ML17059C251
| ML17059C251 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 09/18/1998 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML17059C249 | List: |
| References | |
| NUDOCS 9809230193 | |
| Download: ML17059C251 (12) | |
Text
ghee RECij
~o A0 C
O IVl0v~,
ie
+~
~O
++*++
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON> D.C. 205550001 SAFETY EVALUATIONBYTHE OFFICE OF NUCLEAR REACTOR REGULATION RELATEDTO AMENDMENTNO. 163 TO FACILITYOPERATING LICENSE NO. DPR-63 NIAGARAMOHAWKPOWER CORPORATION NINE MILEPOINT NUCLEAR STATION UNIT NO. 1 DOCKET NO. 50-220
1.0 INTRODUCTION
By letter dated July 16, 1998, as supplemented by letter dated September 3, 1998, Niagara Mohawk Power Corporation (NMPC and the licensee), proposed a license amendment to change the Technical Specifications (TSs) for Nine Mile Point Nuclear Station, Unit No. 1 (NMP1). The proposed amendment would change TS 3/4.2.3 regarding reactor coolant chemistry in accordance with a report by Electrical Power Research Institute, Inc. (EPRI) TR-103515-R1, "BWR Water Chemistry Guidelines, 1996 Revision," also known as Boiling Water Reactor Vessel and Internals Project (BWRVIP)-29. Specifically, the amendment would define new conductivity limits in TS 3.2.3a (when reactor coolant is 200 'F or more and reactor thermal power is no more that 10%), and in TS 3.2.3b (when reactor thermal power exceeds 10%).
The new conductivity limits would be 1 p, mho/cm, which is less than the existing limits of 2 p mho/cm and 5 p, mho/cm.
-The chloride ion limit in TS 3.2.3a, 0.1 ppm, would remain at this value but would be designated as 100 ppb. The chloride ion limit in TS 3.2.3b would be changed from 0.2 ppm to 20 ppb. Sulfate ion limits would be added to TS 3.2.3a and TS 3.2.3b at 100 ppb and 20 ppb, respectively.
The proposed change to TS 3.2.3a would require that the reactor coolant water shall not exceed these new limits specified in TS 3.2.3a for conductivity, chloride ion, or sulfate ion for more than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> when the coolant temperature is equal to or greater than 200 'F and the reactor thermal power is no more than 10 percent, or a shutdown shall be initiated within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> and the reactor shall be shutdown and reactor coolant temperature reduced to below 200 'F within 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br />.
Similarly, TS 3.2.3b would require that the reactor coolant water not exceed the new limits specified in TS 3.2.3b for more than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> when reactor thermal power exceeds 10 percent, or a shutdown shall be initiated within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> and the reactor shall be shutdown and reactor coolant temperature reduced to less than 200 'F within 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br />. TS 3.2.3c would be changed to state: "In no case shall the reactor coolant exceed the following limits at the specified conditions or a shutdown shall be initiated within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> and the reactor shall be shutdown and reactor coolant temperature be reduced to less than 200 'F within 10 hour1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br />s: (1) With reactor coolant temperature at or above 200 'F, the conductivity has a maximum limitof 5 p mho/cm, or (2) With reactor coolant temperature at or above 200 'F and reactor thermal power no more, than 10 percent, the maximum limitof chloride or sulfate ion concentration is 200 ppb, or (3) With reactor thermal power greater than 10 percent, the maximum limitof chloride or sulfate ion concentration is 100 ppb." Existing TS 3.2.3d would be revised to address circumstances previously addressed by TS 3.2.3e, but modified to require that "Ifthe continuous conductivity monitor is inoperable for more than 7 days, a shutdown shall be initiated within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> and the reactor shall be shutdown and reactor coolant temperature be reduced to below 200 'F within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />." TS 4.2.3 would be revised to add that the samples taken and analyzed for conductivity and chloride ion content 9809230i93 9809i8 PDR ADDCK 05000220 P
are also to be analyzed for sulfate ion content.
