ML20141D847
| ML20141D847 | |
| Person / Time | |
|---|---|
| Site: | Waterford  |
| Issue date: | 06/26/1997 |
| From: | Dugger C ENTERGY OPERATIONS, INC. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20141D854 | List: |
| References | |
| W3F1-97-0136, W3F1-97-136, NUDOCS 9706300037 | |
| Download: ML20141D847 (10) | |
Text
I O
Entargy Operations, Inc.
i Kiliona, LA 70066 0751 Tel 504 739 6660 Charles M. Dugger wee s dent. Operaboris l
A4.05 l
PR June 26,1997 j
l U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555 I
Subject:
Waterford 3 SES l
Docket No. 50-382 License No. NPF-38
)
Technical Specification Change Request NPF-38-199 t
Gentlemen:
The attached description and safety analysis supports a change to the Waterford 3 Technical Specifications. The proposed change modifies Technical Specification (TS) Tables 3.7-1 and 3.7-2. Table 3.7-1 is revised to change the MSSVs orifice 2
2 size from 26 in to 28.27 in and to relocate the orifice size from the TS Table to the TS Bases. Table 3.7-2 is revised by deleting the provision that allows continued plant operation with three Main Steam Safety Valves inoperable. The proposed change also revises TS Bases 3/4.7.1.1 to remove the equation used for i
determining the reduced maximum allowable linear power level-high reactor trip settings of TS Table 3.7-2.
l The change to correct the orifice size in Table 3.7-1 is an editorial change to make the TS Table consistent with plant design. The correct orifice size has always been used in the safety analysis. The relocation of this column to the Bases is consistent with NUREG-1432, which allows relocation of design details out of Technical Specifications.
The change to Table 3.7-2 is the result of evaluations conduded in response to a i
[,h report issued pursuant to 10CFR21, by ABB Combustion Engineering, regarding the omission of main steam safety valve piping pressure loss in the safety analyses.
During the review of this change Waterford 3 will provide controls to prohibit plant 9706300037 970626
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Technical Specification Change Request NPF-38-199 W3F1-97-0136 j.
Page 2 June 26,1997 4
operation with three MSSVs inoperable. However, Waterford 3 respectfully requests an expedited review of the proposed change and that the effective date for this change be within 30 days of approval.
.This proposed change has been evaluated in accordance with 10CFR50.91(a)(1),
using the criteria in 10CFR50.92(c), and it has been determined that this request involves no significant hazards consideration.
Should you have any questions or comments concerning this request, please
- contact Mr. Early Ewing at (504)739-6242.
l Very truly yours, j
C. M. Dugger Vice President, Operations Waterford 3 CMD/PLC/ssf
Attachment:
Affidavit NPF-38-199 cc:
E.W. Merschoff, NRC Region IV C.P. Patel, NRC-NRR J. Smith N.S. Reynolds NRC Resident inspectors Office Administrator Radiation Protection Division (State of Louisiana)
American Nuclear Insurers
i 4
UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION in the matter of
)
)
Entergy Operations, incorporated
)
Docket No. 50-382 Waterford 3 Steam Electric Station
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AFFIDAVIT Charles Marshall Dugger, being duly sworn, hereby deposes and says that he is Vice President Operations - Waterford 3 of Entergy Operations, incorporated; that he is duly authorized to sign and file with the Nuclear Regulatory Commission the attached Technical Specification Change Request NPF-38-199; that he is familiar with the.
content thereof; and that the matters set forth therein are true and correct to.the best of his knowledge, information and belief.
~ ~
LJEi x-Charles Marshall Dugger oI i
Vice President Operations - Waterford 3 STATE OF LOUISIANA
)
) ss PARISH OF ST. CHARLES
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Subscribed and sworn to before me, a yotgry Public in and for the Parish and State above named this 2 e t' day of LL -
,1997.
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c d Notary Public My Commission expires
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DESCRIPTION AND SAFETY ANALYSIS OF PROPOSED CHANGE NPF-38-199 The proposed change revises Table 3.7-1 by changing the Main Steam Safety Valves 2
2 (MSSVs) orifice size from 26 in to 28.27 in and relocating the orifice size from Technical Specifications to the Technical Specification Bases. The proposed change modifies Technical Specification (TS) Table 3.7-2 by deleting the provision that allows continued plant operation with three Main Steam Safety Valves inoperable.
