ML17312B016
| ML17312B016 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 10/23/1996 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML17312B015 | List: |
| References | |
| NUDOCS 9610300274 | |
| Download: ML17312B016 (12) | |
Text
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oO UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 205Rr0001 SAF TY EVA UATION BY THE OFFICE OF NUCL AR REACTOR REGULATION RELATED TO AHENDH NT NO.
109 TO FACI TY OP RAT NG LICENSE NO. NPF-41 AH N N
NO. 101 TO FACIL TY OP T
C NS NO. NPF-51 AN 81 TO FACI TY 0 G
C NS NO PF-74 ARI ONA PUBLIC SERVIC OHPANY T AL.
PA 0 VERD NUCLEAR GENERATING STATION UNIT NOS.
1 2
AND 3 DOCKET NOS.
STN 50-528 STN 50-529 AND STN 50-530
- 1. 0 INTRODUCTION By application dated June 17, 1996, the Arizona Public Service Company (APS or the licensee) requested changes to the Technical Specifications (Appendix A to Facility Operating License Nos.
NPF-41, NPF-51, and NPF-74, respectively) for the Palo Verde Nuclear Generating Station, Units 1, 2, and 3.
The Arizona Public Service Company submitted this request on behalf of itself, the Salt River Project Agricultural Improvement and Power District, Southern California Edison
- Company, El Paso Electric Company, Public Service Company of New
- Hexico, Los Angeles Department of Water and
- Power, and Southern California Public Power Authority.
The proposed changes would modify the technical specifications (TS) to change (1) the reference method for calculating dose conversion factors (DCFs) to be used in dose calculations, and (2) the upper and lower limits for operating pressurizer pressure to account for new instrument uncertainties and to reduce the allowed operating band.
.D
~lUAlIIIN Dose Conversion Factors Calculation of dose equivalent iodine-131 is used for evaluating the allowable radionuclide concentrations in the reactor coolant and assessing thyroid doses from releases of radioactivity resulting from design basis accidents (DBAs).
Dose equivalent iodine-131 is defined as that concentration of iodine-131 (microcuries/gram) that alone would produce the same thyroid dose as the quantity and isotopic mixture of iodine-131, iodine-132, iodine-133, iodine-134, and iodine-135 actually present.
A required parameter for translating radioiodine concentration to a
radiological dose to the thyroid is the thyroid DCF.
Revision 1 of NUREG-1432, "Standard Technical Specifications, Combustion Engineering Plants," specifies thyroid dose conversion factors that can be used for calculating dose equivalent iodine-131 at Combustion Engineering plants.
The three references for thyroid dose conversion factors are:
(1) TID-14844, which was published in 1962; (2) Table E-7 of Revision 1 to Regulatory Guide
- 1. 109, "Calculations of Annual Doses to Han from Routine Releases of Reactor 9hi0300274 9bi023 PDR',ADQCK 05000528 P
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Effluent for the Purpose of Evaluating Compliance with 10 CFR Part 50, Appendix I," which was published in 1977; and (3) ICRP-30, which was published in 1980.
Table 1-lists the thyroid DCFs contained in the aforementioned documents.
In a safety analysis contained in its application, the licensee concluded that the requested change to ICRP-30 thyroid DCFs would reduce calculated thyroid dose consequences of design basis accidents by approximately 30 percent, which, in turn, would increase design margin and fuel management flexibilitywhen performing cycle-specific reload analysis.
The licensee stated in its application that the net effect of using the additional design margin will be radiological consequences to the thyroid that are less than or equal to current licensing basis dose consequences.
Radiological consequences to the whole body were:not addressed by the
- licensee, and are beyond the scope of its application.
The staff has reviewed the licensee's request and performed independent check calculations to determine the radiological consequences to the thyroid of the requested change to TS 1. 10 and associated Bases.
The staff calculated thyroid doses using thyroid DCFs contained in TID-14844 and ICRP-30 for a design basis large break loss-of-coolant accident (LOCA) and a steam generator tube rupture (SGTR) accident.
The results of the staff's analysis indicate that for the LOCA and SGTR accidents, replacement of TID-14844, thyroid DCFs with ICRP-30 thyroid DCFs would reduce calculated thyroid doses by greater that 20 percent for individuals located at the exclusion area
- boundary, low-population zone, and control room.
Similar reductions in postulated thyroid doses are expected for other design basis accidents by replacing TID-14844 thyroid DCFs with ICRP-30 thyroid DCFs.
Use of ICRP-30 DCFs is consistent with NUREG-1432 as well as the revisions to 10 CFR Part 20, which utilizes ICRP-30 recommendations and data.
The staff therefore concludes that the proposed change is acceptable.
Change in Pressurizer Pressure Operating Limits The safety analyses for normal operating conditions and anticipated operational occurrences assume initial conditions within the allowed steady state envelope.