The sampling frequency specified in TS 4.2.3 would be increased from "at least 3 times per week with a maximum time of 96 hours0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br /> between samples" to "daily." TS Bases 3/4.2.3 would also be changed to reflect that the purpose of TS 3/4.2.3 is to limit intergranular stress corrosion cracking (IGSCC) crack growth rates to values consistent with Nine Mile Point Unit 1 (NMP1) core shroud analyses in accordance with an NRC letter dated May 8, 1997, and to describe the NMP1 operating philosophy of maintaining levels (averaged over an operating cycle) for conductivity, chloride and sulfate concentration to values that ensure the crack growth rate is bounded by the core shroud analysis.
By letter dated September 3, 1998, NMPC deleted its request regarding two changes that had been proposed as new TSs in the July 16, 1998, application for license amendment.
NMPC also submitted edited versions of TS 3.2.3a and 3.2.3b to improve clarity. These changes do not affect the Commission's finding of no significant hazards consideration that was issued in a Federal ~Re ister notice (63 FR 43432, August 13, 1998).
2.0 BACKGROUND
'uring the 1997 refueling outage at NMP1, NMPC found extensive cracking in the core shroud vertical welds.
By letter dated April 8, 1997, NMPC submitted flaw evaluations and analyses to demonstrate the acceptability of the as-found vertical weld cracking for at least 10,600 hours0.00694 days <br />0.167 hours <br />9.920635e-4 weeks <br />2.283e-4 months <br /> of hot (above 200 'F) operation.
NMPC's flaw evaluation was based upon a bounding crack growthrate of5x10'nch perhour.
The use ofthe bounding crack growthratewas supported by laboratory test data performed on sensitized stainless steel at a range of conductivities from 0.3 to 1.5 pmho/cm.
In a letter dated April 30, 1997, NMPC committed to continue operating NMP1 in accordance with the EPRI Water Chemistry Guidelines, including the most limiting condition of "Action Level 1" specified therein. According to Action Level 1, ifthe conductivity should exceed the limitof 0.3 pmho/cm, appropriate corrective action should be taken to reduce the conductivity to be no more than that value within 96 hours0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br />.
Although NMP1 has been operating at a conductivity of less than 0.3 pmho/cm during the last seven cycles, the conductivity limit in its TS 3.2.3 is 5 pmho/cm (when steaming rate >100,000 pounds per hour).
By letter dated May 7, 1997, NMPC committed to submit an application for license amendment that would address the difference between the current reactor coolant system chemistry req'uirements of NMP1 TS 3.2.3 and the coolant chemistry criteria referenced for core shroud crack growth rates as described in NMPC's letter of April 8, 1997.
By letter dated May 8, 1997, the NRC staff addressed continued operation of NMP1 with the existing core shroud for an additional 10,600 hours0.00694 days <br />0.167 hours <br />9.920635e-4 weeks <br />2.283e-4 months <br /> of hot operation.
The NRC staff found this continued operating period acceptable subject to the conditions that (1) reactor coolant chemistry be maintained within the EPRI guidelines and (2) NMPC submit the license amendment application.
Thus, NMPC's application for license amendment is in response to the conditions specified in the NRC staff's letter of May 8, 1997.
3.0 EVALUATION The proposed TS amendment consists of changes to TS sections 3.2.3 and 4.2.4 and the associated TS Bases regarding the control of reactor coolant chemistry. These proposed changes are summarized and discussed below.
I A
(1) TS 3.2.3, "Coolant Chemistry,"
(I)
In TS 3.2.3a, the proposed changes are:
(a) The reactor operating conditions forwhich the water chemistry limits (conductivity, chloride ion, and sulfate ion concentrations) specified in this section willapply are chang'ed from steaming rates less than 100,000 pounds per hour to the conditions when the coolant temperature is z 200 'F and the reactor thermal power is s 10%.
(b)
The conductivity limit is changed from 2 pmho/cm to 1 pmho/cm.
(c)
A sulfate ion limitof 100 ppb is added.
