ML17202G562
| ML17202G562 | |
| Person / Time | |
|---|---|
| Site: | Dresden, Quad Cities, LaSalle, 05000000 |
| Issue date: | 07/24/1989 |
| From: | Kovach T COMMONWEALTH EDISON CO. |
| To: | Davis A NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| Shared Package | |
| ML17202G563 | List: |
| References | |
| IEB-88-007, IEB-88-7, NUDOCS 8908140023 | |
| Download: ML17202G562 (5) | |
Text
Common.Ith Edison 72 West Ada treet, Chicago, Illinois Address Reply to: Post Office Box 767 Chicago, Illinois 60690 - 0767 Mr. A. Bert Davis Regional Administrator U.S. Nuclear Regulatory Commission Region III 799 Roosevelt Road Glen Ellyn, IL 60137 July 24, 1989
Subject:
Dresden Nuclear Power Station Units 2 and 3 Quad Cities Nuclear Power Station Units 1 and 2 LaSalle County* Station Units 1 and 2 Commonwealth Edison BWR Operating Restrictions to Preclude Regional Oscillations NRC Docket Nos. 50-237/249; 50-254/265 & 50-373/374 References (a):
January 26, 1989, letter from H.E. Bliss to A.B. Davis (same subject).
Dear Mr. Davis:
(b):
February 16, 1989 letter from A.B. Davis to Cordell Reed (same subject).
Reference (a) discussed Commonwealth Edison's intentions for removing certain conservative operating provisions which were developed and implemented
.by Edison prior to the issuance of NRC Bulletin 88-07, Supplement 1.
Edison felt that removing these self-imposed restrictions were appropriate to more closely reflect the GE and NRC prescribed measures.
The attachment to Reference (a) also included a comment on the need for clarification of the Bulletin provisions regarding_ entry into Bulletin Regions A and B under circumstances which challenge vital equipment or fuel.
Prior to submittal of Reference (a), it was discussed with both NRR (B.L~ Siegel) and Region III (M.A. Ring, R. Lanksbury).
In addition, this point was also addressed in a BWR Owners Group (BWROG) letter from D.R. Grace to A. Thadani dated January 26, 1989, and in the CECo response to I.E.Bulletin 88-07, Supplement 1 dated March 3, 1989.
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J.uly 24, 1989 In the Reference (b) letter, Region III indicated that Edison could not unilaterally adopt this interpretation and that the Bulletin requirements must be implemented without exception.
Because of the significance bf this issue, both CECo and BWROG have maintained dialogue with NRR.and your staff in an attempt to reach a final resolution.
During an April 6, 1989 meeting with NRR, the Owners presented their justification for allowing intentional entry into Regions A, B, or C under certain abnormal conditions.
Based on Edison's understanding of that meeting, NRR has agreed in principle that entry into Regions A, B, or C is permissible in response to abnormal operating ~onditions that challenge vital equipment or the fuel.
Edison is currently in the process of implementing this philosophy at all three of our BWR stations.
For your information, attached are the Edison provisions and justifications for allowing entry into the potential instability regions under some circumstances.
Included as part of this attachment is the BWROG Summary of the April 6, 1989, meeting with NRR.
lm Please contact this office should furt~er informatiqn be required.
Very'truly yours,
~*~**
T. ;~:~h Nuclear Licensing Manager Attachment cc:
B.L. Siegel - Project Manager, NRR P.C. Shemanski - Project Manager, NRR T.M. Ross - Project*Manager, NRR S.G. D~Pont -
Senior Resident Inspector, DR R.D. Lanksbury -
Senior Resident Inspector! LSCS R.L; Higgins -
Senior Resident Inspector, QC 0210T:9
July 10, 1989 Messrs:
R. L. Bax G. J. Diederich E. D. Eenl.genburg
Subject:
Inadvertent Entry Into Regions of Potential Instability
References:
- 1. NRC Bulletin 88-07, Supplem:!nt 1, dated December 30, 1989.
- 2. BWRCX; letter to A.. Thadani (NRC), "NRC Bulletin 88-07, Supplarent 1, 'Power Oscillations in Boiling Water Reactors' ", dated January 26, 1989.
- 3. A. Thadani letter to BWRCG, "Pawer Oscillations in Boiling Water Reactors", dated March 22, 1989.
