05000245/LER-1996-060, :on 960408,EDG Air Start Check Valve Internals Were Removed W/O Proper Documentation.Caused by Failure to Document Design Mod.Internals Have Been Reinstalled in Check Valves & Sys Has Been Restored to Original Configuration

:on 960408,EDG Air Start Check Valve Internals Were Removed W/O Proper Documentation.Caused by Failure to Document Design Mod.Internals Have Been Reinstalled in Check Valves & Sys Has Been Restored to Original Configuration

ML20133B073
Person / Time
Site:	Millstone
Issue date:	12/20/1996
From:	Walpole P NORTHEAST NUCLEAR ENERGY CO.
To:
Shared Package
ML20133B059	List: 05000245/LER-1996-060, :on 960408,EDG Air Start Check Valve Internals Were Removed W/O Proper Documentation.Caused by Failure to Document Design Mod.Internals Have Been Reinstalled in Check Valves & Sys Has Been Restored to Original Configuration
References
LER-96-060, LER-96-60, NUDOCS 9701020285
Download: ML20133B073 (3)

LER-1996-060, on 960408,EDG Air Start Check Valve Internals Were Removed W/O Proper Documentation.Caused by Failure to Document Design Mod.Internals Have Been Reinstalled in Check Valves & Sys Has Been Restored to Original Configuration

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(viii) 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition
2451996060R00 - NRC Website

text

-.

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROYED BY OM8 NO. 3160-0104 (4.S5)

EXPtRES 04/30/98 CO$ECT ON O AT RE ST to R$

EPOATED ta^c""'?o^"Lo0lT# "^ni.n'aitMR';* T"2:!$A ^"as LICENSEE EVENT REPORT (LER) 15 mf'u'n',c5H"#o%"tT3T 4#J,s".^o",f'n's"!JM" @

S'ic'sYua^u" foe'0E's"T'a7Ee"TI E45ET"oEao' SOP" (See reverse for required number of digits / characters for each block)

FACluTY NAME III DOCKET NUMBER (2)

PAGE(3)

Millstone Nuclear Power Station Unit 1 05000245 1 of 3 j

TITLE 14)

Emergency Diesel Generator Air Start Check Valve internals Removed Without Proper Documentation EVENT DATE (5)

LER NUMBER (6)

REPORT DATE (7)

OTHER FACILITIES INVOLVED (8)

>IONTH DAY YEAR YEAR SEQUENTIAL REVISION MONTH DAY YEAR FACILITY NAME DOCKET NUMBER NUMBER l

04 08 96 96 060 00 12 20 96 I

OPERATING THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR 5: (Check one or more) (11) i MODE m N

20.2201(b) 20.2203(a)(2Hv) 50.73(a)(2Hi) 50.73(a)(2)(viii)

POWER 20.2203(a)(1) 20.2203(aH3Hi)

X 50.73(aH2Hii) 50.73(aH2)(x)

LEVEL (10) 000 20.2203(aH2Hi) 20.2203(cH3)(ii) 50.73(a)(2Hiii) 73.71 20.2203(aH2)(ii) 20.2203(a)(4) 50.73(aH2)(iv)

OTHER 20.2203(a)(2)(iii) 50.36(cH1) 50.73(a)(2Hv) specify in Abstract below or in NRC Form 366A a

20.2203(aH2)(iv) 50.36(cH2) 50.73(a)(2)(vii)

LICENSEE CONTACT FOR THIS LER (12)

NAME TELEPHONE NUMBER tinclude Area Code)

Robert W. Walpr.ta, MP1 Nuclear Licensing Manager (860)440-2191 I

COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)

{

CAUSE

SYsTE*4 COMPONENT MANUFACTURER REPORTABLE

CAUSE

SYSTEM COMPONENT MANUFACTURER REPORTABLE i

To NPRDs TO NPRDs I

SUPPLEMENTAL REPORT EXPECTED (14)

EXPECTED MONTH DAY YEAR 4

SUBMISSION

[

i YES NO (if yes, complete EXPECTED SUBMISSION DATE).

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

On April 8,1996, with the plant shutdown and the reactor in the COLD SHUTDOWN condition, the ongoing 10 CFR 50.54(f), design basis verification audit, identified that the internals have been removed from two Emergency Diesel Gsnerator (EDG) air start check valves without the proper documentation. The valves are located in the outlet of tha l

tir receivers and provide the separation between air receivers as described in the Upgraded Final Safety Analysis R: port (UFSAR). A subsequent review on November 22, 1996, determined that, since the internals were not i

installed, the starting air system has been operated outside the Plant s Design Basis, and therefore, this was reported pursuant to 10 CFR 50.72(b)(1)(ii)(B). There were no automatic nor n.anually initiated safety system responses as a result of this event.

