NLS8700560, Application for Amend to License DPR-46,changing Tech Specs to Revise pressure-temp Limits for Heatup & Cooldown,Normal Operation & Pressure Testing.Fee Paid
| ML20236K651 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 10/28/1987 |
| From: | Kuncl L NEBRASKA PUBLIC POWER DISTRICT |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| Shared Package | |
| ML20236K655 | List: |
| References | |
| NLS8700560, NUDOCS 8711090298 | |
| Download: ML20236K651 (12) | |
Text
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GENErML OFFICE .
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.NLS8700560 '!
October _28, 1987 1
, ~j U.S. Nuclear Regulatory Commission Document Control Desk J i
Washington, D.C. 2]555 Gentlemen: ,
-l
Subject:
Proposed Change No; 48 to .the Cooper Nuclear Station' Technical. Specifications,-NRC DocketLNo 50-298, DPR-46:
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Reference:
- 1) Letter;NLS8700310,- from G.iA. Trevors to U.S.;NRC. 'i dated July 6. 1987, . " Reactor Vessel ' Material
' Surveillance Program" ;
2). General . Elb.ctric -. Report' . MDE-103-0986, dated .
May 1987, " Cooper Wuclear Station Reactor Pressure j Vessel'. Surveillance Materials Testing and Fracture? ;
Toughness Analysis" In accordance with the applicable ' provisions specified 'in.
10CFR50, Nebraska Public Power? District requests;certain changes.-
to the Technical Specifications forLCooperLNuclear Station. -The- i proposed changes would revise the' pressure-temperature limits;for q heatup and cooldown, normal operationUand pressura testing.
These revisions are required in Lorder-to reflect the resultsJoff the fracture toughness analyses 4and surveillance tests-performed on the reactor vessel material' specimens from the~ first- reactor :
vessel ' surveillance . capsule. These results (Reference 2)) were previously-submitted under Reference 1.
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A discussion and the applicable revised-Technical Specification.
pages are contained in the attachment. These:proposeil changes to.
the Technical Specifications have been evaluated with respect to the requirements of 10CFR50.92'., The resultsiof the 110CFR50.92 :
evaluations are-included in' the attachment. .
By copy of this letter and the' attachments 3 'the_ appropriate State of Nebraska .' Official- is being notified in taccordance'. with
[< a '
10CFR50.91(b). .' f This proposed change 'incorporatesJail amendments to;the Cooper Nuclear Station Facility 10perating License throcgh+ Amendment;111'. k
[ j$7 issued September 17, 1987. b 4
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'NLS87 Page.2~-
October 28, 1987' This' change has .been reviewed by1the necessary Safety. Review -
Committees and payment of $150 is submitted in.accordance with 10CFR170.12. In addition to the signed original, 37. copies. of this submittal are also submitted for your use.
Shou ~ld you have any questions'.orl require additional .information, please contact me. .
Since ly, h
L. G. Kuqcl Vice-President. - Nuclear l
LGK/mtb:dmr31/1 Attachment cc: H. R. Borchert.
Department of Health State of Nebraska NRC Regional Office Region IV- . .
Arlington, TX .
u NRC Resident Inspector Office Cooper Nuclear. Station a .
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NLS87 Page 3 October 28, 1987 STATE OF NEBRASKA) l
)ss PLATTE COUNTY )
L. G. Kunc1, being first duly sworn, deposes. and says that he is an authorized representative of the Nebraska Public Power District, a public corporation and political subdivision of the .
State of Nebraska; that he is duly authorized to submit this I request on behalf of Nebraska Public Power District; and that -I the statements contained herein are true to' the best of his l knowledge and belief. .
/
(
L. G.; Kuncl ^
Subscribed in m resence and sworn to before me this d day of (G_ ; , 1987.
