ML20078P745
| ML20078P745 | |
| Person / Time | |
|---|---|
| Site: | Fort Saint Vrain  |
| Issue date: | 12/14/1994 |
| From: | Warembourg D PUBLIC SERVICE CO. OF COLORADO |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| P-94111, NUDOCS 9412200135 | |
| Download: ML20078P745 (5) | |
Text
o i
O, Public Service' P.O. Box B40 16805 WCR 19 1/2; Platteville, Colorado 80651 December 14, 1994 Fort St. Vrain Unit No. 1 P-94111 U.
S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C.
20555 Docket No. 50-267
SUBJECT:
QUARTERLY SUBMITTAL OF THE 10 CFR 50.59 REPORT OF
- CHANGES, TEST 8 AND EXPERIMENTS FOR FORT ST.
VRAIN DECOMMISSIONING
REFERENCE:
NRC Letter dated November 23, 1992, Erickson to Crawford (G-92244)
Gentlemen:
This letter transmits the quarterly 10 CFR 50.59 Report of Changes, Tests, and Experiments affecting Decommissioning of the Fort St.
Vrain (FSV)
Nuclear Station.
The attached report includes a description of each change, test and experiment as well as a summary of the safety evaluation.
This report covers the period of August 18, 1994 through November 15, 1994.
This report is being submitted pursuant to Condition (b) (2) of the
" Order Approving Decommissioning Plan and Authorizing Decommissioning of Facility", transmitted in the referenced letter, which states the following:
"The licensee shall submit, as specified in 10 CFR 50.4, a report containing a brief description of any changes, tests and experiments, including a summary of the safety evaluation of each.
The report must be submitted quarterly."
9412200135 941214 PDR ADOCK 05000267
{(
.R PDR
'e P-94111 December 14, 1994 Page 2 If you have any questions concerning this report, please contact Mr. M. H. Holmes at (303) 620-1701.
Sincerely, b-V W4/tt J v D. W. Warembourg Decommissioning Program Director DWW/JRJ Attachment cc:
Mr. John H. Austin, Chief i
Decommissioning and Regulatory Issues Branch i
Regional Administrator, Region IV Mr. Robert M. Quillin, Director Radiation Control Division Colorado Department of Health
e t
j DECEMBER'1994 QUAR'i'ERLY 10 CFR 50.59 REPORT OF CHANGES, TESTS AND EXPERIMENTS
.FOR FSV DECOMMISSIONING i
Background:
The following is a brief discussion of 10 CFR 50.59 changes to the l
Fort St. Vrain- (FSV) facility. or procedures as described in the Decommissioning Plan (DP) and tests and experiments not described in the DP, in the time period from August 18 through, November 15, 1994.
While this report is similar to past reports of changes, tests and I
experiments submitted.in accordance with 10 CFR 50.59, the quarterly decommissioning reports are submitted pursuant to Paragraph (b) (2) of the FSV Decommissioning Order (issued in NRC letter dated November 23,
- 1992, Erickson to Crawford),. which states:
"The licensee shall submit, as specified in 10 CFR 50.4, a l
report containing a brief description of any changes, tests and experiments, including a summary of the safety evaluation of each.
The report must be submitted quarterly."
Chances to the FSV Facility or its Procedures as Described in the Decommissionina Plan There wera no changes to the FSV facility as described in the DP i
during this reporting period.
Procedures associated with PCRV shield water chemistry were revised, as described below.
1 l
1.
Changes to the PCRV shield Water Chemistry l
)
DP Section 2.3.3.6.5 describes the original PCRV shield water i
chemistry control program, consisting of Calgon LCS-20 to minimize corrosion and hydrogen
- peroxide, as necessary, to control biological fouling.
Calgon LCS-20 consists of a solution of sodium nitrite, sodium tetraborate and sodium hydroxide.
The Calgon LCS-1 20 program used sodium hydroxide to maintain a
basic pH 4
(approximately 9 to 10), with nitrites to scavenge any oxygen in the shield water, thus minimizing corrosion of the carbon steel PCRV liner and liner insulatiori cover plates.
A polymerization j
compound was also added to resolve a colloidal suspension problem j
caused by entry of some concrete. cutting slurry into the shield j
water.
This water treatment proved adequate during removal of the t
graphite core components (including the core support blocks and posts), core barrel removal and removal of core support floor upper insulation.
\\
Water clarity problems were encountered during core' support floor upper
- insulation. removal and steam generator' inlet duct cutting operations, which were being performed by underwater divers.-
During diving operations in the PCRV, air used by the divers and underwater. vacuum operations continuously bubbled to the surface,
. depleting nitrites which react with oxygen to form nitrates.
This led to the addition of substantial amounts of chemicals to maintain the desired nitrite concentration, resulting _ in formation of a complex colloid that caused deterioration in_ water clarity.
The shield _ water chemistry control program was revised to and-the LCS-20 water treatment, and permit addition of aluminum sulfate
(" alum") to address the colloidal suspension problem and restore-i visibility.
The revised shield water chemistry control program is more compatible with oxygenated water produced by underwater diving operations, using a neutral pH, without the addition of oxygen scavenging chemicals.
The pH is maintained by periodic additions of sulfuric acid.
A polymer (s) is included in the revised water treatment to flocculate materials, enhancing their removal.
The l
safety evaluation for the revised program also considered the use i
of air injected into the bottom of the PCRV to create turbulence and aid in mixing the chemicals added to the PCRV.
Laboratory tests determined that the alum treatment would be effective in re-establishing water
- clarity, with a
pH of I
approximately 6.5 optimal, and that this program had.significant benefits over use of other alternative water treatment programs.
It is possible for some corrosion of carbon steel in the-PCRV to e
occur using the revised water chemistry control program; however, the corrosion will be minimal in the relatively short decommissioning time frame, and a small amount of rust in the water will not significantly reduce visibility.
The probability of a loss of PCRV shield water (evaluated in DP Section 3.4.7),
which is the only accident applicable to this change, is not being increased since the integrity.of the PCRV and shield water piping and components will be unaffected by the revised water chemistry.
Components in the PCRV Shield Water system are designed for this pH range, and materials are compatible i
with the aluminum sulfate and the polymer.
It is considered that there will not be an appreciable increase in the corrosion rate of the carbon steel PCRV liner.
The loss of PCRV shield water evaluated in the DP assumed that 100,000 Curies of tritium contained in 423,500 gallons of shield water is released to the Reactor Building.
The current tritium level and quantity of water in the PCRV are well below this, and the additives in the revised water chemistry will have no effect on accident consequences.
The revised water chemistry control program does not introduce any new accident initiators or failure modes and no new accidents or malfunctions are created.
PCRV shield water chemistry is not i
addressed in the basis of any technical specifications, and~no 2
1 b
margins of safety in the bases are reduced by the changes.
Based on the above, the cafety evaluation concluded that the revised PCRV shield water chemistry control program does not constitute an unreviewed safety question.
Tests or Exneriments not Described in the Decommissionina Plan No tests or experiments were conducted this reporting period that are not described in the DP.
i l
3
.