ML20203C891
| ML20203C891 | |
| Person / Time | |
|---|---|
| Site: | McGuire, Mcguire  |
| Issue date: | 04/14/1986 |
| From: | Tucker H DUKE POWER CO. |
| To: | Harold Denton, Youngblood B Office of Nuclear Reactor Regulation |
| References | |
| RTR-NUREG-0737, RTR-NUREG-737, RTR-REGGD-01.097, RTR-REGGD-1.097 NUDOCS 8604210258 | |
| Download: ML20203C891 (7) | |
Text
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.a Duxe POWER GOMPANY P.O. Box IKil80 CHAl4LOTTE. N.O. 2H242 HAI. B. TIICKEH rromruc>ne rum ressman (704) 373-4fkN mottaan reootrTeame April 14, 1986 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C.
20555 ATTENTION:5 MrEB7J.1YoungbloodfTProject Director PWR Project" Dire'etordte No. 4
Subject:
McGuire Nuclear Station Docket Nos. 50-369 and 50-370
Dear Mr. Denton:
By letter dated February 12, 1986, NRC transmitted the interim Technical Report Regarding (TER) Regulatory Guide 1.97, Revision 2 for McGuire Nuclear Station, Units 1 and 2.
The letter requested Duke's response to eight items which deviate from Regulatory Guide 1.97.
Attached is a response to each item identified in Section 4 of the TER.
Very truly yours, Bl~4 Hal B. Tucker RLG/jgm Attachment xc:
Dr. J. Nelson Grace, Regional Administrator U.S. Nuclear Regulatory Connission - Region II 101 Marietta Street NW, Suite 2900 Atlanta, Georgia 30323 W.T. Orders NRC Resident Inspector McGuire Nuclear Station Darl Hood, Project Manager Division of Licensing 0
Office of Nuclear Regulatory Commission 0
Washington, D.C.
20555 1
1 I
I 9604210258 860414 PDR ADOCK C5000369.
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e Attachment Page 1 of 6 McGuire Nuclear Station Response to Request for Additional Information:
Emergency Response Capability - Regulatory Guide 1.97 NRC Letter Dated February 18, 1986 1.
Neutron flux--the licensee should identify neutron flux monitoring system modifications and submit the information required by Supplement No. I to NUREG-0737 (Section 3.3.1).
Two new, redundant, QA Condition 1 channels of full range neutron flux instrumentation will be added for post accident monitoring. The indicated range of the new instruments will be at least 10 % to 100% full power.
The instrumentation will be powered from Class 1E busses.
Environmental qualification will be as described in the McGuire FSAR, Section 3.11 and will be included in the NUREG 0588 submittal. Seismic qualification will be as described in the Me@iire FSAR, Section 3.10.
This instrumentation will be installed during the 1988 refueling outages of each unit. This instrumentation will comply with Duke's interpretation of RG 1.97, Rev. 2 as clarified in Section 5.5.
2.
Containment sump water level (narrow range)--environmental qualification should be addressed in accordance with 10 CFR 50.49 (Section 3.3.5).
10 CFR 50.49b)1) and 2) specify two situations requiring environmental qualification of a particular instrument. These are (1) nafety-related equipment and (2) nonsafety-related equipment whose failure under postulated environmental conditions could prevent satisfactory accomplishment of certain safety functions by safety-related equipment. No automatic actions of safety-related equipment are initiated based on Narrow Range Containment Sump level. A review was conducted of the emergency procedures t confirm that no manual actions using safety-related equipment were initiated based on this indication and that its failure would not prevent safety-related equipment from accomplishing safety functions.
The results of this review indicate that this instrument need not be environmentally qualified under 10 CFR 5.-49b)1) or 2).
Narrow Range Containment Sump Level is not used in any of the emergency procedures.
Narrow Range Containment Sump Level, has no intended accident or post-accident monitoring function.
It is used only for the detection of leakage during normal operation. The purposes listed in Reg. Guide 1.97 for this instrument would be accomplished by the environmentally qualified Wide Range Containment Sump Level instrumentation during a design basis event. During an accident, Narrow Range Sump Level serves only as backup indi. cation for the Wide Range instruments.
Narrow Range Sump Level is not considered a key variable for McGuire and a classification of Category 3 is considered adequate. Therefore it is Duke's position that environmental qualification is not required in that this instrument provides no required monitoring function for design basis events that could expose the instrument to a harsh environment.
Attachment Page 2 of 6 McGuire Nuclear Station Response to Request for Additional Information:
Emergency Response Capability - Regulatory Guide 1.97 NRC Letter Dated February 18, 1986 This response is identical to that provided by Duke letter dated October 22, 1985 for Catawba Nuclear Station. This response was subsequently accepted by the NRC in Supplement 5 to the Catawba SER, Appendix L, page 7.