Specifically, this change deletes the entry for three MSSVs inoperable in the Table.
The proposed change also revises TS Bases 3/4.7.1.1 to remove the equation used for determining the reduced maximum allowable linear power level-high reactor trip settings of TS Table 3.7-2.
Existing Specification See Attachment A Proposed Specification See Attachment B
Background
During construction, the plant was initially designed with Lonergan safety valves which 2
have an orifice size of 26 in. Later during construction, Waterford 3 switched to Crosby 2
safety valves which have a orifice size of 28.27 in Although Crosby does not 2
manufacture a valve with a 26 in orifice size, the project specification for the Crosby valves listed the orifice size as 26 in. The Technical Specifications were never 2
changed to reflect the actual orifice size, although the safety analyses have always utilized the correct orifice size. The Crosby safety valves have been installed since initial plant startup.
Six Main Steam Safety Valves (MSSVs) are located on each main steam line upstream of the main steam isolation valve. These safety valves protect both the primary reactor coolant system and the secondary plant against overpressurization by removing steam from the main steam line directly to the atmosphere. The valves are sized to remove over 100% of the full main steam flow at rated conditions.
During accident conditions, the MSSVs are designed to remove heat from the secondary side, thus, preventing both secondary and primary overpressurization (along l
with the pressurizer safeties). The MSSVs must be capable of maintaining the following limits during normal operation and all anticipated operational occurrences:
1
1 1.
Primary Pressure < 2750 psia (110% design) and 2.
Secondary Pressure < 1210 psia (110% design).
The limiting event with respect to the MSSVs is the Loss of Condenser Vacuum (LOCV) accident. This accident will result in a turbine trip on a complete loss of the condenser l-heat sink. Since the condenser is unavailable, the MSSVs are required to relieve full secondary steam to the atmosphere to maintain adequate core cooling capability.
On January 17,1997, ABB Combustion Engineering (ABB/CE) issued a report pursuant to 10CFR21 regarding the omission of main steam safety valve piping pressure loss in the safety analyses. The presence of a pressure drop in the system decreases the steam flow rate through the valve which affects the overpressure protection capability of the MSSVs. The concern, that the Waterford 3 safety analysis could be non-conservative due to the omission of the pressure drop from the steam generator outlet to the MSSV inlet, was evaluated. A preliminary evaluation did not expect any adverse impact as a result of the pressure drop with one MSSV inoperable, however, a concern arose whether the acceptance criteria would be met with multiple MSSVs inoperable.
Since Waterford 3 personnel never recalled operating the plant at reduced power levels due to multiple MSSVs being out of service and since all MSSVs were operable, plant operability was confirmed while the pressure drop effect on the MSSVs was further evaluated.
Combustion Engineering analyzed the limiting accidents for the effect of the pressure drop on peak steam generator pressure and Technical Specification 3.7.1.1. The limiting accident with respect to MSSV operation is the loss of condenser vacuum accident. The pressure drop that occurs from the generator outlet up to the MSSV inlet was calculated to be 72 psia. The calculation used a limiting steam generator design pressure of 1210 psia while also applying individual conservatism to various parameters. The pressure drop from the steam generator to the MSSV inlet was modeled by reducing the flow through the valve. Although the setpoint at the valve inlet did not change, the pressure drop resulted in an increased steam generator pressure.
For example, if the setpoint is at 1150 psia and the main steam line pressure drop is 10 psia, the valve will still open at 1150 psia but the steam generator pressure will be at 1160 psia.
During the week of May 11,1997, ABB/CE reported their initial results for accident analyses incorporating the pressure drop between the steam generator and the MSSV inlet. During full power operation, the limiting loss of condenser vacuum analysis yielded acceptable results with peak steam generator pressure and peak pressurizer l
l pressure being well within their acceptance criteria assuming all MSSVs operable.
l Analysis results with one and two MSSVs inoperable were also well within acceptance l
criteria for power operation at the limits specified in Technical Specification Table 3.7-2.
