ML20236R471
| ML20236R471 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek  |
| Issue date: | 07/17/1998 |
| From: | Maynard O WOLF CREEK NUCLEAR OPERATING CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20236R473 | List: |
| References | |
| WM-98-0091, WM-98-91, NUDOCS 9807220056 | |
| Download: ML20236R471 (12) | |
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W$LF CREEK NUCLEAR OPERATING CORPORATION Otto L Maynard President and Chief Executive Officer July 17, 1998 WM 98-0091 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Mail' Station: Pl-137 Washington, D. C. 20555
Reference:
Letter ET 97-0050 dated May 15, 1997, from R. A. Muench, WCNOC, to NRC
Subject:
Docket No. 50-482: Emergency Technical Specification Amendment Application For Technical Specification Section 3/4.7.5, Ultimate Heat Sink Gentlemen:
This letter transmits an application for n emergency amendment to Fac.i U ty Operating License No. NPF-42 for Wolf Creek Generating Station (WCGS), Wolf Creek Nuclear Operating . Corporation (WCNOC) requests that this request be reviewed under the emergency situation provisions of 10 CFR 50.91 (a) (5) This emergency amendment is necessary to prevent plant shutdowns between now arei September 30, 1998, as described below.
This request proposes to revise Technical Specification 3/4.7.5, Ultimate Heat Sink, by adding a new action statement. The new action statement will provide a required action and completion time for the Ultimate Heat Sink (UHS).in the event that plant inlet water temperature exceeds 90*F, as an alternative to the requirement to shut down the unit contained in the current technical specification'. The WCGS cooling lake temperature exceeded 89'F on July 14, 1998. Due to predictions for continuing harsh meteorological conditions over the next several weeks, the concern exists that the plant inlet water 7
temperature may exceed 90*F, forcing a unit shutdown in accordance with Technical-' Specification - 3/4.7.5. This requested amendment is temporary, f' pending long-term resolution of this issue, and is requested to be in effect until September 30, 1998, when the specification will revert back to its J current form.
As stated above, WCNOC requests this license amendment request be processed on an emergency basis in order to prevent an unnecessary unit shutdown. The (g g unustal combination of environmental conditions currently being experienced at WCGS (extremely high temperatures, high humidity and lack of wind) have resultedsin higher. cooling lake temperatures than have previously been
, experienced. This unprecedented condition was not predictable. Therefore,
! WCNOC believes that, given the circumstances surrounding the nature and I discovery of this event, WCNOC has made a best effort to submit a timely I application for this amendment. WCNOC has not delayed any actions in order to create the emergency and therefore "take advantage" of the procedure described in-10 CFR 50.91 for emergency amendments. WCNOC believes that this emergency amendment is unavoidable, and meets the criterion of 10 CFR 50.91(a) (5) for an emergency request.
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JO Rrw A111 Aurhngton, KS 66839 / Phone: (316) 364 8831 9807220056 980717 g oppo,,un,ty Empioyer u/r/HcNET PDR ADOCK 05000482 p PM
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WM 98-0091 Page 2 of 2 A Safety Evaluation for the proposed license amendment request is provided in Attachment I; a No Significant Hazards Consideration Determination, in Attachment II. Attachment III is the related Environmental Impact Determination. Marked up pages are provided in Attachment IV for the current Technical Specifications. A markup for the Improved Technical Specifications and Bases submitted by t r.e Reference is not provided, pending long-term resolution of this issue.
In accordance with 10 CFR 50.91, a copy of this application, with attachments, is being provided to the designated Kansas State Official.
If you hu any questions concerning this natter, please contact me at (316) 364-8831, extension 4000, or Mr. Michael J. Angus at extension 4077 Very truly yours,
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Otto L. Maynard OLM/rir Attachments: I - Safety Evaluation II - No Significant Hazards Consideration Determination III - Environmental Impact Determination IV - Proposed Current Technical Specification Change
- s cc: V. L. Cooper (KDHE), w/a W. D. Johnson (NBC), w/a E. W. Merschoff (NRC), w/a J. F. Ringwald (NRC), w/a K. M. Thomas (*1RC) , w/a l
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- c STATE OF KANSAS )
) SS COUNTI OF OOFFEY )
Otto L. Maynard, of lawful age, being first duly sworn upon oath says that he
- is . President and Chief Executive Officer of Wolf Creek Nuclear Operating Corporation; that he has read the -foregoing document and knows the content thereof; that he has executed that same for and on behalf of said Corporation with full power and authority to do so; and that the facts therein stated are
- true and correct to the best of his knowledge, information and belief.