3.
Accumulator tank level and pressure--the applicant should provide a level or pressure instrument for this variable that is environmentally qualified in accordance with 10 CFR 50.49.
If the level instrument is the variable environmentally qualified then the range should be expanded to that recommended by the regulatory guide (Section 3.3.11).
This item will be addressed following resolution of Dtie's position on the same issue for Catawba Nuclear Station as addressed in c letter by H.B.
Tucker to B.J. Youngblood on March 25, 1986 (copy attached).
4.
Refueling water storage tank level--the licensee should install Category 1 instrumentation with the range recommended by Regulatory Guide 1.97 (Section 3.3.10).
As noted in the TER, Duke Power has identified Refueling Water Storage Tank (FWST) level as a Type A variable for McGuire. Regulatory Guide 1.97 sates that Type A variables " provide the primary information required to permit the coutrol room operator to take specific manually controlled actions for which no automatic control action is provided and that are required for safety systems to accomplish their safety function for design basis events".
At McGuire these actions are:
(1) Transferring the suction of the high head and intermediate head safety injection pumps from the FWST to the containment sump.
(2' Stopping the containment spray pumps.
Action 1) is performed in a series of steps beginning approximately one minute after the FWST low level alarm is received. Action 2) is performed upon receipt of the low-low level alarm on the FWST. The alarms occur at 151.2" and 25.2" respectively. When instrument errors are accounted for the alarms will occur at values no more extreme than 154.6" and 21.8".
These values are within the 0" to 160" range of the Category 1 (QA Condition 1) instrumentation. Extensive analyses have been performed to ensure tha the above setpoints account for all necessary allowances during the transfer of suction from the FWST to the containment sump, including delays for operator response, valve stroke time, limiting single failures, and instrument errors. Duke Power therefore concludes that the 0" to 160" range instruments are adequate for the Type A function.
The non-safety (160" to 500" range) instrument installed for FWST level serves no Type A functions. This instrument provides Type D and Tech Spec monitoring functions with the main uses of indicating that the preaccident
l Attachment Page 3 of 6 McGuire Nuclear Station Response to Request for Additional Information:
Emergency Response Capability - Regulatory Guide 1.97 NRC Letter Dated February 18, 1986 4.
Refueling Water storage tank level continued) level is maintained within Tech Spec limits and of monitoring level during refueling operations. Therefore, Category 1 instrumentation is not required for this range of tank level.
Based on recommendations of the McGuire Coctrol Room Review, the 160" to 500" range of this instrument will be recalibrated to cover 0" to 500".
Also, a new instrument will be added to monitor tank level from 375" to 500" to provide greater accuracy for filling operations and for maintaining the level within Tech Spec limits. Neither of these two instruments will be required for any Type A functions.
The changes listed above will be implemented before or during the 1988 refueling outage for each unit. When completed, each of the two instruments will provide control room indication, will be powered from highly reliable battery backed busses and will be located in a mild environment.
5.
Steam Generator level--environmental qualification should be addressed in accordance with 10 CFR 50.49; seismic qualification should be shown to be in accordance with the plant seismic design criteria (Section 3.3.14).
Due to the diversity and reliability of the McGuire Auxiliary Feedwater System most steam generator level fluctuations during design basis accidents which cause a harsh environment in containment will remain within or be automatically returned to the range of the Category 1 (QA Condition 1) narrow range steam generator level instrumentation.
Of the emergency procedures which cover design basis events that cause a harsh environment inside containment, only one, Response to SG Low Level, has been identified as uaing the wide range steam generator level indication. This indication is used to determine whether or not the steam generator is dry.
If the steam generator is dry, it is preferred that the operator restore auxiliary feedwater to it at a more controlled rate.
Two scenarios have been identified which could result in this procedure being used:
1) a steam line break upstream of the MSIVs 2) an auxiliary feedwater valve failure which causes a complete loss i
of feedwater to one generator In the first case, the procedure Response to SG Low Level, specifically cautions the operator not to restore feedwater to a faulted generator.
In
Attachment Page 4 of 6 McGuire Nuclear Station Response to Request for Additional Information:
Emergency Response Capability - Regulatory Guide 1.97 NRC Letter Dated February 18, 1986 5.
steam generator level (continued) the second case, unavailability of the wide range instrument or an incorrect indication due to instrument failure might cause restoration of feedwater to a dry steam generator at the normal flowrate rather than the reduced flowrate. This could result in additional thermal stresses on *.he steam generator tubesheet. To prevent this possibility, a caution w.11 be added to the procedure this year to direct the operator if he suspects a failed wide range instrument, to assume that the generator is dry.