R RiOTARY PlfByC /
aum mm.m. -
COLLEEN M. KUTA
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Revised Technical Specifications for-Pressure-Temperature Limits-Revised Pages: 132 154 133 155 146 156' 147 157 i
The first reactor vessel surveillance capsule was removed from Cooper! Nuclear l Station following Cycle 9 operation. _ Specimens of plate, weld, and heat . -
, I affected zone (HAZ) material from the CNS reactor vessel were contained in the I I
surveillance capsule, along with flux wires for determination of fluence values. -i The General Electric -Company was contracted to conduct Charpy V-Notch impact : l and hardness testing - and uniaxial tensile ' testing of these specimens. The results of this testing and the fracture toughness analysis of the CNS reactor vessel were submitted toL the staff in' General Electric Report MDE-103-0986, 1 under Letter NLS8700310, dated July 6,1987, . G. A. Trevors . to USNRC. ,
The test data and analyses show higher shifts. in nil-ductility transition temperature than were previously predicted. Therefore, .new. .
pressure-temperature operating limit curves are required in.accordance with 10CFR50 Appendices G and H. Each of the proposed. changes is~ discussed in detail under items a. through d. below,
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- a. The proposed change would delete Figure 3'6.1 on page 154. Currently, Figure 3.6.1 is used to detenmine the shift in the nil-ductility.
transition temperature. The shift is then ' added to the . temperature (T-RT 3.6.1.b, or 3.6.2 (depending on mode of4 opera 52In)) from Figure 3,6.1.a, The temperature plus the shift defines the minimum required temperature of the reactor vessel steel and prceess fluid for a given )
reactor pressure and mode of operation.
The proposed change would eliminate the need for Figure 3.6.1, by adding the Adjusted Reference Temperature (ART) to the temperature versus pressure curves in Figures 3.6.1.a, 3.6.1.b, and 3.6.2.(T-RT'h Ad k)s t equal to the reference nil-ductility transition temperature.(RTNnT) plus ]
DT due to irradiation embrittlement.- The metroH Lof the shift in RT '
incorporating th"e shift into Figures 3.6.1.a, 3.6.1.b, and 3. 6.2 is described in Items b. and c. below. Since the shift is already accounted for in the proposed revised Figures 3.6.1.a. 3.6.1.b, and 3. 6. 2; - Figure 3.6.1 is no longer required.
R b.
The proposed change would revise Figures 3.6.1.a and 3.6.1.b.on pages.155 and 156, respectively. These . changes are due to the results of J the ; <
surveillance testing and fracture toughness ~ analyses performed . on the - i
. reactor vessel plate, weld and HAZ. specimens from the'first ' surveillance I capsule. First', to make the figures easier to use, the multiple curves have been eliminated in favor of ' a single curve. The single curve ,
represents the minimum temperature required for the most limiting reactor vessel material at that point in the curve. Thus, instead of having a complete curve showing the minimum temperature' required at the feedwater c__________. _ _ _ _ _ _ _ _ _ __ - - _ _ _ _ _
l nozzles for all reactor pressures, the single curve would show the i feedwater nozzles as the limiting material between approximately 100 psig ]
and 600 psig. Similarly, beltline materials are limiting at higher j pressures and vossel closure studs-are limiting at lower pressures. This 1 change will provide a single curve for heatup/cooldown and a single curve fJ for critical operation, which identifies the minimum temperature required at any reactor pressure, by simply remaining in the region to the right of the curve.
The second proposed change to Figures 3'.6.1.a and 3.6.1.b is to plot I temperature (T-RT NDT) Pl us ART instead of (T-RT ) only. ART equals the j original RT for the limitin6 beltline matedal, plus the shift in 1 RT NDT alcu ed at twelve (12) effective full power years (EFPY) of j operation. At points on the curve where beltline materials are.not !
limiting, the curve shows the minimum required temperature for the i material that is limiting, based on RT Pl ua any margin specified by NDT 10CFR50 Appendix G or the ASME Code. j l
The final change in Figures 3 6.1.a and 3.6.1.b is that the new curves represent higher' minimum required temperature forLthe vessel beltline ,
materials. This is due to higher measured shifts in reference j nil-ductility transition temperatures (RT than were previously !
predicted. Since the RT ND shifts are high$DT) r, and the new curves include Adjusted Reference Temperature (ART - RTNDT + s t), e gures show higher minimum temperatures The RT shif t measured for the most limiting beltline plate specimen N
was74hTand for the worst case weld metal the measured shift was 55 F.
