ML16152A319
| ML16152A319 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 04/23/1984 |
| From: | Stolz J Office of Nuclear Reactor Regulation |
| To: | Tucker H DUKE POWER CO. |
| References | |
| GL-81-21, NUDOCS 8405040166 | |
| Download: ML16152A319 (5) | |
Text
9 pril 23, 1984 Dockets Nos. 50-269, 270 Distribution:
and 50-287 Docket File EBlackwood Reading File HOrnstein Gray File NRC PDR Mr. Hal B. Tucker Rlngram BSheron Vice President - Steam Production HNicolaras KHeitner Duke Power Company EJordan P. 0. Box 33189 JNGrace Charlotte, North Carolina 28242 LPDR OELD ACRS 10
SUBJECT:
RESPONSE TO GENERIC LETTER 81-21, NATURAL CIRCULATION COOLDOWN
Dear Mr. Tucker:
The NRC staff has reviewed your response to the Generic Letter 81-21, and finds that the concerns regarding RCS voiding and subsequent operator actions during natural circulation cooldown are inadequately addressed.
This letter transmits a request for information (see enclosure) which will be used by the staff to assure that the intent of Generic Letter 81-21 is met for your plant.
The intent of the Generic Letter was to obtain assurance that a natural circulation cooldown could be effected in a reasonable time while maintaining the primary coolant in the liquid phase at all times.
We are currently reviewing an analysis from the licensee for TMI-1 which we find substantially addresses our concerns. We encourage you to use that analysis to the extent applicable to your plant. There may be an advantage also to adopting a Babcock & Wilcox Owners Group (BWOG) approach on this issue because this issue is similar on all B&W plants. A copy of the requests for information transmitted to the B&W licensees involved is being sent to the BWOG Steering Committee Chairman to expedite an Owners Group response in the event you wish to use that approach.
Please provide your schedule for your response to the request within 30 days of the date of this letter. Please contact your NRC Project Manager if you have any questions on this subject.
Sincerel. yours, 57 John F. Stolz, Chief Operating Reactors Branch No. 4 Division of Licensing
Enclosures:
As stated cc w/enclosure:
See next page 8405040166 840423 PDR ADOCK 05000269 P
Duke Power Company cc w/enclosure(s):
Mr. William L. Porter Duke Power Company P. 0. Box 33189 422 South Church Street Office of Intergovernmental Relations Charlotte, North Carolina 28242 116 West Jones Street Raleigh, North Carolina 27603 Honorable James M. Phinney County Supervisor of Oconee County Walhalla, South Carolina 29621 Mr. James P. O'Reilly, Regional Administrator U. S. Nuclear Regulat.ory Commission, Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30303 Heyward G. Shealy, Chief Bureau of Radiological Health South Carolina Department of Health and Environmental Control Regional Radiation RepresentativeBull Street ERegion Raiato ereettv Columbia, South Carolina 29201 EPA Region IV 345 Courtland Street, N.E.
Atlanta, Georgia 30308 Mr. J. C. Bryant Senior Resident Inspector U.S. Nuclear Regulatory Commission Route 2, Box 610 Seneca, South Carolina 29678 Mr. Robert B. Borsum Babcock & Wilcox Nuclear Power Generation Division Suite 220, 7910 Woodmont Avenue Bethesda, Maryland 20814 Manager, LIS NUS Corporation 2536 Countryside Boulevard Clearwater, Florida 33515 J. Michael McGarry, III, Esq.
Bishop, Liberman, Cook, Purcell & Reynolds 1200 17th Street, N.W.
Washington, D. C. 20036
ENCLOSURE 1 REQUEST FOR ADDITIONAL INFORMATION FROM RANCHO SECO, OCONEE 1, 2 AND 3, AND ANO-1 In response to Generic Letter 81-21, dated May 5, 1981, all PWR licensees were required to demonstrate, by analyses and/or test, that a controlled natural circulation cooldown from operating conditions to cold shutdown conditions, conducted in accordance with their procedures, should not result in reactor vessel voiding. Your responses, as given in References 1 and 2, to our request did not provide the required demonstration. Instead you stated that your natural circulation cooldown procedures have not been constructed to attempt to preclude reactor vessel head void formation, but rather to mitigate a void should one form.
The staff has concluded that upper head voiding is not a safety concern provided the operator is equipped with adequate training and procedures.
However, upper head voiding does make RCS pressure control more difficult during a natural circulation cooldown. Thus, it is the staff's position that the natural circulation cooldown procedure should be developed to prevent upper head voiding to the extent possible. The operator procedures must also address means of mitigating a reactor vessel head void should one form. We believe that the demonstration requested by the Generic Letter is required in order to develop these procedures.
We have also been examining the responses to the Generic Letter provided by other licensees with B&W plants. We are concerned about the wide ranqe of cooldown rates, ranging from lioF/hr to 50'F/hr, utilized by B&W plants.
We believe that a coordinated Owner's Group response may be best in oroviding the requested demonstration.
We would like to note that we are aware of the calculations which have been performed to assess the reactor vessel upper head cooldown rate.
These calculations, References 3 and 4, show that the head cooldown rate is approximately 1 1/20 F/hr. We believe that the cooldown times implied by these calculations do not have sufficient technical justification and that they should not be used as the basis for operating procedures.
In summary, the staff requires that you provide the demonstration, via analysis and/or test data, requested in Generic Letter 81-21, to show that a natural circulation cooldown can be performed without formation of a reactor vessel head void.
We believe this response can best be provided via the Owner's Group and are willing to discuss this with you at your earliest convenience.
REFERENCE Duke Power Company
- 1. Letter, W. 0. Parker, Duke Power Co, to H. R. Denton, NRC, 11/5/81.
- 2.
Letter, H. B. Tucker, Duke Power Co., to H. R. Denton, NRC 2/19/83 SMUD
- 1. Letter, J. J. Mattimoe, SMUD, to J. F. Stolz, NRC, 11/16/81
- 2. Letter, W. K. Lathan, SMUD, to J. F. Stolz, NRC, 9/21/83 ANO 1
- 1.
Letter, D. C. Trimble, AP&L, to D. G. Eisenhut, NRC, 11/13/81
- 2.
Letter, J. R. Marshall, AP&L, to J. F. Stolz,-NRC 7/13/83 All
- 3.
Boman, B. L., "Reactor Vessel Head Cooldown During Natural Circulation Cooldown Prepared for Consumers Power Company,"
Babcock & Wilcox Utility Power Generation Division, February, 1983.
- 4. Tally, C. W., "Single Loop Natural Circulation Cooldown Prepared for Consumers Power Company," Babcock & Wilcox Nuclear Power Generation Division, August, 1982.