ML20126C944
| ML20126C944 | |
| Person / Time | |
|---|---|
| Site: | 05000470 |
| Issue date: | 06/04/1985 |
| From: | NRC |
| To: | |
| Shared Package | |
| ML20126C933 | List: |
| References | |
| NUDOCS 8506140585 | |
| Download: ML20126C944 (7) | |
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SAFETY EVALUATION - CESSAR SYSTEM 80 By letter (NRC to CE) dated March 27, 1984, the staff expressed concern related to the availability of the auxiliary pressurizer spray (APS) system to perform its required safety functions for CESSAR System 80 plants (Palo Verde, WNP-3) which are designed without PORVs. As noted in the subject letter, the staff considers that the CESSAR System 80 APS should be treated as safety-related in accordance with Appendix A to 10 CFR 50 and 10 CFR 100 since it is required for safe shutdown of the plant and to mitigate the consequences of an SGTR accident should the main pressurizer spray system become unavailable. APS flow is initiated from the control room by opening at least one of the redundant (parallel) auxiliary spray valves (CH-203 or CH-205) in combination with the closure of the existing loop charging valve (CH-240). The staff expressed concern that a failure of CH-240 to close would negate the safety function of the APS system.
i After being informed of the staff's concern, CE committed (September 18, 1984 l
letter) to modify CESSAR System 80 to provide a valve in series with the existingloopchargevalve(CH-240). However, the staff discovered through discussions that CE planned to use non-Class IE buses to power CH-240 and the new series valve even though they are considered to be safety-related.
The staff found this unacceptable since these valves are required to perform a safety function as discussed above.
85061401435 85064h4 PDR ADOCM 05000470 E
. It is the staff's position that if equipment (pumps, valves) is required to perform a safety-related function, the mechanical and electrical components including any associated electrical power distribution system should be treated as safety-related and implemented as such. Thus, the existing loop charging valve (CH-240) and the additional series valve used to isolate normal charging flow should satisfy the single failure criterion and should not be dependent on the use of non-safety-related equipment including the power distribution system. Specifically, each valve should be powered from separate, electrically independent Class IE buses; any exception to this position must be appropriately
,iustified.
The staff notified CE of the above position by letter dated February 8,1985.
CE responded by letter dated March 22, 1985.
Review of the information supplied in the March letter shows that CE continues to propose the use of non-Class IE buses to power the sub,iect valves but has committed, as an alternative to the use of Class IE power, to provide isolators to the non-safety-related power supply control circuits for protection of valves CH-239 and CH-240.
The staff considers this comitment to be acceptable. However, the staff does require that the isolators be Class IE protective devices and that they be implemented to assure that the capability of the valves to perform the intended safety functions is not degraded below an acceptable level as a result of all possible circumstances that could occur (i.e., overvoltage, undervoltage, low frequency, design basis events, etc.) associated with its non-Class IE power buses. This will require the perfonnance of plant-specific failure modes and effects analyses to support the required safety functions of the valves. The Class IE electrical protective devices must meet the applicable portions of IEEE . 279 (i.e., 4.2 - Single Failure Criterion, 4.3 - Quality of Components, 4.4 -
Equipment Qualfiication, 4.5 - Capability for Test and Calibration, 4.18 -
Identification of Protective Actions, 4.20 - Information Read-Out, 4.21 -
\\
System Repair, 4.22 - Identification). These requirements were established during the review of the Palo Verde application and are to be implemented in the design.
Based on the above commitment and satisfactory adherence to the requirements set forth by the staff, we consider this issue to be resolved on the CESSAR docket.
l i
SAFETY EVALUATION - CESSAR/ SYSTEM 80 SECTION 5.4.3, SHUTDOWN COOLING SYSTEM The shutdown cooling analysis submitted by CE assumes that the Reactor Coolant System Gas Vent System is available for RCS depressurization during plant cooldown. The staff requested that an interface requirement be provided in the CESSAR 80 FSAR to require a safety-related Reactor Coolant Gas Vent System.