These measured shifts were then compared to the shift that woald be ,
predicted by Regulatory Guide 1.99, Revision l', for the same plate and j weld material under the same fluence conditions. RG 1.99 predicts a !
shift of 31 F for the plate and 34 F for the weld. RG 1.99, Revision 1, l under predicts the shifts by a factor of 74/31 or 2.39 for plates and i 55/34 or 1.62 for welds. This was taken into account in Figures 3.6.1.a and 3.6.1.b when calculating the RT MDT shift and corresponding ART. The method used to calculate RT shi n was to use the RG 1.99, Revision 1, correlationmultipliedbya$ctorof2.39forplatesand1.62forwelds.
Thus, Figures 3.6.1.a and 3.6.1.b take into account the actual data from the surveillance capsule. Details of the calculations described above are contained in General Electric Report MDE-103-0986.
- c. The proposed change would make several modifications to Figure 3.6.2 on page 157.
First, since the bottom head of the reactor vessel is not in the core beltline, it will not be subjected to a fluence which is high enough to cause a shi.ft in the nil-ductility transition temperature. Since RT does not shift for the bottom head, it is not necessary to subject it to the higher temperature limits imposed on the beltline materials due to irradiation embrittlement. Therefore , . the proposed change includes a separate curve, with less restrictive minimum temperatures, for the vessel bottom head. This curve is based on the ASME Code Section III, Appendix G limits, at given reactor pressures, for the limiting bottom head materials. This change provides operating flexibility. During pressure testing, the thermocouple which measure bottom head vessel temperature ' will see cooler temperatures, due to CRD w.ter inj ection, L j
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than the thermocouple higher in the vessel. The proposed separate bottom head curve will allow the performance of pressure tests with lower measured temperatures in the bottom head, providing additional operational flexibility. At the - same time, adequate margin against f' . brittle fracture is assured by maintaining the temperature above the i ASME Section III, Appendix G limits ' for the . limiting bcttom head J materials. The Appendix G temperature limits are adequate,.since without any RT ' "*" # " * * ***" *" # # # " D * **
N region.DT
- The second proposed change to Figure 3.6.2 is to show a series of curves )
representing three different service periods; < 8 EFPY, < 10 EFPY, and {
< 12 EFPY. These curves show Adj usted Reference Temperatures j (ART - RT Shift) calculated at the end of 8, 10, and 12 effective 1 fullpowehe+ars(EFPY)ofoperation Thus, for pressure tests. performed up to an accumulated 8 EFPY of operation,- the 8 EFPY curve provides.the-minimum required beltline temperature.. The 10 EFPY curve and 12 EFPY curves specify the minimum temperatures (margin against brittle fracture) for pressure tests up to 10 and 12 effective full power years of 3 operation, respectively. This change allows some operational flexibility j by postponing the increases in minimum temperature required during j pressure testing. At the same time, minimum temperatures are ]
conservatively set by using the calculated ART at the end of the J
specified service period; 8, 10, or 12 EFPY. This is conservative in i that the conditions at the end of the service period yield the highest j fluence, and therefore, the largest predicted shift in RT Assuming )
end of service period shift throughout the - entire perioEy,ields a -j conservative minimum temperature curve. These curves, therefore, provide I adequate margin against brittle fracture and provide additional I operational flexit'lity. j l
The calculated shift and resultant ART are based on the correlation of j Regulatory Guide 1.99, Revision 1. As described in b, above, the RG 1.99 correlation is modified by a 2.39 multiplication factor for plates and n 1.62 multiplication factor for velds. Thus, Figure 3.6.2 also takes into account the measured shift resulting from the first surveillance capsule.
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- d. Technical Specification 3.6. A.2 on page 132 is revised to reflect the l deletion of Figure 3.6.1 and the changes in Figures.3.6.1.a and 3.6.1.b.