2
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7 Number of inoperable MSSVs Peak SG Pressure Acceptance Criteria 0
1195 psia
< 1210 psia 1
1192 psia
< 1210 psia 2
1193 psia
< 1210 psia However, with three MSSVs inoperable, the analysis yieloed results much closer to the acceptance criteria (approximately 1209 psia and the acceptance criteria is < 1210 psia). Based on the these results, Waterford 3 requested parametric studies to be performed on several of the assumed worst case parameters. The parametric studies identified that some of the assumptions were slightly non-conservative by a few psia.
The hi*.' pressure drop resulted in the loss of condenser vacuum accident with three MSF
>perable yielding a peak steam generator pressure slightly greater than 1210 psia.
Description Technical Specificatirn 3.7.1.1 Action a, currently allows power operation with up to three MSSVs inoperable provided that the Linear Power Level-High trip setpoint is reduced per TS Table 3.7-2 within four hours. Since the limiting accident analysis (LOCW with three inoperable MSSVs yields a steam generator peak pressure greater than 1210 psia, the proposed change will eliminate the provision to operate with three MSSVs inoperable. As such, TS Table 3.7-2 will only allow for !ower power operation when one or two MSSVs are inoperable. This proposed change is more restrictive and is made in response to the 10CFR21 report written by ABB/CE on January 17,1997 concerning the omission of the MSSV piping pressure loss in safety analyses.
Technical Specifications Bases 3/4.7.1.1 states that with one or more MSSVs inoperable, the Linear Power Level-High trip setpoint must be reduced linearly to match the decreased MSSV tota! flow capacity, yielding the trin setpoints located in Technical Specification Table 3.7-2. This method does not consider the transient and dynamic effects that are present during anticipated operationel occurrences. The inadequacy of Technical Specification Bases 3/4.7.1.1 is discussed in NRC Information Notice 94-60, Potentia! Overpressurization of Main Steam System. In Attachment I to the Information Notice, Westinghouse states that the linear relationship utilized in the Bases (similar to CE plants)is a non-conservative assumption. Recommendation 2 of the attachment states that the issue may be appropriately addressed by analyzing the limitirig accident at the power level stated in Technical Specification Table 3.7-2 with the corresponding nut iber of MSSVs inoperable.
Waterford 3 currently goes beyond the requirements of the Bases and analyzes the loss of condenser vacuum accident (limiting with respect to MSSVs) when one or more MSSVs are inoperable. The results of these analyses are used to confirm the acceptability of the Linear Power Level-High trip setpoints listed in Technical Specification Table 3.b2. The prc; 4ed change will eliminate the linear power l
l 3
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reduction relationship listed in the Bases and state that the acceptability with one or two 1
l MSSVs inoperable will be determined by the application of the loss of condenser vacuum accident with an initial power level equal to _that listed in Technical Specification l
l Table 3.7-2. Note that the Linear Power Level-High trip setpoints for one or two
)
inoperable MSSVs listed in Technical Specification Table 3.7-2 are not changed. Only the method for determining the acceptability of those setpoints will be conservatively altered by the proposed change to the Technical Specification Bases 3/4.7.1.1.
Changing the orifice sir in Table 3.7-1 to the correct value is an editorial change to correct an error in the Technical Specifications. The relocation of the MSSVs orifice size to the Bases is a change to be consistent with NUREG-1432 which allows relocation of unsurveilled design details. The MSSVs orifice size can be adequately controlled outside e' Technical Specifications. The values will be placed in the Technical Specification Bases which require a 10CFR50.59 safety evaluation to be changed. Also, if the valve orifice size were to change, a station modification would have to be performed which would require a 10CFR50.59 and a revision to the safety analysis. Therefore, this change, relocation of the orifice size from Table 3.7-1 to the TS Bases, will continue to ensure that adequate change control is placed on this design parameter, gpfety Analysis The proposed change described above shall be deemed to involve a significant hazards consideration if there is a positive finding in any of the following areas:
1.
Will operation of the facility in accordance with this proposed change involve a significant increase in the probability or consequences of an accident previously evaluated?
