ML20101S932

Forwards Response to GL 92-01,Rev 1, Reactor Vessel Structural Integrity & Rev 1 to GE Rept Sasr 88-24, PBAPS Unit 2 Vessel Surveillance Matls Testing & Fracture Toughness Analysis, Dtd Dec 1991

ML20101S932
Person / Time
Site:	Peach Bottom, Limerick
Issue date:	07/10/1992
From:	Beck G PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20101S935	List: ML20101S932 ML20101S940
References
GL-92-01, GL-92-1, NUDOCS 9207200156
Download: ML20101S932 (14)

Text

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10 CFR 53.54(f)

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GL 92-01 J PIIILADELI'lllA ELECTRIC COMi%NY NUCLEAR GROUP HEADQUARTERS 955-65 CllESTERBROOK BLVD.

WAYNE. PA 1 % 87-5691 (215) 640-6000 NUCLEAR ENGINEERINO & SERVICES DEPARTMENT Docket Nos. 50-277 50-278 50-352 50-353 License Nos. DPR-44 DPR-56 NPF-39 NPF-85 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555

SUBJECT:

Peach Bottmm Atomic Power Station, Units 2 and 3 Limerick Generating Station, Units 1 and 2 Response to Generic Letter 92-01, Rev.ision 1,

" Reactor Vessel Structural Integrity, 50.54(f)"

REFERENCES:

1) Letter from J. W. Gallagher (PECo) to T. E.

Murley (NRC), dated May 13, 1988

2) Letter from R. D. Binz, IV (BWROG) to B. J.

Elliot (NPC), K. R. Wichman (NRC), and D. G.

Mcdonald (NRC), dated April 10, 1992

3) Internal NRC Memoranduni f rom J. E. Richardson (NRR) to D. G. McDcnald (NRR), dated May 5, 1992

Dear Sir:

Attached are our responses to the information requested by j the subject Generic Letter 92-01, dated March 6, 1992. Generic Letter 92-01 concerns licensee's compliance with requirements and commitments regarding reactor vessul integrity. Attachment A provides the responses for Feach Bottom Atomic Power Station (PBAPS), Units 2 and 3. Attachment B provides the responses for Limerick Generating Station (LGS), Units 1 and 2.

The s'  ; ached responses genera 2 y follow the example responst4 4 eveloped by the Boiling Water Reactor Owners' Group (BWROG) (Reference 2). In addition, the comments of the Nuclear Regulatory Commission (NRC) as described in the Reference 3  ;

letter are addressed at the end of each attachment for PBAPS, Units 2 and 3, and LGS, Units 1 and 2.

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f U. S. Nuclear Regulatory Commission Page 2 Document Control Desk I  :

j In addition to the response to Generic Letter 92-01, the Enclosure to Attachment A provides the " Peach Bottom Atomic Power Station Unit 2 Vessel Surveillance Materials Testing and Fracture Toughness Analysis," Revision 1, dated December 1991.

The original report was submitted in the Reference 1 letter in accordance with the requirements of 10 CFR 50, Appendix H,

" Reactor Vessel Material Surveillance Program Requirements,"

Section III.A. This Revision being submitted includes an analysis of unirradiated plate and weld Charpy specimens.

As noted in Attachment B responses 2b (2), 2b (5), and 3a, a supplemental response to this Generic Letter will be submitted no later than Ncvember 20, 1992.

This response was due to the NRC on July 4, 1992. In a conversation with J. Shea (NRC) on July 1, 1992, an extension waa granted to July 13, 1992.

If you have any questions, please contact us.

Very truly yours, cV

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G. J .~ Beck, Manager Licensing Section Attachments and Enclosure cc: T. T. Martin, Auministrator, Region I, USNRC J. J. Lyash, USNRC Senior Resident Inspector, PBAPS T. J. Kenny, USNRC Senior Resident Inspector, LGS

COMMONWEALTH OF PENNSYLVANIA  :

ss.

