BVY 15-049, Submittal of 10 CFR 71.95 Report Involving 8-120B Cask

Submittal of 10 CFR 71.95 Report Involving 8-120B Cask

ML15237A298
Person / Time
Site:	Vermont Yankee
Issue date:	08/19/2015
From:	Chappell C Entergy Nuclear Operations
To:	Document Control Desk, Office of Nuclear Material Safety and Safeguards
References
BVY 15-049
Download: ML15237A298 (12)

Text

1. a Entergy Nuclear Operations, Inc.

Vermont Yankee 320 Governor Hunt Road SEntergy Vernon, VT 05354 Tel: (802) 257-7711 Coley Chappell Manager, Licensing and CA&A 10 CFR 71 .95 BVY 15-049 August 19, 2015 Attn: Document Control Desk Director, Division of Spent Fuel Storage and Transportation Office of Nuclear Material Safety and Safeguards U.S. Nuclear Regulatory Commission 11555 Rockville Pike Rockville, MD 20852

SUBJECT:

10 CFR 71.95 Report Involving 8-1 20B Cask Vermont Yankee Nuclear Power Station Docket No. 50-271 License No. DPR-28

Dear Sir:

Entergy Nuclear Operations, Inc. (Entergy) hereby submits this report pursuant to 10 CFR 71 .95(a)(3) regarding a potential instance in which the conditions of approval in the Certificate of Compliance (C of C) #9168 for the 8-120B cask may not have been observed in making a shipment for Vermont Yankee Nuclear Power Station (VY). The attached notification (Attachment 1 ) from the cask certificate holder (Energy Solutions) provides the information related to the condition and requirements for this report and was previously submitted to the NRC (ADAMS Accession No. ML15202A058).

On June 24, 2015, Energy Solutions notified Entergy staff at VY and other customers, that their investigation into the recent vent port leak test finding was complete.

Attachment I was developed by the certificate holder and is applicable to the use of the 8-120B cask by Entergy at VY. Due to the time frame (September 2013 - June 2015) over which the discrepancy may have existed with the 8-1 20B cask, VY cannot rule out that a shipment may have occurred in which the C of C conditions were not met. provides the date of potential occurrence at VY.

There are no new regulatory commitments being made in this submittal. Should you have any questions concerning this submittal, please contact me at (802) 451-3374.

Sincerely, 62e~

[CC/JT kj

BVY 15-049 / Page 2 of 2 Attachments:

1. Energy Solutions 10 CFR 71.95 Report on the 8-1 20B Cask

2. List of Vermont Yankee Shipments of the 8-120B Cask, C of C #9168 cc: Mr. Daniel H. Dorman Regional Administrator, Region I U.S. Nuclear Regulatory Commission 2100 Renaissance Blvd., Suite 100 King of Prussia, PA 19406-2713 Mr. James S. Kim, Project Manager U.S. Nuclear Regulatory Commission Mail Stop O-8D15 11555 Rockville Pike Rockville, MD 20852-2378 Mr. Christopher Recchia, Commissioner Vermont Department of Public Service 112 State Street - Drawer 20 Montpelier, Vermont 05602-2601 Mr. Dan Shrum Senior Vice President Regulatory Affairs EnergySolutions 423 West 300 South Suite 200 Salt Lake City, UT 84101

Docket No. 50-271 BVY 15-049 Attachment I Energy Solutions 10OCFR 71.95 Report on the 8-I120B Cask (7 Pages)

- ____ENERGYSOLUTIONS:

June 24, 2015 CD 15-0149 Mark L~ombard, Director Division of Spent Fuel Management Office of Nuclear Material Safety and Safeguards U.S. Nuclear Regulatory Commission Washington 1)0 20555-0001 Arr'N: Document Control Desk

Subject:

10 CFR 71.95 Report on thle 8-120B Cask

Dear Mr,

Lombard:

EnergySolutions hereby submits the attached report providing the information required by 10 CFR 71 .95(a)(3) for instances in which the conditions of approval in the Certificate of Compliance for the 8-120B Cask (Certificate of Compliance #9168) may not havc bcen observed in making certain shipments. The circumstances described in this report are applicable to approximately 235 shipments made by EnergySolutions as a licensee and user of the 8- ] 20B cask over a 21 month period.

If you have any questions regarding this submittal, please contact me at. 801 -649-2109.

