ML20137B323

Forwards Response to NRC RAI Concerning New Rv Pressurized Thermal Shock Assessment,Per

ML20137B323
Person / Time
Site:	Beaver Valley
Issue date:	03/14/1997
From:	Jain S DUQUESNE LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20137B329	List: ML20137B323 ML20137B351
References
NUDOCS 9703210278
Download: ML20137B323 (6)

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t v Valley Power Station Shippingport, PA 15077-0004 l

l SUSHIL C. JAIN (412) 393-5512 00V4,P 3, ehnt

,. March 14,1997 '"" ('i2> e43 80e8 Nuclear Power DMalon U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555-0001

Subject:

Beaver Valley Power Station, Unit No.1 Docket No. 50-334, License No. DPR-66 Response to Request for AdditionalInformation Concerning Reactor Vessel PTS Assessment Attached is our response to an NRC request for additional information provided by letter dated February 10, 1997, concerning the new reactor vessel pressurized thermal shock (PTS) assessment submitted by our letter dated August 2,1996. This response provides information concerning the new PTS analysis that was performed to assess the effect ofincluding updated reactor vessel data. The attachment provides each NRC item followed by our response.

Sincerely, Sushil C. Jain 1 l

c: Mr. D. M. Kern, Sr. Resident Inspector Mr. H. J. Miller, NRC Region I Administrator Mr. D. S. Brinkman, Sr. Project Manager i

9703210278 970314 f

PDR ADOCK 05000334 1 P PDR DEllVERING QUAllTY l ENER6Y 5.EkEk$!.E.ElE

ATTACHMENT Beaver Valley Power Station, Unit No.1 Reactor Vessel PTS Assessment RAI Response 1

Item 1 l Explain which data was used to determine RTNoT63 for Plate B6903-1 and which data was used to evaluate the unirradiated Charpy reference curve for Plate B6903-1 i surveillance material. If all of the data submitted in Table 10 of reference #1 are I believed to be valid tests for detennining the material properties of Plate B6903-1, provide a technicaljustification for the exclusion of cenain data points if all of the data was not used in either of these evaluations.

Response 1 The drop weight test data from the tests performed by Combustion Engineering (CE) and recorded on the material certification and the transverse Charpy test data from the tests performed by Westinghouse and recorded in Table 10 of reference I were used to j determine the initial RTuor oflower shell plate B6903-1.

At the time lower shell Plate B6903-1 was fabricated, only drop weight tests and  !

longitudinally oriented Charpy tests were required. Hence, the vessel fabricator, CE, ,

only performed drop weight tests and longitudinally oriented Charpy V-notch tests.

When Westinghouse developed the Beaver Valley Unit I surveillance program, Westinghouse performed both transverse and longitudinal Charpy V-notch tests. Per NUREG-0800, " Standard Review Plan," Branch Technical Position - MTEB 5-2,

" Fracture Toughness Requirements," the initial RTsor had to be determined using

" specimens oriented in the weak direction (transverse to the direction of maximum  !

l working)". Hence, the initial RTuor of the Beaver Valley Unit I lower shell plate B6903-1 was determined using the transversely oriented Charpy data developed by Westinghouse (Table 10 of reference 1) and the drop weight test data developed by CE (reponed on the CE material cenification) following the ASME procedure given in NB-2331, " Material for Vessels." l l

Therefore, all the available transverse data which is presented in WCAP-8457 is valid.

No valid data points were excluded.

s Attschment Reactor Vessel PTS Assessment RAI Response Page 2 Item 2 If any of this data was excluded in the determination of Plate B6903-1 RTwonu) :

(a) Explain how DLC's analysis meets the requirement of ASME Code paragraph NB-2331(a)(4) which states that the reference temperature may be determined

...from a full Cy impact curve developed from the minimum data points of all the Cy tests performed."

(b) Evaluate what impact the inclusion of the additional data would have on DLC's determination of RTsonu) or m.

Resnonse 2(a)

The only available unirradiated transverse Charpy data for lower shell plate B6903-1 is documented in Table 10 of reference 1 and the only available drop weight test data for lower shell plate B6903-1 is documented on the CE material certification. Hence, per NUREG-0800, " Standard Review Plan," Branch Technical Position - MTEB 5-2,

" Fracture Toughness Requirements," the initial RTuor is to be determined using specimens oriented in the weak direction (transverse to the direction of maximum working). Therefore, the available uninadiated transverse Charpy data for lower shell plate B6903-1 and the available drop weight test data for lower shell plate B6903-1 was used to determine the initial RTuor. Since the data from the unirradiated surveillance data constitutes the only valid data in the transverse direction it is by definition the minimum data points.

