NRC-98-0101, Submits Response to NRC 980518 RAI Re Proposed TS Amend for Safety/Relief Valve Setpoint Tolerance Relaxation

Submits Response to NRC 980518 RAI Re Proposed TS Amend for Safety/Relief Valve Setpoint Tolerance Relaxation

ML20249A184
Person / Time
Site:	Fermi
Issue date:	06/09/1998
From:	Gipson D DETROIT EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
CON-NRC-98-0101, CON-NRC-98-101 TAC-MA0720, TAC-MA720, NUDOCS 9806160151
Download: ML20249A184 (6)

Text

_ _ _ _ _ _ _ - _ _ _ - -___- ._-_ _ _ __-_ ___-____ - _ - _ ______ _ -__ __ ___ ______. _ _ - _ _ - _ _ _ _ _ _ _ _

1

. I)ouglas R. Gipwn Senior Vice l'resi'-nt, Nuclear Generation ferm12 f,400 Nuth !)ixie liwy., Newport, Mic higan 4MIM f Tet at:tra.ral rax:atirm 41n Detroit Edison 7

June 9,1998 NRC-98-0101 U. S, Nuclear Regulatory Commission Attention: Document Control Desk Washington D C 20555-0001

References:

1) Fermi 2 NRC Docket No. 50-341 NRC License No. NPF-43

2) NRC letter from R.C. Jones to C.L. Tully, Chairpeuon, BWR Owners' Group, " Safety Evaluation of General Electric Company Topical Report NEDC-31753P, BWROG In-Service

. Pressure Relief Technical Specification Revision Licensing Topical Report," dated December 9,1992

3) Detroit Edison Letter to NRC, NRC-98-0011 " Proposed Technical Specification Change (License Amendment) to /

Increase the Safety / Relief Valve (SRV) Setpoint Tolerance from O il% to i3%," dated January 28,1998

4) NRC Request for Additional laformation Regarding the Proposed Technical Specification Amendment for Safety / Relief Valve Setpoint Tolerance at Fermi 2 (TAC NO. MA0720), dated May 18,1998

_o

"[J 5) Detroit Edison Letter to NRC, NPC-96-0097, " Licensee Event Report (LER) No.96-017," dated November 15,1996

6) Detroit Edison Letter to NRC, NRC-97-0026, " Licensee Event Report (LER) No.96-017, Revision 1," dated April 18,1997 l

9806160151 990609 ^

PDR ADOCK 05000341 P PDP g A trrM l'.nergy Cornpany

I

• USNRC NRC-98-0101 Page 2' l

7) Detroit Edison Letter to NRC, NRC 97-0071, " Licensee Event Report (LER) No.96-017, Revision 2," dated August 1,1997

8) Detroit Edison Letter to NRC, NRC 97-0101, " Licensee Event Report (LER) No.96-017, Revision 3," dated November 10, 1997

9) Detroit Edison Letter to NRC, NRC-98-0013, "Operadon with Currently Installed Safety / Relief Valves for the Remainder of Cycle 6," dated January 14,1998

Subject:

NRC Request for Additional Information Regarding the Proposed Technical Specification Amendment for Safety / Relief Valve Setpoint Tolerance at Fermi 2 (TAC NO. MA0720) ~

Detroit Edison's response to the N'RC request for additionalinformation (Reference

4) regarding our proposed Technical Specification amendment for safety / relief valve setpoint tolerance relaxation (Reference 3) is provided below:

Ouestion 1 In several Licensee Event Reports (LERs), including LER 96-017 and the three subsequent revisions thereto, the licensee reported the setpoint performance for the plant Target Rock 2-Stage safety / relief valves (SRVs). Several as-found setpoint values were significantly above the 1% tolcrance in the current technical specifications (TS) and the i3% tolerance proposed by the licensee. The analysis provided by the licensee in the submittal dated January 28,1998, is based on the assumption that 11 SRVs are operable (the minimum required by TS) and the -

setpoints of the operable SRVs are no greater than the nominal values plus 3%.

Describe the corrective action (s) taken or planned to improve the plant SRV setpoint performance. In particular, address whether Detroit Edison Company will install new SRV pilot valves with platinum ion beam bombarded discs during the next refueling outage. Discuss whether the analysis for the proposed i3% tolerance is bounding for the expected performance of the SRVs throughout future operating cycles. If the analysis is not bounding, provide a revised analysis which includes the expected upward setpoint drift of the SRVs.

Resoonse 1 The corrective actions taken and those planned to improve the plant SRV setpoint -

[ performance have been extensively provided in LER 96-017 and its three supplements g (References 5,6,7, and 8), as well as in our January 14,1998 response to a similar

request for assurance that the SRVs.could perform their intended function (Reference

9). As~ committed in Reference.8, Detroit Edison willinstall platinum ion beam p-

p. -

USNRC-

. NRC-98-0101 Page 3 bombarded discs during the next (sixth) refueling outage. This outage is currently scheduled to begin in August 1998.

' The analyses presented in Reference 3 in support of this license amendment request .

l were perfonned assuming a i3% setpoint tolerance in accordance with the NRC guidance contained in Reference 2. Although there is no assurance that individual valves will not lift outside of the i3% setpoint tolerance, it is believed that this '

tolerance will be able to be met during future operating cycles. Should Technical Specification limits be exceeded during future operating cycles, Detroit Edison _would

- be required to analyze the resultant potential overpressurization transient for safety significance and to notify the NRC "ia an LER in accor(ance with 10CFR50.73.