Specifically, Technical Specification 3.6.A,2 deletes the statement which .I required referring to Figure 3.6.1 for RT an a ng esWt ND to the curve for the beltline from Figure 3.s6.1. a and 3. 6.1. b . This change reflects the deletion of Figure 3.6.1 and the change to Figures 3.6.1.a and 3.6.1.b to show ART, which already accounts for RT shift. NDT i
Technical Specification 3.6. A.3 on page 132 is revised to reflect the changes to Figure 3.6.2. Specifically, the requirement to add the shift in RT fr m Figure 3.6.1 to the beltline curve of Figure 3.6.2 is deletNT The separate beltline and bottom head curves are addressed, the separate curves for 8, 10, and 12 EFPY are referenced and the requirement' to select the appropriate curve based on current accumulated EFPY are added. These changes reflect the proposed revisions to Figure 3.6.2.
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l The proposed change .would revise Technical Specification 4.6. A.3 on I page 133. The change to Technical Specification 4.6. A.3 deletes the existing paragraphs on page 133. These paragraphs currently prescribe the original schedule for' surveillance capsule withdrawal and the changes _l required if the first capsule data indicate higher than predicted shifts. ;
Since the original withdrawal schedule is no longer. valid and higher than predicted shif ts were measured, the proposed change includes only the l appropriate revised withdrawal schedule. The paragraph describing l removal of the flux wires after the first refueling outage was deleted since it is historical and a new set of flux wires have since been evaluated.
The bases on pages 146 and 147 are also revised. The changes reflect the results of the surveillance testing performed on the first capsule ;
withdrawn from the core. Also, the basis for each of the changes to Figures 3.6.1.a, 3.6.1.b and 3.6.2 are added. In addition, . minor editorial changes are made.
Evaluation of this Amendment with Respect to 10CFR50.92 <
l A. The enclosed Technical Specification change is judged to involse no significant hazards based on the following:
- 1. Does the proposed change involve a significant increase in the probability or consequences of an accident _previously evaluated? )
The basis for establishing pressure-temperature operating limits for the reactor vessel is to ensure that,.as the vessel is pressurized, the steel temperature is maintained above the transition point from aductiletoabrittlegraceprefailuremechanism. Also, at neutron j fluences above 1 x 10 n/cm (> 1 MeV neutrons), embrittlement of I carbon and low alloy steels becomes a concern. To ensure that the )
steel temperatures in the vessel beltline are mainta!ned above the j nil-ductility transition temperature (NDTT) as neutron fluence accumulates, the reference nil-ductility transition temperature (RT ) is shifted higher to account .for neutron embrittlement of the"beltlinevesselsteel. It is recognized _that a brittle fracture failure of the reactor vessel would ' certainly contribute significantly to the consequences of the accidents-analyzed in Chapter 14 of the Updated Safety Analysis Report (USAR). However, as described in Chapter 4, Section 2, of the USAR, the purpose of these pressure-temperature limits is to prevent brittle fracture of the reactor vessel. The revised pressure temperature limits proposed in this change were calculated using the latest approved guidance, take into account the results of surveillance test data and move the minimum required temperatures in the conservative (higher) direction.
- a. The deletion of Figure 3.6.1, "RT Shift versus Vessel Wall Fluence," does no t: constitute a ckDT ange in any requirement of the Cooper Nuclear Station Technical Specifications. The information currently contained in Figure 3.6,1 will be incorporated into Figures 3.6.1. a, 3.6.1.b, and 3. 6. 2. The shift in reference nil-ductility transition temperature (RT due to irradiation embrittlement of vessel materials will N) incorporated into Figures 3.6.1.a, 3.6.1.b, and 3.6.2 by adding 1
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i ART to the ASME Code temperature (T-RT DT). A s equal to {
RT plus the shift in-RT There[ ore, instead of using' l Fihe 3.6.1 to find the sE1Yt, then adding the shift to the - l curves shown in Figure 3.6.1.a, 3. 6.1.b or 3. 6. 2, the revised figures will already include ART (RT NDT Pl us shift). This j change is purely administrative to provide a set of- ~
pressure-temperature curves which are easier to use. This j cha'n ge has no negative affect on any accident. In fact, by i making the pressure. temperature curves easier to use, the likelihood of misreading the minimum required temperature is decreased. Therefore, this change does not increase the probability or consequences of an accident previously evaluated. I
- b. Figures 3.6.1.a and 3.6.1.b show the minimum required .