By ~
/ d(/81/
Otto i.. Mfynard
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President and Chief Executive Officer SUBSCRIBED and sworn to before me this /7 day of M hf , 1998.
-.., 1 Aons 2 Notary Public
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asa~f urAsnso T-/4#m 9 Expiration Date /}_// ![ . t a
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Attachment I' to BM 98-0091 Page'1 of 4 e
I O ATTACHMENT I SAFETY EVALUATION I
Attachment l'to WM 98-0091 Page 2'of 4 Safety Evaluation Description of the Proposed Change This request for an emergency license amendment proposes to revise Wolf Creek Generating Station (WCGS) Technical Specification 3/4.7.5, Ultimate Heat Sink, to add a new action statement. Specifically, the new action statement will allow contiriued operation of the plant with plant inlet water temperature greater thau 90 but less than 95 degrees Fahrenheit (*F) for up to twelve (12) hours before requiring shutdown of the plant.
Background
The ultimate heat sink (UHS) is the normally submerged Seismic Category I cooling pond. The UHS is formed by providing a volume of cooling water behind a Seismic Category I dam built in one finger of the WCGS cooling lake. The two principal functions of the UHS are the dissipation of residual heat after reactor shutdown, and dissipation of residual heat after an accident.
The UHS is the sink for heat removed from the reactor core following all accidents and anticipated operational occurrences in which the unit is cooled down and placed on residual heat removal 'RHR) operation. Its maximum post accident heat load occurs after a design basis loss of coolant accident (LOCA) when the unit switches from injection to recirculation and the containment cooling systems and RHR are required to remove the core decay heat.
The baric performance re quirement s for the UHS are that a 30 day supply of water ' available, and that the design basis temperatures of cafety related equipm nt not be exceeded. The capacity of the UHS is sufficient to provide cooling for the required period of 30 days with no riakeup water under both normal and accident conditions. The UHS is ascumed to supply cooling water to the essential service water system (ESWS) at a rate of 30,000 gpm for the entire 30-day period for this analysis. The UHS has sufficient capacity to supply emergency makeup water to the spent fuel pool and component cooling water systems and to serve as the backup water sapply for the auxiliary feedwater system. The UHS also has sufficient capacity to allow up to 140 gpm of continuous losses throughout the 30 day period due to leakage from the ESWS. At -he start of the analysis, the UHS was assumed to have lost a volume of 155 acre-feet due to sediment.
The UHS is designed in accordance with Regulatory Guide 1.27, which requires a 30 day supply of cooling water in the UHS. The UHS satisfies Criterion 3 of 10 CFR 50.36 (c) (2) (ii) . The UHS design ensures that the design temperatures of safety-related equipment are not exceeded. The design temperature of water supplied to the plant is 95*F.
The operating limits are based on conservative heat transfer analyses for the worst case LOCA. Section 9.2.5 of the Updated Safety Analysis Report (USAR) provides the details of the assumptions used in the analysis, which include worst expected meteorological conditions, conservative uncertainties when calculating decay heat, and worst case single failure.
The UHS is required to be OPERABLE and is considered OPERABLE if it contains a sufficient volume of water at or below the maximum temperature that would allow the ESWS to operate for at least 30 days following the design basis LOCA without exceeding the maximum design temperature of the equipment served by the ESWS. To meet this condition, the plant inlet water temperature should not exceed 90*F and the minimum water level should not fall below 1070 ft mean sea level during normal unit operation.
The UHS design was based upon adverse hydrological and meteorological conditions. The maximum tempe ature and maximum evaporation periods for recorded weather conditions were conridered in sizing of the UHS. Selection r
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Attachment I'to WM 98-0091 Page 3'of 4 of the critical weather periods was based upon a computer analysis (UHSAVG) of meteorological data for a 16-year period which included a severe drought, estimated to have a recurrence interval of 50 years. A weather tape scan of surface weather data for Chanute, Kansas, and of precipitation data for Iola, Kansas, for the period of 1949-1964 was performed. These data includea the historic drought years of 1952-1957 The 16-year weather data were used to evaluate water surface temperatures and evaporation rates for a prescribed rate of heat rejection from the surface of the i)HS. The worst evaporation period was obtained by selecting the weather conditions corresponding to the 30 consecutive days for which evaporation loss was maximum. The worst temperature period was obtained by saving the conditions for the 5 consecutive days, 1 day, and 30 consecutive days resulting in highest average water temperature after which these three periods were combined in the indicated order to produce a synthetic 36-day worst-weather period.