Regarding your request for an all inclusive upper bounding analysis (i.e., Upper Limit) to ensure no future LERs will be necessary, the NRC in Reference 2, mecifically rejected just such a proposal in their review of the BWR General Electric generic licensing report NEDC-31753P, "BWROG In-Service Pressure Relief Technical Specification Revision Licensing Topical Report," even though the BWR Owners Group and the Technical Reviewer (Brookhaven National Laboratory) recommended it. The NRC, in rejecting this concept, stated "The TER [ technical evaluation report]

recommended that the philosophy of an Upper Limit be approved as a means to reduce the number oflicensing event reports (LERs) associated with valve setpoint drift. The Upper Limit, to be established on a plant specific basis, defined the highest actuation setpoint at which the ASME code overpressurization limit will not be exceeded for all licensing basis events. Thus, the TER recommended that for cases where the setpoint is above 3% of the nominal setpoint value but below the Upper Limit, a cyclic repon to the NRC be written within 90 days. The staff, however, finds (

that the relaxation of valve setpoint tolerance from il% to 13% will in itself result in a reduction in the number of LERs required. In consideration of standardization and simplicity in reporting requirements, the staff concludes that the philosophy of an upper limit is not acceptable as a means to further reduce the number of LERs, and that an evaluation to determine the necessity for filing a LER must be made for setpoints when drift outside i3% is found." Therefore, because the SRVs are expected to meet the proposed Technical Specification serpoint tolerance limits, and

because the NRC has not accepted the " Upper Limit" concept in the past, Detroit

. Edison does not believe that any additional analyses are necessary to suppon this L proposed Technical Specification change.

L i

L

&.m ,

, _M L i.. .

_ _ _.___1.____ _ _ _ . _ _ _ _ _ _ _ _ _ _ . _ _ _ _ _ _ _ _ _ . _ _ _ _ _ _ _ . _ _ Q

o USNRC-

.: -NRC-98-0101 Page 4 -

Ouestion 2 Uncertainties of analysis parameters should be accounted for in the safety analyses used to bound limits defined by the plant TS. Provide a discussion of the SRV '

setpoint testing instrument accuracy and how this source of uncertainty is accounted for in the licensee's safety analysis associated with the proposed TS SRV setpoint

tolerance.

+ Response 2 SRV s-found testing is performed in accordance with vendor procedures which meet

. the requirements of ANSI /ASME Standard PTC 25.3-1976, " Safety and Relief Valves." This standard specifies a testing uncertainty for the SRV pressure setpoints ofless than 0.5%. Wyle Laboratories and the other vendors performing setpoint testing for the industry typically use instruments with accuracies ofi0.1% to ensure that the ANSI /ASME criteria are met. This equates to a potentialinstrument inaccuracy of a little more than 1 psi (no greater than 1.2 psi for any SRV).

One psi is a small fraction of the approximate 34 psi (3% of 1135 psig) allowed j setpoint drift proposed for the lowest set SRVs. Additionally, the proposed license amendment request specifies that the SRVs be adjusted to within il% (il1.35 psig for the lowest set SRVs) of their 1.cminal lift setpoints prior to reinstallation following decertification testing. This ensures a 2% (22.7 psig for the lowest set SRVs) margin to the Technical Spraification limit. The small testing uncertainty ofless than 1.2 psig, combined with the required resetting of the SRVs to within il% of their nominal lift setpoints, therefore provides adequate margin (22.7 - 1.2 = 21.5 psig for the lowest set SRVs) such that the instrument accuracy need not be accounted for in the analy.ces.

Finally, it should be noted that the analytical methodology used by the General Electric Company for Detroit Edison in support of this proposed license amendment complies with the NRC guidance provided in Reference 2, and is at least as rigorous as that presented on othc. Jockets for which NRC approval of this particular

. Technical Specification change has already been granted.

Therefore, because of the small uncertainty associated with the accuracy cf the SR V

setpoint testing instrumentation, the requirement to set the SRVs to within il% of their nominal lift setpoints prior to installation, and because the analyses presented in support of this proposed license amendment comply with the NRC guidance provided e in Reference 2, Detroit Edison believes that incorporation of the test instrument uncertainties into the analyses is not necessary in order to support approval of this

' proposed. Technical Specification change.

(

w

- _ __ = -

~

.. USNRC-

. NRC-98-0101 Page 5 '

The commitmeat to install platinum ion beam bombarded discs during the next (sixth) refueling ou. age made in Reference 8 is being reiterated in this letter. Please contact Mr. Normr.n K. Peterson at (734) 586-4258 if you have any further questions regarding this submittal.

Sincerely, b) cc: B. L. Burgess G. A. Harris A. J. Kugler Regional Administrator, Region III Supervisor, Electric Operators, Michigan Public Service Commission i

r e USNRC

• ". NRC-98-0101 l

Page 6 l

l l'

I, Douglas R. Gipson do heieby affirm that the foregoing statements are based on facts and circumstances that are true and accurate to the best of my knowledge and belief.

Douglas RfGipson Senior Vice President Nuclear Generation On this day of lLO 1998 before me personally appeared Douglas R. Gipson being first dyly sworn and says that he executed the foregoing as his free act and deed.

[ ,

Nota:y Public

~

ROSAUE A. AfGETTA nonviypuOuc tmNROECOUNTLMl MYColesOWONEXMRES10f11/us

/