The following is an explanation of how the data was used to comply with the requirements of NB-2331(a)(4):

Per 10 CFR Part 50.61, the initial RTxor of a material is to be " evaluated according to the procedures in the ASME Code, Paragraph NB-2331" and per NUREG-0800,

" Standard Review Plan," Branch Technical Position - MTEB 5-2, " Fracture Toughness Requirements," test results from Charpy specimens oriented in the weak direction (transverse to the direction of maximum working) are to be used when determining the initial RTuor. Hence, the initial RTuor of the Beaver Valley Unit I lower shell plate B6903-1 was determined by applying the ASME Code NB-2331 procedures to the drop weight test results developed by CE and the transversely oriented unirradiated Charpy test results developed by Westinghouse in Table 10 of reference 1.

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Attachment Reactor Vessel PTS Assessment RAI Response ,

Page 3  :

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The ASME Code NB-2331 procedures were applied to the CE drop weight test results and the Westinghouse transversely oriented Charpy test results .as follows: -

i Per ASME Section III, Division 1, NB-2331, " Materials for Vessels," pressure retaining $

material for vessels, other than bolting, shall be tested as follows. ,

(a) Establishing a reference temperature RTsor shall be done as follows.

1) Determine a temperature Txor that is at or above the Nil-ductility transition temperature by drop weight tests.

CE performed drop weight tests that resulted in a Tuor of-50 F. Hence, Tuor oflower shell plate B6903-1 = -50 F

2) At a temperature not greater than Twor + 60 F, each specimen of the Cy test (NB-2321.2) shall exhibit at least 35 mils lateral expansion and not less than 50 ft-lb absorbed energy. Retesting in accordance with NB-2350 is permitted. When these requirements are met, Twor is the reference temperature RTuor.

The transverse Charpy tests did not exhibit 35 mils lateral expansion and greater than 50 ft-lb absorbed energy at 10 F (Twor + 60 F). Thus, this criteria is not met for lower shell plate B6903-1.

3) In the event that the requiremerits of (2) above are not met, conduct additional Cy tests in groups of three specimens (NB-2321.1) to determine the temperature Tcv at which they are met. In this case the reference temperature RTuor = Tc, - 60 F. Thus, the reference temperature RTwor is the higher of Tuor and (Tcv - 60 F).

Based on the Charpy test results given in Table 10 of reference 1, Charpy tests were not performed in groups of three to determine the temperature Tcv at which the transverse Charpy test results exhibit 35 mils lateral expansion and greater than 50 ft-lb absorbed energy. Thus, this criteria is not met for lower shell plate B6903-1.

Attaclunent Reactor Vessel PTS Assessment RAI Response Page 4

4) When a Cy test has not been performed at Twor + 60 F, or when the Cy test at Twor + 60 F does not exhibit a minimum of 50 ft-lb and 35 mils lateral expansion, a temperature representing a minimum of the 50 ft-lb and 35 mils-lateral expansion may be obtained from a full Cy impact curve developed from the minimum data points of all the Cy tests performed.

Based on a curve developed using the minimum transverse Charpy test data points,35 mils lateral expansion is reached at 62 F and 50 ft-lb absorbed energy is reached at 87 F.

The initial RTwor is defined as the higher of Tuor and (Tcv - 60 F). In other Words, RTwor = Tuor, if Twor 2 T 5o(35)- 60 F and RTwor = T5o(35)- 60 F, if T 5o(35)- 60 F > Tuor For the Beaver Valley Unit I lower shell plate B6903-1:

Tc,- 60 F = T m35)-

5 60 F = 87 F - 60 F = 27 F and Twor = -50 F Hence, Tcv - 60 F (27 F) is greater than Twor (-50 F). Therefore, for Beaver Valley Unit I lower shell plate B6903-1:

Initial RTwor = 27 F Resnonse 2(b):

There is no additional data to be considered for the determination of RTxorcu> since there is only one data point. Additionally the standard deviation, e is zero since this is a single discrete measured value determined from the minimum Charpy curve.

Attachment Reactor Vessel PTS Assessment RAI Response Page5 Item 3:

Assess what impact any changes in RTumm) or og from DLC's response to question (2b.) would have on DLC's evaluation of RTrrs value for Plate B6903-1.

Response to 3:

There is no impact on the RTrrs value for Plate B6903-1.

Item 4:

Submit for NRC staff review WCAP-14554, " Beaver Valley Unit 1 Fluence Reevaluation," dated June 1996 and referenced as the basis for the fluence values used in the BVPS-1 PTS assessment. The NRC staff must review the fluence results to assess DLC's determination of the vessel's end-of-license fluence values and the fluence values associated with the vessel's surveillance capsules.

Response 4:

WCAP-14554 has been reviewed by DLC and is attached for your reference and review.

Reference

1. DLC's response to Generic Letter (GL) 92-01 dated July E 1992 (J. D. Sieber (DLC) to the U.S. Nuclear Regulatory Commission Documuit Control Desk) ,

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