Daniel 13. Shrum Dan Shrmm Jun 24 2015 2:58 PM Senior Vice President, Regulatory Affair's (:*s~zn EnergySolutions LLC

Attachment:

Failure to Obscrvc Certificate of Complianec Conditions for the 8-12013 Vent Port Leak Pre-Shipment Leak Test cc: Michele Sampson, Chief Spent Fuel Licensing Branch Pierre M. Saverot Licensing Br ranch 299 South Main Street, Suite 1700

• Salt Lake City', Utah 841_11 (801) 649-2000

• rax: (801) 880-2879. www.energysolutiona.com

_____-~zE NE RGX'SOLUTIONS Failure to Observe Certificate of Compliance Conditions for the 8-120B3 Vent Port Pre-Shipment Leak Test June 24, 2015

1) Abstract During the vent port seal pre-shipmnent leak rate test, a neoprene gasket that was added under the test manifold may have reduced the test sensitivity below the required value. Trhe test manifold and gasket are not licensed packaging components. The gasket was added to the test manifold on some or all shipments to more reliably seal the manifold, saving test time and reducing personnel exposures. The amount of reduction of the test sensitivity cannot be determined for any particular shipment due to several reasons as discussed below. The gasket may have been used on as many as 100 shipments by EnergySolutions as the licensee fi-om September 2013 through June 2015. The condition was determined not to have significant safety consequence because the seals receive periodic helium leak testing as required by the SAR, the vent ports are only opened rarely, there is a margin of conservatism of approximately a factor of 9 on the prescribed vent port leak rate test, and there have been no observations of contamination around the vent port openings that would suggest leakage.

There will be no further tests made using the gaskets since EnergySohaions has replaced all of the subject gaskets with a modified version that does not have the potential to reduce the test sensitivity.

It is uncertain whether, or by how much, the sensitivity of the vent port pre-shipment leak tests was reduced because: 1) Use of the gasket was optional- the gasket may, or may not have been in place for the tests, and 2) The force with which the gasket was compressed during testing is unknown, so it is uncertain if caused the gasket to constrict onto the head of the vent port cap screw.

2) Narrative Description of the Event a) Status of Components All of the 8- 120B packaging components are operating normally. The neoprene gaskets that caused the event have all be removed from service and replaced with a new manifold gasket, as discussed in (4) below.

b) Dates of Occurrences From September 2013, when pre-shiprnent leak tests were first performned using the neoprene gasket, to present, approximately 100 shipments were made by .EnergySohttions as the licensee. Most of thaese shipments uscd the neoprene gasket to perfonzn the pre-shipment leak rate test of the vent port.

2

E N ERG YSOL U TONS c) Cause of Error New 8-1 20B lids went into service in Septembcr 2013. It was found that the manifold sometimes had problems sealing with the vcnt port on these new lids. EnergySolutions personnel found that adding an extra neoprene gasket helped to reduce the false test failures. Since the pre-shipment leak rate test is performed in a radiation environment, false failures are undesirable because they increase the personnel exposure. The pei'sonnet did not realize that the gaskets had the potential to reduce the test sensitivity.

Attachmaent 1 has a detailed description of the test configuration.

d) Failure Mode, Mechanism, and Effects Tihe neoprene gasket can constrict on the head of the vent port plug cap screw when it is compressed by the bottom end of the test manifold stinger, whielh could reduce the sensitivity of the pre-shipment leak test. Consequently, the vent port pre-shipment leak tests performed using thle neoprene gasket may not have provided the required test sensitivity o f I xl0 3 ref-cm3 /sec.

e) Systems or Secondary Functions Affected Not applicable, f') Method of Discovery of the Error On Monday June 1, 2015, an 8.. I120B cask user identified a concern that the neoprene gasket could potentially affect the integrity of the vent port seal pre-shipment leak test.

Later that week EnergySolutions performed a bench test that confirmed that the neoprene gasket can constrict on the head of the vent port plug cap screw when it is compressed by the manifold, resulting in a reduction of the test sensitivity. .

3) Assessment of Safety Consequences Pre-slhiprnent leak tests of all containment seals, including the vent port, were performed prior to every shipment in accordance with the requirements of Chapter 7 of the SAR. In addition, periodic and maintenance leak tests of the containment seals, using helium as the test gas, were performed after maintenance, repair, or replacement of the containment seals in accordance with the requirements of Chapter 8 of the SAR.

The 8-1I20B preshipmnent leak rate test criteria were sized tbr the large primary lid. Since the vent port has a much smaller test volume, the test specification is conservative. Calculations show that the test specified in the SAR is a factor of 9 more sensitive than the t x10 3 ref-cm 3/see required by Chapter 8 of the SAR. Hwever, due to the uncertainties in the effects of the gasket, and the behavior of seals in series, it is not possible to confirm whether the reduction in sensitivity is offset by the test criteria conservatism.

