 1
3.1 Design Inputs None 3.2 References 3.2.1 SP-ST-EE-286, Rev. 6, Guidelines for Calculating Instrument Uncertainties, July
,j 1995 I
3.2.2 Calculation No. S-01228-S2, Revision 3, Millstone Unit 2 Emergency Operating Procedure Setpoint Documentation 4
3.2.3 Calculation No. 92-030- 13 12E2. Revision 2, Millstone Unit 2 Power Range Neutron I
Flux Safety Channels Loop Uncertainty I
I 3.2.4 Millstone Unit 2 Procedure No. SP 2601D, Rev. 15 Change 1; Power Range Safety Channel and Delta T Power Channel Calibration I
Page 4 of 11
Calculation No. PA79-219-0767GE, Rev. 01 Millstone Unit 2 Final Safety Analysis Report Millstone Unit 2 Technical Spec$catic)ns Technical Evaluation M2-EV-01-0002 Rev. 0, Attachment 2, "Gamma-Metrics Report No. QTR 755, Rev. 0, Class IE Environmental QualiJication of Wide Range Channel Amplifier and Monitor Assemlbly and Power Range Monitor for Northeast Utilities, Inc. Millstone Nuclear Power Station - Unit 11" Engineering Record Correspondence, 25203-ER-03-00 1 3 Revision I, "Millstone 2 Wide Range Nuclear Instrument Indicated Flux Change as a Function of RCS Temperature Change" dated 5/2/03 Procedure SP 2401BC1, Rev. 1 Change 2, Channel "A" Wide Range Drawer Calibration Procedure SP 2401BC2, Rev. 1 Change 3, Channel "B" Wide Range Drawer Calibration Procedure SP 2401BC3, Rev. 1 Change 2, Channel "C" Wide Range Drawer Calibration Procedure SP 2401BC4, Rev. 1 Change 5, Channel "DM Wide Range Drawer Calibration ThemoGamma-Metrics Instruction Manual No. 761, Rev. 2, Neutron F l u Monitor For Millstone, VTM Number 25203-3 I 1 -003VTM Rev. 02 ThennoGamma-Metsics Document, Results of 24 Month Drift Testing, dated 1130198 Procedure DCM 04, Rev. 8 "Design Inputs and Design Verification" ASSUMPTIONS None METHOD OF CALCULATION A block diagram of a wide-range nuclear instrumentation channel is shown in Figure
- 1. Reference 3.2.1 describes the method used to combine instrument uncertainties.
The values used for the various components and their sources are described below.
Page 5 of 11
Ca1culat.ion No. PA79-219-0767GE, Rev. 0 1 Indicator 10-8 to 200
% power Bistable 0 9
' Fission Chamber Preamplifier S :i gna 1 output t o Prclcessor RPS 0.005 to 2x1010 nv Figure 1 Wide Range Nuclear Instrumentation Channel 5.1 Process Measurement Accuracv (PMA)
The flux seen by the detectors changes as reactor coolant system (RCS)temperature changes. Reference 3.2.8 determined the temperature decalibration factor to be 3 x la9 % per "F for temperature increases between 280°F and 540°. Changes in indicated wide range nuclear indication flux level due to RCS temperature changes below 280°F are negligible. PMA is then:
PMA =DeltaT x TDF x IS Where, Delta T = 540°F - 280°F = 260°F TDF = Temperature :Decalibration Factor IS = Instrument Span (1 0 decades/100% power)
PMA = 7.8 x 1 o ' ~
decade 5.2 Primary Element Accuracy (PEA)
This term is not applicable, because there is no primary element.