The maximum evaporative and temperature periods were determined to have the following dates:
Maximum Evaporation Period Wolst 30 days: June 24, 1954 to July 23, 1954 Maximum Temperature Period Worst 5 days: June 30, 1949 to July 5, 1949 Worst 1 day: July 2, 1949 (Noon) to July 3, 1949 (Noon) ,
Worst 30 days: July 16, 1951 to August 15, 1951 For the above listed weathe; periods, ultimate heat sink draw-down and plant inlet temperatures were eva;uated as a function of time using a computer model (LAKET-5) which predicts the transient response of the heat sink to external conditions.
Heat rejection rates were taken as those corresponding to a LOCA or Normal shutdown with an assumed total flow of 30,000 gpm. In addition, it was assumed that all of the water in the UHS was at 90*F at the start of this analysie.
Following the loss of the main dam, the highest plant inlet water temperature occurring during the maximum temperature peric,d is predicted to be 95'F. The predicted plant inlet temperature was usually well below 95'F. The predicted plant inlet average temperature over the entJre period wes slightly below 90*F and, 95% of the time, below 94*F.
The maximum drawdown under worst evaporative conditions, including water loss due to lake seepage, was found to be approximately 1.65 feet from the initial elevation of 1070 feet. This corresponds to a decrease in UHS volume of about 39% of the volume existing at the start of the accident. At this point the UHS water level is at 1068.35 feet, and the UHS has already provided the required 390,000 gallons of emergency makeup water and 140 gpm of ESWS losses throughout the 30 days. The plant can achieve safe shutdown in the event of postulated LOCA using only the UHS.
l Evaluation f
l Wolf Creek evaluated the effect of the proposed change on normal plant operation and normal plant shut down with the main dam intact, safe shut down or post-accident operation without the main dam, and LOCA with main dam.
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Attachment I'to WM 98-0091 Page 4.of 4 9
Normal plant operation
'Short term operation with an inlet water temperature of up to 95*F is not expected to negatively affect plant operation, with the possible exception of turbine back pressure. A slight load reduction may be necessary to maintain acceptable turbine back pressure. . Existing plant guidance will be employed if any unexpected transients are experienced. '
Shut down with'the main dam intact The effect of increasing the inlet water temperature from 90*F to 95*F causes the calculated single train time required to cool the unit below 200*F to exceed the 36 hour4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> technical specification limit. To compensate for this concern the requested action statement requires verification of operability of two RHR trains. This will ensure the cooling cap & city is available to meet the shut down time requirements.
Safe shut down or posc-accide.nt operation without the main dam The TS limit of 90*F is not being changed; however, the license amendment '
provides an allowance for operation above that limit, to less than 9 5
- F, for up to a 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> period. Based on a review of recent WCGS cooling lake data, 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> may be necessary to restore the lake below 90*F through diurnal effects.
Safe shut'down capability and post-accident operation without the main dam is ensured when the plant is operated within TS limits. The probability of main dam failure is low compared to the frequency of a large break LOCA initiating event. The probability of main dam failure during the 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> when the inlet water temperature is above 90*F in conjunction with an accident is even lower.
A seismic event is a possible initiating event for causing failure of the main dam. The frequency of the seismic initiator on an annual basis is nearly equal to a large break LOCA. It is also noted that WCGS has a dam monitoring program in place tc ensure continued integrity of the main dam. Therefore, it is concluded that this proposed change is of low risk significance. It is noted that the WCGS accident analyses assume a plant inlet water temperature of 95'F.
LOCA with the main dam The effect of full power plant operation on plant inlet water temperature during worst case predicted summer environmental conditions is approximately 0.5'F. The peak heat rejection rate by the plant post-LOCA would be approximately 5% of the continuous heat rejection rate of the plant during normal operation. Therefoie, the effect of post-LOCA heat loads on plant inlet water temperature would be less than 0.l*F.
The current UHS analysis assumes that there has been a main dam failure and uses synthetic we,rst case environmental conditions. The results indicate that with an initial UHS temperature of 90*F, plant intake water temperature remains below 95'F. Current plant Design Basis Accident analyses were performed assuming a continuous plant intake wat2r temperature of 95*F. The UHS. analysis results also indicate that the environmental conditions have a much greater effect on peak plant intake water temperature than does the heat rejected from the plant. The current UHS analysis is recogni7ed as bounding
- l. the LOCA condition without a main dam failure because the voluna of the UHS is l significantly smaller than the volume of the WCGS cooling lake, approximately 1%.
