ML20101B874

Requests NRC Approval to Leave Shield Blocks & Steel Plates in SNEC Facility Containment Vessel,In Place After Completion of Reactor/Fuel Storage Cavity Characterization Activities

ML20101B874
Person / Time
Site:	Saxton File:GPU Nuclear icon.png
Issue date:	03/08/1996
From:	Kuehn G SAXTON NUCLEAR EXPERIMENTAL CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
C301-96-2016, NUDOCS 9603150106
Download: ML20101B874 (7)

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SAXTON NUCLEAR EXPERIMENTAL CORPORATION GENERAL PUBLIC UTILITIES SYSTEM 1 Jersey Central Power & Light MAluNG ADDRESS:

General Public Utilities Nuclear Corporation One Upper Pond Road g .N

• Metropolitan Edison Company Parsippany, NJ 07054 p ,Q Pennsylvania Electric Company

e. March 8, 1996 C301-96-2016 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555 Gentlemen,

Subject:

Saxton Nuclear Experimental Corporation (SNEC)

Operating License No. DPR-4 Docket No. 50-146 Request for NRC Approval to Replace the Shield Blocks Removed for Characterization with Steel Plates During the January 16, 1996 meeting between SNEC and the NRC, SNEC representatives addressed the desirability of net returning the reactor / fuel storage cavity shield blocks to their pre-characterization position. Since the SNEC facility Technical Specifications do not permit facility modification without NRC approval, the purpose of this letter is to request NRC approval to leave the shield blocks in their present stored condition in the SNEC facility Containment Vessel and leave the steel plates currently covering the opening in place after the completion of reactor / fuel storage cavity characterization activities.

As background, the key block and two 20 ton shield blocks were removed in mid-June 1995 to permit characterization studies in the reactor / fuel storage cavity. Shield block removal was permitted by the Technical Specifications as a characterization activity. The NRC Staff safety evaluation supporting the license amendment permitting performance of characterization activities stated that the blocks would be reinstalled following the completion of reactor / fuel storage cavity characterization activities.

SNEC considered it prudent to eliminate the potential for an unplanned or unauthorized entry into the cavity by covering the resultant opening with steel plates during periods when characterization activities within the cavity were not in progress. Because reinstallation of the shield blocks is a difficult and man-power intensive operation and the plates are as effective an access barrier as the shield blocks, SNEC requests permission to leave them in place after the completion of cavity characterization activities in the reactor / fuel storage cavity. The attached engineering safety evaluation supports this action and concludes that no unreviewed safety question exists.

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C301-96-2016 Page 2 of 2 Sincerely, 7

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Vice President SNEC Attachment cc: Administrator, NRC Region I NRC Project Manager NRR NRC Project Scientist, Region I l

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l ATTACHMENT SAFETY EVALUATION IN SUPPORT OF NOT INSTATT.ING THE CAVITY SHInr.fi nr.Orr slt AT THE SAXTON FACILITY t

PURPOSE AND SCOPE i

The purpose of this document is to provide a safety evaluation in I

support of leaving the r'eactor/ fuel storage cavity shield blocks

'in their present stored condition at the Saxton . Nuclear Experimental Corporation (SNEC) facility at Saxton, Pennsylvania.

l Two shield blocks were removed in mid June 1995 , to permit l characterization . studies in the cavity. The current Technical l Specifications permitted their removal for characterization but

! are silent on the issue of leaving-them remQved. However, the NRC Staff stated in their safety evaluation that they would be reinstalled sfter completion of characterization activities.

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BACKGROUND 1 The Saxton Deconunissioning Plan And Safety Analysis Report, dated

April 1972, was submitted to the US Nuclear Re'gulatory Commission .

L to describe the plan for decommissioning of the Saxton reactor facility. It described the intended "as left" condition of the facility and presented-a safety analysis of those conditions. The following are significant points regarding the shield blocks in.

that report:

1. The report- states, "The reactor vessel will be contained inside of the reactor / fuel storage compartment which cannot be breached without the use of special equipment which will not be in service on site." Further, it states that " entry to the high radiation area reactor / fuel storage compartment will

, require physically restoring the electrical supply l

(major breakers) to the rotary b. ridge crane in order to remove the 20 ton shield blocks ...".

2. In describing the conditions of the- containment j vessel, the report states that the removable concrete

! shield blocks over the reactor vessel will be left in l . place and that the rotary bridge crane (i.e. the polar crane) which is required for removal of the blocks 1

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t would be positioned so that it couldn't be used for shield block removal and electrically-deactivated.

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3. The safety analysis section of the report states that

" entry into the high radiation area reactor / fuel storage compartment will require replacing power supply breakers and lifting the 20 ton shield blocks".

The primary concern at the time the document was' written was the potential of an unplanned or unauthorized entry into a high radiation area of a. facility that had a minimal < level of on-site staffing and direct management and administrative controls. The potential for such an entry creating a threat to the public health and safety or an environmental concern was insignificant.

However, it could have resulted in considerable hazard to th'e  :

individual making such an unauthorized entry.

SNEC letter to the USNRC dated February 20, 1975,~ documented the final as-left condition of the Saxton site as compared to the approved decommissioning plan. That report stated, "The-removable concrete shield blocks.are in place over the reactor / fuel storage compartment and the rotary bridge crane which is required for removing these shield 1 blocks has been positioned so that it cannot be utilized for their removal. Electrical power to the rotary bridge crane is disconnected."

As with the original decommissioning plan, the final status report implies that the intient of " parking" the polar crane was to prevent removal of the shield blocks and allow'an unauthorized entry into the reactor / fuel storage cavity.