COUNTY OF CHESTER  :

D. R. Helwig, being first. duly sworn, deposes and says:

That he is Vice President of Philadelphia Electric Company;

-s that he has read the response to Generic Letter No. 92-01, arid knows the contents thereof; and that the statements and matters set forth therein are true and correct to the best of his knowledge, information and belief.

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Vice Preside Subscribed and sworn to beforemethis/0 day of ( [ 1992,

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.c Notary Public NctandSeal Erica A.Sarton, Notary PitAc My JLAy 995 t

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ATTACHMENT A PEACH BOTTOM ATOMIC POWER STATION UNITS 2 AND 3 RESVONSE TO GENERIC LETTER 92-01

Request 1:

"1. Certain addresseen are requested to provide the following information regarding Appendix H to CFR Part 50:

Addrescoes who uo not have a surveillance program meeting ASTM E185-73, -79, or -82 and who do not have an integrated surveillance program approved by the NRC (see Enclosure 2), are requested to describe actions taken or to be taken to ensure compliance with Appendix H to 10 CFR Part 50. Addresses who plan to revise the surveillance program to meet Appendix H to 10 CFR Part 50 are requested to indicate when the revised program will be submitted to the NRC staff for review. If the surveillance program is not to be revised to meet Appendix H to 10 CFR Part 50, addressees are requested to indicate when they plan to request an exemption from Appendix H to 10 CFR Part 50 under 10 CFR 50.60(b)."

Response

10 CFR Part 50, Appendix H, Paragraph II.B.1 requires, "That part of the surveillance program conducted prior to the first capsule withdrawal must meet the requirements of the edition of ASTM E 185 that is current on the issue date of the ASME Code to which the reactor vessel was purchased."

The Peach Bottom Atomic Power Station (PBAPS), Units 2 and 3 vessels were designed to the Winter 1965 Addenda to the 1965 Edition of Section III of the ASME Boiler and Pressure Vessel Code. Since the design of the surveillance program is "part of the surveillance program conducted prior to the first capsule withdrawal", the edition of the standard applicable to the PBAPS programs design is E185-61.

The PBAPS, Units 2 and 3 surveillance programs meet the intent of E185-82 with the following clarifications and alternate positions:

1. ASTM E185-82 in paragraph 5.1.1 requires, "...The base metal, weld metal and HAZ materials included in the program shall be those predicted to be the most limiting, with regard to setting preesure-temperature limits, for operation of the reactor to compensate for radiation effects during its lifetime."

4 The plate material used in makinc the base metal, weld metal and heat affected zone (HAZ) surveilleace specimens for Unit 2 is not the most limiting. The difference is not significant since chemistry factors provided in Regulatory Guida 1.99, Revision 2 are used to account for this deviation. Utilizing a chemistry factor of 131 for the most limiting plate and 121 for the surveillance sample results in a 3.5" difference in the Adjusted Reference Temperature (ART) at 32 EFPY.

2. ASTM E185-82 in paragraph 6.2 requires, "...so that the major axis of the specimen is parallel to the surface and normal to the principal rolling direction for plates,..."

All the Charpy and Tensile specimens for the Units 2 and 3 capsules were made parallel to the principal direction of rolling. However, the data from these longitudinal charpy specimens has been utilized by incorporation of a correction factor of .65. This correction

PBAPS Unite 2 and 3 Attachmont A Rosponso to GL 92-01 Pago 2 factor is discussed in Branch Technical Position MTEB 5-2 (" Fracture Toughness Requirements"), Revision 1.

3. ASTM E185-82 in paragraph 7.5.2 requires, "one set of temperature monitors shall be located within the capsule...".

The capsules in both Unit 2 and Unit 3 do not contain temperature monitors. This lack of temperature monitors is not a serious concern for the PBAPS, Unita 2 and 3 pressure vessel surveillance programs because the capsules in both vessels are located at '.nid-core height on the vessel wall in the annulus regions where high water flow to the recirculation suction piping keeps the capsules the same temperature as the vessel wall. Therefore, varying radiation effects due to temperature differences are negligable.

