05000245/LER-1997-003-02, :on 970306,svc Water Effluent Was Not Monitored Per Requirements of Ts.Caused by Inadequate Design Change Package.Procedures to Ensure That SW Effluent from Reactor Bldg Operated within Design Basis Revised

:on 970306,svc Water Effluent Was Not Monitored Per Requirements of Ts.Caused by Inadequate Design Change Package.Procedures to Ensure That SW Effluent from Reactor Bldg Operated within Design Basis Revised

ML20137S818
Person / Time
Site:	Millstone
Issue date:	04/07/1997
From:	Robert Walpole NORTHEAST NUCLEAR ENERGY CO.
To:
Shared Package
ML20137S814	List: 05000245/LER-1997-003, Forwards LER 97-003-00 Which Documents an Event That Occurred at Mnps,Unit 1 on 970306,per 10CFR50.73(a)(2)(i). Commitments Made within Ltr,Listed 05000245/LER-1997-003-02, :on 970306,svc Water Effluent Was Not Monitored Per Requirements of Ts.Caused by Inadequate Design Change Package.Procedures to Ensure That SW Effluent from Reactor Bldg Operated within Design Basis Revised
References
LER-97-003-02, LER-97-3-2, NUDOCS 9704150254
Download: ML20137S818 (4)

LER-1997-003, on 970306,svc Water Effluent Was Not Monitored Per Requirements of Ts.Caused by Inadequate Design Change Package.Procedures to Ensure That SW Effluent from Reactor Bldg Operated within Design Basis Revised

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(viii) 10 CFR 50.73(a)(2)(ii) 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2) 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(i)
2451997003R02 - NRC Website

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NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY oMB NO. 3160 0104 (4 91.)

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FACluTY NAME n)

DOCKET NUMBER (2)

PAGE13)

Millstone Nuclear Power Station Unit 1 05000245 1 of 4 TITLE 14)

Service Water Effluent Not Monitored Per Requirements of Technical Specifications EVENT DATE (5)

LER NUMBER (6)

REPORT DATE (7)

OTHER FACILITIES INVOLVED (8)

MONTH DAY YEAR YEAR SEQUENTIAL REVISION MONTH DAY YEAR FActuTY NAME DOCKET NUMBER NUMBER 03 06 97 97 003 00 04 07 97 OPERATING THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR i: (Check one or more) (11)

MODE (9)

N 20.2201(b) 20.2203(a)(2)(v)

X so 73(a)(2)(i) 50.73(a)(2)(viii)

POWER 20.2203(alt 1) 20.2203(a)(3)(i) 50.73(a)(2)(ii) 50.73(a)(2)(x)

LEVEL (10) 000 20.2203(aii2)(i) 20.2203(a)(3)(ii) 50.73(a)(2)(iii) 73.71 20.2203(a)(2)(ii) 20.2203(a)(4) 50.73(a)(2)Ov)

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20.2203(a)(2)(iii) 50.36(c)(1) 50.73(a)(2)(v) specifyin Abstract below N

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20.2203(a)(2)(iv) 50.36(c)(2) 50.73(a)(2)(vii)

LICENSEE CONTACT FOR THIS LER (12)

NAME TELEPHONE NUMBER (include Area Code)

Robert W. Walpole, MP1 Nuclear Licensing Manager (860)440-2191 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)

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CAUSE

SYSTEM COMPONENT MANUFACTURER REPORTABLE

CAUSE

SYSTEM COMPONENT MANUFACTURER REPORTABLE To NPRDs To NPRDs I

SUPPLEMENTAL REPORT EXPECTED (14)

EXPECTED MONTH DAY YEAR i

SUBMISSION f

YES NO Of yes, complete EXPECTED SUBMISSION DATE).

ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines) (16)

On March 6,1997, a review of plant drawings revealed that the Service Water (SW) System in the Reactor Building has a potential unmonitored release path. At the time of discovery, the plant was in COLD SHUTDOWN, and SW flow to and from the Reactor Building was isolated for maintenance. Spent Fuel Pool cooling was being provided from the Turbine Building Closed Cooling Water (TBCCW) System. An unmonitored release could occur if, Reactor Building Closed Cooling Water (RBCCW) leaked into the SW while the SW continuous vent lines of the RBCCW heat exchanger (s) were,in service.