This LER is being reported in accordance with the requirements of 10 CFR 50.73(a)(2)(ii)(B). The cause nf this event is the failure to properly document a design modification and therefore maintain the design basis of the EDG air start system. The safety consequence is minimal since both air receivers have been available to provide the required EDG sttrts during the surveillance tests. The check valve internals have been reinstalled so that the separation as discussed in the UFSAR has been restored. To ensure that the air compressors properly maintain the pressure in the air receivers within the required range, the compressor start and stop pressure switches will be arranged such that thry directly sense the pressure in the air receivers.

970102020 f961220 PDR ADOCK 05000245 i

S PDR

• 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 REVISION Millstone Nuclear Power Station Unit 1 05000245 NUMBER NUMBER 2 of 3 96 060 00 TEXT (11more space is required. use additional cop $ofiC rorm 366A) (11) 1.

Description of Event

On April 8,1996, with the plant shutdown and the reactor in the COLD SHUTDOWN condition, the ongoing 10 CFR 50.54(f) design basis verification audit, identified that the internals have been removed from two EDG air start check valves without a proper documentation. The valves,1-DGSA-18A and 1-DGSA-18B, provide separation between the receivers so that in the event that one receiver is punctured the other one will remain pressurized to provide the required air for an EDG start. This event was not reported at the time that it was initially discovered, due to the failure to recognize that this condition was outside of the design basis.

These check valve internals were re-installed on July 10,1996, and October 23,1996, for 1-DGSA-18A and i

1-DGSA-18B respectively, On November 22,1996, during an investigation of the inadvertent EDG start or. Newember 12,1996, it was determined that having the check valve internals removed violated the design basis of the EDG air start system. This was reported pursuant to 10 CFR 50.72(b)(1)(ii)(B) as a condition that is outside the design basis of the plant.

11. Cause of Event

The cause of this event is the failure to document a design modification and therefore maintain the design basis of the EDG air start system. The internals were removed from the check valves without proper design change documentation.

111. Analysis of Event The EDG system uses compressed air injected into the cylinders to achieve a diesel start. The air supply is provided by an AC or DC air compressor and is stored in two air receivers. The air receivers are intended to be independent of each other. This conclusion is confirmed by the UFSAR, which states that the two air j

receivers are each capable of a minimum three independent cold starts without recharging. Without the check valve internals, the air receivers are directly linked and cannot be considered independent. Therefore, this condition is reportable pursuant to 10 CFR 50.73(a)(2)(ii)(B) as a cordition that was outside the design i

basis of the plant.

1 The sensing point for the pressure switches that are intended to monitor the pressure in the receivers, and i

start and stop the air compressors, is located in the common air header leading to the EDG, from the air receivers, down stream of the subject check valves. Since the internals have now been re-installed in the check va.ves they are prever' ting flow in the reverse direction and therefore preventing the pressure switches from monitoring the air receivers. Consequently, if the pressure in the air receivers was to fall below the compressor start setpoiat, the compressor would not start until the pressure across the check valves equalizes and the pressure in the air header reaches the compressor start setpoint. This condition is not acceptable and so the location of the sensing point for the pressure switches will be moved to the air receivers.

There are no actual safety consequences as a result of this event since the failure to maintain independence did not lead to failure to supply the required air for EDG starts during past surveillance tests.

o.-

NRC FORM 326A U.S. NUCLEAR REGULATORY COMMISSION (4-95)

LICENSEE EVENT REPORT (LER) i TEXT CONTINUATION 1

FACILITY NAME (1)

DOCKET NUMBER (2)

LER NUMBER (6)

PAGE (3)

YEAR SEQUENTIAL REVISION Millstone Nuclear Power Station Unit 1 05000245 NUMBER NUMBER 3 of 3 96 060 00 TEXT (If more s.a:*:e is required use edwtional copies of NRC Form 366Al (17)

IV. Corrective Action

7 The internals have been reinstalled in the check valves and the system has been restored to the original i

configuratior. In order to ensure that the air compressors properly maintain the pressure in the air receivers within the required range, the compressor start and stop pressure switches will be arranged such that they directly sense the pressure in the air receivers. This will be completed prior to declaring the EDG operable.

As committed to in LER 96-055-00, Commitment Nu. B16022-1, the design basis of the EDG air start j

system will be established prior to declaring the EDG operable.

I The design control process has been strengthened which includes a revision to the Design Control manual.

The current revision became effective for Millstone Unit No.1 on July 15,1996.

Also, committed to in LER 96-055-00 was Commitment No. B16022-3 that stated that a review of other systems to identify and resolve design discrepancies is ongoing as part of the design verification program.

V.

Additional Information

2

Similar Events

LER 96-055-00 has reported a similar event involving design control of the EDG air start system. Much of the corrective actions that were developed for LER 96-055-00 are also applicable to this LER.

1 Manufacturer Data None.

ij l