Feedwater would then be conservatively restored at the lower rate.
Restoration of feedwater is preferred but not necessary from a decay heat removal standpoint since the other three steam generators would continue to provide an adequate heat sink. Revision 1 of the Westinghouse Owners Group Emergency Response Guidelines (ERGS) has provided procedural guidance for both environmentally qualified and unqualified wide range steam generator level instrumentation. The relevant ERGS recommend suitable substitute instrumentation if the wide range instrument is unqualified. The McGuire emergency procedures have incorporated this guidance.
6.
Steam generator pressure--the licensee should provide the range recommended by the regulatory guide (Section 3.3.15).
Improper pressure information was supplied in Duke's position concerning this variable. The maximum system pressure during the worst postulated loss of heat sink accident is no greater than 1221 psig. This pressure in derived from transient analyses which conservatively model safety valve opening at 1185 psig plus 3% accumulation. The McGuire safety valves are actually expected to begin opening at 1170 psig + 1%.
This provides a significant margin (approximately 80 psi) between the highest steam line pressure and the upper range limit in a design basis event.
Three additional considerations were questioned regarding the sufficiency of the installed upper range limit:
(1) Pressure drop across the flow restrictor, (2) Pressure instrumentation accuracy, (3) Tolerance on the safety valve lift setpoints.
The pressure drop across the flow restrictor is minor (approximately 3 psi). The normal channel accuracy on the pressure instrument is calculated to be 32 psi. The lift tolerance on the safety valves is already accounted for in the 1221 psig figure given above. Duke Power maintains that the
r i
i Attachment Page 5 of 6 McGuire Nuclear Station Response to Request for Additional Information:
Emergency Response Capsbility - Regulatory Guide 1.97 t
NRC Letter Dated February 18, 1986 l
l 6.
Steam generator pressure (continued) range of the Installed instrumentation is adequate for the McGuire design and considers this instrumentation adequate for the intended monitoring function.
7.
Condensate storage tank water level--the licensee should provide the information required by Supplement No. I to Section 6.2 of NUREG 0737 for this variable (Section 3.3.17).
(The information supplied here is per Section 6.2 of Supplement 1 to NUREG 0737 as requested in Section 3.3.17.)
McGuire has one channel of Condensate Storage Tank level instrumentation.
This instrument provides a control room indication of 0 to 12 feet corresponding to the usable volume of the tank. Additionally, a control room alarm indicates when the tank is not full (<97%). The instrument is powered by the normal station air system and is located in a mild environment. This instrument does not serve a safety or accident function and Duke considers a classification of Category 3 as adequate for the intended monitoring function.
8.
Containment sump water temperature--the licensee should install the instrumentation recommended for this variable or provide information on satisfactory alternate instrumentation (Section 3.3.13).
l Containment Sump Water Temperature instrumentation is not currently installed at McGuire.
It is neither recorded nor indicated as it is not i
required to mitigate the consequences of a design basis event.
l l
(1) The available NPSH for the Residual Heat Removal pumps is l
conservatively calculated with a sufficient safety margin such that an indication of sump temperature is not required in order to ensure adequate NPSH, (2) No automatic or manual actions are initiated based on this temperature.
(3) For containment cooling, Containment Pressure is the variable of primary importance (see variable sheet B-13).
Alternate indications of containment cooling status are provided by l
Containment Atmosphere Temperature (see variable sheet D-24) and l
Containment Spray Flow (variable sheet D-22).
(4) An alternate temperature indication for long term operation in cold leg recirculation is provided by Residual Heat Removal heat exchanger inlet temperature.
e m
Attachment Page 6 of 6 McGuire Nuclear Station Response to Request for Additional Information:
Emergency Response Capability - Regulatory Guide 1.97 NRC Letter Dated February 18, 1986 8.
Containment sump water temperature (continued)
Duke considers the existing instrumentation to be adequate and therefore Containment Sump Water Temperature instrumentation need not be added.
i m
m.
W DMEE POWER GOMPANY p.o. sox aates CMARI.OTfv., M.o. 98249 MALB.T1*CEER tus.arssona messa a remeewevem (F04) 373-4M4 March 25, 1986 Mr. Enrold R. Denton, Director Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D. C.
20555 Attention:
Mr. B. J. Youngblood, Project Director PWR Project Directorate No. 4 Re: Catawba Nuclear Station Docket Noe. 50-413 and 50-414
Dear Sir:
On December 17, 1982 issued by the NRC.
Generic I4tter 82-33 (Supplement I to NUREG-0737) was Regulatory Guide 1.97, Revision 2.This letter included additional clarification regarding By letter date'd September 26, 1983 Duke Power Company (Duke) responded, identifying twenty exceptions and deviations.
