ML19312C427
| ML19312C427 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 11/23/1977 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19312C420 | List: |
| References | |
| NUDOCS 7912130950 | |
| Download: ML19312C427 (5) | |
Text
.
/
- g UNITED 5TATES 8
NUCLEAR REGULATORY COMMISSION o
WA SHINGTON, D. C. 20555 k*,,,*/
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENCMENT NO. 53 TO LICENSE NO. OPR-38 AMENCMENT NO. 53 TO LICENSE NO. OPR-47, AND ANENDMENT NO. 50 TO LICENSE NO. OPR-55 DUKE POWER CCMPANY DOCKET NOS. 50-259, 50-270 AND 50-287 Introduction By letter dated November 9,1977, Duke Pcwer Ccmpany (the licensee) requested Technical Specification changes en quadrant flux tilt and control red position limits to the Facility Operating License for the Oconee Nuclear Sta-icn, Unit 1, Cycle 4.
The request was initiated by tne licensee's cesire for full power operaticn with quadrant neutron flux tilt (potential pcwer peaking) which has been observed. On October 31,1s77, the staff issuec amendments which allowed continued operaticn and testing with an increased flux tilt at 75% power with conservative restrictions on core themal pcwer, nuclear power trip setpoint, and rod position limits. With this centinued ocera-tion and testing, the tilt has decreased to a value near the current Technical Specification limit for 1001, power. The licensee has stated in the November 9,1977 letter, that the recuested change would provice a restriction on pcwer peaking, and that the proposed operation is more desirable and prudent t!;,an the current Technical Specificaticn limits on the basis of the pcwer peaking restriction.
Evaluation The licensee's analysis in support of the preposed Technical Scecifications is for the first 100 effective full pcwer days (EFFD) of operatien. Analysis for operation beyond 100 EFFD will be supplied at a later date.
The licensee
, has stated that the propcsed Technical Scecificatiens have been established with the same calculation mcdels and metneds as previcusly reviewed and found acceptable for. Oconee 'l Cycle 4.
The.prepcsed Technical Speci.fications would allow operation in an unrodded mcde (change in red position limits) with a' maximum quadrant tilt of 6.03%
The rod position limits are based on the most limiting of the follcwing three criteria:
ECCS power peaking, snutdown margin, and potential ejected rod worth. The quadrant tilt limits are established to prevent the linear heat generation rate peaking beyond analyzed conditions. A discussion of these considerations follow.
791213096D
~
+e
The licensee performed the power ceaking analysis for Oconee 1 Cycle 4
~
operation frca 0 to 100 EFPD in tne unrodded mode with an assumed 6.03%
quadrant tilt througnout the range of pcwer levels.
This analysis was based on calculation using the P0Q computer code and shewed a 9% increase in local peaking based on the relationship between peaking and tilt.
The licensee has sucplied a ccmparison of calculated and measured power distributions at 40% and 75% of full pcwer.
The licensee has stated that these pcwer distributions in conjunction with the standard total and radial nuclear uncertainty factors show that the 9% increase in local peaking is conservative.
The licensee calculated the total peaks during various times of the fuel cycle through 100 EFPD for the proposed Technical Specification limits.
This calculation showed that the total peaks would be reduced frem the values for the current Technical Specificationlimits at all times frca 4 EFPD to 100 EFPD. Oconee Unit 1. Cycle 4 is beyond the 4 EFPD value, so that the pcwer peaking will be reduced for the Oconee Unit 1 prooosed operation.
The licensee has pointed out that operation in the unredded mcde provides a means to restrict power peak'ing to ncminal values.
This protection is gained at the expense of operational flexibility. With this mode of operation the plant has a greatly reduced maneuvering capability. Mcwever, the usual peaking factors due to xenon changes induced by normal maneuvering were included in the analysis, providing additional conservatism.
The ejected rod worth insertion limits were determined based on using the hot, zero pcwer measured values of rod worth to correct for the quadrant tilt effects. The resulting maximum effected red worth correction factor was over 50%. This factor was used to adjust calculated ejected rod worths for the existence of the quadrant tilt.
The net result of this procedure is the decrease in the amount that the cperating banks may be inserted to satisfy the criteria during a postulated ejected rod accident. The resulting red insertien limits were less limiting than shutdcwn margin criteria at all pcwer levels above zero pcwer. Thus, cnly at the :ero pcwer limit are the red position limits based on ejected rod criteria.
The shutdown red insertion limits were deternined using standard techniques
, based on synmetric conditions and adjusting these calculations to acceunt for the tilt. The calculated srtuck rod worths are increased over 50%.
The.
measured values of banks 5, 6 and 7 at Hot Zero Power were also used to determine the shutdcwn margin red insertion limits. As an added conservatism the beginning of life calculated total rod worth was used at 100 EFP0 to determine the limits at this time. 'The licensee stated that this procedure results in conservative shutdcwn rod insertion limits.
The licensee has concluded that the net effect of all these conservatisms is that the core is restricted in operating flexibility but allowed to operate at full power in a safe manner. The current Axial Power Shaping Rods position limits and imbalance limits for 0 to 100 EFPD are more restrictive than necessary for the proposed mode of rod-out-operations.
The rod position limits were determined based on the sucer-position of the most conservative calculated and measured data.
It has The proposed unrodded opeyation is not 'a new o'pegational mode.
been previously submitted and found acceptable.
The regulatory position in reference 2 suggests that Technical Specifications include a two-hour hold at 90% of rated power to ensure that transient xence.dces not increase the linear heat rate by more than 5%, and quadrant tilt verifications at two-hour intervals.