Based on the above discussion, and the responses to requests 2 and 3 below, it can be concluded the PBAPS, Units 2 and 3 surveillance programs effectively meet the objective of Appendix H to "... monitor changes in the fracture toughness properties of ferritic materials in the reactor-vessel beltline region of light water nuclear power reactors resulting from exposure of these materials to neutron irradiation and the thermal environment."

The PBAPS, Unit 2 and 3 surveillance programs' designs were approved during the FSAR approval process. Additionally, the Units 2 and 3 surveillance programs satisfy the requirements of paragraph II.B.1 of Appendix H. Therefore, an exemption is rat considered necessary.

Request 2a a "2. Certain addressees are requested to provide the following information regarding Appendix G to 10 CFR Part SO:

a. Addressees of plants for which the Charpy upper shelf energy is predicted to be less than 50 foot-pounds at the end of their licenses using the guidance in Paragraphs C.l.2 or C.2.2. in Re' tlatory Guide 1.99, Revision 2, are requested to provide to the NRC the Charpy upper shelf energy predicted for December 16, 1991, and for the end of their current license for the limiting beltline weld and the plate or forging and are requested to describe -the actions taken pursuant to Paragraphs IV.A.1 or V.C of Appendix G to 10 CFR Part 50."

Response

The upper shelf energies (USE) of the beltline materials at PBAPS, Units 2 and 3 are not expected to be less than 50 ft-lb by the end of 32 Effective Full Power Years (EFPY). Therefore, Request 2a does not apply to PBAPS, Units 2 and ' 3. A description of the USE evaluation supporting this conclusion follows.

USE data were not developed during fabrication of the= plates or welds used in the beltlines of either PBAPS, Units 2 and 3. However, in connection with the testing and evaluation of the first surveillance capsules removed-from both units, archive specimens from the same plates and_ similar 1

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PBAPS Units 2 and 3 Attachmcnt A 4 Responso to GL 92-01 Pago 3 i

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] electroslag welds were tested. The significant results_of the irradiated ,

I and unirradiated Charpy V-notch data are depicted in Table 5-5 of the

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respective reports (" Peach Bottom Atomic Power Station Unit 2. Vessel Surveillance Materials Testing and Fracture Toughness Analysis", dated ~

December 1991 (Enclosure 1), and,- " Peach Bottom Atomic Power Station Unit 3 Vessel Surveillance Materials Testing and Fracture Toughne9s Analysis,"

j dated June 1990 and submitted in a letter from G. A. Hunger (PECo) to USNRC, dated June 27, 1990 (Enclosure 2)). Figure 2 of Regulatory Guide l

1.99, Revision 2, was used to calculate an USE of 132 ft-lb longitudinal /86 ft-lb transverse for Unit 2 and 122 f t-lb longitudinal,'79 i ft-lb transverse for Unit 3 for the surveillance plates and an USE of 80 i ft-lb for Unit 2 and 82 ft-lb for Unit 3 for vertical electroslag welds at j 32 EFPY.

I j In the cas of those materials not covered by the surveillance program, j the BWROG report "BWR Beltline Material Upper Shelf Energy Estimation

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Methods", submitted to the NRC in a letter dated June 12, 1992, was used l

j' to calculate the USEs. The lowest upper shelf energy at 32 EFPY i calculated for PBAPS, Unit 2 was 61.2 ft-lbs and for PBAPS, Unit 3 was 60.6 ft-lbs as documented in the June 12, 1992 let"er.

i f Request 2b "b. Addressees whose reactor vessels were constructed to an ASME - Code j earlier than the Summer 1972 Addenda of 3 1971 Edition are requested to describe the consideration 9' s to the following material properties in their evaluations performed pursuant to 10 CFR 50.61 and Paragraph III.A of 10 CFR Part 50, Appendix G -

i l (1) the results from all charpy and drop weight tests for all j unirradiated beltline materials, the unirradiated reference l temperature for each beltline material, and the method of determining