5.3 Sensor Calibration Accuracv (SCA)
The wide-range channels are adjusted at power levels to agree with the power range channels with 111 scale of 10.000 volts corresponding to 100 % power (References 3.2.9 through 3.2.12). This adjustment affects all calibration points within the signal processor. The power-range channels are adjusted to agree with the calorimetric calculation (see Reference 3.2.4). Sensor calibration accuracy is then the nonlinearity of the detector. From Reference 3.2.13, Section 1.1, this is equal to f 1 %. Then SCA is:
Page 6 of 11
Calculation No. PA79-219-0767GE, Rev. 01 SCA= 5 1.4%span SCA = f 1.4% span x (10 decades/100% span)
SCA = + 0.14 decade Sensor Drift (SD)
This term does not apply, because the fission chambers provide pulses proportional to the neutron flux and are not subject to drift.
Sensor Tem~erature Effects (STE)
The fission chambers are not sensitive to changes in temperature. Therefore, this term is not applicable.
STE = NIA Sensor Pressure Effect (SPE)
This term is not applicable.
SPE = NIA Rack Calibration Accuracy (RCA)
Reference 3.2.7 provides a linearity tern of 1 % (0.1 decade).
RCA~R
= + 0.1 decade For the zero power mode bypass, the bistable portion of the signal processor must also be accounted for. From Reference 3.2.7, the accuracy of the bistable is stated as rf:
0.25 % of the 10 decade span, or f 0.025 decade. The calibration procedures (References 3.2.9 through 3.2.12) have an acceptance criterion of 7.1 x 10-5 to 1.2 x 10-4 (5 0.001 decade). The larger of the two values will be used.
RCAzp = f 0.10 decade Page 7 of 11
Calculation No. PA79-219-0767GE, Rev. 01 Rack Drift (RD)
Reference 3.2.14 provides a drift value of 79 mV. This equates to rt 0.79 % span
(+ 0.08 decade, conservatively).
RD = f 0.08 decade Rack Temuerature Effects (RTE)
Reference 3.2.13, Section 1.l, provides a value of k 0.04 %l°C. Section 9.9.10.2.1 of Reference 3.2.5 states a control room temperature in winter of 72 OF. Technical Specifications (Reference 3.2.7, Section 4.7.6.1) allow operation with control room temperature I 100 OF. Therefore a temperature span of 30 O F is used to determine RTE.
RTE=f TDFxTSxTCFxIS Where, TDF = Temperature Decalibration Dactor (5 0.04 % spdoC)
TS = Temperature Span (30°F)
TCF = Temperature Conversion Factor (5/9 *CI0F)
IS = Instrument Span (1 0 decades11 00% span)
RTE = f 0.07 decade Measurement and Test Equipment Allowance (MTE)
Since the wide-range indication is adjusted to agree with the power-range indication, MTE is the term from Reference 3.2.3, + 0.1 % power.
MTE = f 0.1 % power x (1 0 decades11 00% power)
MTE = f 0.01 decade Radiation Allowance (RA)
This term is not applicable (see Section 1.0).
RA = N/A Page 8 of 11
Calcu1at:ion No. PA79-219-0767GE, Rev. 01 5.12 LOCNHELB Effects (DLH) 1 This term is not applicable (see Section 1 -0).
DLH = N/A 5.13 LOCA/HELB Effects (PLH)
This term is not applicable (see Section 1.0).
PLH = N/A 5.14 Overall Indicator Accuracy (OM)
This term is included in the accuracy specification of Section 5.3 above. Therefore:
OIA = N/A 5.15 Overall Digital Accuracy (ODA)
This term is not applicable.
ODA = N/A I
5.16 Insulation Resistance Effects (IRE)
This term is not applicable (see Section 1.0).
RA = N/A 5.17 Seismic Effects (SE) 1 This term is not applicable. The design basis of Millstone 2 does not require reactor protection coincident with or immediately following an earthquake (Reference 3.2.5, Section 7.2.1). Following an operating-basis earthquake, a determination will be made whether to continue to operate or shut down the plant. Following a safe-shutdown earthquake all safety related components, systems and equipment will be evaluated extensively for post-seismic function (Reference 3.2.5, Section 5.8.6.3).
Note that the wide range nuclear instrumentation drawers are seismically qualified (Reference 3.2.8).
