ML051450512

Draft Findings Re Safety Valves - IR 2005-02

ML051450512
Person / Time
Site:	Millstone
Issue date:	05/20/2005
From:	- No Known Affiliation
To:	Office of Nuclear Reactor Regulation
References
FOIA/PA-2005-0208
Download: ML051450512 (2)

Text

6

b. Findings Introduction. Millstone Unit 2 failed to meet the surveillance requirements of TS 3.7.1.1, Safety Valves, in that it did not properly establish and implement a procedure for insitu testing and calibration of Main Steam Safety Valves (MSSV, Code Safeties). Using Appendix A, Phase I of MaRual Chapter (MC) 0609, the finding was determined to be of very low safety significance( reen) and was characterized as an NCV of TS 3.7.1.1.

Description. In 1990, Dominioi received a Part 21 from the Dresser company that identified errors in the data provided from Dresser to Dominion concerning MSSV insitu testing. Dresser provided supplemental data to Dominion which was incorporated into surveillance procedure SP-27301 Main Steam Safety Valve Testing (IPTE) .

Surveillance procedure SP-2730 Main Steam Safety Valve Testing was modified without receiving any documented tQchnical or independent review.

AnalVsi7. Th-einspectors determined that surveillance procedure was inadequate inthat it contained data, an algorithm and a coirection factor that were not objectively verifiable by the NRC. The following deficiencies vrere identified:

a he calibration accuracy data provided for the Hydroset MTE equipment did not Ca F meet Dominion accuracy requirements (less than 1/4 of the test result accuracy) and was not rigorously traceable to a r\ational standard.

b. The experimental methodology used by Dresser to determine the K factor for the Millstone MSSV used only one valve to establish the comparison. This approach 6, did not account for manufacturing differences between MSSV, and was not statistically valid.

c. The calibration data provided for the Hydroset MTE was set for approximately 400 psig when the Hydroset pump pressure range experienced during the insitu testing was approximately 0 tol 60 psig. In addition, the Hydroset MTE correction factor established by Dresser wasM constant (3 psig), however, the test data was not linear and ranged from 1 to psig.

d. A special test was conducted of the Hydroset MTE at Wylie laboratories. When t compared to "as set" values determined by Wylie instruments the Hydroset MTE varied up to 0.80% which was 80% of the total MSSV variance allowed by TS (1%). These test comparisons used 80% of the allowable MSSV TS setpoint variance without considering any valve behavior orperformance error which are the objects of the TS surveillance.

e,~ The Dominion surveillance does not account for the reference elevation of the MTE compared to the MSSV being tested.

f. -The Dominion surveillance Includes an acceptable band of ambient temperature

/s\butdoes not account for difference between MSSV amntent testing and ambient

< operating temperatures and MSSV setpoint testing results.

g. Ad The Dominion surveillance allows a relatively large variance in valve body

- >temperature without adjusting the expected testing results. \

The previous conversion factor had been the subject of a historical vendor part (5

21 which identified the error and indicated that there was no impact to the

~licensee. The inspectors determined that the stated error was not linear and could have absorbed the total allowable TS MSSV test variance.\

.11 I. Y 14v

- 1X I.-tt The vendor material documented a second conversion factor related to the internals of the M&TE used by Dominion in the performance of its surveillance.

The surveillance procedure did not address the development of this second 7

Q conversion factor nor its impact on testing assurance, variation or error.

J. Vendor technical materials that were related to the M&TE used in the Millstone Unit 2 surveillance iq1dicated that the M&TE is to be used only for confirming G valve set pressure once the valve has been adjusted by the use of full system DJ over pressure ("full lift ") testing. Dominion documentation indicates that the M&TE was used on several Main Steam Code Safety Valves following full valve lifts that resulted from lant transients.

Analysis. The inspectors det ined that Dominion's failure to properly establish, implement and maintain an ad uate Main Steam Code Safety Valve surveillance procedure is a violation of TS 3 7.1.1 and constitutes a performance deficiency.

This finding is more than minor cause it was associated with the Main Steam Code Safety Valve, post accident. equi ment Derformance attribute and it affects the'.

mitigating systems cornerstone objective. The finding was determined to be of very low safety significance (Green) since p st trip, Main Steam Code Safety Valve, historical performance has been determined t be adequate by Dominion.

This finding is greater than minor because it affected the Initiating Events cornerstone objective to limit the likelihood of thosevents that upset plant stability and challenge critical safety functions during power opt-rations. The TS surveillance requirement was established to ensure that the MSSV fun'ctioned within pressure bands to prevent the number of initiating events resulting from \SSV actuations. Between 1990 and 2004 Millstone Unit 2 experienced routine lifting~of the MSSV following uncomplicated reactor and turbine trips while operating at full po er. The finding is of very low safety significance since none of the actual MSS' actuations caused more significant events.

Therefore, using NRC Manual Chapter 061S, Appendix A Enforcement. TS 3.7.1.1, "Safety Valveso requires that each main steam line code safety valve shall be demonstrated operable {ith lift (actuation) settings as shown In Table 4.7.1. Contrary to the above, from 1994 to 2004, Dominion MSSV surveillance procedure was inadequate to ensure TS complince. Because this finding is of very low safety significance and Seabrook entered tHis finding into the corrective action program (CR CR-05-03069), this violation is being treated as an NCV consistent with Section VL.A of the NRC Enforcement Policy (NOV 50-442/2005-02-Oxx, Failure to Meet the Surveillance Requirements of TS 3.7.1.1.

MSSV Operability As indicated above, the specto identified a failure to comply with the surveillance requirement of TS 3.7.1.1. In response to this issue the licensee Issued a CR and attempted to develop sufficient data \o dispel any MSSV operability concerns. Unresolved item (URI) 05000336/2005002-Ox was issued to track NRC evaluation of Dominion's investigation, operability deter' ination and corrective actions associated with the development of design data to verify ompliance with TS 3..7.1.1 surveillance requirements.

A f%9llr A ^"IitIrItI r^ Al

&t. w I "F-11 #A%, II v II 1=0 LVIAJ