Rancho Seco Unit 1 Technical Specifications allow operation in an unrodded mode. The staff ccmpared these to the Oconee 1 Technical Specifications. We have found that the Rancho Seco Unit 1 Technical
. Specifications are compatible with the Oconee 1 Technical Specifications and that the intent of the regulatory positions are satisfied by the current Oconee 1 Technical Specificaticas which are not changed for this snenc=ent.
We have reviewed 'he licensees current surveillance program. We consider t
that additional surveillance is necessary to assure that operational anomalies are observed on a timely basis. Thus, the licensee has agreed to increase surveillance of reactor power distribution to daily.
We have also agreed to remove the requirement for'a report in 24 EFPD since the licensee must justify continued operation past 100 EFFD and this justification will address the flux tilt experienced curing Oconee 1 Cycle 4.
Based on the licensee's* submittal which shcws that the red position limits
~
conservatively ccmpensate for the increased potential tilt, the previous staff review of unrodded operation for Rancho Seco Unit 1, the ccmpliance of Oconee Unit 1 to the regulatory position for unrodded cores, and the increased power distribution surveillance, we find the requested enange in red position and tilt limits to be acceptable.
. We consider operation at 100% power or below acceptable with a flux tilt of 6.03%. However, we have evaluated operation for only 100 EFFDs. Operation past 100 EFFD must 'be. supported by an amendment request by the licensee wi'th suitable justification. We. are r'equesting that a request'-to' amend:
~
the license for operation past 100 EFPD be subnitted no later than 80 EFFD.
Based on our evaluation, operation in the proposed manner does not reduce the safety margins of the current Technical Specificaticn limits. We conclude that the probability or consequences of any transients and accidents considered in the FSAR are not increased and that the safety margins are not reduced. Thus, we conclude that these changes do not involve a significant ha:ards consideration.
4-Environmental Consideratien
'~
We have determined that these amendments do not authorize a change in effluent types or total amounts nor an increase in pcwer level a nc will not result in any significant environmental impact.
Having made this determination, we have further concluded that these amendments involve an action which is insignificant from the standpoint of environmental impact and pursuant to 10 CFR 551.5(d)(4) that an environmental impact statement, negative declaration, or environmental impact appraisal need not be preapred in connection with the issuance of these amendments.
Conclusion We have concluded, based on the considerations discussed above, that:
(1) because the amendments do not involve a significant increase in the probability or consecuences of accidents previously considered and do not involve a significant decrease in a safety margin, the amendments do not involve a significant ha:ards consideration, (2) there is reasonable assurance that the health and safety of the public will not be endangered by coeration in the proposed manner, and (3) such activities will be conducted in compliance with the Commission's regulaticns and the issuance of these amendments will not be inimical to the common defense and security or to the health and safety of the public.
Date:
.!avember 23, 1977 9
4
\\
5-i References
" Operational Parameters for Rancho Seco, Unit 1," TRG-73-47, 1
October 1973.
2 Memorandum frem V. Stello to R. C. DeYoung, " Review of Babcock and Wilcox letter Report Entitled, Operational Parameters for Rancno Seco Unit 1,'
October 1973, TRG-73-47," October 16, 1973.
e*
e 4
e e
O N
9 4
I re e
mo em
..m.==.
..-e-...
UNITED STATES NUCLEAR REGULATORY COMMISSICN DOCKET NOS. 50-259, 50-270 AND 50-287 DUKE POWER COMP ANY NOTICE OF ISSUANCE OF AMENCMENTS TO FACILITY OPERATING LICENSES The U. S. Nuclear Regulatory Ccmission (the Ccmmission) has issued
~
Amendment Nos. 53, 53 and 50 to Facility Operating License Nes. CPR-38, CPR-17 and CPR-55, respectively, issued to Duke Fewer Cc=any which revised the Technical Speci'ications for c;eraticn of the Ocenee Nuclear Station, Unit Nos. 1, 2 and 3, located in Ocenee County, South Carolina. The amendments are effective within 30 days after the date of issuance.
These amendments revise the Technical Specifications to allow operat':n of Ocenee Unit 1 Cycle 4 at 100% full pcwer with a flux tilt of 5.03% in an unrodded mode.
The apolication for the amendments ccmolies with the standards and recuirements of the Atemic Energy Act of 1954, as amended (the Act), and the Comission's rules and regulations. The Comissicn has made appropriate findings as required by the Act and the Comission's rules and regulations in 10 CFR Chapter I, which are set forth in the license amendments.
Prior public notice of these amendments was not recuired since the amendments do not involve a significant ha:ards ccnsideratien.
l l
7702?ose
~
p 3-The Commission has determined that the issuance of these amendments will not result in any significant environmental impact and that pursuant to 10 CFR 551.5(d)(4) an environmental. impact statement or negative declaration and environmental impact appraisal need not be prepared in connection with the issuance of these amendments.
For further details with respect to this action, see (1) the application for amendments dated November 9,1977,(2) Amendment Nos. 53,
53 and 50 to License Nos. OPR-38, CPR-47 and CPR-55, respectively, and
~(3) the Commission's related Safety Evaluatien. All of these items are l
available for public inspection at the Cemnission's Public Document Roem,-
s 1717 H Street, NW., Washington, D.C. and at the Ocenee Ccunty Library! '.
201 South Spring Street, 'Aalhalla, South Carolina 29691. A cocy of items (2) and (3) may be obtained upon request addressed to the U.S..
Nuclear Regulatory Commission, Washingtor, D.C.
20555, Attention:
Director, Division of Operating Reactors.
Dated at 5ethesda,. Maryland, this 23rd day of November 1977.
FOR THE NUCLEAR REGULATORY COMMISSICN
~
~
sg g
Alfred Burcer, Actine Chief Operatin'g ienctors 5fanch !1.
Division of Operating Reactors l
2 I
'Y"
_-