- t. temperatures for non-nuclear heat up and cooldown and critical ,
core operation. The proposed revisions to Figures 3.6.1.a and I 3.6.1.b would combine the multiple curves into a single curve showing the minimum required temperature for the limiting material, change the curve to include APT and show higher ,
,i minimum required temperatures for beltline materials due to higher measured RT sM.
NDT The change to a single curve has no affect on the minimum required temperature. Instead of having to ensure that the curve representing the most limiting reactor vessel material is consulted, only the most limiting temperature is shown at a given reactor pressure. The purpose for establishing pressure-temperature limits for the reactor vessel is to provide adequate margin against. brittle fracture of the vessel steel, by specifying a minimum required vessel wall temperature throughout the range of reactor pressures. This change only makes the method of presenting the minimum required temperature easier to use and, therefore, has no affect on any accide'nt previously analyzed.
The purpose for changing Figures 3.6.1.a and 3.6.1.b from plotting temperature (T-RT versus pressure to temperature plus ART versus pressure is"$w)ofold. ~First,-since ART already takes into account RT NDT (ARhRTNDT + 8 ), a P l ot of (T-RT l fortNDT)PusARTversusreactorpressureeliminatestheneed e curve of Figure 3.6.1, and makes the figures easier to use. The second reason for using ART, calculated at 12 effective full power years (EFPY), is to be conservative. The predicted ART at 12 EFPY is conservative in that the irradiation embrittlement at 12 EFPY is greater than that in previous years due to a higher fluence. Using the end of service period ART throughout the period ensures a conservative minimum required temperature, since the RT *"
- highest at the end of the period. The change NDT to ART* makes the figures easier to use and ensures conservative minimum required vessel temperature. Since the minimum temperatures are moving-in the conservative direction, this change has no negative affect on protection of the reactor vessel against brittle fracture. Therefore, this change does not increase the probability or consequences of an accident.
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The final change to Figures 3.6.1.a and 3.6.1.b is to incorporate the higher minimum required temperatures for reactor vessel beltline materials. The results of testing of the plate and weld specimens from the first surveillance capsule withdrawn from the Cooper Nuclear Station core indicate that the shift in reference - nil ductility transition temperature (RT is greater than was previously predicted.
The method usekDIo) calculate the shift in RT for the proposed change was to use the correlation prYvided in Regulatory Guide 1.99, Revision 1. The . RG 1.99 results were then multiplied by 2.39 for plates and 1.62 for welds. This !
represents the ratio of the measured RT shift to the RG 1.99 NDT predicted shift. Thus, the proposed new minimum required temperatures for beltline materials . in Figures 3.6.1.a and 3.6.1.b are based on the RT shifts calculated in accordance with the latest approved Nb guidance, with an additional measure of conservatism added by using a multiplication factor to account for the higher measured shifts from the' first surveillance capsule. This change increases minimum required temperatures for vessel beltline materials and, therefore, is a change in the conservative direction. Also, this change meets l NRC guidance and the requirements of 10CFR50 Appendices G and H. Since this change makes the minimum vessel temperatures
! more conservative and, therefore, increases the protection of the reactor vessel against brittle fracture, this change has no negative affect on the probability or consequences of any accident previously evaluated,
- c. The proposed change to Figure 3.6.2, " Minimum Temperature for Pressure Tests such as Required by Section XI," provides a separate pressure-temperature limit curve for the bottom head of the vessel, provides a series of curves for 8, 10, and i 12 EFPY and reflects higher minimum required temperatures for j the vessel beltline due to ' gher RT g shifts.