(d)
The chloride ion limit remains the same but is designated as 100 ppb instead of 0.1 ppm.
(e)
Ifthe water chemistry limits specified in this TS are exceeded for >24 hours, a shutdown of the reactor shall be initiated within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> and the reactor coolant
~
temperature shall be reduced to <200 'F within 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br />.
(ii) ln TS 3.2.3b, the proposed changes are:
(a)
The reactor operating conditions forwhich the water chemistry limits specified in this TS will apply are changed from steaming rates greater than or equal to 100,000 pounds per hour to the conditions when the coolant temperature is z 200 'F and the reactor thermal power is > 10%.
(b)
The conductivity limit,is changed from 5 pmho/cm to 1 pmho/cm.
(c)
A sulfate ion limitof 20 ppb is added.
(d)
The chloride ion limit is changed from 0.2 ppm to 20 ppb.
(e)
Ifthe water chemistry limits specified in this TS are exceeded for >24 hours, a shutdown of the reactor shall be initiated within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> and the reactor coolant temperature shall be reduced to <200 'F within 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br />.
(iii) In TS 3.2.3c. the proposed changes are:,
(a)
The maximum conductivity limitis changed from 10 pmho/cm to 5 pmho/cm.
(b)
The maximum limitof chloride ion concentration is changed from 0.5 ppm to 100 ppb and 200 ppb for reactor coolant temperature z 200 'F and reactor thermal power > 10% or s 10%, respectively.
(c)
The maximum limits of sulfate ion concentration of 100 ppb and 200 ppb are added for reactor coolant temperature a 200 'F and reactor thermal power a 10%
or c10%, respectively.
(d)
Ifthe water chemistry limits specified in this TS are exceeded at any time, a shut down of the reactor shall be initiated within one hour and the reactor coolant temperature shall be reduced to <200 'F within 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br />.
(iv) In TS 3.2.3d, the proposed change is:
(a)
This TS is deleted because the reactor shutdown conditions are specified in TSs 3.2.3(a), (b) and (c).
(v) In TS 3.2.3e, the proposed changes are:
(a)
This TS is renumbered as 3.2.3d.
(b)
When the continuous conductivity monitor is inoperable for more than seven days, the requirement to place the reactor in cold shutdown condition within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> as currently specified is changed to initiating a reactor shutdown within one hour and the reactor coolant temperature is required to be reduced to < 200 'F within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
The NRC staff notes that the bounding crack growth rate of 5 x 10~ inch per hour used in calculating the crack growth in the core shroud vertical welds is supported by laboratory test data performed on sensitized stainless steel at conductivities ranging from 0.3 to 1.5 pmho/cm.
Therefore, the proposed conductivity limitof 1 pmho/cm for normal operation in the TS is consistent with the analysis assumptions for the core shroud crack growth evaluations.
The NRC staff also notes that the requirement to reduce the reactor coolant temperature to < 200 'F within a specified period of time (within 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> in TSs 3.2.3a, b and c or 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> in TS 3.2.3d) during reactor shutdown is added.
This additional requirement is desirable in limiting the potential crack growth due to IGSCC, since IGSCC is known to become inactive at a tempe'rature below 200 'F. Overall, the proposed reactor water chemistry limits are much more conservative than those currently specified and, thus, willlimit the potential crack growth in the core shroud due to IGSCC. The NRC staff h'as determined that the proposed changes in TS 3.2.3 are acceptable because the specified water chemistry limits are consistent with EPRI's BWR Water Chemistry Guidelines, 1996 Revision, and as discussed in the NRC staffs letter of May 8, 1997, are consistent with the analyses accepted by the NRC for continued operation of NMP1 for at least 10,600 hours0.00694 days <br />0.167 hours <br />9.920635e-4 weeks <br />2.283e-4 months <br /> of the current fuel cycle.
(2) TS 4.2.3, "Coolant Chemistiy."