! the unirradiated reference temperature f rom ' the Charpy and drop l weight test;"

I Response:

For the beltline plate materials, Charpy and dropweight tests were a performed. The Charpy specimen orientation was longitudinal and the test

- requirement was to meet 30 ft-lb at 10*F. In order to demonstrate

. fracture toughness equivalent to Appendix G requirements, a General Electric procedure, described in Section 3.2.4 of the " Vessel Surveillance i Materials Testing and Fracture Toughness Analysis" reports for PBAPS, Units 2 and 3 (Enclosures 1 and 2, respectively), was used to adjust the 30 ft-lb longitudinal Charpy data to determine the temperature T.o, at-

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which an equivalent 50 ft-lb transverse Charpy energy could be expected.

The unirradiated RTun., was then selected as the higher of (Tso,- 60*F) or the-dropweight nil-ductility temperature (NDT).

For the beltline weld materials, only Charpy tests were performed. The specimens were cut transverse to the weld length and the test requirement was 30 ft-lb at 10*F. As with the plate, the GE procedure was used to adjust the 30 ft-lb Charpy data to determine (Too, - 60*F) or -50*F.

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$ PBAPS Unite 2 and 3 Attachment A j Rosponse to GL 92-01 Pago 4

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$ Table 3-2 in Enclosures 1 and 2 depict the requested information for

! PBAPS, Units 2 and 3, respectively.

i Request 2b (2):

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l "(2) The heat treatment received by' all beltline and surveillance materials;"

{ Responses

! The fabrication process for the plate material (ASME SA302, Grade B ,

l modified) for both Units 2 and 3 vessels employed double quench and temper j heat treatment immediately after hot forming, then electroslag or j submerged arc welding and post-weld heat treatment. The post-weld heat j treat.nent was typically for 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br /> at temperatures of 1125 25*F.

j The base metal specimens were cut from beltline plates. The test plates j

were double quenched and tempered and then given a stress relief heat treatment for 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br /> at 1125 t 25'F to simulate the post-weld heat j treatment of the vessels.

! The weld metal and HAZ specimens were fabricated from trim-off pieces from

, beltline plates and were welded together by electrostAg welding, using the same process for the longitudinal seam welds in the beltline, and i post-weld heat treated for 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br /> at 1125 1 25'F to simulate the l post-weld heat treatment of the vessels.

I j Request 2b (3):

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"(3) the heat number for each beltline plate or forging and the heat number of wire and flux lot number used to fabricate each beltline weld;"

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l The beltline consists of portions of the lower shell and lower-intermediate shell. Each shell is formed from three plates, so the beli ' 'e includes portions of six plates, six vertical welds and one

. circumferential welds. All beltline plate and weld material were l considered in the Appendix G evaluation. The requested information is 3

depicted in Figure 3-2 and Tables 3-1 and 3-2 of the Enclosures 1 and 2

! for PBAPS, Unita 2 and 3, respectively.

Request 2b (4):

"(4) the heat number for each surveillance plate or forging and the heat number of wire and flux lot number used to fabricate the surveillance weld;"

Response

The heat numbers for the surveillance plates are C2761-2 for Unit 2 and  ;

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C3103-1 for Unit 3. Only one weld wire heat was used for the vessels' l

electroslag welds, and the usual Babcock and Wilcox practice was to.use '

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PBAPS Units 2 and 3 Attachment A Response to GL 92-01 Pago 5 the same heat in the surveillance welds. However, the chemical analyses of the irradiated surveillance welds do not appear to support the assumption that the surveillance and beltline welds are the same . heat .

This matter is discussed in detail in Sections 3.2.3 of Enclosures 1 and 2 for PBAPS, Units 2 and 3, respectively.