The bottom head of the vessel is not in the vessel beltline. {
The bottom head will be subject to a much lower flgegce thpn j the beltline and the fluence will not reach 1 x 10 n/cm . j Therefore, it is not necessary to account for RT shift-in j the bottom head. ThenewseparatecurvefortheNoitomheadis j based only on the ASME Boiler and Pressure Vessel Code j requirements for the bottom head. .Without the affects of I radiation, the ASME Code . limits are well proven to be an j adequate margin against brittle fracture. Therefore, this j i change does not increase the probability or consequences of an j accident. , )
The proposed change would revise the existing curve of --
temperature (T-RTND ) versus rea tor pressure to a series of temperature curves including Adjusted Reference Temperature (ART - RT }' ## "" * * * * #" ' l plotted as NDT a + functionof reactor pressure.' This change i provides operating flexibility, by allowing the minimum temperature required during pressure tests:to rise more slowly j using step increases up to 12 EFPY. However, using the 8 EFPY
4 curve up to 8 EFPY of operation, 10- EFPY curve from 8 to' i 10 EFPY of operation and 12 EFPY curve from 10 to 12 EFPY .is conservative in that the highest RT shift occurs at the end oftheperiodand.isusedthroughoubtbeperiod. This yields a conservatively high minimum temperature throughout the service period. Therefore, this change does not increase the j probability or consequences of any accident. j The final change to Figure 3.6.2 . incorporates higher RT NDT shifts for beltline materials due to the higher shifts measured 1 during surveillance testing. The method used to calculate the
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RT shift used in the 8, 10, and 12 EFPY ART curves was l caN1ated using the same method as that' used in j Figures 3.6.1.a and 3.6.1.b. Since . the RTNDT *
- calculated using NRC approved guidance and accounts for the j actual shifts measured, and since the temperatures increase, 1 this change is conservative and does not increase the .,
probability or consequences of an accident. )
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- d. The changes to the text of Technical Specifications.3.6.A,2, j
- 3. 6. A. 3, 4. 6. A. 3 and the Bases are all editorial in nature, j The changes modify the text to reflect the results of the '
surveillance capsule testing and to be consistent with the i revised pressure-temperature curves of Figures 3.6.1.a, 3.6.1.b, and 3.6,2. No changes, other than those previously discussed are made, therefore, this change does not increase ,
the probability or consequences of an accident.
- 2. Does the proposed change create the possibility for a new or j different kind of accident from any accident previously evaluated? '
The purpose of the pressure-temperature operating limits . in to protect the reactor vessel against brittle fracture. The purpose of {
this proposed change is to make the pressure-temperature' curves easier to use and to update the curves to reflect more conservative {
minimum required temperatures due to' higher measured RT s W ts.
NDT ]
- a. The deletion of Figure 3.6.1 can not create any new or different kind of accident, since the RT 8hift previously NDT obtained from this figure has been incorporated into Figures 3.6.1.a, 3. 6.1.b , ' and 3. 6. 2. This change revises the l method of presenting RT NDT shift. The possibility for errors j in determining the minimum required temperatures is reduced by )
eliminating one calculation. This editorial change could not create any new kind of accident,
- b. The revised Figures 3.6.1.a and 3.6.1.b contain one _ curve . . ,
showing the minimum temperature for. the limitin5 reactor vessel j material over the range of reactor pressures.
RT The shift in was ca eu ated at 12 eHecthe full power years - (EW ,
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anNDTa multiplication factor was incorporated into the Regulatory Guide 1.99, Revision 1 ' method, to account for higher shifts measured'in the surveillance specimens. These changes revise the existing temperature limits to account for surveillance data, and revise the temperatures in the N
9 conservative direction. This change revises the minimum temperatures in the conservative direction in accordance with NRC guidance, aitd therefore has no negative affect on brittle fracture of the vessel. Since the purpose for establishing pressure-temperature limits on the vessel is to provide margin against brittle fracture of the vessel, this change does not create any new or different kind of accident.
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- c. Figure 3.6.2 is revised to reflect minimum required temperature curves calculated using . 8, 10, and 12 EFPY ART, a separate curve for the bottom head of the vessel and higher beltline temperatures due to higher measured RT shifts. Separate curves for beltline materials and the Netom head provide flexibility, while maintaining adequate margin against brittle j fracture. The separate 8,.10, and 12 EFPY curves also provide ,
operating flexibility by slowing the rise in. minimum vessel .
temperature during pressure tests. Conservative margin against brittle fracture is maintained for beltline materials. The higher shifts were calculated in accordance with NRC approved {
methods, take into account surveillance data and move the minimum temperatures in the conservative direction. Since the basis for pressure-temperature operating limits is to prevent brittle fracture, no new accident or different kind of accident !
is created,
- d. The changes to Technical Specifications 3.6.A.2, 3.6.A.3, f 4.6.A.3 and the Bases do not reflect any additional changes to the requirements. The text is updated to reflect the surveillance results and the revisions to the figures. This does not create any new or different kind of accida.nt.
