RBG-25276, Responds to NRC Re Violations Noted in Insp Rept 50-458/86-36 on 861012-23.Corrective Actions:Temporary Alteration & Prompt Mod Request Removed After Determining That Unreviewed Safety Question May Exist

Responds to NRC Re Violations Noted in Insp Rept 50-458/86-36 on 861012-23.Corrective Actions:Temporary Alteration & Prompt Mod Request Removed After Determining That Unreviewed Safety Question May Exist

ML20213A501
Person / Time
Site:	River Bend
Issue date:	01/28/1987
From:	Deddens J GULF STATES UTILITIES CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
EA-86-183, RBG-25276, NUDOCS 8702030312
Download: ML20213A501 (6)

Text

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• GULF STATES UTILITIES COMPANY river BEND STAflON POST OFFICE Box 220 ST. ,RANCISVILLE. LOUISIANA 70775 AREA CODE 504 635-6094 346 8651 January 28, 1987 RBG- 25276 File Nos. G9.5, G15.4.1 U.S. Nuclear Regulatory Commission Document Control Desk washington, D.C. 20555 Gentlemen:

River Bend Station - Unit 1 Refer to: Region IV Docket No. SG-458/ Report 86-36/EA 86-183 This letter responds to the Notice of Violation, "NRC Inspection Report No. 50-458/86-36", transmitted to Gulf States Utilities Company (GSU) in a letter dated December 29, 1986. That letter refers to an inspection performed by Mr. D. D. Chamberlain during the period October 12-23, 1986 of activities authorized by NRC Operating License NPF-47 for River Bend Station.

GSU's response to Notice of Violation 458/8636-01, " Failure to Meet the Requirements of 10CFR50.59", is provided in the enclosed attachment in accordance with 10CFR2.201. This completes GSU's response to the Notice of Violation.

Sincerely, J. C. Deddens Senior Vice President River Bend Nuclear Group Attachment cc: Mr. Robert D. Martin, Regional Administrator U.S. Nuclear Regulatory Commission Region IV 611 Ryan Plaza Drive, Suite 1000 Arlington, TX 76011 NRC Resident Inspector

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8702030312 B70128 PDR G

ADOCK 05000458 PDR

1REITD SDGES T NERICA It) CLEAR REGUIJSORY CCBGEISSICE SDGE T IDUISIANA PARISH T WEST FELICIANA

• Docket Nos. 50-458 In the Matter of CUIF SDGES LTfILITIES CXMPANY (River Bend Station, Unit 1)

AEIIRVIT J. C. Deddens, being duly sworn, states that he is a Senior Vice President of Gulf States Utilities Cmpany; that he is authorized on the part of said Cmpany to sign and file with the Nuclear Regulatory ca mission the documents attached hereto; and that all such documents are true and correct to the best of his knowledge, infonnation and belief.

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J. g Deddens l

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i Subscribed and sworn to before me, a Notary Public in and for the State and and Parish above named, this I I day of OnllOftl,19 .

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/,JoanW.Middlebrooks v Notary Public in and for West Feliciana Parish, Iouisiana My Ccanission is for Life.

RESPONSE TO NOTICE OF VIOLATION 50-458/8636-01 REFERENCE Notice of Violation - Robert D. Martin Letter to W. J. Cahill, Jr., dated December 29, 1986.

FAILURE TO MEET THE REQUIREMENTS OF 10CFR50.59 Air flow problems in the control building had been causing numerous control building air-conditioning (HVC) and chilled water (HVK) system transfers. Temporary Alteration (TempAlt) 85-HVK-026 of October 29, 1985 and Prompt Modification Request (PMR) 86-0038 of June 27, 1986 were installed to mitigate these transfers. The Unreviewed Safety Question Determinations (USQD) for the tempolary alteration did not address all possible consequences of this change with respect to FSAR Section 9.2.10.5. The potential effects of this change were realized during further engineering review of the design to clear the plant of TempAlts.

In the original design, starting the control building chilled water system (HVK) pump A(B) would cause standby service water (SWP) Pump A(B) and C (D) , HVK chiller A(B), control room air handling unit (AHU) A(B), switchgear room AHU A(B) and chiller.

room AHU A(B) to start. To automatically start the opposite division, the HVK pumps trip on low air flow in any one of the three AHU's (or loss of the running chiller) in that division thereby causing low HVK water flow. HVK pump A(B) would automatically start on low water flow in the opposite division.