Th'e probability that environmental conditions significantly worse than those causing entry-into the LCO is low. The probability of these conditions ;
occurring siruitaneously with a LOCA is even lower. j
a Attachment I'I to WM 98-0091 Page 1 of 3 t e ATTACHMENT II NO SIGNIFICANT HAZARDS CONSIDERATION DETERMINATION 1
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Attachment I'I to WM 98-0091 Page 2 of.3 No Significant Hazards Consideration Determination Proposed Change )
This license amendment request proposes to revise Wolf Creek Generating Station. (WCGS) < Technical Specification 3/4.7.5, Ultimate Heat Sink, to add a new action - statement. Specifically, the new action statement will allow continued operation of the plant with plant inlet water temperature greater than 90 but less than 95 degrees Fahrenheit (*F) for up to twelve (12) hours before requiring shutdown of the plant. ;
'The following sections discuss the proposed change under the three standards of 10 CFR 50.92.
Standard I -
Involves a Significant Increase in the Probability or Consequences of an Accident Previously Evaluated The proposed change does not involve any physical alteration of plant systems, structures or components. The proposed change provides an allowed time for the plant to continue operation with plant inlet water temperature in excess of the current technical specification limit of 90*F, but less than the design limit of 95'F fer plant components. The plant inlet water temperature is not assumed to be' an initiating condicion of any accident analysis evaluated in the updated safety analysis report (USAR). Therefore, the allowance of a limited time for the water temperature to be in excess of the current limit does not involve an increase in the probability of an accident previously evaluated in the USAR. The UHS supports operability of safety related systems used to mitigate the consequences of an accident. Plant operation for brief periods with plant inlet water temperature greater than 90*F but less than 95'F will not adversely affect the operability of these safety-related systems and will not adversely impact'the ability of these systems to perform their safety-related functions. Therefore, the preposed change-does not involve a significant increase in. the probability or consequences of an accident previously evaluated in the USAR.
Standard II - Create the Possibility of a New or Dd!ferent Kind of Accident from any Previoualy Evaluated The proposed change does not involve any physical alteration of plant systems, structures or components. The temperature of the plant inlet water being greater than 90*F but less than 95*F for a short period does not introduce new failure mechanisms for systems, structures or components not already considered in the USAR. Therefore, the possibility of a new or different kind of accident from any accident previously evaluated is not created.
Standard III - Involve a Significant Reduction in the Margin of Safety The proposed change will allow an increase in plant inlet water temperature-above the current technical spe itication limit of 90*F for the Ultimate Heat l Sink, and delay the requirement to shutdown the plant when the plant inlet. j water system temperature limit is. exceeded for 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. The propor i change j does not alter any safety limits, limiting safety system settings, or limiting conditions for operation, end the proposed temperature increase will remain below the design limit cooling water. input value for safety-related equipment.
Thus, the proposed change does not involve a significant reduction in any margin of safety. !
Based on the above discussions, it has been determined that the requested technical specification revision does not involve a significant increase in the probability of consequences of an accident or other adverse conditions
! . over . previous evaluations; or create the possibility of a new or different kind of accident or condition over previous evaluations; or involve a l
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Attachment I'I'to WM 98-0091'
-* - Page 3 of 3 s'ignificant reduction;in a margin of safety. Therefore, the requested license
- amendment does-not involve a significant hazards consideration.
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Attachment I'II to WM 98-0091 Page 1 of 2 o
1 ATTACHMENT III ENVIRONMENTAL IMPACT DETERMINATION ,
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Attachment NI to WM 98-0091 Page 2 of 2 Environmental Impact Determination 10 CFR 51.22 (b) ' specifies the criteria for categorical e4clusions from the requirement' for a specific environmental assessment per 10 CFR 51.21. This amendment request meets the criteria specified in 10 CFR 51.22 (c) (9) as specified below:
.(i) the amendment involves no significant hazards consideration As ' demonstrated in Attachment II, the proposed changes do not involve any
.significant hazards considerations.
(ii) there is not significant change in the types or significant increase in the amounts of any effluents that may be released offsite The proposed change does not involve a change:to the facility or operating procedures that would cause an increase in the amounts of effluents or create new types of . ef fluents. While the predicted increase in cooling lake temperature is higher than previously experienced, this increase is due to environmental effects of nature, not from plant operation. Plant operation with plant inlet water temperature greater than 90*F but less than 95*F for short periods will not cause a significant change in the types of or a significant increase in the amounts of any effluents that may be released offsite.
(iii) there is no significant increase in individual or cumulative occupational radiation exposure This change has no relation to occupational radiation exposure, either
-individual or cumulative.
Based on the above, it is concluded that there will be no impact on the environment resulting from . this change and the change meets the criteria specified in 10 CFR 51.22 for a categorical exclusion from the requirements of-10 CPR 51.21 relative to requiring a specific environmental assessment by the
. Commission.
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