Request 2b (5):

"(5) the chemical composition, in particular the weight in percent of copper, nickel, phosphorous, and sulfur for each beltline and surveillance material; and"

Response

Chemical composition weight percent data for beltline materials are shown in Tables 3-1 of the Enc'oeures 1 and 2 for PBAPS, Units 2 and 3, respectively. Beltline material chemistries, or upper bound assumptions, were used in accordance with Regulatory Guide 1.99, Revision 2, to determine the limiting beltline material, the adjusted reference temperat.ure versus EFPY for that material, and the predicted USE at 32 EFPY.

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Verification chemical composition weight percent data for the irradiated 3 I

surveillance plate and weld are shown in Tables 3-3 of the Enclosures 1 j and 2 for PBAPS, Units 2 and 3, respectively. These analyses compare f avorably wit h the fabrication analyses for the plates but not favorably for the welds as discussed above in response to Request 2b (4).

! Reque',c 2b (6):

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, ",6) the heat number of the wire used for determining the weld metal chemical composition if different than Item (3) above."

Responses As discussed above in responses to Request 2b (4) and 2b (5), there is an

! apparent dissimilarity between the weld wire used for the surveillance

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specimens and that used for the electroslag longitudinal welds of the vessels. This dissimilarity does not pose a problem because it is bounded i by using the highest chemical factors for the welds. The Adjusted Reference Temperatures (ART) at 32 EFPY, based on Regulatory Guide 1.99, i

Revision 2 calculations, are acceptable.

Requent 3a:

"3. Addressees are requested to provide the following information regarding commitments made to respond to GL 88-113 a "ow the e,Srittlement effects of operating at an irradiation amperature teold leg or recirculation auction temperature) below 25"F were considered. In particular licensees are requested to describe consideration given to determining the effect of lower irradiation temperature on the reference temperature and on the Charpy upper shelf energy."

PBAPS Unite 2 and 3 Attachmont A Response to GL 92-01 Pago 6

Response

Since surveillance specimens are exposed to the same temperature conditions as the beltline materials, temperature effects, if any, will be ,

reflected in the surveillance reaults. When the surveillance results are fotored into the Appendix G analysis per Regulatory Guide 1.99, Revision 2, temperature effer:ts, if any, will be' accounted for inherently.

Operation with PBAPS, Units 2 and 3 beltline regions below 525'F was not considered in the Appendix G analyses for response to Generic Letter 88 because the steady-state operating temperature of the coolant in the beltline region is slightly greater. Based on the temperature in the recirculation suction piping, which draws water directly from the beltline region, the steady-state temperature in the beltline is greater than 527*F.

Only during startup and operati .. without feedwater heating, which occurs when feedwater heaters are out of service or when the turbine is oft line and the reactor steam is routed through the turbine bypass. does the beltline experience coolant temperatures lese thaa 425*P whta the reactor is critical. The time of operation in these consitions has been estimated to be less than 1%, and the associated temperatures for most-of that time are 515'F cr higher. The Peach Bottom, Unit 2 32 EFPY fluenc9 with the 1/4T lead factor is estimated to be 5.5 X 10 ' ^' n/cm3 with an upper bound of 6.9 X 16 ' n/cm2 , and the Peach Bottom, Unit 3 32 EFPY fluence with the 1/4T lead factor is estimated to be S.O X 10 n/cm3 with an upper bound of 6.3 X 10 n/cm'. Using the upper bound, the fluence accumulated below 525"F would be atsut 6.9 X 10 n/cm* for Unit 2 and 6.3 X 10 n/cm3 for Unit 3. This combination of low fluence and small deviation from the 525'F level will not significantly affect ~ beltline RTun.r or USE predictions.

Request 3bs "b. How their surveillance results on the predicted amount of embrittlement were considered."

Response

Regulatory Guide 1.99, Revision 2, Paragraph C.2 requires credible data from two surveillance capsules before adjustments to the prediction.

methods are made, and only one capsule from Unit 2'and one capsule from Unit 3 have been tested. Thereforo, the beltline predictions are based on l

Revision 2 methods without consideration of surveillance.results.