As the plant was configured under the TempAlt and PMR, under certain conditions manual acticn would be required to mitigate the consequences of a single failure in the system. Under normal operation with Division I, Train 'A' HVK pump would not trip on a LOCA signal concurrent with off-site power available and an air handling unit failure. Since 'A' train HVK water flow is maintained, Train 'B' would not automatically start. Operator action would be required to maintain area temperature. The other division of air-conditioning could be manually started, however, no analyses had been performed which assumed manual action after initiation of the event. This condition may have increased the consequences of an air handling unit failure as previously evaluated in the safety analysis. Further analysis should have .

been completed prior to the change to determine that it was not an Unreviewed Safety Question.

REASON FOR THE VIOLATION In the original plant design, as described in FSAR section 9.2.10.5, low air flow through any control building air handling

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d' unit or a trip of the' running chilled water compressor would trip the associated chilled water recirculation pump. This causes a low water flow condition which would automatically start the other division of control building chilled water / air conditioning. The control building environment safety analyses assumes automatic operation of this system following a loss of coolant event with or without offsite power available.

In the original USQD for the tenporary alteration, it was believed that the low AHU air flow pump trip was only necessary to protect the chilled water compressors from heat load transiento. Since the compressors have their own low load protection circuitry and air flow problems were causing spurious pump trips, TempAlt 85-HVK-026 was written to defeat these pump trips on pumps A and B. PMR 86-0038 was written to defeat the trips on the C and D pumps. The unreviewed safety question determination (USQD) review was performed relying on the previous evaluation performed for the temporary alteration and did not identify all of the bases for the trip. Without this pump trip feature, automatic operation of this system could not occur as analyzed in a scenario of a loss of coolant event with offsite power available and failure of a control building air-conditioning system air handling unit. The consequences of this scenario were not analyzed prior to the change.

An evaluation was performed to determine the extent of the problem and the root cause. The extent of the problem was found to be confined to the cases identified above. Specifically, an independent review and unreviewed safety question determination was redone for all open Quality Assurance (QA) Program applicable temporary alterations and prompt modification requests. No additional inadequate USQD's were found.

The cause of this event has been determined to be failure to review all the design bases of a system during the engineering of the temporary alteration and prompt modification request to that system. The root cause is inadequate training and procedures for unreviewed safety question determinations. The evaluation identified a need to strengthen requirements for independent reviews by prohibiting reviews by telephone and requiring that independent reviewers be knowledgeable in the engineering discipline involved.

CORRECTIVE STEPS WHICH HAVE TAhEN AND THE RESULTS ACHIEVED TempAlt 85-HVK-026 and PMR 86-0038 were both promptly removed on October 16, 1986 after it was determined that an Unreviewed Safety Question may exist. It addition, calculations were then prepared which show that room temperatures would not have exceeded the design bases during the above described scenario assuming manual actuation of the system in 20 minutes. Air handling unit failure and associated damper loss of power or trip alarms ate provided for each of the major areas served by the L

Control Building Air Conditioning System (i.e., the Control Room, Switchgear Room and Chiller Rooms) . In addition, the Control Room is continuously manned and it is expected that personnel would notice any significant rise in temperature and compensate for any failure; the switchgear room air handling unit discharge temperature is alarmed in the control room; and since the Chiller Room does not have any associated dampers, the only credible failure is the AHU, which is alarmed. Therefore, the modifications have been determined to have had no impact on plant safety.

CORRECTIVE STEPS WHICH WILL BE TAKEN TO AVOID FURTHER VIOLATIONS The remaining QA Program applicable TempAlts installed in River Bend Station have been either removed or the design and USQD have been independently reviewed under the current design control procedures. Also, an independent review has been conducted on Quality Assurance Program applicable PMR's to assure adequate USQD's were performed.

Corrective action to prevent recurrence included training and procedure improvement. The temporary alteration procedure is no longer in use at River Bend Station. Therefore, action to prevent recurrence is applicable only to the Prompt Modification Request procedure.

Training has been provided to all engineering personnel to reinforce the need for careful design and unreviewed safety question determinations regardless of schedule pressures. This training emphasized the need to consider the design basis in addition to the technical specifications. Procedural requirements were revised to strengthen the requirements for independent reviews. Additional training on unreviewed safety question determinations has been provided to the Facility Review Committee.

To prevent recurrence, engineering personnel who have not had training in performing USQD's are not allowed to do so. Similar training for performing USQD's has been provided to the Facility Review Committee members and alternates. Additionally retraining in the performance of USQD's will be provided to the Engineering Staff and to the FRC on an annual basis. Further, procedural enhancements are being considered which could provide additional information to assist engineers in performing USQD's. Also, procedures for design review have been revised to require on-site l independent reviews by individuals who are kncwledgeable in the area of concern.

In addition, GSU has verified that plant alarm response procedures currently require plant operators to start the redundant division of the control building ventilation system upon receipt of an indication that the running division has tripped.

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... e DATE WHEN FULL COMPLIANCE WILL BE ACHIEVED River Bend Station is currently in full compliance.

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