In response to the staff request, CE, in a letter dated March 22, 1984, provid'ed a new interface requirement as follows:
5.4.7.1.3.P 4.
Reactor Coolant Gas Vent System (RCGVs).
The RCGVs shall be designed as Safety Grade and shall meet the single failure criterion of IEEE 279.
The staff concluded that this interface requirement is acceptable.
Section 15.6.3, Steam Generator Tube Rupture (SGTR)
Combustion Engineering's analysis of a postulated Steam Generator Tube Rupture (SGTR) with loss of offsite power and a stuck open atmospheric steam dump valve (ADV) case takes credit of the ADV block valves.
In response to the staff request, CE, in a letter dated March 15, 1985, proposed the following revised CESSAR Interface Requirements to be included in a future amendment to CESSAR FSAR:
. CESSAR Section 5.1.4 Item B.2 The steam piping and associated supports from the steam generator up to and including the Main Steam Isolation Valves (MSIVs), the ADVs and their associated isolation valves, and any auxiliary steam supply systems up to the isolation valves which connect upstream of the MSIVs shall be Seismic Category I and designed to ASME B&PV Code,Section III, Class 2 require-ments.
Item 1.14 If the isolation valves upstream of the ADVs are electrically controlled or operated, the valve operator and control systems shall be designed to the same IEEE standards as applied to the ADVs.
The staff has reviewed the revised CESSAR interface requirements above and has
. concluded that they are acceptable. The ADV block valves do not have to be remotely operable, because the SGTR analysis in CESSAR assumes manual actions to close the block valve. However, the staff will review the accessibility of the ADV block valves on each referencing applicant's docket if the local manual operator ADV block valves are used in the plant design.
REVIEW STATUS OF PROPOSED CESSAR CHANGES SUBMITTED AFItR FDA-2 1.
CESSAR CONSISTENCY REVIEW CHANGES (10/22/84 SUBMITTAL)
All changes in this submittal have been found acceptable, except the change in Table 9.3-1, Operating Chemistry Limits, which is still under review. This review has been performed in parallel with that of the corresponding topic on the Palo Verde docket (Palo Verde 1 License Condition No. 23). This issue has been closed on the Palo Verde docket, and the staff expects to close it on the CESSAR docket by June 17.
2.
CESSAR CONSISTENCY REVIEW CHANGES (CE LETTER LD-84-069, DATED DECEMBER 5, 1984)
The staff has completed its review of all the changes proposed in this submittal, and found them acceptable.
3.
CESSAR AMENDMENT 10 (CE LETTER LD-84-070 0F DECEMBER 5,1984)
This submittal involves the following changes:
3.1 Changes in Chapter 5, 7 and 14 and in Appendix A These changes have been found acceptable.
3.2 Chapter 6 changes These changes have since been withdrawn by CE (letter LD-85-021, of April 26,1985).
.... 3.3 Changes in Appendix 6B and in Chapters 9 and 10 Those changes have been reviewed in parallel with the corresponding issues on the Palo Verde docket (Palo Verde 1 license condition 23).
A request for additional information was sent to CE on March 25, 1985.
CE replied by a letter dated April 25, 1985. The staff cxpects to complete its review by June 17.
3.4 Chapter 16 changes These will be part of the Technical Specifications review (see 4 ).
4.
HIGH PRESSURE SAFETY INJECTION FLOW (CE LETTER LD-84-071 0F DECEMBER 5, 1984)
The changes proposed in this submittal have since been withdrawn (CE letter LD-85-021 of April 26,1985).
5.
RESULTS OF CE's INDEPENDENT AUDIT As stated in our March 26 letter, CE's submittal LD-85-004, dated January 11, 1985, satisfies the concerns expressed in our October 22, 1984 letter.
6.
REVISIONS TO CESSAR (CE LETTER DATED MARCH 22,1985)
Those revisions to CESSAR, submitted to reflect design changes to System 80 resulting from hot functional testing at Palo Verde 1, are being reviewed by the staff. We expect to complete our review by June 17.