Th3 continuous vent lines were installed under a plant design change. The cause of the unmonitored release p'ath was an inadequate design change package. An inadeouate review of the design change was performed during the approval process. This resulted in the plant failing to realize that a new discharge path was created. Northeast Nuclear Energy Company (NNECO) will revise procedures to ensure that Service Water effluent from the Reactor Building is operated within design basis and Technical Specifications. There were no safety consequences, since there were no releases that exceeded tha release limit. During the period of time when the RBCCW continuous vents were in service,1987 to 1989, the RBCCW system had detectable contamination levels. This contamination was from a Spent Fuel Pool heat exchanger tube leak.

Contamination levels were kept low by a feed and bleed of the RBCCW system. Isotopic sample results for the RBCCW fluid showed that the concentration of radionuclides was maintained below the limits allowed for radioactivity in effluents to unrestricted areas as defined by 10CFR20. In addition, SW flow through the Reactor Building would have provided at lacst a 10 to 1 dilution for any RBCCW fluid that leaked into the SW system and was discharged through the continuous vants. Therefore, this event has no safety significance.

9704150254 970407 PDR ADOCK 05000245 S

PDR

RRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (4-95) i UCENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACluTY NAME (1)

DOCKET NUMBER (2)

LER NUMBER (6)

PAGE (3)

YEAR SEQUENTIAL REVISION Millstone Nuclear Power Station Unit 1 05000245 NUMBER NUMBER 2 of 4 97 003 00 TEXT (If more space is required, use additional copies of NRC Form 366A) (17) 1.

Description of Event

On March 6,1997, a review of plant drawings revealed that the SW System in the Reactor Building has a potential unmonitored release path. At the time of discovery, the plant was in COLD SHUTDOWN, and SW flow to and from the Reactor Building was isolated for maintenance. Spent Fuel Pool cooling was being provided from the TBCCW System.

The SW system design provides for continuous venting of the RBCCW heat exchangers to remove any accumulated gases in the outlet water box. Venting is for both in-service and standby heat exchangers.

Liquid flow from these continuous vents bypasses the permanent radiological monitor (RE 1754). Also,

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this flow is not routinely monitored.

Originally float traps were used to provide a constant vent for the RBCCW heat exchangers. The elevation difference between heat exchangers and the SW discharge header easily creates a slight vacuum in the heat exchangers' outlet water boxes. Float traps require a positive pressure to vent gases, and do not function under a vacuum. Float traps were replaced with rotameters under a design change. Rotameter I

indication shows water flow or lack of water flow. Water flow indicates that the heat exchanger is vented. When there is no flow indication, operator action (adjustments in the outlet throttle valve) i pressurizes the outlet water box. With the outlet water box pressurized, water and any accumulated gas would then be forced out of the continuous vent. Thus, there is indication that heat exchanger tubes are not air bound, and heat exchanger performance is not impaired.

The original float trap design only passed gas. After implementation of the design change, a vented heat exchanger is verified by ensuring water flow from a heat exchanger. The original design did not discharge liquid, thus an unmonitored liquid release path did not exist ur.til after the installation of the rotameters.

The design change was installed under a Plant Design Change Request (PDCR) in 1987. Neither the associated 10CFR50.59 Safety Evaluation nor the Radiological Environmental Review for the PDCR addressed the creation of the new liquid discharge path.

II.

Cause of Event

The cause of the unmonitored release path was an inadequate design change package. An inadequate review of the design change was performed during the approval process. This resulted in the plant failing to realize that a new discharge path was created.