Response
No in response to the ABB/CE report pursuant to 10CFR21 regarding the omission of Main Steam Safetv Valve (MSSV) piping pressure loss in safety analyses, the proposed change will eliminate the ability to operate the plant in accordance with Technical Specification 3.7.1.1 Action a with three MSSVs inoperable. The Bases to this Technical Specification will also be revised to state that the acceptability for operation at lower power levels with one or two MSSVs inoperable will be determined from results obtained from a loss of condenser vacuum accident analysis under these conditions. Deleting the allowance for continued operation with thrae MSSVs inoperable does not increase the probability of an accident. The consequences of an accident will not be increased by these changes. These changes are mcre restrictive and ensure 4
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i that the MSSVs maintain their safety functior, of removing adequate heat from the steam generator in order to maintain peak steam generator pressure and -
peak pressurizer pressure well below their respective acceptance criteria during normal operation and all anticipated operational occurrences.-
Changing the MSSVs ori5ce size listed in TS to their actual size and the orifice size utilized in the safety analysis, and relocating the MSSVs' orifice size to the j
Technical Specification Bases does not affect the probability or consequences of an accident. The correct orifice size was used in the safety analysis and it is not j
subject to change unless a station modification is performed which will require a l
10CFR50.59 evaluation and revision of the safety analysis. The MSSVs orifice size can be adequately controlled in the TS Bases which will also require a j
10CFR50.59 to be changed.
j Therefore, operation of Waterford 3 in accordance with this proposed change will not involve a significant increase in the probability or consequences of an accident previously evaluated, l
2.
Will operation of the facility in accordance with this proposed change create the possibility of a new or different type of accident from any accident previously evaluated?
Response
No 1
The proposed change will eliminate the ability to operate the plant in compliance with Technical Specification 3.7.1.1 Action a with three MSSVs inoperable. The Bases for this Technical Specification will also be revised to state that the acceptability for operation at lower power levels with one e two MSSVs inoperable will be determined from results obtained from a loss of condenser vacuum accident under these conditions. The proposed change also revises the MSSVs orifice size to reflect the actual orifice size and the orifice size utilized in the safety analysis, and relocates the orifice size from Technical Specifications to the Technical Specification Bases. The proposed change does not involve any new equipment, components, or modifications and does not create any new system interactions or connections. Therefore, operation of Waterford 3 in accordance with this proposed change will not create the possibility of a new or different type of accident from any accident previously evaluated; I
3.
Will operation of the facility in accordance with this proposed change involve a significant reduction in a margin of safety?
Response
No l
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i The proposed change will ensure that all appropriate acceptance criteria for the MSSVs are met during normal operation and all anticipated operational occurrences. The Technical Specification Bases 3/4.71.1 will be updated to state that the acceptance criteria for operation in accordance with Technical Specification 3.7.1.1 Action a will be determined from the results of the limiting
]
loss of condenser vacuum accident. This change ensures that the transient and dynamic effects which occur during accident scenarios are fully evaluated.
Thcse changes also ensure that the MSSVs will maintain peak steam generator pressure and peak pressurizer pressure well below their respective acceptance i
criteria during normal operation, design basis accidents and anticipated operational occurrences.
The proposed change also revises the MSSVs orifice size to reflect the actual 2
orifice size and the orifice size utilized in the safety analysis, and relocates the orifice size from Technical Specifications to the Technical Specification Bases.
j TMs change corrects an editorial error in the.Technica! Specifications and j
relocates unsurveilled design details from the Technical Specifications.
Adequate control of the orifice size will remain adequate because any changes to the orifice size or the orifice size listed in the Bases will require a station modification and a TS Bases change. Station Modifications and TS Bases changes requires evaluation in accordance with 10CFR50.59.
Therefore, operation of Waterford 3 in accordance with this proposed change will not involve a significant reduction in the margin of safety.
a 1
Safety and Significant Hazards Determination Based on the above safety analysis, it is concluded that: (1) the proposed change does not constitute a significant hazards consideration as defined by 10CFR50.92; and (2) there is a reasonable assurance that the health and safety of the public will not be endangered by the proposed change; and (3) this action will not result in a condition which significantly alters the impact of the station on the environment as described in the NRC final environmental statement.
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e NPF-38-199 ATTACHMENT A
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