3

__ _- EN E RGYSOL UTIONS There has been no indication of any leakage from the vent port from any shipment, and therefore, no exposure of individuals to radiation or radioactive materials due to the gaskets.

It is also noted that it is unusual for the vent port seal to be opened during cask operations, in which case the previous helium leak test of the vent port seal provides added assurance of seal integrity.

Therefore, it is concluded that there has been no safety consequence from performing vent port pre-shipment leak tests that may not have provided the required test sensitivity of 1x10.3 ref-cm-3 /sec.

4) Planned Cor'ective Actions EnergySolutions has taken corrective actions to assure that use of the old neoprene gasket design for the vent port pre-shipment leak test is immediately discontinued.

• EnergySolutions notified all 8-120B cask users with upcoming Shipments to require use of a new procedure, in conjunction with the new manifold gasket design, for pre-shipment ]eak testing of the vent port seal on all fiuture shipments.

o EnergySohutions designed and tested new manifold gasket design that does not constrict onto the head of the vent port plus screw when compressed, and therefore it does not reduce the test sensitivity. The new gaskets have been distributed to all upcomaing shipment users. The new manifold gasket design is shown in Attachment 1.

The EnergySolutions'drawing for the 8-] 20B air drop manifold have been revised to include the new gasket seal, and the air pressure drop test procedure TR-TP-002 has been revised to incorporate the new pre-ship~ment leak test procedure for the vent port. Use of the new procedure and the new manifold gasket will assure that the pre-shipmcnt leak tcst satisfies the required test sensitivity and that the manifold gasket is removed fi-om the test port after completing the pre-shipment leak test.

5) Previous Similar Events Involving the 8-1208 No previous similar events have been identified.

6) Contact for Additional Information Dant Shrum EnergySoluuons Senior Vice President, Regulatory Affairs (801) 649-2109

7) Extent of Exposure oflIndividuals to Radiation or Radioactive Materials None.

4

ENER G SOL UTIONS Attachment I Details of ihc 8-1 20B Vent Port Leak Rate Test Setutp The 8-120B CoC requires the package to be prepared for shipment and operated in accordance with Chapter 7 of the SAPR, and tested and mnaintained in accordance with Chapter 8 of the SAR.

Step 7.1.14 of the SAPR requires a pre-shipmecnt leak test of the primary lid, secondaiy, lid, and vent port seals to be perfbnined in accordance with Section 8.3.2.2 prior to every shipment to assure that the containmaent system is properly assembled. Per Table 8-2 of the SAR, the pre-Shipment leak test of the vent port is performed by connecting a test manifold to the vent port, pressurizing the seal and head of the vent port cap screw to 18 psig with dry air or nitrogen, and monitoring the pressure for at least .15 minutes to assure that it does not drop by more than 0.1 psig.

The pre-shipmnent leak test of the vent port is a pressure drop test performed using a dedicated test manifold. T/he test manifold is not a part of the licensed package. It includes a stinger (shown below), an 0-ring seal that contacts the stinger and the bottom of the vent port hole, and a sleeve rut to compress the 0-ring seal. The test manifold was designed so that it surrounds the vent port cap screw, leaving a small gap between itself and the vent port cap screw. The 8-1 20B cask fleet began to ship with a new lid design in September 2013, and operations staff noted more frequent difficulty getting the manifold to seal. It became desirable to find a better way to seal the bottom of the manifold in order to minimize operator exposure. They found that adding a neoprene gasket (also not part of the licensed package) under the base of the stinger as shown below helped reduce testing time and exposure.

5

-- EN ERGVSOLUTIONS.

PRIMARY LID

"' I O-RING SEAL

'" ,./MANIFOLD

'1/ (NOT LICENSED EQUIPMENT)

VENT PORT SEAt NEOPRENE GASKET - SHOWN UNCOMPRESSED VENT PORT CAP SCREW (NOT LICENSED EQUIPMENT) 6

ENER(ISOLUTIONS Corrective Action - Modified Test Seal The new manifold gasket design, shown below, replaces the manifold 0-ring seal and neoprene gasicet previously used with a neoprene gasket thaat fits within the notch at the base of the manifold stinger.

VENT PORT SEAL NEW MANIFOLD GASKET (SHOWN UNCOMPRESSED)

VENT PORT CAP SCREW 7

Docket No. 50-271 BVY 15-049 Attachment 2 List of Vermont Yankee Shipments of the 8-1 20B Cask, C of C #9168 (1 page)

List of Vermont Yankee Shipments of the 8-120B Cask (C of C #91 68)

Shipment ID Date Cask ID Destination 2014-55 9/15/2014 8-120B-2S WCS, TSD, Andrews, TX