Ill. Analysis of Event Section 3.8 of the Technical Specifications and the Radiological Effluent Monitoring and Offsite Dose Calculation Manual (REMODCM), Table C1, specifies that SW affluent from the Reactor Building is to be monitored. The requirements of the REMODCM are implemented via plant procedure SP 832. This procedure provides two options for sampling Reactor Building SW effluent. The procedure allows the SW sample to be collected from either the in-service heat exchanger (s), or the SW discharge header at the Millstone Unit No.1 Discharge Structure.

Flow from the continuous vents on the standby heat exchanger (s) is not monitored when the SW sample is collected from the in-service heat exchanger (s).

RRC FORM 366A (4-95)

m RRC FORM 366A U.s. NUCLEAR REGULATORY COMMISSION (4-95)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME (1)

DOCKET NUMBER (2)

LER NUMBER (6)

PAGE (3)

YEAR SEQUENTIAL HEVISION Millstone Nuclear Power Station Unit 1 05000245 NUMBER NUMBER 3 of 4 97 003 00 TEXT (if more space is required, use additional copies of NRC Form 366A) (17)

Manipulation of the valves associated with the continuous vent lines are procedurally controlled. The current revision of these documents isolates the continuous vents.

However, revisions of these documents used between 1987 and 1989 aligned the vent valves to continuously vent all RBCCW heat exchangers. While the continuous vents were in service, SW exited the Reactor Building from standby RBCCW heat exchanger (s). An unmonitored release could occur if, RBCCW leaked into the SW while the SW continuous vent lines of the RBCCW heat exchanger (s) were in service. Historical use of the continuous vents violated the monitoring requirements of the REMODCM and Technical Specification Surveillance Requirement 4.8.C.1. Thus, this event is reportable pursuant to 10CFR50.73(a)(2)(i) as any operation or condition prohibited by the plant's Technical Specifications.

The RBCCW heat exchangers and associated fresh water system remove nuclear decay heat from the Shutdown Cooling heat exchangers and from the Spent Fuel Pool heat exchangers. A radioactive liquid

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release from the SW effluent from the Reactor Building could only be caused by a high activity level in the RBCCW system concurrent with a tube leak in a RBCCW heat exchanger.

The RBCCW system activity is monitored by two methods: 1) a weekly chemistry grab sample isotopic analysis, and 2) a permanent RBCCW radiological monitor, if the RBCCW system were to experience a coolant ingress, the incident would be detected by one of the two above methods and appropriate i

corrective actions would be taken.

During the period of time when the RBCCW continuous vents were in service,1987 to 1989, ine RBCCW system had detectable contamination levels. This contamination was from a Spent Fuel Pool heat exchanger tube leak. Contamination levels were kept low by a feed and bleed of the RBCCW system.

Isotopic sample results for the RBCCW fluid showed that the concentration of radionuclides was maintained below the limits allowed for radioactivity in effluents to unrestricted areas as defined by 10CFR20. In addition, SW flow through the Reactor Building would have provided at least a 10 to 1 dilution for any RBCCW fluid that leaked into the SW system and was discharged through the continuous vents. Therefore, this event has no safety significance. There were no safety consequences, since there were no releases that exceeded the release limit.

IV. Corrective Action

There are no immediate corrective actions required since the current procedures do not permit this unmonitored release path.

NNECO will revise procedures to ensure that SW effluent from the Reactor Building is operated within design basis and Technical Specifications prior to operating Cycle 16.

Additionally, NNECO will perform a review, prior to operating Cycle 16, if system configuration enhancements will be made.

The safety evaluation / screening process and training has been strengthened.

The design control process and the design engineering organization have been strengthened. The design controlimprovements include a revised Design Control Manual.

RRC FORM 366A (4-95)

f i

1 i

I j

AIRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION I

(4 95) l UCENSEE EVENT REPORT (LER) i TEXT CONTINUATION FACILITY NAME (1)

DOCKET NUMBER (2)

LER NUMBER (6)

PAGE (3)

YEAR SEQUENTIAL REVISION l

Millstone Nuclear Power Station Unit 1 05000245 NUMBER NUMBER 4of4 j

97 003 00 1

TEXT Uf more space is required, use additionalcopies of NRC Form CS6A) (17) i V.

Additional Information

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