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PBAPS Units 2 and 3 Attachment A Response to GL 92-01 Pago 7 Request 3c "c. If a measured increase in reference temperature exceeds the mean plus-two standard deviations predicted by Regulatory Guide 1.99, Revision 2, or if a measured decrease in Charpy upper shelf energy

_ <ceeds the value predicted using the guidance in Paragraph C l.2 in Regulatory Guide 1.99, Revision 2, the licensee is requested to report the information ar.d describe the effect of the surveillance results on the adjusted reference temperature and Charpy upper shelf energy for each beltline material as predicted for December 16, 1991, and for the end of its current license."

Responses Measured increases in the reference temperatures for PBAPS, Unita 2 and 3 based on surveillance tests of the first capsules were less than the mean-plus-two standard deviations predicted by Regulatory Guide 1.99, Revision 2. Since only one set of surveillance results are available, the effects of the measured changes on the beltline predictions have not been considered for either unit, per Paragraph C.2 of the Regulatory Guide.

Measured decreases in USE from the first surveillance capsules for PBAPS, Units 2 and 3 were within the predictions for both plates and welds.

Since only one set of surveillance results are available, the effects of the raeasured changes on the beltline predictions have not been considered for either unit, per Paragraph C.2 of the Regulatory Guide.

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PBAPS Unite 2 and 3 Attcchmont A Responce to GL 92-01 Pago 8 Response to Additional Items Identified in

May 5, 2992 NRC Internal Memorandum Request la "For cases where an ASTM E185 standard earlier than the 1973 revision is involved for a licensee's 10 CFR 50, Appendix H, surveillance program, .the licensee should include a discussion of the effectiveness of its program in assessing radiation embrittlement."

Response

This information is contained in our reply to Request 1 of Generic Letter 92-01.

Request 2:

"A detailed description should be provided to clearly show 'ow initial ,

upper shelf energy data were estimated for those vessels whers the initial upper shelf energy was not available from existing data."

Response

This information is contained in our reply to Request 2a of Generic Letter 92-01.

Request 3:

"The staff believes that every ef fort should be made to retrieve records and data relating to each licensee's reactor vessel and surveillance sample material chemistry and heat number identification. The 7xtent of this offort should be described in the submittal."

Response

This information is contained in our reply to Request 2b (1) through 2b (6) of Generic Letter 92-01.

Request 4:

"The details . of the BWROG's SSP and its topical report on fracture ~

t toughness should be provided to the NRC staff, for information, prior to licensee submittals which reference them."

Response

The BWROG report "BWR Beltline Material upper Shelf. Energy Estimation Methods" was submitted to the NRC on June 12, 1992.

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PBAPS Unita 2 and 3 Attachmont A Response to GL 92-01 Pags 9 Request 5:

"Basie and justification should be provided or referenced to demonstrate that the General Electric procedure used to estimate unirradiated reference temperatures is equivaler.t to current requirements."

Response

This information is contained in Section 3.2.4 of Enclosures 1 and 2, respectively.

Request 6:

L "If a reactor vessel operated at a consthnt temperaturo less than 525"F, 4

the licensee should report an estimate of the neutron fluence accumulated l at that temperature."

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Response:

1 This information is contained in our reply to Request 3a of Generic Letter 92-01.

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Request 7:

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l " Details should be provided by each licensee for actions being taken when the measured increases in-reference temperature or measured decreases in USE exceed, by more than 2-sigma, those predicted by RG 1.99, Revision 2,-

for the first surveillance capsule. The BWROG was encouraged to have licensees not wait for the results of the second surveillance capsule e

before actions are taken to determine the validity of the measured data."

Response

The results depicted in Enclosures 1 and 2, respectively, indicated that the increase in reference temperature and the decrease in USE are within 2-sigma.

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Enclosure 1 to Attachment A

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