Page 9 of 11
Calculation No. PA79-219-0767GE, Rev. 01 Other Effects (OE)
No other effects are considered significant.
OE = N/A BODY OF CALCULATION Normal Conditions Control Room Indicator The total probable error, over the power range, (TPE~R) is given by:
TPEPR = PMA k [SCA~ + R C A ~ ~ ~
-k R D ~
+ RTE~ e MTE~]"~
T P E ~ R
= 7.8 x lov8 + 0.20 decade PMA is insignificant when compared to the remaining combined random errors.
Therefore, TPEpR = rl: 0.20 decade Normal Conditions Zero Power Mode Bwass The total probable error (TPEzp) is given by:
TPEzp = PMA + [SCA~ + R C A ~ ~
+
+ RTE' + MTE~]"
TPEzp = 7.8 x 1 o - ~
f 0.20 decade PMA is insignificant when compared to the remaining combined random errors.
Therefore, TPEzp = k 0.20 decade Page 10 of 11
Calculation No. PA79-219-0767GE, Rev. 01 REVIEWER'S COMMENTS AND RESOLUTION Review Method Check of each original computation and review to the requirements of Reference 3.2.15.
Reviewer's Comments See pages B1 and 32.
ATTACHMENTS A. ThermoGamma-Metrics Document, "Results of 24 Month Drift Testing" dated 1/30/98 B. Calculation Review Comment and Resolution Forms C. DCM Form 5-ID Page 11 of 11
RESULTS OF 24 MONTH DRIFT TESTING
Background:
In December of 1995, a drift test was begun on the combination Wide Range, Power Range neutron flux monitor used at the St. Lucie station. This unit contains components similar or identical to the standard GAMMA-METRICS Wide Range Channel Signal Processor and the entire Power Range Channel. In January 1998, the test was completed.
Results:
The test resultsare grouped based on the circuit tested. Part numbers of assemblies that have similar or identical drift characteristics are listed in the next column. The drift value listed is the difference between the highest observed value and the lowest observed value during the two year period.
CIRCUIT TESTED I SIMILAR ASSEMBLIES I DRIFT I
1 Wide Range Log Countrate (Level)
I E%
Wide Range Log Amplifier Gevel) 1 100623 100950 I
I Bistable Setpoint 1 100277 1
Bistable Reset I same as bistable setpoint 37 mV Isolated Output (Level) 101033 201621 12 mV Power Range Calibrated SumIAverage 100972 1101039 For the Isolator and Bistable values, the worst case ofthree circuits was used. For the Power Range UpperLower value, the worst case of two circuits was used. For all others, only one circuit was tested.
Interpretation:
In order to use the data properly it is important-to interpret the data correctly. First, the values above are for time drift only and do not include other accuracy variables such as:
temperature drift, alignment error, alignment testequipment error, or adjustment resolution.
Temperature drift values can be obtained fiorn thk qualification report issued with the system or directly from GAMMA-METRICS. Second, for the Wide Range Log Level instrument the data does not include the Bandpass Filter Redifier in the Wide Range Amplifier.
The drift value listed is the difference between the highest reading and the lowest reading.
This is unrelated to the starting value, the average value, or the median value. Most circuits drift primarily in one direction from the initial value. And almost no circuit will drift equally above and below the average. The most conservative approach is to assume the circuit will drift above and/or below the initial value by the drift value listed above. For example: The Wide Range Log Countrate circuit was adjusted to 5.380VDC at 100KHz. During the next two years the highest value expected is 5.380+0.079=5.459VDC and the lowest value is 5.380-0.079=5.301VDC. Note that in some setpoint methodologies the time drift is combined with other errors using the square root of the sum of the squares method.
Summary:
GAMMA-METRICS has concluded a two year drift test and reported the results here. Plants can now use this data to justify the current surveillance schedule or build a case to increase surveiltance intervals. If the plant has any que~tions or needs addition information, they should contact GAMMA-METRICS.
I