On August 6,1985,, the NRC transmitted a draft Technical Evaluation Report (TER).
deviations to Regulatory Guide 1.97 were justified and requested addit justification for the remaining eight exceptions.
On October 22, 1985, Duka responsed to the Staff's request.
In Supplement 5 to the Catawba Safety Evaluation Report, the Staff found the identified deviations acceptable, except for accumulator tank level and pressure.
the Staff required Dulre'to designate either level or pressure as the key As a result variable to directly indicate accumulator discharge and, before that is qualified per the provisions of 10 CFR 50.49 In our October 22, 1985 the accumulator pressure and level instrumentation is to monitor theresponse, pre-accident status of the accumulators to assure that this passive safety system is in a ready state to serve its safety function.
function of the accumulator tank is to empty upon rapid, uncontrolledThe only safety depressurisation of the primary system.
Accumulator tank level and brais events which may cause a harsh environment. pressure are not refere these procedures are based on accumulator indications.No operator actions in The only operator action involving the accumulator portion of the Safety injection System is to isolate the accumulator when the primary system pressure is below 1000 peig and primary systes conditions indicate that the accumulator inventory is not needed to make up lost Reactor Coolant System volume.
is based on system pressure for which fully qualified instruments are That action provided (see variable sheet A-1, form the original response to RG 1.97).
p yY-f-%'
Mr. Harold R. Denton, Director March 25,1986 Page Two Cold leg accumulator tank pressure is used in certain emergency procedures which deal with events beyond the design basis of Catawba.
These procedures are EP/1C5, Loss of Emergency Coolant Recirculation, EP/251 Inadequate Core Cooling, and EP/2B2, Degraded Core Cooling.
In these procedures, accumulator pressure is used to determine when to isolate the accumulator after it has emptied.
In an internal NRC document. H. B.
Clayton to D. L. Ziemann, " Meeting Summary, Westinghouse Owners' Group and Westinghouse Emergency Operating Procedures Guidelines", February 24, 1982, the NRC acknowledged that "for some accident sequences, non-safety-grade equipment and instrumentation is needed and this is reflected in the guidelines".
The use of cold leg accumulator pressure in the above mentioned McGuice and Catawba emergency procedures is in accordance with this philosophy.
The refore, it is Duke's position that the accumulator tank level and pressure are not key variables for any design basis events which result in a harsh environment.
Providing environmental qualification for the post accident in-containment harsh environment should not be required in that the instruments have no post-secident safety function nor provide any required post accident monitoring function.
In Section 7.5.2.1 of Supplement 5 to the Catawba Safety Evaluation Repert the Staff responded as follows:
"The staff disagrees.
It. is necessary to have knowledge e t the statun of these tanka during a loss-of-coolant accident (LOCA) in order to monitor whether they have discharged their contents ir co the reactor coolant system."
This rather brief evaluation by the Staff doesn't provfaa sufficient technical basta for Duke to justify the replacement o' the 16 level or pressure transmitters at Catawba and a like number as McGuire,-where the Staff has taken a similar position. Therefore, in srder for Duke to evaluate the merits of the Staff's requirement to provide qualified accumulator level or pressure indication, it is requested that the Staff provide the following information:
(1)
The NRC has reviewed and approved Rivision 0 of the Westinghouse Owners Group Emergency Reeponse Guidelines (ERC's) and is in the process of reviewing Revision 1 o; the ERG's.
These ERG's are the basis of the Catawba emergen.y procedures.
Therefore, please identify by reference to appropriate ERC's how accumulator level or pressure is used in the management of a design basis accident.
(2)
Assuming the operator had qualified accumulator level or pressure indications, what post-LOCA actions would the operator be able to take based on this information?
(3) What would be the effect of the operator actions in (2) above on the course and consequences of a LOCA7
Mr. Harold R. Denton, Director March 25, 1986 Page Three (4)
Would the repiscenent of the 16 accumulator level or pressure transmitters provide a sabstantial increase in the overall protection of the public health and safety or common defense and security?
Please explain.
(5)
Would the direct and indirect costs of replacing the accumulator level or pressure transmitters be justified in view of any increased protection identified in (4) above?
Please explain.
Based on receipt of responses to the above questions, it is anticipated that Duke would either propose an implementation schedule or pursue the issue further through the NRC's appeal process.
Very truly yours, d Y Hal B. Tucker ROS: sib D'.. J. Nelson Grace, Regional Administrator xe:
'd. S. Nuclear Regulatory Commission
. Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 NRC Resident Inspector Catawba Nuclear Station i'
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