In TS 4.2.3 the proposed changes are:
(i)
In addition to the conductivity and chloride ion content, the sulfate ion content is also required to be analyzed in the coolant samples.
(ii) The frequency of analyzing the samples is increased from three times every week to once every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
The NRC staff has determined that the proposed changes to the surveillance requirements in TS 4.2.3 are acceptable, since the scope of the coolant sample analyses is increased to include sulfate ion concentration and the monitoring frequency is also increased to provide assurance that the limiting condition for operation as specified in the TS willbe adequately monitored.
(3) TS Bases 3.2.3 and 4.2.3 NMPC has revised the TS Bases for TSs 3.2.3 and 4.2.3 to provide more detail regarding the control of the coolant water chemistry. The revised discussion also identifies the administrative controls that apply to coolant water chemistry.
Significant items discussed in the proposed TS Bases include the following:
(i) The purpose of the TS is to limitthe potential crack growth in the core shroud through tight control of the reactor coolant chemistry so that the analysis assumptions in the core shroud crack growth evaluations are met.
(ii) NMPC discusses its commitment to operate NMP1 in accordance with EPRI's BWR
'ater chemistry guidelines, including its administrative control of the water chemistry to meet the Action Level 1 limits (conductivity of 0.3 pmho/cm and chloride or sulfate ions of 5 ppb).
(iii) NMPC's goal in controlling coolant conductivity is to not exceed 0.19 pmho/cm.
Additional coolant sample analysis will be performed within eight hours ifconductivity exceeds 0.19 pmho/cm for longer than 30 minutes.
I (vi) The locations of the coolant samples taken for analysis are identified.
4 The NRC staff notes that EPRI's water chemistry guidelines do not require a plant shutdown if the water chemistry limit corresponding to Action Level 1 is exceeded.
- Rather, it requires that water chemistry be reduced below the Action Level 1 limitwithin 96 hours0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br />.
Furthermore, ifthe Action Level 1 limits cannot be restored within 96 hours0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br />, a long-range program to improve the water chemistry is required to be initiated. Since the water chemistry Action Level 1 limits do not require a reactor shutdown when the limits are exceeded, the NRC staff agrees that it is appropriate to control these limits administratively, instead of by the TS. The NRC staff also notes that, even, if the Action Level 1 limitfor conductivity (0.3 pmho/cm) is exceeded, it willnot impact the validity of the analysis assumptions for the core shroud crack growth evaluations, because the bounding crack growth rate (5x10 'nch/hour) used in the crack growth calculation is supported by the test data performed in an environment with conductivity ranging from 0.3 to 1.5 pmho/cm. The reactor shutdown requirements in TS 3.2.3 would become applicable if conductivity were to exceed 1 pmho/cm for over 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
The NRC staff has reviewed NMPC's proposed TS changes and concludes that (1) the proposed reactor water chemistry limits and monitoring frequency meet the guidance in EPRI's BWR water chemistry guidelines and (2) the specified conductivity limits are consistent with assumptions used in the analysis previously reviewed and accepted by the NRC staff regarding the NMP1 core shroud crack growth evaluations.
Furthermore, NMPC's administrative control of reactor coolant chemistry willprovide additional assurance in limiting the potential crack growth in the core shroud.
4.0 STATE CONSULTATION
In accordance with the Commission's regulations, the New York State officialwas notified of the proposed issuance of the amendment.
The State official had no comments.
5.0 ENVIRONMENTALCONSIDERATION The amendment changes a requirement with,respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and changes surveillance requirements.
The NRC staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure.
The Commission has previously issued a proposed finding that the amendment involves no significant hazards consideration, and there has been no public comment on such finding (63 FR 43432). Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR 51.22(b)
0 "0
W no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the aniendment.
6.0 CONCLUSION
The Commission has concluded, based on the considerations discussed above, that:
(1) there is reasonable assurance that the health and safety of the public willnot be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment willnot be inimical to the common defense and security or to the health and safety of the public.
Principal Contributors:
W. Koo D. Hood Date:
September 18, 1998
4
\\
j I