GPU Nuclear safety evaluation SE-510000-001, dated July 18, 1994, provided an evaluation in support of reactivating the polar crane i while the shield blocks were in place. Subsequently, the USNRC approved License Amendment No. 12 which allowed removal of the shield blocks for characterization activities in the reactor / fuel storage cavity.

CURRENT CONDITIONS The reactor / fuel storage cavity was opened for ac' cess by remov;ng two adjacent 20 ton shield blocks a,s well as the ' key' block .n  ;

mid June of 1995. When access to the cavity is not required, the opening left by the removal of the . shield blocks is coverec by four steel plates that weigh about 750 pounds each. These pie es prevent unauthorized access yet are strong enough to suppor' normally expected personnel- traffic over top of the ca*/. .

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i Administrative controls are in . place to assure that ' the - polar crane is operated in accordance with procedures, and to control access to the containment vessel. In addition, entry into the reactor / fuel storage cavity requires ' additional access controls in the form of radiation work permits. The general area radiation levels on the operating floor area of the containment vessel are

! abo ~ut 0.2 to 0.3 mrem /hr in areas back a few feet from the l l opening.to the cavity. These. levels do not vary appreciably with removal or installation of the steel, cover plates. The radiation level three feet above the cavity cover plates is about 4 I

mrem /hr, and about 5 mrem /hr on contact with the cover plates. ].

1 The NRC Staff's safety evaluation in support of License Amendment l No. 12 stated that the shield blocks would be reinstalled as soon  !

.as practicable after completion of the characterization _ program.

However, at this time, it is desirable to leave the cavity l opening covered with the steel plates rather than reinstalling the shield blocks. The removal and reinstallation of the blocks is a difficult, man-power intensive operation due to the_ weight of each block being very near the design limit of the polar crane

, and the very close tolerances between the blocks,and the support l ledge in the cavity. Although the risk assessment prepared prior-l to removal of the shield blocks, and actual experience gained in i their removal, have demonstrated that the task can be performed

safely, there is very little enhancement to the plant safety to be gained by their reinstallation.

SAFETY EVALUATION l Although the provisions of 10CFR50.59 are no longer applicable to  !

the Saxton facility, this safety evaluation uses the criteria of i l 10CFR50.59 to _ demonstrate that leaving the shield blocks un- -l l installed does not . constitute an unreviewed safety question and i j should be permitted under the current license conditions.

l Our proposal to leave the reactor / . fuel storage cavity shield blocks in their stored position rather than reinstalling them l over the cavity does not involve an unreviewed safety question l- based on the following:

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1. The reactor / fuel storage cavity shield blocks serve to shield the operating floor and-its equipment from the

. extremely high radiation levels that would exist ,

during periods of reactor operation. Since the reactor

! was shut down, defueled, and all fuel removed from the site, they provided an intrusion barrier against j unapthorized entry into the high radiation area around 3

the reactor vessel during the period when the site had minimal staffing and administrative controls. If an

. intruder were to _ gain unauthorized and undetected 1 access .to the containment vessel, entry into the cavity would require operation of the polar crane to lift the 20 ton shield blocks clear of the cavity opening. When' the cavity is open, , administrative controls are in place to assure that proper radiological controls are in place such that. only authorized and properly trained- individuals are allowed to enter _ both the . exclusion area (i.e.- the containment vessel) and the high radiation area. When not open for planned-and controlled access,.the cavity is presently covered with four steel plates that weigh about 750 pounds each. Thus, even with the shield blocks removed, access would still require the operation of the polar crane since..there is . no other available equipment capable of lifting the 750 pound

. weight. In addition to the normal procedural controls on crane operation, the _ polar crane is provided with a pendant control ' station which is the only station from which the crane can be operated, and a ' lockable j main power supply breaker. The pendant control box is  !

a plug-in module that is readily removable from the l pendant ' cable. The operating procedures require that' l the control box be physically removed.and stored in-a l locked container, and the main power supply breaker is ]

locked open when the crane is not in use for authorized activities.

In the event all safeguards failed ~ under the present -

conditions, the consequences of the f ailure . would be an unplanned radiation exposure to the individuals involved. The efforts required to bypass the present I safeguards and the consequences of bypassing them are the same whether the cavity is covered with the concrete shield blocks or the steel plates. Thus, with the current controls in place, leaving the cavity covered with the steel plates rather than the shield blocks does not result in an increase in the. ,

probability of occurrence or the consequences of an accident or malfunction of equipment important to safety previously evaluated in , the safety analysis report.

ii. As previously stated, the potential accident for which the, shield blocks were put .in place was unplanned s

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radiation exposure resulting from unauthorized . entry into the reactor / fuel storage cdvity. Routine. access to the cavity was permitted under the former operating license when the . reactor was shut down and proper radiological controls were in effect, and there was no

, requirement .to install the shield blocks under shut down conditions as a routine means of preventing access. In fact, the current controls over cavity access exceed those in place when the reactor was licensed for operation. Therefore, the activity of.

leaving the shield blocks removed does not create the possibility of any accidents or malfunctions of a I different. type than any evaluated previously in the ,

safety analysis report. i l

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iii. The margin to safety was based upon access controls l l

-that prevented unauthorized entry .into the. cavity. 1 This activity does .not reduce those access controls. 1 l

Thus, the margin of safety has not been reduced by this proposed activity.

l In conclusion, the proposed activity does not require any. license  ;

or Technical Specification changes and does not' involve an '

unreviewed safety question. Therefore, they'are permissible under -

10CFR50.59. '

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