- 4. BWRCG letter to A. Thadani, dated June 14, 1989 (enclosed).
- In reference 1, the NRC provided operating guidance for avoiding postulated :p::Mer oscillations and required that General Electric's "Interim Reccrcrnendatioris ForStability Actions" be adopted. These reccrcrnendations*
prohibit intentional entry into the low flow, high :p::Mer operating regions known to be susceptible to instabilities.
Following the issuance of Reference 1, the BWR o.vners Group (BWRCG) has worked closely with the Ccmnission to clarify this issue and identify circumstarices under which entry into the defined regions may be necessary.
In the reference 2 letter to the Ccxrrnission, the BWRCX; provided an interpretation to the Bulletin supplarent which stated that entry into the stability regions may be required to protect fuel or equiptent vital to plant safety.
The NRC responded to the o.vners position in Reference 3 stating that justification should be prepared for plants adopting this
- interpretation.
The BWRCX; provided justification for such entry during an April 6, 1989 rreeting between the BWRCX; Stability Ccmnittee and NRC staff personnel.
To ensure the NRC and BWRCX; had reached a mutual understanding during the April 6 rreetio.g, a subsequent telecon was held between the NRC (L. Phillips and H. Rlchings) and BWRCX; representatives (T. J. Rausch et. al.) on June 6, 1989, to discuss the maeting highlights (see Reference 4, enclosed).
The rationale for allowing entry into either region A, B or C defined in Reference 1 was found acceptable by the NRC and. is surrmarized below:
- 1.
Current operator training places strict emphasis on prc.mpt correC:tive action and-close adherence to procedures. Abnonnal operating procedures have been developed to mitigate specific plant casualties. It is pr).ldent operating practice to handle the specific event at hand and not distract the operator by imposing additional stability related restrictions. The Bulletin Supplement requi.ratEnts *are interim in nature and conser\\ratiyely minimize the potential for unacceptable instabilities after entering the associated region(s).
Therefore, changing this fundanental operating philosophy by placing a priority on instability avoidance over responding to postulated events is detri.nEntal to safe operating practices.
- 2.
Abnonnal Operating procedures for.responding to stability concerns have been developed and will be consulted for the appropriate corrective actions if one of the regions of
. potential instability is entered following the response to an unusual event.
- 3.
It is not always possible to detei:mine beforehand if the plant will end up in region A, B or C for every possible transient or.
equipnent failure response.
Since a scram is not required by
- the interim recamiendations upon entering regions B or C, it is inappropriate to require a scram prior to taking action which may result in entry ihto these regions. Although a scram is required for LaSalle upon entry into region A or upon loss of forced recirculation, it is rrore important to respond to the irrmediate concern at hand rather than distract the operator's attention by requiring him to detei:mine if a given set of responses will cause the unit to end up in Region A or natural circulation.
For the reasons stated above, entering the regions of potential instability (i.e., regions A and B) to protect vital equiprent or fuel should not be construed as "intentional" entry provided the appropriate corrective actions for that region are Pr<:111?tly administered in accordance with the Bulletin supplement~
Although this letter provides circumstances under which the potential exists for entry into regions A, B, or C, each station must ensure the Bulletin requirenents are adhered to following such entry.
An acceptable method is to place an appropriate reference to the stability abnonnal response procedure in those nonnal and abnonnal operating procedures having the potential for initiating en~ry into the stability regions. Alternate methods may also be employed. (e.g. operator aids that signal entry into the defined stability regions), but such alternates must be approved by Nuclear Fuel Services and this office. Contact Tan Rausch
(X3850) or Ma.rk Wagner (X3497) to discuss the acceptability of alternative rrethods for ensuring that proper operator actions will be taken following entry into the stability regions.
Each station is requested to resp:md in writing to the manager of Nuclear Fuel Se:rvices (with copy to T. J. Rausch) by August 31, 1989, surrmarizing their proposed strategy for ensuring the newly clarified Bulletin requireTEnts are net.
Cc:
C. Reed L. O. DelGeorge D. M. Farrar W. F. Naughton.
B. B. Palagi T. J. Kovach/J. A. Silady A. L. Misak M. A. Falcone E. A. McVey T. J. Rausch
~M. E. Wagner File: Stability
"]) e \\A""""~ c: a 0Qa Dennis Galle