ML20211H893
| ML20211H893 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 09/26/1997 |
| From: | Hunger G PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| IEB-96-003, IEB-96-3, NUDOCS 9710070181 | |
| Download: ML20211H893 (3) | |
Text
_ _ _ _ _ _ - _. _ _ _ _ - _ _ _ _ _ _ _ _ _ _ _ _ - _ _ _ _ _ _ _ - _ _ - _ _
Stalion 0uppori Department l
, = = =
~
PECO NUCLEAR item c -
l Nudear Gmup thwhattws A Uvr or l'fCO IMmr 965 OnteirtutxA ikxhord j
W.ryte. FA 190075091 l
l l
September 20,1997 Dockot Nos. 50-277 50-278 License Nos. DPR 44 DPR 56 1
1 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555
Subject:
Peach Bottom Atomic Power Station, Units 2 and 3 Efforts Associated With implementation of NRC Bulletin 96-03,
- Potential Plugging of Emergency Core Cooling Suction Strainers by De5ris in Bolling Water Reactors" Gen. amen:
By letter dated May 5,1997, PECO Energy submitted a request for license amendments to Facility Operating License Nos. DPR-44 and DPR 56 for Peach Bottom Atomic Power Station (PBAPS), Units 2 and 3, respectively. PECO Energy submitted this request,in accordance with the requirements of 10CFR50.59(c) and 10CFR50.90, in order to facilitate implementation of a plant modification at PBAPS to install new replacement Emergency Core Cooling System (ECCS) pump suction strainers. This plant modification is being instituted in response to NRC Bulletin (NRCB) 96-03,
- Potential Plugging of Emergency Core Cooling Suction Strainers by Debris in Boiling Water Reactors?
In support of this plant modification, PECO Energy performed a 10CFR50.59 Review which l
concluded that certain design aspects of the modification constituted an Unreviewed Safety g 'O Question (USQ), and therefore, a license amendment is required as stipulated in 10CFR50.59(c).
Specifically, the USO pertained to the design assumptions used for determining the amount of debris that would be expected to be generated under Loss of Coolant Accident (LOCA) conditions y This information was crucialin sizing the strainers, The new stralners must and the amount of material that would be transpotted to the suppression chamber (i.e., torus).
to accommodate the expected debris loading in order to ensure that the ECCS is capable of performing its intended safety function. The information submitted in our May 5,1997 letter, discussed the specific aspects of the USO and provided the substantiating information in support of the no significant hazards consideration.
9710070181 970926 PDR ADOCK 050002 7s t
0M M ll3 gppp(Ill
September 26,1997 Dock:t Nos.
50 277 Page 2 50 278 PECO Energy will be installing the replacement brainers in response to the recommended actions specified in NRCB 96-03, on each unit during its next respective refueling outage (i.e., PBAPS, Unit 3 October 1997 and PBAPS, Unit 2 October 1998). These now strainers will be installod l
on the ECCS pump suction piping with the exception of the High Pressure Coolant injection l
(HPCI) system. In our May 5,1997, letter we requested that the NRC approve the license I
amendment requests by September 30,1997, in order to support installation of the modification on Unit 3 during its October 1997 refueling outage (3R11).
As a result of subsequent correspondence and discussions with the NRC regarding these license amendment requests, severalissues have boon identified in which the NRC indicated that additional information is necessary in order to achieve resolution of NRCB 96-03 related issues.
In particular, by letter dated August 14,1997, the NRC requested additionalinformation concerning the amount of containment overpressure credited in the PBAPS, Units 2 and 3, current design basis in evaluating available Not Positive Suction Head (NPSH) for the ECCS pLmps. The NRC also requestod information regarding the minimum containment pressure that would be availablo under post LOCA conditions in order to justify the need for containment overpressure in meeting ECCS pump NPSH requirements. This request was reiterated during a September 15, 1997, meeting between NRC and PECO Energy representativos. During this meeting, PECO Energy requested that approval of the license amendments, which are associated with the USQ (1.o., the debris generation and transport methodology for strainer sizing), be separated from the NPSH-related issues. These issues could be addressed separately as part of the final resolution to NRCB 96-03 for PBAPS, Units 2 and 3. Separating these issues would enable PECO Energy to install the replacement strainers on Unit 3 during the October 1997 refueling outage and restart while at the sc,no time address and resolve the concerns associated with crediting containment ovorpressure as it rotates to ECCS pump NPSH requirements. The NRC representatives were amenable to this request and fully supported the installation of the replacement strainers on Unit
- 3. The NRC indicated that they were working with other licensees Iri similar circumstances by considering granting schedule deferrals for completing the actions associated with NRCB 90-03.
Incorporation of the now debris loading design requirements into the PBAPS, Units 2 and 3, licensing basis will occur upon final closure of NRCB 96-03.
Therefore, PECO Energy is requesting that the NRC approve the pending license amendment requests to support the replacement strainer installation and Unit 3 startup following the outage.
We are also requesting that the schedule for completing the final resolution of NRCB 96-03 for PBAPS, Units 2 and 3, be extended until December 31,1998. This will provide PECO Energy the opportunity to install the now strainers on Unit 3 and continue to work on reaching a satisfactory long-term resolution for NRCB 96-03. We are requesting an expeditious review and approval of this request since the Unit 3 refueling outage is scheduled to finish by the end of October,1997.
The following information is being provided as additional justification for granting our request.
laf0HDation Suoportina RequesdotDeferral PECO Energy will be installing the new large-capacity, passivo, suction strainors on the ECCS pump suction piping, with the exception of the HPCI system, during the October 1997 refueling outage for PBAPS, Unit 3 (3R11). This outage is scheduled to begin on October 3,1997. Tho strainer modification work is the critical path activity for the outage. Startup from the outage is scheduled for October 27,1997. Therefore, approval of the license amendments and deferral of final resolution of NRCB 96-03 actiont is crucial to outage activities. The new strainers will be installed on the ECCS at PBAPS, Unit 2, during its October 1998 refueling outage.
S:ptember 26,1997 Docktt Nos.
60 277
[
Page 3 60 278
.+
PECO Energy is working with its Nuclear Steam Supply System (NSSS) vendor, as necessary, to clarify the availability of containment overpressure in meeting ECCS pump NPSH requirements under post LOCA conditions. Upon completion of this analysis and review by PECO Energy, the information will be submitted to the NRC. It is important to mention that containment overpressure was credited in the initial licensing of PBAPS, Units 2 and 3, as noted in the original NRC Safety Evaluation Report (SER) for PBAPS.
Additionally, PECO Energy will continue to perform the compensatory actions which have been previously committed to as documented in our letters dated November 16,1995, June 10,1990, November 1,1996, and April 3,1997, which were submitted in response to NRC generic communications and requests for additional information regarding the suction strainer clogging concern. These actions include: 1) sampling of water and sludge for the presence of fibrous material,2) monitoring ECCS pump differential pressure data from inservice Inspection Testing (IST),3) visual examination of strainer surfaces for the presence of fibrous material,4) inspection of the suppression chamber floor, and 6) cleaning of the suppression chambers, as necessary, based on the results of inspection findings. The compensatory actions are discussed in more detail in our April 3,1997 letter, in which we indicated that certain compensatory measures would be discontinued following closure of NRCB 96-03, if you have questions or require additional Information, please do not hesitate to contact us.
Very truly yours, 1,
G. A. Hunger, Jr.
Director. Licensing cc:
H. J. Miller, Administrator, Region 1. USNRC USNRC Senior Resident inspector, PBAPS a