The limiting condition for operation (LCO) provided in TS 3.2.8 for minimum and maximum RCS pressures, as measured at the pressurizer, ensure that the actual value of pressurizer pressure is maintained during normal operation within the range of values used in the safety analysis, thereby providing assurance that the minimum departure from nucleate boiling ratio (DNBR) will meet the required criteria for each of the transients analyzed.
Table 2 provides a comparison of the old and proposed values of the upper,and lower pressurizer pressure l,imits for the Safety Analysis and the TS LCO. The proposed TS 3.2.8 LCO accounts for new instrument uncertainties, and reduces the allowed operating band.
These more restrictive initial conditions are used in bounding safety analyses for some events previously analyzed on cycle-specific bases, which will provide more flexibility in fuel management in future cycles.
The reduction of the upper limit from 2,300 psia to 2,295 psia accommodates an increase in pressure transmitter instrument uncertainty.
The increase in the lower limit from 2,025 psia to 2,130 psia accommodates the new
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instrument uncertainty, and provides the increased flexibility in fuel management in future cycles.
The current pressurizer pressure upper and lower safety analysis analytical limits are 2,325 psia and 2,000 psia, respectively.
These were the analytical limits from which the current TS 3.2.8 LCO values were derived, with a 25 psia uncertainty.
Surveillance procedures that verify compliance with TS 3.2.8 previously used 2,025 to 2,300 psia as the acceptance range which included the total loop uncertainty, including the pressure indicator.
The new safety analysis analytical values for the upper and lower limits will be 2,325 and 2, 100 psia, respectively.
Pressure transmitter uncertainty has increased due to a change to the transmitter temperature effect specification communicated to ITT Barton users in an Industry Advisor letter dated September 14, 1995.
The original pressure uncertainty specification due to transmitter temperature variation was 21 percent of full span per 100'F.
The new specification includes an additional 3 psi of uncertainty per 100'F.
When the additional transmitter bias of 3 psi is accounted for, the loop uncertainty results are +28.2/-28. 1 psi, which is greater than the allowed
%25 psi value.
The new loop uncertainty value was obtained by rounding up to a more conservative value of i30 psi uncertainty.
Using the new %30 psi uncertainty value, the new TS LCO upper and lower values for pressurizer pressure are modified to 2,295 psia and 2, 130 psia, respectively.
TS 3.2.8 establishes the range of the initial conditions for pressurizer pressure considered for transients analyzed in the safety analyses.
The licensee stated that the proposed change associated with the pressurizer pressure will implement a more restrictive acceptance criteria in surveillance procedures to ensure that safety analysis assumptions are maintained.
The licensee further stated that the more restrictive range of operation is currently analyzed and bounded by the existing safety analyses.
The staff reviewed the licensee's submittal, and agrees with the licensee's conclusion that the more restrictive range of operation is bounded by the existing safety
- analyses, and is therefore acceptable.
3.0 STAT CONSU T TION In accordance with the Commission's regulations, the Arizona State official was notified of the proposed issuance of the amendments.
The State official had no comments.
- 4. 0 NV RON NTA CONSIDERATION The amendments change a requirement with respect to the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20.
The NRC staff has determined that the amendments involve no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure.
The Commission has previously issued a proposed finding that the
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amendments involve no significant hazards consideration, and there has been no public comment on such finding (61 FR 47963).
Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendments.
5.
~LU ON The Commission has concluded, based on the considerations discussed
- above, that (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed
- manner, (2) such activities will be conducted in compliance with the Coaeission's regulations, and (3) the issuance of the amendments will not be inimical to the common defense and security or to the health and safety of the public.
Attachments:
1.
Table 1
2.
Table 2
Principal Contributors:
A. Huffert H. Balukjian Date:
October 23, i996
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TABLE 1
THYROID DOSE CONVERSION FACTORS REFERENCED IN COHBUSTION ENGINEERING STANDARD TECHNICAL SPECIFICATIONS IODINE
~SOTOP I-131 I-132 I-133 I-134 I-135 TID-14844 Q~mC~i 1.48 x 10 5.35 x 10 4.00 x 10'.50 x 10 1.24 x 10 RG 1.109
~Rem Ci 1.49 x 10 1.43 x 10 2.69 x 10'.73 x 10 5.60 x 10 ICRP-30
~Rem Ci 1.08 x 10 6.44 x 10 1.80 x 10'.07 x 10 3.13 x 10
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TABLE 2 COHPARISON OF PRESSURIZER PRESSURE LIHITS Upper Limit (psia)
Lower Limit (psia)
Safety Analysis 01d New 2,325 2,325 2,000 2,100 Tech Spec LCO 2,300 2,295 2,025 2,130
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