- 3. Does the proposed change involve a significant reduction in a margin of safety?
- a. Figure 3.6.1 was previously used to determine the shift in l RT based on the service years accumulated. Figure 3.6.1 can ;
beTele ted, since the RT s as en nc YPorated hto Figures 3.6.1.a, 3. 6.1. b ,NDTand 3.6.2. Since this change does not delete or add any requirements, it does not reduce any margin of safety,
- b. Figures 3.6.1.a and 3.6.1.b have been modified ' to show temperature (T RTNDT) Pl us ART for the limiting vessel j materials over the range of reactor pressures. The shift in -l RT ND used to calculate beltline ART used the NRC approved [
ReguIatoryGuide1.99, Revision 1,methodandamultiplication "
factor to account for actual' surveillance data. This resulted in higher (more conservative) limits on minimum required temperatures for beltline materials. Since this change makes a change in the conservative direction, it does not involve a reduction in a margin of safety.
- c. The revisions to Figure 3.6.2 modify the pressure-temperature limits for pressure testing to show temperature plus ART calculated at 8., 10, and 12 EFPY, to show a separate curve for 1
= _ _ n
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the vessel bottom head and to show higher ' minimum beltline )
. temperatures due to higher measured shifts. .The change to show 1 (T-RT plus ART calculated at 8, 10, and 12 EFPY adds j opera $ kin)al flexibility by establishing three separate service l periods instead of one. Thus, while using the ART for 8 EFPY l 1s conservative up to 8 EFPY of operation, it is not .a s j conservative as using the ART for- 12 EFPY for the entire ]
period. Using the.8 EFPY curve up to 8 EFPY of operation, is j conservative in that a higher temperature shift will be derived from 8 EFPY than would be if the shift were calculated at 6 or 7 EFPY due to higher accumulated fluence. Thus, the ART will remain conservative by shifting every two EFFY to the next ,
higher curve up to 12 EFPY of operation. The margin of safety over the current Figure 3.6.2 is actually increased, since the shift is now calculated based on the current service year ,
instead of an end-of-service-period shift. This change does R not reduce the margin of safety, in. fact, the margin of safety is actually increased over current Technical Specifications.
The separate bottom head curve also adds operating flexibility.
The bottom head is not subj ect to a significant beltline fluence and, therefore, is not subject to RT shift'.
NDT Therefore, adequate margin against brittle fracture is provided' by meeting ASME Code requirements. This change does reduce the 1 conservatism in the minimum required temperature for the bottom head of the vessel. That is, subjecting the bottom head to the same minimum temperature requirements as the beltline would j mean that the affects of RT shift are also applied to the bottom head. This is overff conservative at the fluences experienced at the bottom head (<1becauq9, x 10 n /cm EOL) ,
2 shift in RT is not a concern. Since the vessel bottom head is not subj$$b to RT shift, the ASME Code limits for the limiting bottom headNDT materials are adequate to protect against brittle fracture. Based on the above, this change does not significantly reduce any margin of safety,
- d. The changes to the text of Technical Specifications 3.6.A.2, 3.6.A.3, 4.6.A.3 and the Bases do not contain any additional revisions not previously discussed. The only changes reflect the revised figures and the results of the surveillance testing. This does not constitute a reduction in a-margin of safety.
B. Additional basis for proposed no significant hazards consideration determination:
The Commission has provided guidance concerning the application of the standards for determining whether a significant hazards consideration exists by providing certain examples (48FR14870). Item a. above deletes Figure 3.6.1 and incorporates the requirements elsewhere. The District considers this change to be: "(1) a purely administrative change."-
Changes b. and c. above revise Figures 3.6.1.a. 3. 6.1.b , and 3. 6. 2 to show higher ART for the vessel beltline due to surveillance data which measured higher shifts in RT fall within the example: Iff5. The District a change thatconsiders these constitutes an changes to adaitional limitation...."
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